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Icebergs drifting from Canada to Southern Florida

June 16, 2021

Woods Hole, MA (June 16,2021) — Woods Hole Oceanographic Institution (WHOI) climate modeler Dr. Alan Condron and United States Geological Survey (USGS) research geologist Dr. Jenna Hill have found evidence that massive icebergs from roughly 31,000 years ago drifted more than 5000km (> 3,000 miles) along the eastern United States coast from Northeast Canada all the way to southern Florida. These findings were published today in Nature Communications.

Using high resolution seafloor mapping, radiocarbon dating and a new iceberg model, the team analyzed about 700 iceberg scours (“plow marks” on the seafloor left behind by the bottom parts of icebergs dragging through marine sediment ) from Cape Hatteras, North Carolina to the Florida Keys. The discovery of icebergs in this area opens a door to understanding the interactions between icebergs/glaciers and climate.

“The idea that icebergs can make it to Florida is amazing,” said Condron. “The appearance of scours at such low latitudes is highly unexpected not only because of the exceptionally high melt rates in this region, but also because the scours lie beneath the northward flowing Gulf Stream.”

“We recovered the marine sediment cores from several of these scours, and their ages align with a known period of massive iceberg discharge known as Heinrich Event 3. We also expect that there are younger and older scours features that stem from other discharge events, given that there are hundreds of scours yet to be sampled,” added Hill.

To study how icebergs reached the scour sites, Condron developed a numerical iceberg model that simulates how icebergs drift and melt in the ocean. The model shows that icebergs can only reach the scour sites when massive amounts of glacial meltwater (or glacial outburst floods) are released from Hudson Bay. “These floods create a cold, fast flowing, southward coastal current that carries the icebergs all the way to Florida” says Condron. “The model also produces ‘scouring’ on the seafloor in the same places as the actual scours”

The ocean water temperatures south of Cape Hatteras are about 20-25°C (68-77°F). According to Condron and Hill, for icebergs to reach the subtropical scour locations in this region, they must have drifted against the normal northward direction of flow — the opposite direction to the Gulf Stream. This indicates that the transport of icebergs to the south occurs during large-scale, but brief periods of meltwater discharge.

“What our model suggests is that these icebergs get caught up in the currents created by glacial meltwater, and basically surf their way along the coast. When a large glacial lake dam breaks, and releases huge amounts of fresh water into the ocean, there’s enough water to create these strong coastal currents that basically move the icebergs in the opposite direction to the Gulf Stream, which is no easy task” Condron said.

While this freshwater is eventually transferred northward by the Gulf Stream, mixing with the surrounding ocean would have caused the meltwater to be considerably saltier by the time it reached the most northern parts of the North Atlantic. Those areas are considered critical for controlling how much heat the ocean transports northward to Europe.  If these regions become abundant with freshwater, then the amount of heat transported north by the ocean could significantly weaken, increasing the chance that Europe could get much colder.

The routing of meltwater into the subtropics –  a location very far south of these regions – implies that the influence of meltwater on global climate is more complex than previously thought, according to Condron and Hill. Understanding the timing and circulation of meltwater and icebergs through the global oceans during glacial periods is crucial for deciphering how past changes in high-latitude freshwater forcing influenced shifts in climate.

“As we are able to make more detailed computer models, we can actually get more accurate features of how the ocean actually circulates, how the currents move, how they peel off and how they spin around. That actually makes a big difference in terms of how that freshwater is circulated and how it can actually impact climate,” Hill added.




Key Takeaways

  • The discovery of icebergs in this area opens a door to understanding the interactions between icebergs/glaciers and climate.
  • Evidence suggests that there may be hundreds of undiscovered scours that range in ages
  • A newly developed iceberg computer model helped the researchers understand the timing and circulation of meltwater and icebergs through the global oceans during glacial periods, which is crucial for deciphering how past changes in high-latitude freshwater forcing influenced shifts in climate.

Some Forams Could Thrive with Climate Change, Metabolism Study Finds

May 27, 2021

Woods Hole, Mass. (May 27, 2021) – With the expansion of oxygen-depleted waters in the oceans due to climate change, some species of foraminifera (forams, a type of protist or single-celled eukaryote) that thrive in those conditions could be big winners, biologically speaking.

A new paper that examines two foram species found that they demonstrated great metabolic versatility to flourish in hypoxic and anoxic sediments where there is little or no dissolved oxygen, inferring that the forams’ contribution to the marine ecosystem will increase with the expansion of oxygen-depleted habitats.

In addition, the paper found that the multiple metabolic strategies that these forams exhibit to adapt to low and no oxygen conditions are changing the classical view about the evolution and diversity of eukaryotes. That classical view hypothesizes that the rise of oxygen in Earth’s system led to the acquisition of oxygen-respiring mitochondria, the part of a cell that generates most of the chemical energy that powers a cell’s biochemical reactions. The forams in the study represent “typical” mitochondrial-bearing eukaryotes. However, these two forams respire nitrate and produce energy in the absence of oxygen, with one colonizing an anoxic environment, often with high levels of hydrogen sulfide, a chemical compound typically toxic to eukaryotes.

“Benthic foraminifera represent truly successful microbial eukaryotes with diverse and sophisticated metabolic adaptive strategies” that scientists are just beginning to discover, the authors noted in the paper, Multiple integrated metabolic strategies allow foraminiferal protists to thrive in anoxic marine sediments appearing in Science Advances.

This is important because scientists have studied forams extensively for interpreting past oceanographic and climate conditions. Scientists largely have assumed that forams evolved after oxygen was on the planet and likely require oxygen to survive. However, finding that forams can perform the processes described “throws a whole new wrench in interpretations of past environmental conditions on Earth, driven by the foram fossil record,” said co-author and project leader Joan Bernhard, senior scientist in the Geology and Geophysics Department at the Woods Hole Oceanographic Institution (WHOI).

Bernhard said that over the past several decades she has worked to establish that forams can live where there is little or no oxygen. “We never knew exactly why forams can live where there isn’t any oxygen until molecular methods got good enough that we could really start to ask some of these questions. This is our first paper that’s coming out with some of these insights,” she said.  Bernhard added that with thousands of foram species living today, and with hundreds of thousands extinct, it is likely that this is “the tip of the iceberg” in terms of possibly discovering other metabolic strategies invoked by these forams.

Specific insights from the paper pertain to two highly successful benthic foraminiferal species that inhabit hypoxic or anoxic sediments in the Santa Barbara Basin, a sort of natural laboratory off the coast of California for studying the impact of oxygen depletion in the ocean.

Through gene expression analysis of the two species—Nonionella stella and Bolivina argentea—scientists found different successful metabolic adaptations that allowed the forams to succeed in oxygen-depleted marine sediments and identified candidate genes involved in anaerobic respiration and energy metabolism.

The N. stella is a sort of kleptomaniac, utilizing a technique to steal chloroplasts—the structure in a cell where photosynthesis occurs—from a particular diatom genus. What makes this particularly interesting is that N. stella lives well below what is considered to be the zone where photosynthesis can happen. The authors noted that there has been discussion in the literature questioning the functionality of these kleptoplasts in the Santa Barbara Basin N. stella but the new results show that these kleptoplasts are firmly functional, although exact metabolic details remain elusive.

In addition, the scientists found that the two foram species in the study use different metabolic pathways to incorporate ammonium into organic nitrogen in the form of glutamate, a metabolic strategy that was not previously known to be performed by these organisms.

“The metabolic variety suggests that at least some species of this diverse protistan group will withstand severe deoxygenation and likely play major roles in oceans affected by climate change,” the authors wrote.

The study “gives the scientific community a new direction for research,” said lead author Fatma Gomaa, who, at the time of the study, was a postdoctoral investigator at the Geology and Geophysics Department at WHOI. “We are now starting to learn that there are microeukaryotes living in habitats similar to those in Earth’s early history that are performing very interesting biological functions. Learning about these forams is very intriguing and will shed light on how early eukaryotes evolved.”


About Woods Hole Oceanographic Institution

The Woods Hole Oceanographic Institution (WHOI) is a private, non-profit organization on Cape Cod, Massachusetts, dedicated to marine research, engineering, and higher education. Established in 1930, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate an understanding of the ocean’s role in the changing global environment. WHOI’s pioneering discoveries stem from an ideal combination of science and engineering—one that has made it one of the most trusted and technically advanced leaders in basic and applied ocean research and exploration anywhere. WHOI is known for its multidisciplinary approach, superior ship operations, and unparalleled deep-sea robotics capabilities. We play a leading role in ocean observation and operate the most extensive suite of data-gathering platforms in the world. Top scientists, engineers, and students collaborate on more than 800 concurrent projects worldwide—both above and below the waves—pushing the boundaries of knowledge and possibility. For more information, please visit

Authors: Fatma Gomaa1,2*, Daniel R. Utter2, Christopher Powers3, David J. Beaudoin1, Virginia P. Edgcomb1, Helena L. Filipsson4, Colleen M. Hansel5, Scott D. Wankel5, Ying Zhang3, and Joan M. Bernhard1*


1Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA, USA

2Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA

3Department of Cell and Molecular Biology, College of the Environment and Life Sciences, University of Rhode Island, Kingston, RI, USA

4Lund University, Department of Geology, Lund, Sweden.

5Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA

*Corresponding author


WHOI President & Director Dr. Peter de Menocal Recognized as AAAS Fellow

November 24, 2020

WHOI’s 11th President and Director Peter de Menocal. (Photo by Daniel Hentz, © Woods Hole Oceanographic Institution)

Dr. Peter de Menocal, President and Director of Woods Hole Oceanographic Institution of has been named a Fellow of the American Association for the Advancement of Science (AAAS). Election as a AAAS Fellow is an honor bestowed upon AAAS members by their peers.

This year 489 members have been awarded this honor by AAAS because of their scientifically or socially distinguished efforts to advance science or its applications.

This year’s AAAS Fellows will be formally announced in the AAAS News & Notes section of the journal Science on 27 November 2020. A virtual Fellows Forum—an induction ceremony for the new Fellows—will be held on 13 February 2021.

As part of the Geology and Geography section, Dr. Peter de Menocal was elected as an AAAS Fellow for his fundamental contributions to understanding human physical and cultural evolution in relation to paleo-environmental change on the African continent.

“I’m honored to be included in this distinguished group,” said de Menocal. “The mission of AAAS aligns well with WHOI’s in our quest to share scientific knowledge and inform people and policies for a healthier planet.”

The tradition of AAAS Fellows began in 1874. Currently, members can be considered for the rank of Fellow if nominated by the steering groups of the association’s 24 sections, or by any three Fellows who are current AAAS members (so long as two of the three sponsors are not affiliated with the nominee’s institution), or by the AAAS chief executive officer. Fellows must have been continuous members of AAAS for four years by the end of the calendar year in which they are elected. The AAAS Fellow honor comes with an expectation that recipients maintain the highest standards of professional ethics and scientific integrity.

Each steering group reviews the nominations of individuals within its respective section and a final list is forwarded to the AAAS Council, which votes on the aggregate list.

The Council is the policymaking body of the Association, chaired by the AAAS president, and consisting of the members of the board of directors, the retiring section chairs, delegates from each electorate and each regional division, and two delegates from the National Association of Academies of Science.

AAAS encourages its sections and Council to consider diversity among those nominated and selected as Fellows, in keeping with the association’s commitment to diversity, equity and inclusion.


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About Woods Hole Oceanographic Institution

Woods Hole Oceanographic Institution (WHOI) is a private, non-profit organization on Cape Cod, Massachusetts, dedicated to marine research, engineering, and higher education. Established in 1930, its mission is to understand the ocean and its interactions with the Earth as a whole, and to communicate an understanding of the ocean’s role in the changing global environment. WHOI’s pioneering discoveries stem from an ideal combination of science and engineering—one that has made it one of the most trusted and technically advanced leaders in fundamental and applied ocean research and exploration anywhere. WHOI is known for its multidisciplinary approach, superior ship operations, and unparalleled deep-sea robotics capabilities. We play a leading role in ocean observation, and operate the most extensive suite of ocean data-gathering platforms in the world. Top scientists, engineers, and students collaborate on more than 800 concurrent projects worldwide—both above and below the waves—pushing the boundaries of knowledge to inform people and policies for a healthier planet. For more information, please visit


About Dr. Peter de Menocal

Dr. Peter de Menocal is a marine geologist and paleo-oceanographer who studies deep-sea sediments as archives of past climate change, illuminating centuries of climate history and ocean circulation patterns in the geological record and drawing connections to the human dimensions of climate change today.

De Menocal was the Thomas Alva Edison/Con Edison Professor in the Department of Earth and Environmental Sciences at Columbia University’s Lamont-Doherty Earth Observatory. De Menocal also served as Columbia’s Dean of Science for the Faculty of Arts & Sciences between 2016-2019, overseeing the University’s nine scientific departments. During his tenure as Dean of Science, he developed and executed on a strategic plan that helped double philanthropic support for the sciences, significantly increase success in winning large center and institute awards, and double faculty hiring rates for women and under-represented minorities in the natural sciences.

De Menocal has published more than 150 scientific papers over his decades-long career in oceanography. He is also the founding director of Columbia’s Center for Climate and Life, a team of more than 120 PhD scientists and other experts mobilizing use-inspired science to understand how climate impacts essential aspects of human life, including food security, water, shelter, and sustainable energy solutions. Under de Menocal’s leadership, the Center pioneered collaborations with the private sector to inform science-based solutions.


About the American Association for the Advancement of Science

The American Association for the Advancement of Science (AAAS) is the world’s largest general scientific society and publisher of the journal Science, as well as Science Translational Medicine; Science Signaling; a digital, open-access journal, Science Advances; Science Immunology; and Science Robotics. AAAS was founded in 1848 and includes more than 250 affiliated societies and academies of science, serving 10 million individuals. The nonprofit AAAS is open to all and fulfills its mission to “advance science and serve society” through initiatives in science policy, international programs, science education, public engagement, and more. For additional information about AAAS, see

Study reconstructs ancient storms to predict changes in a cyclone hotspot

November 16, 2020

Intense tropical cyclones are expected to become more frequent as climate change increases temperatures in the Pacific Ocean. But not every area will experience storms of the same magnitude. New research from the Woods Hole Oceanographic Institution (WHOI) published in Nature Geosciences reveals that tropical cyclones were actually more frequent in the southern Marshall Islands during the Little Ice Age, when temperatures in the Northern Hemisphere were cooler than they are today.

This means that changes in atmospheric circulation, driven by differential ocean warming, heavily influence the location and intensity of tropical cyclones.

In the first study of its kind so close to the equator, lead author James Bramante reconstructed 3,000 years of storm history on Jaluit Atoll in the southern Marshall Islands.  This region is the birthplace of tropical cyclones in the western North Pacific—the world’s most active tropical cyclone zone. Using differences in sediment size as evidence of extreme weather events, Bramante found that tropical cyclones occurred in the region roughly once a century, but increased to a maximum of four per century from 1350 to 1700 CE, a period known as the Little Ice Age.

Bramante, a recent graduate of the MIT-WHOI Joint Program in Oceanography/Applied Ocean Science and Engineering, says this finding sheds light on how climate change affects where cyclones are able to form.

Key Takeaways

  • Researchers reconstructed the history of tropical cyclones in the southern Marshall Islands over the last 3,000 years. The western North Pacific is the world’s most active zone for tropical cyclones, but has been understudied compared to the North Atlantic.
  • During the Little Ice Age, tropical cyclones formed in the western North Pacific deep tropics more frequently than any other time in the record. Data from the sediment samples recorded four tropical cyclones per century, which is well above the 3,000-year average of one per century.
  • Climate change is projected to create conditions opposite of the Little Ice Age, indicating that tropical cyclones will form less often in the southern Marshall Islands, even as storms are expected to be more frequent and intense at higher latitudes.

Marshall Islands WHOI researchers reconstructed 3,000 years of storm history on Jaluit Atoll in the southern Marshall Islands. This region is the birthplace of tropical cyclones in the western North Pacific—the world’s most active tropical cyclone zone. (Map by Natalie Renier, ©Woods Hole Oceanographic Institution)

“Atmospheric circulation changes due to modern, human-induced climate warming are opposite of the circulation changes due to the Little Ice Age,” notes Bramante.  “So we can expect to see the opposite effect in the deep tropics—a decrease in tropical cyclones close to the equator. It could be good news for the southern Marshall Islands, but other areas would be threatened as the average location of cyclone generation shifts north,” he adds.

During major storm events, coarse sediment is stirred up and deposited by currents and waves into “blue holes”, ancient caves that collapsed and turned into sinkholes that filled with sea water over thousands of years. In a 2015 field study, Bramante and his colleagues took samples from a blue hole on Jaluit Atoll and found coarse sediment among the finer grains of sand. After sorting the grains by size and analyzing the data from Typhoon Ophelia, which devastated the atoll in 1958, the researchers had a template with which to identify other storm events that appear in the sediment record. They then used radiocarbon dating—a method of determining age by the ratio of carbon isotopes in a sample—to date the sediment in each layer.

Armed with previously-collected data about the ancient climate from tree rings, coral cores, and fossilized marine organisms, the researchers were able to piece together the conditions that existed at the time. By connecting this information with the record of storms preserved in sediment from Jaluit Atoll, the researchers demonstrated through computer modeling that the particular set of conditions responsible for equatorial trade winds heavily influenced the number, intensity and location where cyclones would form.

Jeff Donnelly, a WHOI senior scientist and a co-author of the study, used similar methods to reconstruct the history of hurricanes in the North Atlantic and Caribbean. He plans to expand the Marshall Islands study westward to the Philippines to study where tropical cyclones have historically formed and how climate conditions influence a storm’s track and intensity. Better understanding of how storms behaved under previous conditions will help scientists understand what causes changes in tropical cyclone activity and aid people living in coastal communities prepare for extreme weather in the future, he said.

“Through the geologic archive, we can get a baseline that tells us how at-risk we really are at any one location,” Donnelly says. “It turns out the past provides some useful analogies for the climate change that we’re currently undergoing. The earth has already run this experiment.  Now we’re trying to go back and determine the drivers of tropical cyclones.”

Additional co-authors of this study include WHOI geologist Andrew Ashton; WHOI physical oceanographer Caroline Ummenhofer; Murray Ford (University of Auckland, New Zealand); Paul Kench (Simon Fraser University, British Columbia, Canada); Michael Toomey (US Geological Survey, Reston, Virginia); Richard Sullivan of Texas A&M University; and Kristopher Karnauskas (University of Colorado, Boulder).

This research was funded by the Strategic Environmental Research & Development Program, a partnership between the Department of Defense, the Department of Energy, and the Environmental Protection Agency.

The Woods Hole Oceanographic Institution (WHOI) is a private, non-profit organization on Cape Cod, Massachusetts, dedicated to marine research, engineering, and higher education. Established in 1930, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate an understanding of the ocean’s role in the changing global environment. WHOI’s pioneering discoveries stem from an ideal combination of science and engineering—one that has made it one of the most trusted and technically advanced leaders in basic and applied ocean research and exploration anywhere. WHOI is known for its multidisciplinary approach, superior ship operations, and unparalleled deep-sea robotics capabilities. We play a leading role in ocean observation, and operate the most extensive suite of data-gathering platforms in the world. Top scientists, engineers, and students collaborate on more than 800 concurrent projects worldwide—both above and below the waves—pushing the boundaries of knowledge and possibility. For more information, please visit


Antarctic Ice Sheet Loss Expected to Affect Future Climate Change

September 25, 2020

Research simulates dramatic climate impacts for future Antarctic ice sheet melt

In a new climate modeling study that looked at the impacts of accelerated ice melt from the Antarctic Ice Sheet (AIS) on future climate, a team of climate scientists led by Alan Condron at Woods Hole Oceanographic Institution (WHOI), reports that future ice-sheet melt is expected to have significant effects on global climate.

The research team, which also included Shaina Sadai and Rob DeConto at the University of Massachusetts Amherst, and David Pollard at Pennsylvania State University, presented their findings this week in Science Advances. The study predicts how future climate conditions could change under high and low greenhouse gas emissions scenarios, while accounting for accelerated melting of the AIS.

Scientists have long recognized that future meltwater input from the Antarctic will affect the Southern Ocean and global climate, but ice-sheet processes are not currently included in even the most state-of-the-art climate prediction simulations. The research team reports that their new models with the added ice melt information reveal important interacting processes and demonstrate a need to accurately account for meltwater input from ice sheets in order to make confident climate predictions.

“In the ice sheet models run by my co-authors Rob DeConto and David Pollard, large parts of the West Antarctic ice sheet (WAIS) rapidly collapse about 100 years from now,” says Condron. “Simply put, previous climate models have not addressed how all that fresh water coming out of the AIS might impact future climate.”

“We found that future meltwater coming off Antarctica leads to huge amounts of thick sea ice around the continent,” adds Sadai, lead author of the study and PhD graduate student of Condron. “With higher greenhouse gas emissions, the ice sheet melts faster, which in turn leads to more freshwater flowing into the ocean and more sea ice production.”

All this additional sea ice dramatically slows the pace of future warming around Antarctica, the researchers report, which is seemingly welcome news. The climate impacts are not just restricted to the Antarctic, Condron points out that the cooling effects of this melt water are felt worldwide.

“It’s important to note that this is not a global ‘cooling’ scenario as average global temperatures would still be roughly three degrees Celsius warmer than today due to human greenhouse gas emissions, even with the cooling effects of this melt water on climate,” says Condron.

But that is not the end of the story. “Even though the atmospheric warming slows, in the deeper part of the ocean where the base of the WAIS is touching the ocean floor, we see  water temperatures warming up to one degree Celsius. This subsurface warming could make the ice sheet much more unstable and accelerate rates of sea level rise beyond current projections,” Condron says.

While the delayed future warming found in the new simulations may sound like good news, the researchers say it is important to keep in mind  that serious warming and sea level rise will still occur with unabated greenhouse gas emissions, which will impact coastal communities and ecosystems worldwide.

This research was supported by the National Science Foundation (NSF) Office of Polar Programs through NSF grant 1443347, the Biological and Environmental Research (BER) division of the U.S. Department of Energy through grant DE-SC0019263.

The Woods Hole Oceanographic Institution (WHOI) is a private, non-profit organization on Cape Cod, Massachusetts, dedicated to marine research, engineering, and higher education. Established in 1930, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate an understanding of the ocean’s role in the changing global environment. WHOI’s pioneering discoveries stem from an ideal combination of science and engineering—one that has made it one of the most trusted and technically advanced leaders in basic and applied ocean research and exploration anywhere. WHOI is known for its multidisciplinary approach, superior ship operations, and unparalleled deep-sea robotics capabilities. We play a leading role in ocean observation, and operate the most extensive suite of data-gathering platforms in the world. Top scientists, engineers, and students collaborate on more than 800 concurrent projects worldwide—both above and below the waves—pushing the boundaries of knowledge and possibility. For more information, please visit

Key Takeaways

  • Even the most state-of-the art climate models currently do not account for changes in the melting of the Antarctic Ice Sheet (AIS) caused by climate change. In particular, they do not consider the vulnerability of the West Antarctic Ice Sheet (WAIS) to rapid retreat and collapse.
  • Using a sophisticated new ice sheet and climate model, the study found that a future collapse of the WAIS could dramatically cool the Southern Hemisphere by up to 10 degrees Celsius. Significantly, this cooling reduces the projected rise in global temperature by up to two degrees Celsius.
  • The global temperature reduction should not be regarded as a ‘global cooling’ scenario though. Average global temperatures would still be around three degrees Celsius warmer than today about a century from now, but this is cooler than the roughly five degrees Celsius warming currently projected under high greenhouse gas emission scenarios.
  • The opposite temperature response is found in the ocean at the base of the ice sheet where the ice is ‘glued’ to the bedrock. Here, water temperatures could warm by one to two degrees Celsius, which could reduce the future stability of the AIS and accelerate rates of ice loss and projected rates of sea-level rise beyond current projections.


WHOI Scientists Make Woods Hole Film Festival Appearance

July 17, 2020

Woods Hole Oceanographic Institution (WHOI) scientists appear in two shorts and a feature film at this year’s Woods Hole Film Festival (WHFF). In addition, scientists will also participate in Q&A sessions connected to three of the festival’s feature-length, ocean-themed entries.

The short films, “Divergent Warmth” and “Beyond the Gulf Stream” are part of a program titled “The Blue Between Us,” offered on-demand from July 25 to August 1 as part of the festival’s virtual program.

In “Divergent Warmth,” producer-director Megan Lubetkin gives viewers a behind-the-scenes look at the synchronized ballet aboard a research vessel during a recent expedition to the East Pacific Rise. Experimental music provides rhythm to imagery of deck operations, launch and recovery of the human-occupied submersible Alvin, and other-worldly views of seafloor hydrothermal vents and lava flows. Interwoven throughout is an evocative reading of Adrienne Rich’s poem, “Diving into the Wreck.”

Dan Fornari, a WHOI emeritus research scholar, acted as associate producer of the 10-minute film. As one of the scientists on the December 2019 expedition, he invited Lubetkin, herself a scientist and the creative exhibits coordinator with the Ocean Exploration Trust, to assist with subsea camera operations and video data management on board. Lubetkin spent her free time shooting additional video, which she edited together while still on the ship to produce a first draft of “Divergent Warmth.”

“I was blown away. It was just fabulous,” Fornari said of his first viewing. “It captures the spirit of going out to sea and being involved in this exploratory effort in the alien realm, where very few people get to go.”

The complex winter currents that collide off the coast of Cape Hatteras are the focus of “Beyond the Gulf Stream,” a short documentary by the Georgia-based production company MADLAWMEDIA. Filmed aboard the WHOI-operated research vessel Neil Armstrong, the 10-minute film features WHOI physical oceanographers Magdalena Andres, Glen Gawarkiewicz, and graduate student Jacob Forsyth as they share their perspectives on the challenges and rewards of doing scientific research at sea, often in difficult conditions.

“I think we have a responsibility to communicate science and the process of doing of science to the public,” said Andres about the film, which was produced in collaboration with WHOI and the Skidaway Institute of Oceanography at the University of Georgia. “It does a really nice job of capturing life at sea in the wintertime.”

As a scientist who uses video to capture data from the ocean depths, Fornari is highly attuned to the impact that visual media can have in capturing the public’s imagination about the ocean.

“These kinds of artistic expressions help open doors to people’s minds.” he said. “That’s crucial for getting the public to understand how critically important the oceans are. Then maybe more students will say, ‘I want to be an ocean scientist when I grow up.’”

In addition to the shorts program itself, WHOI scientists, staff, and students will also participate in “Filmmaker Chats” open to the public and broadcast via Zoom, as well as the WHFF Facebook and YouTube channels. Maddux-Lawrence will take questions about “Beyond the Gulf Stream” on Sunday, July 19, beginning at 9:00 a.m. On Friday, July 31 at 9:00 a.m., Lubetkin will appear with Fornari, as well as Alvin pilot Drew Bewley, MIT-WHOI Joint Program graduate student Lauren Dykman, and Texas A&M graduate student Charlie Holmes II to discuss the making of and science behind “Divergent Warmth.” Recordings of both sessions will also be available for viewing afterward on the festival website.

In addition to the short films, WHOI whale biologist Michael Moore appears in the feature-length documentary “Entangled,” which looks at the intertwined plights of the critically endangered North Atlantic right whale and coastal fishing communities in New England and eastern Canada. After being hunted for centuries, the whales face new challenges in the form of climate change and increased fishing and shipping activity, and Moore has been an outspoken proponent of the need for increased protections to stave off their slide to extinction within the next 20 years.

WHOI scientists will also add their perspective to Q&A sessions following several ocean-themed, feature-length films selected for the festival:

  • Thursday, July 30, at 10:00 p.m.: Research specialist Hauke Kite-Powell will answer questions related to aquaculture and seafood in relation to the film “Fish & Men.
  • Saturday, August 1, from 4:00 to 5:00 p.m.: Marine chemist Chris Reddy will answer questions about microplastics in relation to the film “Microplastics Madness.”
  • Saturday, August 1, from 7:00 to 8:00 p.m.: Marine biologist Simon Thorrold will answer questions about marine protected areas and fishing in connection with the film “Current Sea.”

Key Takeaways

  • Films featuring WHOI scientists will be screened as part of “The Blue Between Us” shorts program at the virtual Woods Hole Film Festival, which may be viewed online by festival passholders and individual ticketholders during the festival, which runs from Saturday, July 25, to Saturday, August 1. Tickets and more information is available here.
  • Whale biologist Michael Moore will appear in the feature-length film “Entangled” about the plight of critically endangered North Atlantic right whales.
  • WHOI scientists will also participate in Q&A sessions associated with several ocean-themed, feature-length festival films.
  • More information is available on the festival website.
plutonic rocks

Microbes far beneath the seafloor rely on recycling to survive

March 11, 2020

Scientists from Woods Hole Oceanographic Institution (WHOI) reveal how microorganisms could survive in rocks nestled thousands of feet beneath the ocean floor in the lower oceanic crust, in a study published on March 11 in Nature. The first analysis of messenger RNA—genetic material containing instructions for making different proteins—from this remote region of Earth, coupled with measurements of enzyme activities, microscopy, cultures, and biomarker analyses provides evidence of a low biomass, but diverse community of microbes that includes heterotrophs that obtain their carbon from other living (or dead) organisms.

“Organisms eking out an existence far beneath the seafloor live in a hostile environment,” says Dr. Paraskevi (Vivian) Mara, a WHOI biochemist and one of the lead authors of the paper. Scarce resources find their way into the seabed through seawater and subsurface fluids that circulate through fractures in the rock and carry inorganic and organic compounds. 

To see what kinds of microbes live at these extremes and what they do to survive, researchers collected rock samples from the lower oceanic crust over three months aboard the International Ocean Discovery Program Expedition 360. The research vessel traveled to an underwater ridge called Atlantis Bank that cuts across the Southern Indian Ocean. There, tectonic activity exposes the lower oceanic crust at the seafloor, “providing convenient access to an otherwise largely inaccessible realm,” write the authors.

Researchers combed the rocks for genetic material and other organic molecules, performed cell counts, and cultured samples in the lab to aid in their search for life. “We applied a completely new cocktail of methods to really try to explore these precious samples as intensively as we could,” says Dr. Virginia Edgcomb, a microbiologist at WHOI, the lead PI of the project, and a co-author of the paper. “All together, the data start to paint a story.”

Key Takeaways

  • Scientists collected rock samples from the lower oceanic crust down to 2,400 feet beneath the ocean floor in search of life.
  • In the first analysis of genetic material from this region to uncover how organisms might survive, researchers provide evidence that microbes efficiently recycle and store available organic compounds.
  • Genetic material suggests that many lower crust microbes cannot produce their own food and rely on carbon found in the environment to obtain energy.
  • These findings provide a more complete picture of carbon cycling by illuminating biologic activity deep below the planet’s surface.


Researchers Benoit Ildefonse (left) of University of Montpellier and Virginia Edgcomb of WHOI select a sample for microbiology during the expedition at Atlantis Bank, Indian Ocean. (Photo by  Jason Sylvan, TAMU) Researchers Benoit Ildefonse (left) of University of Montpellier and Virginia Edgcomb of WHOI select a sample for microbiology during the expedition at Atlantis Bank, Indian Ocean. (Photo by Jason Sylvan, TAMU)

By isolating messenger RNA and analyzing the expression of genes—the instructions for different metabolic processes—researchers showed evidence that microorganisms far beneath the ocean express genes  for a diverse array of survival strategies. Some microbes appeared to have the ability to store carbon in their cells, so they could stockpile for times of shortage. Others had indications they could process nitrogen and sulfur to generate energy, produce Vitamin E and B12, recycle amino acids, and pluck out carbon from hard-to-breakdown compounds called polyaromatic hydrocarbons. “They seem very frugal,” says Edgcomb. 

This rare view of life in the far reaches of the earth extends our view of carbon cycling beneath the seafloor, Edgcomb says. “If you look at the volume of the deep biosphere, including the lower oceanic crust, even at a very slow metabolic rate, it could equate to significant amounts of carbon.” 

This work was supported by the National Science Foundation.The research team also included colleagues from Tongji University, University of Bremen, Texas A&M University, Université de Brest, and Scripps Institution of Oceanography.

The Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate a basic understanding of the ocean’s role in the changing global environment. For more information, please visit

Missoula floods

Study reveals Missoula Floods impact on past abrupt climate changes

February 28, 2020

A new study by scientists from Woods Hole Oceanographic Institution (WHOI) and colleagues shows for the first time how massive flood events in the eastern North Pacific Ocean—known as the Missoula Floods—may have in part triggered abrupt climate changes in the Northern Hemisphere during the last deglaciation (approximately 19,000–11,700 years ago). The findings, published Feb. 26, 2020, in the journal Science Advances, are contrary to the long held notion that cooling was primarily driven by changes in North Atlantic circulation.

“Everyone’s been searching for evidence of floods into the North Atlantic that might have caused various cooling events, but very little has been done to investigate whether the Missoula Floods had any impact beyond the Pacific Northwest,” says lead author Summer Praetorius, a Research Geologist with the U.S. Geological Survey and former WHOI research assistant.

Sedimentary deposits on land indicate that the Missoula Floods occurred nearly 100 times during the first part of deglaciation as former Glacial Lake Missoula in Montana repeatedly filled and drained enormous volumes of fresh water down the modern-day Columbia River, into the northeastern Pacific Ocean.

“The peak discharge of water during these flood events would have been equivalent to the flow of 85 Amazon Rivers,” says Alan Condron, a climate scientist at WHOI and coauthor of the paper. “In fact, these floods were the largest on Earth, dwarfing outburst floods from the Laurentide ice sheet that have frequently been proposed as major triggers of abrupt deglacial climate change, but little is known about what happened once the waters entered the Pacific Ocean.”

Key Takeaways

  • Scientists used a high-resolution model for the first time to trace the trajectory of Missoula Flood waters exiting the Columbia River during the last deglaciation.
  • Abrupt climate changes in the Northern Hemisphere may have been triggered in part by Missoula Flood events and changes in Pacific Ocean circulation, contrary to the notion that they were primarily driven by changes in North Atlantic circulation.
  • These results improve our understanding of the fate of the Missoula Flood waters once entering the Pacific Ocean and suggest an important role for North Pacific circulation changes in affecting Northern Hemisphere climate, which has previously been overlooked.
Canyons View of one of the canyons in Washington state, U.S., where the enormous Missoula floods once drained through as they flowed to the Pacific ocean. These steep walls were carved as floods plucked away at columnar basalt. (Photo courtesy of Tamara Pico, California Institute of Technology)

In this study, Praetorius and Condron, along with collaborators Alan Mix, Maureen Walczak, Jennifer McKay and Jianghui Du from Oregon State University, show for the first time the trajectory of Missoula Flood waters exiting the Columbia River.

Using Condron’s high-resolution climate model, they found that meltwater flowed across the North Pacific following coastal boundary currents and ultimately made it as far west as Japan, where it was incorporated into the Kuroshio Current—the Pacific equivalent of the Gulf Stream current.

While the largest of the Missoula Floods occurred when sea levels were much lower than today due to water being locked up in large ice sheets, the final Missoula floods occur close to the time when the Bering Strait land bridge between Russia and Alaska was finally submerged by rising sea level and Pacific waters entered the Arctic. To account for this, Condron also ran his climate model with the Bering Strait open, much like modern day to trace the water’s route in both scenarios.

“We were excited and surprised to find that when the Bering strait land bridge was submerged,  floodwaters from Glacial lake Missoula flowed through the Arctic Ocean to the North Atlantic where processes controlling the strength of the Gulf Stream and transport of heat to Europe and North America take place,” says Condron. “Basically this is the region of the ocean that seems capable of triggering large-scale climate change.”

The above model shows meltwater released from the Columbia River (bright blue) flowing north towards Alaska in narrow coastal boundary currents. The meltwater, which is less salty or “fresher” than the surrounding water, continues west, reaching Japan after just one year before recirculating eastwards towards the west coast of North America. In just three years, the entire subpolar North Pacific ocean has become “fresher” as a result of the floods, although the exact amount would have been dependent on the size of each flood event, which varied through time.

The precise timing of when the Bering Strait opened is still a matter of some debate and on-going research, Condron notes, but is does demonstrate a possible connection between Pacific meltwater and the North Atlantic that was not known before.

In order to assess the evidence for how Missoula flood events may have impacted ocean circulation and climate, the researchers compiled an extensive collection of data from fossil plankton in marine sediment cores throughout the Northeast Pacific to reconstruct changes in sea surface temperature, sea surface salinity, and deep-water circulation.

 The compilation shows that there were two major periods of ocean freshening (a decrease in salinity) and cooling during the last deglaciation. The first was early in the deglaciation, at about the same time the largest of the Missoula floods occurred. Curiously, this was a time of cooling in the Northern Hemisphere that has previously been attributed to a massive release of icebergs to the North Atlantic. Recent evidence suggesting that the icebergs drifted into the North Atlantic after the cooling had already started though has meant the cause of the cooling is still a mystery. Praetorius, Condron and colleagues now point to the Missoula Floods as a possible cause of this early cooling event.

Similarly, the team found a second interval of ocean cooling and freshening during the Younger Dryas period—an abrupt cooling period in the Northern Hemisphere that has a long history of contentious debate on its causes. Some scientists say it was floods into the Atlantic that caused the cooling, some say it was a comet impact, and now Praetorius and collaborators are adding a new twist.

Condron notes that the results are quite humbling as the geologist, J Harlen Bretz, who first recognized in the 1920’s that these floods shaped the landscape of the Pacific northwest, was initially derided by the geological community as his findings were considered ‘preposterous’ and ‘incompetent.’

“Yet, close to 100 years on, our results suggest that meltwater into the Pacific may have also played a role in the climate shift,” he adds.

These findings highlight the importance of changes in North Pacific circulation as an integral player in deglacial climate events.

Funding for this work was provided by the National Science Foundation. Numerical model simulations were run in-house at WHOI on the new HPC resource, Poseidon.

Collaborators on this study are from U.S. Geological Survey, Woods Hole Oceanographic Institution, and Oregon State University’s College of Earth, Ocean, and Atmospheric Sciences.

The Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate a basic understanding of the ocean’s role in the changing global environment. For more information, please visit

For now, river deltas gain land worldwide

January 23, 2020

Researchers from Utrecht University in the Netherlands, Woods Hole Oceanographic Institution (WHOI), and colleagues found that delta areas worldwide have actually gained land in the past 30 years, despite river damming. However, recent land gains are unlikely to last throughout the 21st century due to expected, accelerated sea level rise. The researchers published their findings in the journal Nature.

River deltas rank among the most economically and ecologically valuable environments on Earth. People living on deltas are increasingly vulnerable to sea-level rise and coastal hazards such as major storms, extremely high tides, and tsunamis. Many deltas experience a decline in sediment supply due to upstream damming, making them even more vulnerable. However, the new study found that long-term, large-scale, upstream deforestation has resulted in soil erosion that increased the amount of sediment transported to many deltas.

“A large driver for these gains turned out to be human action,” says lead author Jaap Nienhuis, a geoscientist at Utrecht University and a graduate of the  MIT-WHOI Joint Program. “Twenty five percent of delta growth can be attributed to upstream deforestation, which results in soil erosion and increased sediment delivery to the coast. Human action such as damming causes sediment starvation and increased importance of wave- and tide-driven transport, which can also change delta shape.”

The relationship between the sediment deposited by rivers, oceanographic forces of waves and tides, and delta shape has remained poorly understood. To address this, the international team of researchers developed and applied a novel theory that can quantify how waves and tides influence delta shape. The availability of global satellite imagery allowed them to test their new model on over 10,000 deltas worldwide, ranging from small to mega-deltas.

“Applying this novel prediction of delta shape to global examples allowed us to quantify how delta shape affects change,” says WHOI geologist Andrew Ashton, a coauthor of the paper. “For example, when sediment supply diminishes, deltas dominated by waves tend to erode, while tide-dominated deltas continue to grow.”

The next step in the research is to extend the model to make predictions of future delta change, particularly for rising sea levels. Understanding how waves and tides modify river deltas will be critical for anticipating future change, both locally and globally.

The research team also included colleagues from Florida State University, Wageningen University and Research, Tulane University, Indiana University, University of Colorado Boulder Institute of Arctic and Alpine Research, and Los Alamos National Laboratory.

The work was funded by the National Science Foundation and the Netherlands Science Organization NWO.

Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the oceans’ role in the changing global environment. For more information, please visit

 Key Takeaways

  • Delta areas worldwide have gained land in the past 30 years, despite river damming.
  • Large-scale, upstream deforestation has resulted in soil erosion that increased the amount of sediment transported to many deltas.
  • These land gains are unlikely to last throughout the 21st century due to expected, accelerated sea level rise.
  • Understanding how waves and tides control river delta shape is critical for anticipating future change, both locally and globally.
  • The next step is to extend the new model to predict how sea-level rise will affect future delta change.

Study weighs deep-sea mining’s impact on microbes

January 16, 2020

The essential roles that microbes play in deep-sea ecosystems are at risk from the potential environmental impacts of mining, found a new paper by researchers at Bigelow Laboratory for Ocean Sciences, Woods Hole Oceanographic Institution (WHOI), and colleagues. The study reviews what is known about microbes in these environments and assesses how mining could impact their important environmental roles. The findings are published in the journal of Limnology and Oceanography.

“The push for deep-sea mining has really accelerated in the last few years, and it is crucial that policy makers and the industry understand these microbes and the services they provide,” said Beth Orcutt, a senior research scientist at Bigelow Laboratory for Ocean Sciences and the lead author of the study. “This paper establishes what we know and suggests next steps for using the best science to evaluate the impacts of this new human activity in the deep sea.”

Microbes across the seafloor are responsible for essential ecosystem services, from fueling the food web to powering global nutrient cycles. Environments that are promising for mining are also often the sites of globally-important microbial processes and unusual animal communities – and may be slow to recover from disturbances.

Orcutt and her coauthors analyzed four types of deep-sea mineral resources, including the metal-rich rocks that stud underwater mountains and lie on the seafloor. Their findings indicate the likely impacts of mining on microbial communities vary substantially, from minimal disturbance to the irreversible loss of important habitat services.

Hydrothermal vent systems, for example, are particularly sensitive – and valuable. The hot, mineral-rich waters support robust communities of microbes that form the vital base of the food web in these ecosystems. The extreme environmental conditions also foster rich genetic diversity among the microbes, making them promising candidates in the search for anti-cancer drugs and other new biotechnology applications.

“These microbes have incredible potential to inspire new solutions to all sorts of medical and technical challenges we face today,” said Julie Huber, a WHOI scientist and co-author of the new study. “But if we damage or destroy a habitat like a hydrothermal vent, we lose the diverse the pool of microbial genetic information from which we can find new enzymes or drugs.”

Consumer demand for products like smartphones and electric cars is driving the rapidly growing interest in deep-sea mining for metals like cobalt and rare earth elements, which are used in lithium-ion batteries. The International Seabed Authority of the United Nations is working to establish guidelines for countries and contractors to explore the seafloor for minerals, and to eventually mine them.

While guidelines for licensed exploration already suggest that site assessments should include how much microbial life is present, the researchers on the new study emphasize that it is equally important to determine what roles the microbes are playing and assess how they would be impacted by mining.

“It is important to understand the potential impacts of mining activities to figure out if they should occur and how to manage them if they do,” said James Bradley, a scientist at Queen Mary University of London and co-author on the paper. “This is an important conversation between policy makers, industry, and the scientific community, and it’s important that we work together to get this right. Once these ecosystems are damaged, they may never fully recover.”

This study was supported by the NSF-funded Center for Dark Energy Biosphere Investigations (C-DEBI) and the Sloan Foundation-funded Deep Carbon Observatory.

Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the oceans’ role in the changing global environment. For more information, please visit

Key Takeaways

  • Seafloor microbes are responsible for essential processes from fueling the food web to powering global nutrient cycles.
  • Environments that are promising for deep-sea mining are also often the sites of globally-important microbial processes and unusual animal communities, which may be slow to recover from disturbances.
  • The likely impacts of mining on microbial communities vary substantially, from minimal disturbance to the irreversible loss of important habitat.
  • If hydrothermal vent habitats are damaged or destroyed, we could lose the diverse pool of microbial genetic information from which we may find new enzymes or drugs.

Oceanus Magazine

From Mars to the deep

April 28, 2021

From Mars to the deep

New navigation system helps autonomous vehicles find their way

By Evan Lubofsky | May 6, 2021

Citizen scientist Seán Doran created this mosaic of NASA’s Mars rover Perseverance and Ingenuity helicopter, using 62 images captured by Perseverance on April 6, 2021. (Image courtesy of Seán Doran, NASA JPL Caltech / MSSS)

Last February, the Mars rover Perseverance-the most advanced robot ever to explore another world-landed on Mars. It tore through the planet’s wispy-thin atmosphere at 12,000 mph before a drogue parachute opened to slow the spacecraft down for its first glimpse at the planet’s rocky, pink surface.

Soon, the navigation system that made that journey possible could guide robots in another unexplored terrain that’s much closer to home: the deepest trenches of the ocean. Russell Smith, an engineer with NASA’s Jet Propulsion Laboratory (JPL) is involved with both projects. He recalls the thrill of watching the rover land.

“My heart was pounding in my chest,” says Smith, who was virtually strapped in at home during the live YouTube broadcast of NASA’s Perseverance landing. Smith was personally vested: he had spent many long day and nights building a system which simulated reduced gravity environments in order to test the Mars Helicopter, dubbed Ingenuity. The helicopter hitched a ride to Mars aboard the rover, and went on to perform the first powered controlled flight of an aircraft on another planet.

“It was really thrilling!” Smith says. But, he says, those “seven minutes of terror”-NASA-speak for the time it takes for a spacecraft to enter, descend, and land on Mars-were also nerve-wracking. As the rover descended, he was relieved to see that the navigation systems appeared to be working. The Lander Vision System (LVS) using Terrain Relative Navigation (TRN) enabled the Perseverance to not only land safely in “a field of dangers,” he says, but to do so within a car’s length of the landing target. The helicopter’s flight was one step closer.

Now, Smith has his sights set on moving similar TRN-based navigation technology (called xVIO) into the hadal zone, the deepest, the darkest reaches of the sea, extending from 6,000-11,000 meters below the surface. He’s working with WHOI biologist Tim Shank, WHOI research engineer Casey Machado, and others on WHOI’s HADEX program team to integrate the technology into Orpheus-class hadal robots. These relatively small, bright-orange drones are specifically designed for hadal zone exploration.

On Earth, advanced GPS systems are sufficient for navigation-at least on land. “But deep in the ocean it’s far more difficult,” Smith says. Space and the deep ocean both lack the constellations of sensors that make such navigation technology possible.

TRN, however, could be an ideal solution. The concept behind the technology is simple- it works much like you do when walking around your own house. You know where you are based on the objects you see: doors, furniture, the refrigerator, a staircase. But in order for a robot to function in this way, a tightly integrated system of advanced machine vision cameras, lighting, and pattern-matching software algorithms is necessary. These components enable the system to reconstruct the seafloor by creating three-dimensional maps that stitch together images of features it sees, such as rocks and clams. The maps are stored in the system’s memory, so when Orpheus flies back over a mapped area of the ocean, it will know where it is based on the familiar objects it sees.

But the maps are more than simply a navigation tool. They will also enable Orpheus to locate scientifically interesting features like cold seeps, hydrothermal vents, and even animals. Shank says this could be a revolutionary advance.

Casey Machado, Tim Shank, and NASA engineer Russell Smith cluster around an Orpheus hadal robot. (Photo by Taylor Heyl, © Woods Hole Oceanographic Institution)

Tim Shank and Casey Machado Casey Machado, Tim Shank, and NASA engineer Russell Smith prepare Orpheus for its deepest dive to 1,600 meters below the surface in Veatch Canyon off the New England Continental Shelf. (Photo by Taylor Heyl, Woods Hole Oceanographic Institution)

“These will be the most detailed maps we’ve ever had on the seafloor, with a resolution that gets down to the biological scale,” he says. “From there, we want to be able to command, ‘Go back to that clam we saw earlier’ and have the system tell the vehicle how to get back there. It’s a huge step we hope to reach.”

Another key advantage of this navigation system, according to Shank, is that it is compact. “To do conventional mapping in the ocean, you typically have to mount heavy sonars on the vehicle,” he says. This system, by contrast, adds very little weight.

But getting the technology to work well in the ocean will be a challenge. On Mars, visibility is relatively good due to the planet’s thin atmosphere (unless you find yourself in the middle of a dust storm). But the ocean is often murky, and conditions change quickly. The combination of turbulence, particulates, and even sea life swimming around a robot’s cameras can make it difficult for the system to recognize landmarks.

WHOI engineer Molly Curran works with Russell Smith to calibrate the TRN software during Orpheus operations. (Photo by Ken Kostel, © Woods Hole Oceanographic Institution)

Shank and Smith believe the system will nevertheless be a game-changer for ocean exploration. They will field test it next month, when Orpheus and its twin robot Eurydice descend to the Blake Plateau in the Western Atlantic Ocean.

“To date, we’ve been testing the system out on a mini version of Orpheus in a tank at JPL,” Shank says. “So, we’re excited to be able to finally get it into deep ocean conditions. The seafloor is relatively flat along the Blake Plateau, but there is relief there that we think may be coral mounds and methane seeps which we’re very interested in studying.” 

For Smith, the field tests will give him yet another opportunity to watch with bated breath as an autonomous robot roams a completely different unexplored world. “The engineering challenge of working in extreme environments like this is always fun because you don’t know the challenges you’re going to hit,” he says. “And down there, there’s so much potential for finding interesting things.” 

AUV Orpheus HADEX Seafloor & Below

Finding answers in the ocean

November 10, 2020

Finding answers in the ocean

In times of uncertainty, the deep sea provides potential solutions

By  | November 9, 2020

Deep-sea hydrothermal vents harbor diverse microbes whose enzymes can be used in diagnostic tests, like the ones to detect the novel coronavirus and other pandemics like AIDS and SARS. (Video acquired from the submersible Alvin at the East Pacific Rise near 9° 50’N at 2510 meters depth. © WHOI-NDSF, Alvin Group, National Science Foundation) vent Deep-sea hydrothermal vents harbor diverse microbes whose enzymes can be used in diagnostic tests, like the ones to detect the novel coronavirus and other pandemics like AIDS and SARS. (Video courtesy of Chris German, WHOI/NSF/ROV Jason/2012/© Woods Hole Oceanographic Institution)

The test being used to diagnose the novel coronavirus—and other pandemics like AIDS and SARS—was developed with the help of an enzyme isolated from a microbe found in marine hydrothermal vents as well as freshwater hot springs.

Biomedical breakthroughs sometimes happen in the most unlikely places. Take the deep ocean, for example, where mineral-laden fluid superheated by magma gushes from hydrothermal vents. Under extreme pressure and acidity, at times with no oxygen to speak of, microbes not only survive there, they thrive. This incredible adaptation offers insight into how life evolved billions of years ago—and how modern humans may be able to fight infections and disease.

“We’ve found marine microorganisms that produce antimicrobials—basically chemical weapons that help them fight off other organisms, and molecular mechanisms that help them resist viruses,” says Virginia (Ginny) Edgcomb, a WHOI microbiologist who investigates fungi and bacteria living in the deep sea and deep subsurface biosphere. These microbes feed on tough compounds like hydrocarbons and produce antimicrobial compounds. “Almost every antibiotic we have was produced by microorganisms. Who knows—maybe we’ll find new antimicrobials when we start to look in deep ocean habitats.”

The deep ocean has already given us compounds to treat cancer, inflammation, and nerve damage. But breakthroughs have also come from the ocean depths in the form of diagnostic tools. Case in point: the test being used to diagnose the novel coronavirus—and other pandemics like AIDS and SARS—was developed with the help of an enzyme isolated from a microbe found in marine hydrothermal vents as well as freshwater hot springs.

The pathway to developing this test started back in 1969 when scientists discovered a bacterium, Thermus aquaticus, living in the extreme temperatures of a hot spring in Yellowstone National Park. Two decades later, WHOI biologist Carl Wirsen and colleagues discovered new strains of bacteria on a hydrothermal vent off of Italy that could withstand even greater extremes (including heat, pressure, and lack of oxygen). More heat-loving microbes have since been found in hydrothermal vent communities across the globe to depths as great as 5000 meters beneath the sea surface.

By the mid-1980s, the unassuming microbes had enabled a major advance in the emerging field of genetics. Scientists found that their enzymes remained stable, even at the temperatures required to perform a revolutionary procedure known as polymerase chain reaction (PCR). With enzymes recovered from the microbes, it became possible to make millions of copies of a single DNA sequence in just a few hours, essentially upgrading geneticists’ tools from carbon-copy paper to state-of-the-art Xerox machinery. A technique using these enzymes, termed DNA polymerases, as well as enzymes isolated from viruses, now make it possible to quickly test for viruses, including coronaviruses like SARS (avian flu) and COVID-19.

Identifying microbial processes in the deep ocean is an essential first step for discerning human applications, says WHOI microbiologist Julie Huber.

“A lot of people think of the deep sea as a desert,” she says. “To our naked eye, it looks like there’s nothing there. But hydrothermal vents have a remarkable diversity of microbes, including genetic diversity. There’s huge potential there. What I can do as a basic science researcher is describe them and make their genome available. And folks in applied science can take that data and turn it into something useful.”

Edgcomb says the coronavirus outbreak underscores the importance of funding basic exploratory research, which may help lead to a cure or diagnostic tool in the future.

“You need to have people exploring different habitats in order to continue feeding the pipeline of medically-relevant enzymes (proteins),” she says. “This is a tough lesson to learn, with this pandemic, but I do hope people realize that the more we can learn more about microbes, the better off we are.”

biology Hydrothermal Vents Ocean Chemistry
Peter de Menocal

Who is Peter de Menocal? A Conversation with WHOI’s new President & Director

October 29, 2020

Oceanus: Welcome to WHOI!

De Menocal: Thank you very much.

Oceanus:  If you don’t mind, let’s start at the beginning: Where did you grow up, and what aspects of your childhood eventually led you to a career as a marine geologist and climate scientist?

De Menocal: I grew up in Rye, New York, in what was then a small, quiet suburb just north of New York City. I have always been drawn to the ocean, even from childhood. My family and I would visit my grandparents who had retired and moved to Nantucket in 1945, when it really was the remote and eponymous “far-away island.” I remember asking endless questions about the sea and marveling at its immensity and power. But it would be many years before I realized that I could turn my curiosity about the ocean into a career.

Peter de Menocal Photo courtesy of Lamont-Doherty Earth Observatory of Columbia University

Funny enough, my professional connection to the sea began at WHOI. At the time, I was a clueless but optimistic studio-art and math major at St. Lawrence University in far upstate New York, near the Canadian border. On a crisp day in the spring of 1979, I hitchhiked south to visit a friend on Cape Cod. My last ride dropped me off in front of the Quissett campus, where stern signs saying “Secure Area: No Trespassing” beckoned me to investigate.

I reached the Clark Building, walked inside, and was stunned by what I saw: gleaming labs, computer centers, and gaggles of students everywhere. A big bear-paw of a hand grabbed my shoulder and asked in a booming voice, “Son, can I help you?” The hand and voice belonged-not to a security guard, as I first thought-but to famed marine geologist Charley Hollister. He pulled me into his office, and I spent the next several hours listening to his tales of going to sea, traveling the world, building scientific instruments, and conducting oceanographic research. I was riveted. When I walked out of Clark that day, I knew what I wanted to do with my life.

Oceanus: You have had a long and successful career at Columbia University. What were some of the highlights of your time there?

De Menocal: I came up from the mailroom, as it were. I entered as a graduate student in 1987, studying marine geology and paleoceanography at the Lamont Doherty Earth Observatory, one of best Earth science research labs. These were heady, exciting times at Columbia, as climate science was really taking off. After I finished my Ph.D. in 1992, I spent seven years as a soft-money research scientist and gained a deep, personal understanding of the benefits and challenges of grant-funded research. I was invited to join the Columbia faculty in 1999, was selected as department chair, and eventually became Dean of Science, managing 240 faculty across nine science departments in the School of Arts and Sciences. It was quite a ride!

I think the experience that has most prepared me to take on a leadership role at WHOI was founding and directing Columbia’s Center for Climate and Life. Faced with an urgent need for climate solutions-and declining federal funding for climate science-I wanted to develop a new funding model that incentivized scientists to pursue high-risk, high-value research to accelerate innovation. With about $15 million in new philanthropic support, I started a prestigious Fellows program that freed scientists to think deeply and creatively about developing actionable knowledge for the public good. The model relies on private sector partnerships. It is scalable. And it works.

Oceanus: Why come to WHOI, and why now?

De Menocal: The simple answer is that WHOI is the best and most distinguished oceanographic institution in the world. But more importantly is that they have-or we have-a strategic distinctiveness that sets us apart from every other institution: this marriage of engineering and technology with scientific inquiry. It’s that connection between a search for basic knowledge on the scientific side with developing really innovative tools on the engineering side that will invite and enable the discovery we need today.

If you think about the challenges facing humanity in the coming decade-climate change, carbon management, growing food, water, and energy needs-they all connect directly to our changing oceans. So, we’ll need a much better understanding and monitoring of these changes and how they affect things we fundamentally care about. And it’s going to require innovations in marine engineering and technology: big data and ocean data science, remote observations, and an “internet of things” in the ocean.

It’s going to take a discovery approach that is unlike anything we’ve ever done before. And that can only happen in a place like WHOI.

Oceanus: Along with advancing science and engineering, WHOI is committed to education-academically, but also more broadly, through public engagement with the ocean. In your opinion, how important are ocean education and literacy to WHOI’s mission, and why?

De Menocal: WHOI’s educational efforts are broad-based and essential to the Institution’s mission. Through its graduate and post-doctoral programs, undergraduate summer student fellowships, and K-12 outreach, WHOI is educating and inspiring the next generation of ocean engineers and scientists.

Since 1968, WHOI has partnered with MIT to form one of the premier marine science and engineering graduate programs in the world-the MIT-WHOI Joint Program in Oceanography, Applied Science & Engineering. The Joint Program gives students unmatched access to instruments, ships, technology, and instruction and mentoring from some of the world’s best ocean researchers and innovators. In 2018, the program marked its 50th year, having graduated more than 1,000 scientists and engineers, many of whom have gone on to make valuable contributions-in research, but also in teaching, government, industry, and the Navy. Additionally, WHOI supports early-career scientists through its post-doctoral scholar and fellow appointments. And at the undergraduate level, WHOI’s summer programs give aspiring oceanographers of diverse backgrounds the opportunity to work alongside world-class researchers and gain hands-on experience in the lab, in the field, and at sea.

WHOI also has a role to play in K-12 STEM outreach. Ocean education for K-12 students is a triple-win for society, fostering better health, equity, and sustainability. It builds a society that understands the value of our greatest planetary resource and life support system-the ocean. And it increases diversity in the sciences by inspiring bright young minds from underrepresented groups to pursue ocean science careers.

Lastly, our path to a sustainable future on this increasingly crowded planet begins with the call for a healthy, stable, and protected ocean. Winning hearts and minds to protect the oceans-so they will continue to protect us-requires more than just our amazing science, engineering, and discovery. It takes an outward-facing, forward-looking effort to communicate to the public and to policymakers how the oceans are changing-­­­­­in ways that directly impact our health, economy, and security. We can use our convening power to drive greater public engagement on societally-relevant issues. Recent research shows that every dollar invested in resilience saves six dollars in future cost. Science-informed action protects us from outcomes we really want to avoid.

Oceanus: As you mentioned, your own academic background and research is in marine geology and paleoceanography. Have you been to sea?

De Menocal: Yes-mostly on WHOI ships! I’ve been on the R/V Oceanus, and on the R/V Knorr-a couple of times on each. My field work has involved deep-sea sediment coring, typically piston coring, in the North Atlantic and Arabian Sea. My most recent seagoing work has been mainly off the coasts of East and West Africa.

One of the areas that I’ve worked on is trying to understand changes in African vegetation and climate linked to human evolution. And in particular, looking at the shifting hydro-climate-basically, the rain and the drought cycles-that have occurred in the geologic past. The instrumental record only gets us back a hundred years, but if we want to go back thousands of years, or tens of thousands of years, we have to use the ocean sediments as a proxy or archive.

Oceanus: What was your most memorable at-sea experience?

De Menocal: I was on a sediment-coring cruise on a Dutch ship, the R/V Pelagia, in the Gulf of Aden-this was only three months before 9/11. Pirate activity was on the rise, and to avoid being detected as we sailed along the Somali coast, we had to shut down all the ship’s navigation lights and radio communications. The only way we had to get updates about ship attacks was via transmissions on a weather fax. We’d get this chunka, chunka, chunka, chunka of the fax machine, churning out a map of where the latest attacks were happening. Pirate attacks were getting more frequent, but no one knew why-9/11 hadn’t happened yet. And it was wild, because some of the attack coordinates were right near the coring sites we were steaming toward.

There we were, on this incredibly slow diesel electric ship that was doing maybe ten knots. I mean, we were just chugging along in these dangerous waters in the black of night with no navigation lights. We had regular drills-like, if we were to be boarded, what would we do? You have to lock this door, and hide in this chain locker…It was a little like Captain Phillips. We went through several weeks of this before we finally passed through the Strait of Bab el-Mandeb-the entrance to the Red Sea-and into the safety of Saudi Arabian waters. The incident was written up in The Atlantic more than a decade later, when we published the results of our research in Science. The lead author on that paper was actually my former post-doc Jessica Tierney, then a paleoclimatologist at WHOI.

Oceanus: The latest issue of Oceanus magazine is about the risks and rewards of the ocean. We weren’t thinking about pirates (!), but about the ocean’s role in human health. How do you see humanity’s relationship to the ocean?

Peter de Menocal Photo courtesy of Lamont-Doherty Earth Observatory of Columbia University

De Menocal: The Earth appears as a blue marble from space. With more than 70 percent of our planet’s surface covered by ocean, it’s no surprise that human health is directly linked to ocean health. The ocean is our planet’s life support system. It is the primary driver of Earth’s climate system, weather, and water cycle; it feeds and sustains billions, including many of the world’s poorest people; and it makes life as we know it possible. Most importantly for people today is that the oceans are in transition: surface water temperatures, sea ice, fisheries, and the health of coral reefs are all shifting away from historical norms. We still have time to avoid bad outcomes, but that window of opportunity is narrowing.

Oceanus: Science research is founded on analyzing data-observations, facts-and reaching conclusions in an unbiased way. But given the importance of the ocean to human health, should a research institution such as WHOI play a role in advocating for ocean sustainability and stewardship?

De Menocal: Our primary role is to provide expert, scientifically-based guidance on issues of societal importance. The role of a scientific institution such as WHOI is to advance the state of knowledge so that factual, informed decision-making can prevail above convenient opinion. As such, we are advocates for science and discovery as they inform knowledge, policy, and practice in service of the common good. But we should refrain from specific advocacy.

Oceanus: The American Geophysical Union recently released a strategic plan in which they signaled a shift away from pure basic research toward greater focus on solutions to the problems facing society. “AGU members,” the plan states, “have the potential, opportunity and responsibility not only to advance further discovery but also to accelerate our efforts to address societal challenges in the coming century.” What are your thoughts on this shift toward solutions thinking, and what are the implications for WHOI?

De Menocal: Ultimately, WHOI’s work must be rooted in strong, fundamental science. I don’t think we can lose sight of that as we search for solutions. But I do believe we are in a time of deep societal need that calls upon WHOI scientists and engineers to step up and lead, pursuing use-inspired basic science that can accelerate solutions. By “use-inspired basic science,” I mean research that both seeks a fundamental understanding of scientific problems and also has value for society. The phrase was coined by Donald Stokes in his book Pasteur’s Quadrant-the work of scientist Louis Pasteur is thought to exemplify research that bridges the gap between “basic” and “applied.” That’s where we need to be.

Pursuing use-inspired basic science invites scientists and engineers to take on really difficult, risky, but critically important questions that have useful answers for humanity. We need to incentivize that kind of creative, risky thinking to address the urgency and the magnitude of the changes-warming, ice melt, sea level rise, and their repercussions and impacts-that we know are ahead of us.

Oceanus: The best engineering and science often grows out of collaborations and teamwork. Do you see collaboration across disciplines and among institutions as a means of addressing large-scale problems facing the world?

De Menocal: The challenges we face are bigger than any one institution. Moreover, the problems require transdisciplinary partnerships and solutions that engage the private sector. I believe in a shared mission approach that aligns scientific, technological, philanthropic, policy, and business partners towards a common, problem-solving goal. We can learn from successful solutions to big, complex environmental challenges such as acid rain or ozone depletion: Science frames the debate, public engagement provides urgency, and public-private sector partnerships build viable, science-based solutions.

Oceanus: Staying with the subject of collaborations and teamwork-ocean science has a very poor track record when it comes to diversity, equity, and inclusion, despite the fact that studies have shown that diverse teams, in which everyone’s contributions are valued, consistently outperform homogeneous ones. What actions will you take to improve diversity, equity, and inclusion at WHOI, at all levels?

De Menocal: Well, we’re already looking into hiring a diversity officer. One of the first things I want to do is to have somebody join me at the directorate level to lead our activities and our diversity, equity, and inclusion initiatives. I mean, it’s just fundamentally important. I’ve had the really great fortune of having been at a place like Columbia, where they’re very serious about it. They committed hundreds of millions of dollars to diversifying faculty. It’s not easy. There is systematic bias. But what I can say is that having been at Columbia for 33 years, I did see a department with no women go to 40 percent women. I did see the hiring of underrepresented minorities increase dramatically in the sciences, from a near-zero baseline.

There’s so much work to do. I suppose it’s daunting. But it’s so gratifying to see change. A lot of it comes down to the courage to lead and just committing to it. And a lot of it has to do with having resources and applying them, because it does require targeted investment. But Diversity, Equity, and Inclusion (DEI) work is absolutely one of my top priorities.

Oceanus: What other challenges do you expect to face at WHOI?

De Menocal: Meeting 1,100 people in my first month (laughs)? But that’s a big part of what I want to do, is to get to know our people.

I think the biggest challenge-not for me, really, but for oceanography-is finding our path forward to use our knowledge to make a difference in the world. Because the world needs us. The question is how we, as an oceanographic community, will meet this challenge and adjust our way of doing science, of funding science, of going after big audacious problems, with the kind of commitment and resolve that’s needed. I believe we can. And WHOI has a very special role to play in this-I think it’s a chance for us to be part of something bigger than ourselves.

Art Maxwell

Celebrating an oceanographic life

July 1, 2020

Celebrating an
oceanographic life

By Véronique LaCapra

Arthur (Art) Maxwell was more than a brilliant ocean scientist: He was a generous, approachable leader who cared deeply about his colleagues and students.

“Art was a legend, a mentor, and a trusted friend,” said Woods Hole Oceanographic Institution (WHOI) Trustee Jamie Austin, a senior research scientist at the University of Texas Institute for Geophysics where Maxwell spent the final decade of his long career.

In the 1960s and 70s, Maxwell served as WHOI Director of Research and Provost, working closely with WHOI President Paul Fye and helping to found the MIT-WHOI Joint Program in Oceanography. During his time at the Institution, Maxwell also pursued his own research in geophysics. Among other achievements, he was appointed President of the American Geophysical Union (1976-1978) and co-led an expedition of the Deep-Sea Drilling Project, which provided critical evidence to support the theory of plate tectonics by demonstrating that the seafloor under the South Atlantic was spreading.

Maxwell began his career in one of the most dangerous jobs in the U.S. Navy, serving as quartermaster on the ammunition ship Lassen in the Pacific during World War II. After the war, Maxwell went to Scripps Institute of Oceanography, where he worked with pioneering oceanographers Walter Munk and Roger Revelle; the latter was so impressed with Maxwell that he took on the role of graduate advisor for the first time in order to mentor him. Maxwell then moved from California to Washington, DC, to work for the Office of Naval Research at a time when the Navy was a leading funder of research in ocean science.

“It was always very interesting around our household,” reminisced Maxwell’s daughter, Delle. “Scientists from around the world were always passing through. We met people like Jacques Piccard and Willard Bascom—leading lights in oceanography. As a child, I imagined theirs to be a most exotic and adventurous lifestyle. In retrospect, my father was always at the intersection of adventure, intellectual pursuit, and academic pioneering.”

“Art was a legend, a mentor, and a trusted friend.” —Jamie Austin, WHOI Trustee

Art Maxwell Art Maxwell (center), along with Jim Dean and Dick Von Herzen, remove a core aboard Glomar Challenger on Deep-Sea Drilling Project (DSDP) Leg 3 in 1968. (Photo credit: DSDP)

In 2018, a year before his death, Art Maxwell returned to WHOI at the age of 93 to attend the commemoration of the 50th anniversary of the Joint Program, which he helped initiate half a century before. To celebrate his contributions to WHOI, Delle and her husband Pat Hanrahan gave $1.5 million to endow the Maxwell-Hanrahan Fund for Education and Research at MIT, which funds students to carry out oceanographic research at sea. They gave an additional $1 million to WHOI’s Arthur E. Maxwell Graduate Student Fund, established in 2003 by Austin—a Joint-Program alumnus (PhD ’79)—to honor his much-beloved mentor.

“I can say without hesitation that his input steered me in good directions for more than four decades,” Austin said. “I will never forget him.”

Art Maxwell Art Maxwell (center), along with Jim Dean and Dick Von Herzen, remove a core aboard Glomar Challenger on Deep-Sea Drilling Project (DSDP) Leg 3 in 1968. (Photo credit: DSDP)

Art Maxwell (center), along with Jim Dean and Dick Von Herzen, remove a core aboard Glomar Challenger on Deep-Sea Drilling Project (DSDP) Leg 3 in 1968. (Photo credit: DSDP)

Walking on polar ice

Oceans of Change

February 27, 2020

Oceans of Change

WHOI scientists learn how the ocean shapes—and is shaped by—global climate

By Madeline Drexler

(Photo by Simon Buchou on Unsplash)

“THE SEA NEVER CHANGES, AND ITS WORKS, FOR ALL THE TALK OF MEN, ARE WRAPPED IN MYSTERY.” So observed the narrator of “Typhoon,” Joseph Conrad’s 1902 novella. But today, we know that his mariner protagonist was wrong on both counts. The ocean, in fact, is changing profoundly. And while its complex mechanisms are no longer shrouded in mystery, countless riddles remain unsolved.

Covering 71 percent of our blue planet, the ocean is a focal point for climate research. Because it stores 95 percent of the excess heat created by greenhouse gases that humans put into the atmosphere, the ocean acts both as a buffer against rapid warming stoked by today’s greenhouse gas emissions, and as a memory bank of today’s rising temperatures.

As world leaders in ocean science and engineering, researchers at Woods Hole Oceanographic Institution (WHOI) are at the front line of climate science. Directly or indirectly, virtually all of their work is answering fundamental questions about how the waters that wrap the Earth are responding to a warming planet. Taken together, their investigations are helping to shed light on a troubling new era.

“Ninety-seven percent of our water is in the ocean. If you want to understand anything about rainfall on land or even about drought, you need to understand the ocean.”
WHOI climate modeler Caroline Ummenhofer

(Photo by Christopher Linder, ©Woods Hole Oceanographic Institution)

“The urgency of understanding climate change is really the urgency of understanding the impacts of climate change. And to do that, you have to know how the ocean works.”

~WHOI physical oceanographer, Susan Wijffels

Headline News

Evidence for the ocean-climate connection is everywhere.

In 2014, a report from the Intergovernmental Panel on Climate Change (IPCC) noted, with italicized emphasis: “It is virtually certain that global mean sea level rise will continue for many centuries beyond 2100.”

Not only is the ocean warming and expanding, it is also acidifying as it absorbs carbon dioxide (CO₂). “Once-in-a-century” storms that have killed thousands of people are making regular appearances: from Hurricanes Katrina in 2005, Sandy in 2012, and Harvey and Maria in 2017, to Myanmar’s Cyclone Nargis in 2008 and the Philippines’ Typhoon Haiyan in 2013. Devastating droughts, a consequence of the altered global water cycle, are parching South Asia, Africa, Australia, Central America, and the American West. Scientists speak matter-of-factly of the possibility that, within the next 500 years, Greenland’s ice sheet could disappear entirely.

“The realization of what a vital role the ocean plays in Earth’s climate system has driven not just scientific developments, but observational and engineering developments, too,” said Susan Wijffels, a physical oceanographer whose work on past and present ocean data has changed the way researchers quantify the ocean’s uptake of heat. Growing up in the Australian outback, Wijffels learned early on about the central role of the ocean in tempering the earth’s climate. Today, her mission is to decipher the intricacies of this natural buffering process.

“If we want to have a shot at navigating changes over the next 50 or 100 years, we have to demystify the ocean,” she said.

“Traditionally, the earth’s water cycle has been observed from land—hydrologists, water resource managers, and atmospheric scientists worked on it,” said climate modeler Caroline Ummenhofer. Her studies of Indian Ocean monsoon patterns, and of extreme weather events from Australia to the U.S. Midwest, have challenged conventional scientific wisdom.

“Ninety-seven percent of our water is in the ocean,” Ummenhofer said. “If you want to understand anything about rainfall on land or even about drought, you need to understand the ocean.”

According to biological oceanographer Carin Ashjian, who has made critical findings about how global warming has affected marine ecosystems, “The urgency of understanding climate change is really the urgency of understanding the impacts of climate change. And to do that, you have to know how the ocean works.”

Woodcut of HMS Challenger The HMS Challenger expedition yielded a wealth of information about the ocean, which WHOI scientists use to study current climate conditions. (Creative Commons)

Oceanic Memory

Since the turn of the 20th century, the average level of the global ocean has crept up between 6 and 8 inches.

It is rising primarily because of two factors. One is melting ice sheets and glaciers. The other is warming water itself, which takes up more volume because of thermal expansion.

When Geoffrey “Jake” Gebbie, a physical oceanographer and paleoclimatologist, analyzes today’s rising ocean, he looks to the distant past. Waters receded and waters rose long before human-induced climate change. Understanding how, and at what pace, these natural phenomena occurred will sharpen predictions about how the ocean in the anthropocene (the current, human-dominated geologic age) will respond to global warming.

In a paper published in January 2019, Gebbie presented a curious discovery. While today’s ocean surface waters are warming, waters in the middle layer of the Pacific—about 2 kilometers (1.2 miles) down—are actually getting colder, in response to the cooling trend that marked the onset of the Little Ice Age, which lasted between the 14th and 19th centuries. The period was marked by severe winters that arrived early and lingered well into spring (Dutch paintings from the era often featured ice skaters frolicking on frozen canals).

To arrive at this finding, Gebbie and his colleagues drew on observations from the 1872–1876 voyage of the HMS Challenger—a three-masted wooden sailing ship that made the first modern oceanographic expedition, lowering thermometers to the sea floor using hemp ropes. Comparing these historical data with modern-day measurements, Gebbie found evidence of waters untouched by the planetary warming that began with the Industrial Revolution.

“These waters are so old and haven’t been near the surface in so long, they still ‘remember’ what was going on hundreds of years ago,” he said.

Although the net effect of this submerged layer of cool water on future climate conditions is unclear, there is an upside.

“The long memory of the ocean is a saving grace,” said Gebbie. “It has been buying us more time than we otherwise would have had to come up with solutions that address climate change.”

The downside is that this thermal shock absorber comes with a price: Once today’s warm surface waters reach the depths, they will stay there for several hundred to a thousand years.

“The ocean cannot destroy the heat that it’s currently taking up,” Gebbie said. “It will sequester today’s warm surface water, recycle it, and later expel it back into the atmosphere.”

In a separate 2019 study, Gebbie looked at paleo-oceanographic records—such as the chemical composition of shells found on the sea floor—to calculate how much the ocean has risen due to warming waters since the end of the last Ice Age some 20,000 years ago. The answer: about 130 meters (427 feet), which comes to about one meter for every two degrees Celsius of warming (or three feet for every one-degree-Fahrenheit rise).

“That’s alarming,” Gebbie said, “because the world has already warmed by one degree Celsius just over the last 150 years. And although our inference may only apply over long time periods, it does give some guidance on where the planet is headed. Even greater sea-level rise could occur if Greenland or West Antarctica pass a threshold of excess melting.”

“These waters are so old and haven’t been near the surface in so long, they still ‘remember’ what was going on hundreds of years ago”

~ WHOI physical oceanographer and paleoclimatologist Geoffrey “Jake” Gebbie

Collecting carbon clues—Marine chemist Ken Buesseler (left) and research specialist Steven Pike prepare to deploy a sediment trap to gain insight into the role of the upper ocean in Earth’s carbon cycle and climate system. (Photo by Jennifer Kenyon, ©Woods Hole Oceanographic Institution)

The Twilight Zone’s Crucial Carbon Pump

When CO₂ enters the ocean, where does this heat-trapping gas go?

Geochemist Ken Buesseler and others have shown that one key to the ocean’s capacity to remove or sequester carbon is the ocean’s “twilight zone,” a mysterious stratum of ocean beneath the sunlit surface layer, which ranges from 30-200 meters (about 100-650 feet), to about 1,000 meters (3,300 feet) down. Also called the mesopelagic zone, this enigmatic mid-layer of water is home to otherworldly creatures with names to match—bristlemouth, hatchetfish, devil squid, stoplight loosejaw. Were it not for these deep, inky-black waters, the climate on our planet would be unrecognizably warmer.

The removal of CO₂, its conversion to organic carbon, and the carbon’s dispatch to the ocean’s depths is known as the ocean’s biological pump.

“If you turned off this biological carbon pump—let’s say, you somehow made the ocean sterile and sucked out all of the twilight zone’s organisms—you would more than double the amount of CO2 in the atmosphere that humans have added,” said Buesseler. “That would take us to temperatures we haven’t seen in 50 million years, when the Earth was 20 degrees Fahrenheit warmer than today, there was no ice on either Pole, the seas were much higher, and many parts of the world where people now live were uninhabitable.”

The pump operates through different mechanisms. In one, a flurry of carbon-laden particles from the surface—dead phytoplankton, feces produced by zooplankton, and other material collectively known as “marine snow”—sink, with about 90 percent serving as the food supply for twilight zone animals and bacteria.

In addition, multitudes of fish, squid, zooplankton, and other mid-ocean denizens migrate nightly close to the ocean’s surface to feed, returning to the twilight zone by daybreak, carrying the carbon in their food with them. Theirs is the largest animal migration on the planet, and a vertical one at that. These migrating species transport massive amounts of carbon from surface waters to the deep ocean.

At the same time that the biological pump moves carbon, physical processes such as the global ocean’s overturning circulation—a system of surface and deep currents around the globe—transport suspended and dissolved carbon to the deep ocean, but on longer time scales.

Buesseler wants to know exactly what fraction of surface carbon is being shuttled to the twilight zone and on to the deep ocean, where it may stay for hundreds to thousands of years. That calculation would profoundly shape climate predictions.

“The twilight zone is the gateway to the deep ocean for carbon sequestration,” Buesseler explained. “But there’s a huge range of estimates of how much is entering the twilight zone—from four to 12 gigatons of carbon annually.” (For comparison, one gigaton weighs about the same as six million blue whales.) “That eight-gigaton difference in the estimates is huge—about the same magnitude as the amount of carbon humans put into the atmosphere every year. If we reduced that uncertainty, we could predict climate changes better and more wisely invest the billions of dollars that go to climate adaptation or mitigation. We could better predict sea level rise and help planners determine where to build roads and bridges and how to adapt our coastal cities to rising sea levels.”

Today, Buesseler sees a new potential danger on the horizon. Located largely in waters outside of national boundaries, the twilight zone is starting to pique the interest of commercial fishing operations harvesting organisms to be converted into feed for chickens, farmed fish, or the nutraceuticals market. Unless it is done sustainably, such extraction could disrupt the ocean’s vital carbon pump.

“This threat has motivated WHOI’s Ocean Twilight Zone program to some extent,” he said. “We need to understand how much carbon is getting through to the twilight zone, and this takes knowing not only how many organisms are there but much more about their life histories and diversity. We need to get ahead of the game before it becomes commercialized.”

The monsoon’s rainfall, drought, and winds are notoriously hard to predict.

(Photo downloaded from PBS LearningMedia,

Precious Coral Archives

The South Asian monsoon—the fiercest monsoon system in the world—affects one-sixth of the human population.

The main source of water for nearly one billion people living on the Indian subcontinent, the South Asian monsoon drives the region’s health, well-being, and prosperity. (Sixty percent of Indian agriculture, for example, depends on rain rather than on irrigation, and farming employs about half of India’s population.) Yet the monsoon’s often-torrential summer rainfall, winter drought, and seasonal winds are notoriously hard to predict. Equally baffling is how the monsoon has responded to anthropogenic factors, and whether global warming is exacerbating its powerful forces.

Biogeochemist Konrad Hughen has devised ingenious methods of tracking the monsoon’s evolution across centuries, filling in a picture of Earth’s natural climate variability and the places where climate shifts have altered familiar weather patterns. This year, in a study that analyzed Red Sea corals, he showed that monsoon winds have strengthened over the past 250 years.

Corals contain some of the best environmental records of long-term climate change nature has to offer, and Hughen—a leading coral “archivist”—effusively praises their value.

“They are amazing archives, time machines, incredible scrolls from the past,” he said. “They are meteorological stations that have been chugging away for hundreds of years, preserving faithful data about climate. And they don’t move, so you can clearly see changes over time.”

Tropical corals grow fast, live for hundreds of years, and lay down annual growth bands—similar to tree rings or ice cores—in their calcium carbonate skeletons. Not only do these bands serve as a timescale going back 400 to 500 years or more, but the coral skeleton chemistry also reflects ocean conditions at the time the coral was alive and accreting its structure. Researchers use microdrills to sample every half millimeter of coral cores, then chemically analyze the powders from these coral “log books,” which are more like monthly or even weekly weather diaries.

Divers extracting corals WHOI researchers Justin Ossolinski and Konrad Hughen extract corals in search of past climate data. Coral growth bands serve as a timescale going back hundreds of years, and coral skeleton chemistry reflects ocean conditions at the time the coral was alive. (Photo courtesy Konrad Hughen, ©Woods Hole Oceanographic Institution)

In conceiving his 2019 study, Hughen drew on the fact that winds driven by the South Asian monsoon stirred up howling dust storms through the Tokar Gap in Sudan, eventually depositing the dust into the Red Sea. The dust releases the element barium into the seawater, which dissolves and is then incorporated into coral skeletons. Hughen used barium levels as a proxy for wind speed, demonstrating that as the climate warmed, monsoon winds became both more intense and less variable.

Analyzing coral core samples, Hughen has proven that the variability of the North Atlantic Oscillation—a cycle of high and low atmospheric pressure systems between the Azores and Iceland—is increasing.

“The highs get higher, the lows get lower,” he said. This more extreme pattern may intensify winter weather patterns, both mild and severe, in the U.S.

Hughen worries that warming waters and ocean acidification will destroy the coral reefs—and the climate records their skeletons contain.

“Corals are dying and disappearing in the same way that ice caps are melting,” he said. “Coral bleachings from 2015 through 2017 were hideous, and they were globally widespread. I’ve been doing this for 20 years, and I feel like more often than not, I’m coring dead or dying or bleached coral.”

If corals continue to perish on massive scales, their dead colonies will become susceptible in less than a decade to bioeroders such as burrowing worms and clams—eroding their skeletons, and the precious climate records they contain.

Hughen sees an urgent need for a global coral sampling program to collect cores from healthy reefs while they are still alive. These cores would be a trove of climate information to be analyzed over the coming decades.

“We need to do it now,” Hughen said. “Even five years from now might be too late. The window is closing.”

Caroline Ummenhofer at computer with climate models Caroline Ummenhofer, (Photo by Thomas N. Kleindinst, ©Woods Hole Oceanographic Institution)

People don’t realize how much their weather—in particular, rainfall—is affected by the ocean.

~ WHOI climate modeler
Caroline Ummenhofer

Models of Change

In addition to preserving long-term records of past climate, the ocean provides clues to predicting future short-term weather patterns, such as storms and droughts.

One of the challenges of predicting climate trends is that human-caused changes overlap with natural fluctuations in climate that have existed for millennia—predictable patterns of wet years and dry years, for example. How can scientists tease apart natural cycles of weather from human-induced “outlier” events that seem to crowd the weekly news cycle?

Climate modeler Caroline Ummenhofer utilizes climate models to reveal connections between ocean processes and their impacts all over the world. She is especially intrigued by the Indian Ocean—a remote body of water that has historically been undersampled by scientists. Her studies have linked conditions in the Indian Ocean to the Asian monsoon, and to droughts, floods and/or wildfires in Australia, East Africa, and Indonesia.

Research based on ocean models and observational data suggests that this scientifically overlooked body of water may have absorbed an astonishing 70 percent of the earth’s global heat gain from 2000 to 2015. And the Indian Ocean is holding on to that heat because—unlike the Atlantic and Pacific Oceans, which are not hemmed in by land—it is bounded on the north by the Indian subcontinent and the Mideast.

“The Indian Ocean is a hotspot of climate change,” Ummenhofer said. “It is the canary in the coal mine.” Heat waves are affecting its waters, fish populations are being displaced, kelp forests are collapsing, and corals are suffering massive bleaching.

Ummenhofer wants to know how that extra heat will affect the Indian subcontinent’s monsoons. Adding heat to any body of water “energizes the system,” she said, ramping up the likelihood of extreme weather.

“We’ve seen this with tropical cyclones and big rainfall events. When air holds more moisture, it can also rain out more water in a shorter amount of time.”

In 2010, for example, Australia suffered extreme flooding—rescue workers compared it to Hurricane Katrina’s devastation in the U.S. in 2005. It was Australia’s wettest spring on record, with much of the country drenched with four times the normal amount of rain. Indeed, so much water had fallen, scientists detected a drop in global sea level from the evaporation that caused the torrents.

Ummenhofer sought to find out whether warming temperatures in the Indian Ocean and western Pacific played a role. She created two computer simulations: one that included a warming ocean, the other in which she artificially stripped out the warming trend—in a sense, fashioning an alternate reality. She ran the models not once but up to 100 times, to tease out the true climate signal amid all the statistical noise.

“No matter what, 2010 was going to be a wet year,” she said. “But that it was so wet was significantly more likely because of the extra warming.”

Ummenhofer has also researched ocean saltiness. Scientists have long considered sea surface salinity levels to be “Nature’s rain gauge,” because when seawater evaporates it leaves salt behind, while the evaporated water is eventually released over land as rain. Ummenhofer, along with WHOI physical oceanographer Ray Schmitt and Laifang Li (now at Duke University), found a clear link between higher salinity levels in the North Atlantic Ocean and increased rainfall on land in the African Sahel. The trio also showed that surface salinity in the subtropical North Atlantic was a strong warning signal for extreme rainfall in the U.S. in 2015, a year that saw record-breaking floods in the South and was the second-wettest year on record in the Midwest.

“People don’t realize how much their weather—in particular, rainfall—is affected by the ocean,” she said. “If you’re a farmer in Iowa and you care about how much rain your crops are getting, then you should care about the ocean.”

Warm ocean temperatures caused large-scale ecological disruption that affected different species, including lobster. (AP Photo/Robert F. Bukaty, File)

The Ocean’s Moveable Feast

Today, warming waters are redrawing the lines of the marine food web.

Over the past few decades, biologist Carin Ashjian has explored this movable feast and how it has responded to changing ocean conditions. She wants to know how ecosystems are shifting, how species are moving, and how these factors fray or strengthen food webs.

Because of warming seas, southern species have found northern waters newly hospitable. Killer whales now show up in Alaskan waters north of the Bering Strait. Salmon species are wending their way to lagoons north of the Arctic Circle, where indigenous fishermen catch fish with nets cast out from the beach. Ashjian fears that commercial fishing—currently prohibited in Arctic waters because the ecosystem is still not fully understood—might ruin the Arctic habitats if not effectively regulated.

To gain a better understanding of the impacts of such climatic changes, Ashjian serves on the scientific steering committee for a developing international effort called the Synoptic Arctic Survey, or SAS, in which scientists on research cruises in the Arctic will collect data on ocean circulation, carbon cycling and ocean acidification, and ecosystem functioning and productivity. This comprehensive dataset will serve as a baseline by which researchers can track changing ocean conditions and their impacts over the coming years, decades, and centuries.

* * *

Physical oceanographer Glen Gawarkiewicz is tracking those changes, and their practical implications, right now. In May 2012, he was on a cruise around Cape Hatteras, North Carolina with fisheries biologists and acousticians, searching for cold-water fish.

“But we had a nine-degree-Fahrenheit anomaly. It was so warm, there were no cold-water species. I thought, ‘Oh, my word.’ It was a change I never could have imagined.”

Since then, Gawarkiewicz has expanded his field of vision, from what he calls the “small patch” of the North Atlantic that was and still is his specialty to the warming Arctic atmosphere, the Jet Stream, and the Gulf Stream.

“They’re all interconnected,” Gawarkiewicz said.

The temperature anomaly that astonished him was due to a stationary wave in the U.S. Jet Stream (a meandering current of air in the atmosphere) that for six weeks held back the cold air in southern Canada that would normally have moved down into southern New England.

“The air temperature was very warm—we were wearing t-shirts in mid-January on Cape Cod,” Gawarkiewicz said. “That skewed ocean temperatures for months afterward. And it caused incredible, large-scale ecological disruption that affected different species, such as puffin chicks and lobster.”

Gawarkiewicz has since documented similar disturbances in his small patch of ocean.

“Cold-water fish are struggling. Cod, in particular, has been retreating to the north. On the other hand, sea bass and Jonah crab are coming in because of warm waters,” he said. “There are huge year-to-year differences in abundance, and we’re not sure what drives them.”

To help answer this question, Gawarkiewicz teamed up with the Commercial Fisheries Research Fleet to recruit fishermen as citizen scientists.

“The climate shifts that we talk about theoretically, they’re experiencing every day,” Gawarkiewicz said.

The fishermen take bi-weekly measurements of salinity, temperature, and depth, and note unusual ocean conditions. The scientists and fishermen later discuss and interpret the data. Scientists benefit because the fleet is a cost-effective way of collecting data, since research expeditions are typically expensive to conduct, while fishermen gain insights into the ecosystems on which their livelihoods depend. It’s an effective win-win scenario.

“There are huge year-to-year differences in abundance, and we’re not sure what drives them.”

~ WHOI physical oceanographer Glen Gawarkiewicz


Summertime ice melt along the Greenland Ice Sheet has sped up in recent decades, with more fresh water flowing into the surrounding ocean. (Photo by Matt Osman, ©Woods Hole Oceanographic Institution)

“The current melt and runoff in Greenland is unprecedented and is also increasing at an accelerating rate.”

~ WHOI glaciologist Sarah Das

A Melting Arctic

On August 1, 2019, during the tail end of an intense heat wave over Europe, the Greenland ice sheet experienced its biggest one-day melt in recorded history, spewing 12.5 billion tons of water into the sea—enough to fill 5 million Olympic-sized swimming pools.

The news headlines didn’t surprise glaciologist Sarah Das. She focuses on the cryosphere—the frozen water part of the earth’s surface. Today, the Arctic is one of the regions most sensitive to climate change, with air temperatures rising faster than anywhere else on the planet.

In December 2018, Das and her colleagues published a study showing that surface melting and runoff across Greenland’s mile-thick ice sheet started increasing in the mid-19th century—the dawn of the Industrial era, when humans began burning coal, oil, and natural gas that emitted tons of carbon dioxide into the atmosphere. The melting sped up dramatically in the 20th and 21st centuries, and shows no signs of abating.

“We were able to show for the first time, and unequivocally, that the current melt and runoff in Greenland is unprecedented and is also increasing at an accelerating rate,” she said.

As a geologist, Das tries to frame her work in Earth-history time scales—far longer than the brief (years-to-decades) modern observational record—to put today’s rapid changes into a larger perspective and to inform how the future might unfold.

While calving icebergs represent one highly visible aspect of rising sea levels, more than half of the Arctic water pouring into the ocean comes from runoff from melted snow and glacial ice. Between 2005 and 2014, loss of ice mass from the Greenland ice sheet alone accounted for a fifth of global mean sea level rise. Now the second-largest contributor to rising seas worldwide, Greenland is on track to become the top source of added water.

Das’s study drew on data gleaned from ice cores extracted from more than 100 meters (about 330 feet) down into the ice, frozen records by which she reconstructed past melt intensity year by year. She found that, rather than increasing in a steady linear trend as climate warms, the melt rate trajectory of Greenland’s ice sheet is “nonlinear,” curving up faster and faster for every degree of warming. According to Das, compared to even the late 19th century, it now takes very little additional warming to trigger huge spikes in ice sheet melting and runoff.

Warmer air temperatures, which are amplified in the Arctic, bring more summer heat, more melt, and more ice loss to the ocean. At the same time, warmer waters lapping Greenland’s shores creep up on the ice sheet from the edges and the underside, causing the ice to melt faster and to calve off into icebergs.

Current projections of sea level rise range from 0.3 to 1.5 meters (one to five feet) between the years 2000 and 2100, and from 1.0 to 12 meters (three to 38 feet) between the years 2000 and 2300, with a large part of that projected to come from increased land ice loss. While IPCC projections take into account many aspects of the atmospheric part of the ice-loss process, they don’t account for all of the newly understood, ocean-driven dynamic changes in glacial behavior—especially the melting of ice from underneath by warm waters—that may prove to be far more consequential, especially in the continent-size ice sheet at the bottom of the globe.

“Antarctica is still the biggest wild card when it comes to ice loss,” said Das. Projections indicate that if all of Greenland’s ice melted, the global sea level would rise by nearly seven meters (24 feet)—which is frightening enough, but if all of Antarctica liquefied, global seas would rise by more than 61 meters (200 feet).

Researcher with REMUS Researcher uses a REMUS to collect data. (Photo by Robin Littlefield, ©Woods Hole Oceanographic Institution) World map showing locations of Argo floats Around the globe—Argo is a global array of 3,800 free-drifting profiling floats that take ocean measurements globally. (Illustration by Argo Information Centre)

Watchful Eyes on the Ocean

Oceanographers frequently use the scientific terms “synoptic” (a wide range of observations made in a single period of time) and “panoptic” (panoramic and continuous surveillance over a longer period of time).

WHOI President and Director Mark Abbott, a biological oceanographer, translates these elegant Greek-derived words into plain English: “everywhere and all the time.” That’s the kind of research it will take to figure out the ocean’s role in our changing climate.

“The quality of weather forecasts and the fact that meteorologists can do pretty good forecasts 10 days out is a transformation, both in atmospheric observations and weather models,” Abbott said. “But we haven’t achieved the same sophisticated forecasting with the ocean. Our observing systems have nowhere near the time and space scales needed to understand both long-term trends nor how ecosystems change rapidly.”

One of the boldest “everywhere and all the time” efforts right now is the Argo Program, a global array of some 3,800 free-drifting floats that measure temperature, salinity, and velocity of the upper 2,000 meters (6,500 feet) of the ocean, with all data relayed and publicly available within hours after collection. This vast trove of information will be key to tracking changing ocean conditions globally. Within the next decade, Deep Argo floats will be dispatched 4,000-6,000 meters (13,123-19,685 feet) down, to measure warming closer to the sea floor. As part of the Argo Program, WHOI deploys about 100 floats, mainly in the Atlantic Ocean.

An international effort that began in 1999, Argo has transformed ocean science.

“There are too many discoveries to count. About a paper a day comes out,” said physical oceanographer Susan Wijffels, co-chair of Argo’s international steering team, the program’s primary scientific oversight group. “Besides tracking big shifts in ocean heat from region to region—shifts that were associated with major climate cycles like the El Niño weather pattern—there have been big surprises relative to how surface waters mix with deeper waters in the winter, and how the ocean’s circulation moves heat around.”

And, said Wijffels, “For the first time ever, we can now track the planetary heat imbalance in real time, because 95 percent of the excess heat from the enhanced greenhouse gas effect goes into the ocean. By tracking ocean heat content month-to-month, we can see warning signals clear as day.”

Ocean observations made by the Argo array also help ground climate model simulations in real-life data.

“Today, there’s a whole set of climate projections out there—some are very optimistic, some are not,” Wijffels said. “Argo is a tool that tells us whether our climate models are correct. It tells us exactly what trajectory we’re on and when and if we have slowed down warming—which so far, we haven’t.”

“Science can inform the best path forward.”
~ WHOI geochemist, Ken Buesseler

(Photo by Christopher Linder, ©Woods Hole Oceanographic Institution)

Looking to the Future

Many WHOI researchers would like to see similar long-term and cross-disciplinary collaborations—using satellites, ship-based arrays, new generations of sensors, and other technologies—to record, map, and analyze shifts in the global ocean that portend further changes to Earth’s climate.

WHOI’s range of expertise in every realm of ocean science, coupled with its unique culture of inquiry, discovery, and innovation, make it a leader in this effort.

“We bring the best science and engineering,”
said Abbott. “And we bring a no-boundaries attitude.”

Gebbie agrees. “At WHOI, we’re an artists’ collaborative—but with scientists. We have the freedom to go where the problems lead us.”

Or as Hughen puts it, “WHOI’s the kind of place where you can think of a question on a Monday and have an answer by Tuesday—just by walking into somebody’s lab and asking: ‘Is it possible to do this?’ and having that colleague reply, ‘Let’s find out.’”

This scientific scope and collegiality breeds optimism.

“The ocean is changing. And it is knowable,” Ummenhofer said. “It will require a great deal of effort, technology, research, and investment to know it. But if we do know it, the outcomes could be huge—better climate predictions, better weather forecasts, a blue economy.”

“Science can inform the best path forward,” said Ken Buesseler. “We need to do something big and aggressive. It’s not outside of our capabilities.”

As Abbott sums it up, “We live on an ocean planet. Going forward, we will need to learn how to live on it, by understanding how the ocean works, how it is changing, and how those changes could profoundly alter our lives. That is why we do what we do.”

Madeline Drexler is a Boston-based science journalist and editor of Harvard Public Health.

This article was originally published in Oceanus magazine, Fall 2019, Vol. 54, No. 2.  If you would like to receive Oceanus magazine twice a year, Become a Member.

How Do Corals Build Their Skeletons?

How Do Corals Build Their Skeletons?

November 12, 2018

Corals are under a lot stress these days—from pollution, overfishing, sea level rise, warmer seawater temperatures, and the increasing acidity of the oceans. Among these stressors, the impact of ocean acidification is often the most insidious and difficult to detect. It threatens coral reefs by making it harder for corals to build their skeletons. But exactly how do corals go about growing their skeletons?

Nathaniel Mollica, a graduate student in MIT-WHOI Joint Program, was part of a team that delved into the details of how coral skeletons are built. What they found will help scientists predict more precisely how corals throughout the world will fare under ocean acidification.

Coral skeletons are made of aragonite, a form of calcium carbonate. To grow up toward sunlight, corals construct a framework of aragonite crystals. At the same time, they buttress this framework with bundles of additional crystals, which thicken and strengthen the skeletons to help them withstand breakage caused by currents, waves, storms, and boring and biting by worms, molluscs, and parrotfish.

Ocean acidification is caused by rising levels of carbon dioxide in the atmosphere, mostly from burning fossil fuels. The carbon dioxide (CO2) is absorbed by seawater (H2O), setting in motion chemical reactions that produce more bicarbonate (HCO3) and fewer carbonate (CO32-) ions. Coral polyps—the tiny living soft-bodied coral animals—bring in seawater containing these ions, along with calcium (Ca2+) ions, into a “calcifying space” between its cells and the surface of their existing skeletons. They pump hydrogen ions (H+) out of this space to produce more carbonate ions (CO32-) ions that bond with (Ca2+) ions to make calcium carbonate (CaCO3) for their skeletons. Because there are more HCO3 ions but fewer CO32- ions in acidified seawater, the corals have to expend more energy to pump out H+ ions from their calcifying space to build skeletons.

Laboratory experiments and field studies, however, have shown that acidification affects skeletal growth in some cases, but not in others. To explore this ambiguity, a research team led by Woods Hole Oceanographic Institution scientists Weifu Guo, Anne Cohen, and Mollica dove into the problem. Literally. Something Mollica had never envisioned he would be doing in his career.

A meandering career path

Mollica grew up in Fort Collins, Colo. “My mom was a ballet teacher and my dad ran a landscaping business,” he said. “My parents took me out hiking, and I always enjoyed nature. My dad had a degree in botany, and we’d go up and down trails and he would say, ‘Nathan, that plant is called this and, that one is called that,’ and would make me repeat it back to him.”

“Despite my interest in the outdoors, I was never really interested in science until middle school, when I was close to failing biology because I wasn’t turning in my homework,” he said. “My teacher offered me extra credit if I participated in an academic competition called Science Olympiad. I said, I would, because I thought it would get me out of a tight spot with my parents.”

“But it was great,” he said. “I continued those competitions throughout high school and met a lot of people interested in science.” To prepare to answer questions for the competitions, he pored through science textbooks that his coach sent him home with. His high school team won regional, then state, competitions, and went to the national Science Olympiad every year. He also competed in a Jeopardy-style competition called the Science Bowl. “It was a lot of fun.”

His favorite subject was geology, which led him to apply to the Colorado School of Mines. The school was primed to train students to go into applied fields in the oil and gas industry or civil engineering. Those didn’t interest Mollica, so he took a year off, taught math at a refugee school in Denver, and looked at options for graduate school.

His particular interest was in the formation process of carbonate rocks, and his grad school explorations led to Cohen, a scientist in WHOI’s Geology and Geophysics Department. Cohen informed him that her lab didn’t do research on carbonates in a geological sense but on the primary architect of carbonate systems: corals. More specifically, the lab focused on how corals are affected by their environment, and how that, in turn, affects their ability to produce carbonate skeleton.

“That became way more interesting to me,” Mollica said. “Corals are the ultimate carbonate generator. Coral reefs have persisted through geological history and built most of the carbonate geology that there is. It was cool to be handed what I was looking for without knowing what I was looking for. I never thought I was going to be an oceanographer—right up until it happened.”

Diving into his research

Among the first things Mollica had to do when he arrived at WHOI was take a month-long course to learn how to scuba dive for his research. He and colleagues dove on reefs and used a drill to extract tubular, 3.5-centimeter-diameter cores from coral skeletons in four locations in the Pacific Ocean, where seawater conditions spanned a wide range of pH levels and carbonate ion concentrations.

The researcher team, which also included Cohen and WHOI scientist Weifu Guo, used a 3-D Computerized Tomography (CT) scanner to image the skeletal cores, which reveal annual growth bands, much like rings on a tree. From the scans, they could discern the upward and thickening components of the coral growth. Their analyses revealed that skeletons of corals in more acidic (lower pH and fewer carbonate ions) waters were significantly thinner. But they found no correlation between upward growth and carbonate ion concentration.

The researchers examined the coral growth process more closely. They determined that declining pH and carbonate ions in seawater strongly affected the corals’ ability to produce the aragonite bundles it uses to thicken their skeletons. In acidified conditions, corals continue to invest in upward growth, but “densification” or thickening suffers. As a result, the less-dense skeletons of corals in lower pH waters are more susceptible to damage from pounding waves or attacks by eroding organisms.

Finally, Mollica and the research team developed a model simulating this new-found detailed skeletal growth mechanism and coupled it with projected changes in ocean pH around the world. They published their results in January 2018, in the journal Proceedings of the National Academy of Sciences.

“By incorporating the nuances of coral skeletal growth,” Mollica said, “we can more precise project how, where, and by how much, ocean acidification will affect tropical reef-building corals.”

The research team included Nathan Mollica, Weifu Guo, Anne Cohen, and Andrew Solow (WHOI), Kuo-Fang Huang (Academia Sinica in Taiwan), and Hannah Donald and Gavin Foster (University of Southampton in England). The research was funded by the National Science Foundation, The Robertson Foundation, the WHOI Ocean Life Institute, and the WHOI Investment in Science Fund.

Searching for ‘Super Reefs’

Searching for ‘Super Reefs’

October 15, 2018

A newborn coral—shaped like a very tiny grain of rice—drifts through the open ocean. It gets one chance to choose a home where it might survive. After settling down, it never moves again. If it finds the right place, the young coral dives down and begins adding to an underwater metropolis pulsing with life. But will its new neighborhood continue to thrive or go downhill in the future?

Corals are superheroes in the oceans. Majestic reefs arise from the hard skeletons corals build around themselves. These can withstand centuries of being battered by waves, and they provide habitats for a spectacular array of fish and other critters. Inside their soft tissues, corals also offer protection for another inhabitant: algae. These microscopic plants use the sunlight streaming into the ocean to make food and share it with their coral hosts, trading dinner for shelter.

But like any superhero, corals have weaknesses. When ocean waters warm up, their algae die or are evicted from their coral homes. The algae give corals their vibrant color, so their departure leaves corals stark white—a process known as coral bleaching. Bleached corals may look like elegant marble sculptures, but they are starving. A few weeks of this too-strict diet can be fatal.

The villain in this story is carbon dioxide (CO2). Our fossil-fueled lifestyles release CO2 into atmosphere, where it serves as an insulating blanket warming our planet. The oceans have been absorbing the brunt of this excess heat, making coral bleaching more common.

CO2 also threatens corals in another way. It mixes into seawater, driving a domino chain of chemical reactions that changes the ocean’s pH (a measure of how acidic or basic a liquid is). As the ocean becomes more acidic (lower pH), a key molecule called carbonate becomes scarcer in seawater. Carbonate is what corals use to construct their skeletons, so as the ocean’s pH declines, building skeletons becomes more arduous.

In the past, when our newborn coral had found the perfect reef on which to settle, it might have grown for hundreds of years. Today, climate change is rapidly creating unfavorable conditions on once-ideal reefs.

Is there any hope?

A natural laboratory

The answer to that question lies in our ability to understand whether some corals could handle the increasingly adverse conditions of their oceanic home. We can find clues from corals that are already living in seawater with higher temperatures and/or lower pH, as well as corals that have survived past heat waves.

Anne Cohen, a scientist at Woods Hole Oceanographic Institution, has focused on doing exactly that. In partnership with other coral reef scientists, conservation organizations, and several coral reef island nations, she and scientists in her lab launched an initiative to find “Super Reefs”—coral reefs that can survive extreme conditions. They have explored corals from the Pacific coast of Panama, across the equatorial Pacific, and into the South China Sea and Micronesia.  In some places, they have discovered coral reefs that have survived heat waves and other reefs that thrive despite very warm or low-pH waters.

One of those places is the island country of Palau in the western Pacific Ocean—at once a tropical paradise and a fantastic natural laboratory. It has an extensive barrier reef offshore in the open ocean. Farther inland, south of Palau’s mainland, is an area known as the Rock Islands with hundreds of small islands, many distinctively umbrella-shaped, that are surrounded by vibrant coral reefs.

In a collaboration with The Nature Conservancy, Cohen and her students discovered that Rock Islands reefs have waters that are much warmer and have lower pH than Palau’s open ocean reefs. Although these conditions should be stressful to corals, those in the Rock Islands are doing well.

They also found that Rock Island corals are less vulnerable to bleaching. During two successive global-scale bleaching events, corals in the Rock Islands experienced minimal bleaching, even though they were exposed to water temperatures much higher than other places that did bleach.

Closets in the skeletons

Because of the way corals grow, we can find out how a coral responded to heat in the past—even if there was no one there to see it—by extracting core samples of coral skeletons. Corals form their skeletons and grow upward and outward, adding floors and wings to their undersea castles. As they grow, they leave behind a detailed record in their skeleton—a diary, if you will. Learn to read it and it can reveal how the coral and the reef they live in were doing years and even decades ago.

We take cores using a drill, powered by compressed air from an oxygen tank. The corals that we core grow in a dome/sphere shape. The living coral tissue is only at the surface of the sphere, up to a few centimeters thick (about 1/3 of an inch at most). Deeper below is the old skeleton, which no longer has living tissue in it.

The cores we take are between 1 and 2.5 inches in diameter. So we are only affecting that surface area of live coral. The polyps that are around the core hole are unaffected. We then plug the core hole using a cap made from underwater epoxy or cement, so that the plug is level with the unaffected polyps that surround the core hole. Those polyps can then grow “sideways,” that is, they divide asexually to produce new polyps that spread over the clean epoxy-cemented area. These new polyps then continue growing upward with the rest of the colony.

We have monitored cored colonies in many places and have never observed mortality from coring. These new polyps in the cored area grow a little bit more slowly as they spread over the area, but then they catch up to the rest of the colony as they start to grow upward.

If we put our coral cores in a CAT scanner, you can see bands of growth, much like the rings in trees. With Cohen and her students Hannah Barkley and Tom DeCarlo, we discovered a particular kind of band produced by the coral when it is bleaching. By looking for these bleaching bands, you can determine how a coral colony responded to temperature spikes in past years.

Across the oceans, a climate cycle called the El Niño Southern Oscillation (ENSO) can cause strong heat waves during its El Niño phase. This can lead to widespread bleaching and coral mortality. Some reefs are more heavily affected by El Niño, bleaching heavily and sometimes losing nearly all their coral. Some of these reefs may take decades to recover, while others are resilient and bounce back fairly quickly. Looking at the cores from many regions we can better pinpoint which reefs are resilient and which are resistant to bleaching despite high temperatures.

An important part of the Super Reefs initiative is to uncover how Super Reef corals tolerate conditions that kill or stifle corals elsewhere. This can help us better understand corals’ ability to adapt and evolve, and give us insight into the future of coral reefs.

Huskies and chihuahuas  

So, just how do these reefs defy the odds? Can these reefs help other reefs that aren’t as tough? Building on the research cited above, I’m adding an additional tool—genetics—to help further elucidate this mystery.

As a graduate student in the MIT-WHOI Joint Program, I teamed up with Cohen Lab to study these resilient corals. My goal is to better understand how they tolerate relatively extreme conditions. To answer these questions, I had to go to the source. I joined the team’s expeditions aboard sailboats and research vessels, dove the reefs and took small tissue samples from which I could extract DNA. I focused on a coral that is commonly found across the Indo-Pacific: Porites lobata. This species, which grows like a sphere, can reach the size of small car and live for hundreds of years.

Using DNA allows me to determine how closely related, or “genetically connected,” corals from different reefs are to one another. This tells us whether offspring from one reef have dispersed to other reefs where they were able to reproduce and incorporate themselves. If the larval offspring from one reef can’t physically make it to a second reef, or can’t survive to adulthood even if they do, then these reefs don’t exchange genetic material. We would consider them genetically isolated. In nature, populations usually lie on a spectrum between fully connected and fully isolated.

Connectivity and isolation can be beneficial in different circumstances.  When newcomers reproduce with individuals in an established population, their offspring may have novel genetic combinations that may be even better suited for that environment, so that more of them survive, reproduce, and prosper. In such a case, connectivity aids the well-known process of natural selection.

But that’s not always the case. Isolation can sometimes make natural selection more efficient by letting it pick winners without bringing in new players in every round. New “blood” may bring new tricks, but it can also wash out the tried-and-true ones.

Let’s take, for example, our beloved fluffy companions: dogs. Dog breeders created breeds by selecting for characteristics that were best suited to certain environments or tasks. A husky is well equipped to tolerate cold temperatures, frolic in the snow, and pull sleds. A chihuahua, not so much.

Now, if breeders wanted to develop a small dog that was well suited for places with both very cold winters and very hot summers, then mixing a chihuahua and a husky may just yield the combination of genetics they need. Connectivity in this case would be beneficial. However, it would have been much more difficult for the breeder to get the qualities they wanted in a husky if they kept adding a chihuahua parent into the line every few generations. Here, connectivity would have worked against becoming better adapted to cold conditions.

Seeding resilient reefs

Nature does its own breeding through natural selection. In Palau’s Rock Islands for example, corals that can’t withstand warmer temperatures or low pH probably won’t make it. In the central Pacific, corals that can’t tolerate periodic heat spikes can get filtered out. The degree to which these reefs are isolated or connected from other nearby reefs can make this process more or less efficient.

By studying DNA of corals from reefs that live under more extreme conditions, I can determine if their resilience is more likely enhanced by being genetically isolated, or if perhaps some other aspects of the environment help them offset stressful conditions.

At the same time, as our oceans warm up and conditions in reefs around the globe become more extreme, connectivity can play a vital role in spreading corals that are better at dealing with those conditions to new places. Figuring out where they might spread is where my field, population genetics, can help.

Measuring how related different reefs are to one another can also tell us how often offspring from one area make it to another. If two areas are genetically connected now, they will likely remain connected in the near future. If we combine genetic connectivity information with knowledge of where the more tolerant reefs are, then we can begin to build a map of which reefs can serve as sources for resilient corals and which other reefs dispersing larvae of tolerant corals can go to and thrive.

The Rock Islands are a current-day simulation of what scientists expect temperature and pH conditions at coral reefs worldwide will be like in a few decades. In other words, over time, conditions in the outer reefs will become more and more similar to how the Rock Islands are now. The corals that have adapted to and thrive under conditions in the Rock Islands could start providing more offspring into the outer reefs. This dynamic can provide a stream of new heat-tolerant baby corals that can replenish and maintain the outer reefs over time. The same dynamic can help sustain reefs across larger spatial scales, such as the central Pacific.

Scientists are searching for other reefs like those in Palau and the central Pacific that may fare well into the near future. It is important to remember, however, that these Super Reefs won’t be able to save all the world’s corals. They will be exceptions in a global trend of reef decline. Taking care of our oceans and our planet should be a top priority. As much as corals would like to keep up with our changing world, we need to do what we can to slow down climate change and give them a better chance to catch up.

This research was funded by National Science Foundation, the Dalio Foundation, Inc., the WHOI Access to the Sea Fund, the WHOI Ocean Venture Fund, the WHOI Coastal Ocean Institute, the MIT Sea Grant Office, The Nature Conservancy, New England Aquarium, and the Robertson Foundation. The Charles M. Vest Presidential Fellowship, the National Defense Science and Engineering Graduate Fellowship Program, Gates Millennium Scholars Program, the Martin Family Fellowship for Sustainability, the American Association of University Women, and the J. Seward Johnson Fund provided funding for Hanny Rivera.

The Discovery of Hydrothermal Vents

The Discovery of Hydrothermal Vents

June 11, 2018

“Wait a minute. What is that?”

It was February 1977, and Robert Ballard, a marine geologist at Woods Hole Oceanographic Institution (WHOI), sat aboard the research vessel Knorr 400 miles off the South American coast, staring at photos before him.

“I think there’s shimmering water right over here to the left, coming out right off the top.”

The photos had been taken by cameras towed 8,000 feet (2,500 meters) below the surface on a platform called ANGUS. They unveiled a discovery that would turn our understanding of life on Earth on its head: Warm water was drifting out of the seafloor along the Galápagos Rift.

Ballard, along with a team of thirty marine geologists, geochemists, and geophysicists, had found the world’s first known active hydrothermal vent. There were no biologists aboard—because no one had expected the second shocking discovery that came soon after: Life was thriving in the abyss. Foot-long clams and human-sized tube worms with tulip-looking heads made the already extraterrestrial landscape look, well, alien.

Hydrothermal vents form in volcanic areas where subseafloor chambers of rising magma create undersea mountain ranges known as mid-ocean ridges. Cold seawater seeps into cracks in the seafloor and can be heated up to a raging 750° F (400° C) by interacting with magma-heated subsurface rocks. The heat stimulates chemical reactions that pull in minerals and chemicals from the rocks, before the fluids percolate back up through vent openings as a chemical-laden soup.

It turns out that nutrients and chemicals belching out of the vents were fueling a rich and productive ecosystem. Communities of microbes fed off chemicals in the vent fluids. The microbes were hosted symbiotically by the strange creatures of the deep, which provided shelter in exchange for food. No plants, no sunlight. Just microbes converting carbon dioxide in the ocean into organic compounds—for themselves and for their hosts.

The long-held notion that life at the bottom of the ocean couldn’t exist without food that rained down from the sunlit surface was tossed out the window. Along with photosynthesis, there was chemosynthesis supporting an entirely new kind of ecosystem in the abyss.

“Everyone sat around speechless,” said Ballard. “It was like processing a nonlinear equation. It was pretty amazing to find these creatures.”

Two years after the first vent was found off Galápagos, scientists exploring another mid-ocean ridge a few hundred miles north found never-before-seen geysers of hot, dark, mineral-rich fluid erupting from tall, chimneylike structures jutting up from the seafloor. The fluids trailed away in underwater plumes like smoke from smokestacks. They called these new types of vents black smokers.

Since then, hundreds of vents have been discovered across the global ocean, from Antarctica to the Arctic, along with an estimated eight hundred vent animal species and countless microbial species. The rate of discovery shows no signs of leveling off.

In August, 2017, WHOI scientist Stefan Sievert organized the Elizabeth W. and Henry A. Morss Colloquium “Life Without Sunlight at Deep-Sea Hot Springs”  to celebrate the 40th anniversary of the discovery of these unique ecosystems and to inform the public about the implications of chemosynthesis for life on Earth and possibly other planetary bodies. It coincided with the 6th International Symposium on Chemosynthetic-Based Ecosystems (CBE6) at which scientists from around the world convened to discuss the current state of hydrothermal research and where things are headed as our understanding of life without sunlight evolves.

Old vents, new places

As scientists began finding additional vent sites in the decades following the initial discovery, most were in volcanically active areas along mid-ocean ridges similar to the Galápagos Rift. In the early 2000s, however, things began to change. Scientists discovered a vent system known as the Lost City Hydrothermal Field near the ridge axis in the Atlantic Ocean. Sitting on an ancient slab of seafloor crust, the field contained vent structures as tall as the Leaning Tower of Pisa and, unlike previously discovered vents, this system was hosted not in crustal rocks, but in peridotite, the rock type that makes up most of Earth’s upper mantle.

“Folks began finding hydrothermal systems that were not hosted in basalt—the main rock we find in the oceanic crust,” said Frieder Klein, a geochemist at WHOI. “This had important implications for our understanding of these systems and their associated ecosystems, because it makes a difference whether seawater is reacting with oceanic crust, or with Earth’s mantle.” It changes the chemistry of fluids emanating from the vents.

As scientists expanded their explorations in other types of geological settings—at the margins of continents and arc island volcanoes, for example, or at subductions zones, where one plate dives beneath another—they found a diversity of vents and other kinds of seafloor fluid flow that can support chemosynthetic life, said WHOI scientist Chris German.

Exploration enablers

Finding vent systems in diverse oceanic environments takes curiosity, determination, and, well, guts. It also takes some pretty robust technology. Metal-crushing pressure, scorching-hot seawater, and rugged, dark landscapes are just some of the extreme conditions that make vent research tough on scientists and the tools they bring down there.

Fortunately, the challenges of extreme deep-sea exploration have led to tight collaboration between marine scientists and engineers and the emergence of a variety of enabling technologies driving these new discoveries. Towed platforms such as ANGUS and human-occupied submersibles such as Alvin were followed by tethered remotely operated vehicles such as Jason. Then came deep-diving autonomous underwater vehicles, or AUVs. These pilotless vehicles swim at depths of 6,000 meters, or nearly 4 miles, performing a number of key functions, including high-resolution seafloor mapping, collecting seawater data, and imaging.

“Before the arrival of these autonomous vehicles, we could only suspend in situ sensors from deep-tow cables, which made operations very unwieldy,” said German. “We had to lower gear to the seafloor on thick cables, which then could only be towed slowly through the oceans at 1 to 1.5 knots and in straight lines to avoid entanglement. With AUVs, we can attach the same sensors and make tight turns and systematically map things out in 3-D grid patterns.” That gives scientists the ability to visualize entire vent fields over a 5-mile range.

To work well in the deep sea, an AUV needs the ability to hover, stop, and reverse in unknown terrain, while mapping out various shapes and hazards as it approaches a vent site. And, if it gets stuck, it needs the smarts to bail itself out.

“In 2005, we had ABE, our Autonomous Benthic Explorer, parked nose-up against a black-smoker chimney at three thousand meters in the remote South Atlantic,” said German. “After ten minutes, ABE reversed back the way it had come to get dislodged, stepped across ten meters to the left, and got back on with the program.”

German also credits developments in sensor technology as a breakthrough area for vent research. In particular, in situ sensors that can find hydrothermal plumes have been key for investigating new sites since the 1980s, when oceanographers began using optical clarity sensors to look for murky, mineral-laden plumes spewing from black-smoker vents. More recently, scientists have also advanced technology for chemical sensors that can detect chemical signals in hydrothermal plumes.

“These sensors offer a great way to prospect for submarine fluids that only recently entered the ocean and haven’t yet had a chance to fully react with seawater,” said German “and that tells us when we are getting close to a source. The main challenge for the future will be to provide enough power for the sensors, so they can provide reliable and stable data sets for long periods in the deep ocean, as we develop next-generation robots that can explore for days and weeks on end, over hundreds of kilometers.”

When it comes to scientists and technology, of course, there’s always a wish list. German has his sights set on a sensor that can simultaneously measure a variety of key “tracer” elements in a hydrothermal plume in real time. This way, he and other scientists could know what types of seafloor fluids to expect at a site before a submersible heads down to the seafloor to investigate in detail.

Teeming with life

From the first jaw-dropping glimpses in the late 1970s, we’ve known that vents are teeming with curious life: jumbo clams, deep-sea tubeworms, Yeti crabs, and shrimp with primitive “eyes” that detect black body radiation emitted from hot objects (such as vents). The shrimp, as well as other vent animals, live in a complex symbiosis with bacteria. Despite the absence of sunlight, all of the essential ingredients are there: heat from the Earth, mineral-rich vent fluids, and a vast universe of microbes that use chemicals produced by these volcanic systems—such as hydrogen sulfide, hydrogen, and even natural gas—as energy sources.

But at what rates are these microorganisms using the chemicals? How much carbon do they produce and how fast do they grow? And what role do they play in supporting the deep sea and beyond? These, according to WHOI biologist Stefan Sievert, are fundamental questions that have been on scientists’ minds since vents were first discovered and investigated by WHOI scientists such as Holger Jannasch, Carl Wirsen, and Craig Taylor, among others.

“There’s always been a great need to place hydrothermal systems in more of a quantifiable biogeochemical context for the rest of the ocean,” he said. “We’ve known that the mixing of hydrothermal fluid with seawater is driving chemosynthesis, and that there appears to be high activity at vent sites and biological processes happening faster than in the rest of the deep ocean. But we haven’t been able to really quantify how fast the microbes are oxidizing chemicals and growing and how much biomass—particularly carbon, the building block of life—they are producing.”

Sievert points out that most of our current understanding of vent ecosystem productivity is based on theoretical estimates and lab experiments—not on direct observations at the actual vent sites. This means the pressure, temperatures, and chemical concentrations microbes are exposed to in the lab may not correspond well with what they experience a few thousand meters down.

To bridge this knowledge gap, Jesse McNichol, a former graduate student in Sievert’s lab, and other scientists at WHOI and elsewhere have performed incubation experiments on cruises in which they’ve collected deep-sea vent microbes in water samplers that maintain the seafloor pressure of the vent sites. The scientists then analyze the samples to measure the rates and activities of the microbes.

The research is making headway, thanks to powerful new analytical tools that can, for example, match up a microbe’s identity with its biochemical activity down to the level of a single cell. A recently developed instrument known as Vent-SID, for Vent Submersible Incubation Device, enables scientists incubate microbes and measure their growth rates even right at the seafloor.

“What we’ve found is that these microbes are really active and quite fast growing,” Sievert said. “In fact, based on our shipboard experiments, some can double their numbers within a few hours. That’s at least as fast as many of the microbes we find in the surface ocean.”

Sievert adds that these techniques are helping scientists to shed more light on interactions among organisms in vent food webs. They are also helping them assess the role of deep-sea vents in cycling chemicals such as carbon, nitrogen, and sulfur between rocks, the ocean, and living things. How much carbon, for example, is recycled within the food web at deep-sea vents versus exported to the surrounding deep ocean?

Distance swimmers

As Sievert and others push our understanding of vent biological productivity forward, other scientists have been digging deep for answers to another fundamental question: How do communities survive the violent and extreme conditions of these volcanically active underworlds? Given the dust particle size and so-so swimming skills of their dispersive, planktonic larvae, it’s a fair question.

And a difficult one, said WHOI biologist Lauren Mullineaux, who has been investigating the seemingly impossible resilience of colonies living around vents.

“One of the first questions people asked when vents were first discovered was how these communities could persist, given that their habitats were sitting on top of active volcanoes,” she said. “When a vent erupts, it can destroy the populations living around it.”

In 2002, scientists returned to the Galápagos to explore one of the first vent communities ever found. It was called Rose Garden because of the proliferation of red-tipped tubeworms that looked like roses. They never found it again. The seafloor is dynamic, and an eruption had paved it over sometime in the ensuing 25 years.

Scientists assumed that the only way for the population to get re-established was through larval dispersal from other places, Mullineaux said. But it seemed unlikely since the distances between neighboring vents were initially thought to be long. And, at the time, it didn’t appear as though the larvae were adapted to migrating hundreds of kilometers through the ocean.

But as more vent sites were found in the following decades, it became clear that vents weren’t always as far away from each other as originally thought. Clusters of vent sites existed with just a few dozen kilometers in between. So the idea of dispersal began to make more sense.

Surprisingly, however, it turned out that vent larvae didn’t need particularly short commutes from one vent site to the next: These little swimmers could go the distance.

“One of the big breakthroughs in our research is the recognition that larvae can colonize from as far as 350 kilometers away,” said Mullineaux. “In 2006, eruptions on the East Pacific Rise wiped out a vent community that had been well studied. After monitoring the site after the eruptions, we found a new species colonizing there that had come from a population from several hundred kilometers away.”

The larvae, explained Mullineaux, were carried by ocean currents, which play a key role in larval transport between vent sites—due in part to the way deep-sea currents interface with seafloor ridge topography. The currents form jets that are steered along the flanks of the mid-ocean ridge “mountain range” and, hence, have the potential to channel larvae horizontally along the ridge directly to neighboring vents.

In certain circumstances, surface winds, too, can play a role in deep-sea larval dispersal. Diane Adams, a former MIT-WHOI Joint Program student who tragically passed away shortly before the CBE6 meeting, discovered a strong correlation between eddies generated by surface winds and larval transport in deep waters.

“Diane was fearless and determined in her research,” said Mullineaux. “She combined deep-sea observations, numerical models, and satellite remote sensing in a way that demonstrated an entirely novel mechanism for dispersal of deep-sea vent species.”

While our understanding of the larvae dispersal puzzle has broadened, most of the research on this topic, to date, has been limited to eastern Pacific vents. There hasn’t been the same kind of detailed work on larval transport in the western Pacific, where vent populations are facing new kinds of disturbances that have little to do with volcanic eruptions.

“Vent systems in the western Pacific are the ones that are likely to be mined for minerals in the future,” said Mullineaux. “People tend to use our results from places like the East Pacific Rise and Juan de Fuca Ridge off the U.S. Pacific Northwest as examples of vent populations being fairly resilient to disturbances. The risk is that they will extrapolate that out and conclude that populations in the western Pacific are resilient too, and that it is OK to mine vents there. That may not be the case, so we need to get beyond the focus we’ve had on vents that are easy to get to and explore new territory.”

Applying a human lens

No one lives in the deep ocean. We don’t make seafood casseroles from the eyeless shrimp hanging out at vent sites. And there are no beaches down there. So why have we spent time and money studying hydrothermal vents over the last several decades? Do vents contribute to our well-being as humans?

These are questions WHOI senior research specialist Stace Beaulieu has taken a hard look at since 2015, when she began researching the economic and societal value of deep-sea ecosystems. She is one of a handful of scientists applying a “human lens” to deep-sea research, and she believes hydrothermal vent systems contribute to society in a variety of ways.

“My work involves looking at the ecosystem services the deep sea provides and what value we as humans derive from it,” said Beaulieu. “Perhaps the most important contribution vents make in this regard is in research and education. We’ve learned so much about life on Earth by studying vents and how life functions in these unique habitats.”

Not only does the research expand what we know about our world today, but it also provides potential clues about the origins of life on Earth.

“There is good support for the hypothesis that life began at hydrothermal vents, and a number of studies suggest certain microorganisms found at vents trace back to ancient lineages,” said Mary Voytek, director of NASA’s astrobiology program and one of the panelist at the Morss colloquium.

The Morss Colloquium scientists were also quick to point out that the discovery of chemosynthetic life under extreme conditions on Earth opened an entirely new window on the possibility of life on other planetary bodies and now guides our search for extraterrestrial life. We now also know that chemosynthesis plays an important role in many other ecosystems besides deep-sea vents—in salt marshes, for example.

There are also a number of tangible benefits people can get from the deep sea, she said. Hydrothermal vents may offer valuable marine genetic resources in the future, including enzymes found in vent organisms, which have unusual and potentially useful capabilities forged by their extreme environments.

“Prospecting for biological compounds in organisms that live in high pressures and temperatures may lead to important industrial applications,” she said.

Mineral deposits on the seafloor may also provide tangible benefits. They could be an answer to growing shortages of metals and ores and boost the quality of life for those in developing nations.

But the question of whether or not to mine the seafloor comes down to understanding the consequences, Beaulieu said. While untapped minerals in the deep sea could provide value to humans, we need to understand the costs of mining them. Could extraction occur in a way that mitigates damage to marine ecosystems? What is the engineering feasibility? And can legal boundaries be applied to assure the resources are accessed in a responsible and fair way?

“There are still a lot of unanswered questions,” she said.

Beaulieu also looks at the softer side of vent-related ecosystem services, which she refers to as the existence value. The premise is that there’s value in these ecosystems just by virtue of their existence and our sharing the Earth with them.

“Most people are never going to go down to a vent site in a submersible or physically experience one of these ecosystems,” she said, “but they can value the existence of it the same way they value the existence of other species on Earth and the stewardship and conservation of those species.”

How Is the Seafloor Made?

How Is the Seafloor Made?

March 21, 2018

Board a ship in Los Angeles and head southwest until you lose sight of land. Then keep going, and going, and going, until you reach the middle of nowhere in the Pacific Ocean. There’s nothing to see there but water in all directions. But if you had been there in December 2011, you would have encountered a ship sailing in a peculiar pattern. It moved east and west and north and south and around a semicircle. And all the while, a fountain of bubbling seawater erupted behind the ship every four minutes like clockwork.

This was not a military exercise or a signal to UFOs, nor some strange luxury cruise. The passengers on the research vessel Marcus G. Langseth were scientists, and the large bubbles came from airguns that emitted compressed air. The bubbles burst with loud pops, sending sound waves down through the water and below the seafloor. The sound waves reverberated through subseafloor rocks and were recorded by listening devices placed on the seafloor. Like bats navigating by echolocation, the researchers were using sound to compensate for a lack of sight as they surveyed the rocks that lie beneath the ocean.

By now, you may be wondering why we scientists specifically targeted the middle of the Pacific. The rocks beneath the Pacific are part of the Pacific tectonic plate, one of about a dozen huge plates that make up the brittle outer layer of our planet and fit together like the pieces of a jigsaw puzzle. Tectonic plates move around like gigantic, slow-motion bumper cars, building mountain ranges when they collide, shaking the planet with earthquakes when they slip and break, and gradually, constantly reorganizing the world map.

Scientists have studied oceanic plates in great detail near the shifting boundaries between plates, and near unique features such as the Hawai’ian islands. But we don’t really know what a “normal” oceanic plate looks like. You can think of it this way: Imagine that modern medicine knew everything there is to know about rare genetic diseases, but no one could agree on the average temperature of a healthy human body.

That’s more or less the situation with marine geophysicists and ordinary oceanic plates—hence, the ship in the middle of nowhere. This spot in the Pacific is as normal as they come. The seafloor here is about 70 million years old. It sits far from the complications of plate boundaries and volcanic hotspots. If we want to figure out the very basics of an oceanic plate—how an ordinary plate is made and how it changes over time—the middle of nowhere is exactly where we want to be.

Listening for echoes

The scientists aboard the Langseth couldn’t see or touch the solid seafloor far below the vessel’s hull. Even if they could get down to the bottom of the ocean, the rocks we’re interested in are miles farther down, deep under the seafloor. How can you study something so inaccessible? By sending down sound waves and recording the echoes returning after the sound has traveled through the subsurface. The time it takes for the sound to travel from the sound source to an ocean-bottom seismometer listening on the seafloor can tell us about what’s beneath the surface—because the speed of sound depends on the composition and structure of the material the sound wave is traveling through, as well as the temperature and pressure that material is under.

This technique is called active-source seismology—as opposed to passive seismology, where earthquakes provide a naturally-occurring but uncontrolled sound source. It’s not a perfect technique. But by listening to the echoes and reverberations from the intermittent bubbly wake trailing the ship, we can find clues left in the rocks as they melted, flowed, cooled, and cracked over tens of millions of years. And we can begin to trace the history of an ordinary piece of oceanic plate.

The scientists on the Langseth collected data over a patch of seafloor roughly 400-by-600 square kilometers (250-by-375 square miles), measuring the speed of sound waves traveling in different directions. The data show that sound travels about 0.6 kilometers per second (2,000 feet per second) faster going east and west than going north and south at this site. We expected to find that, give or take a few percent. But the data also show something else: The speed of the sound waves going east and west increases as you go deeper into this piece of oceanic plate, but north–south sound speed stays constant. What can this tell us about how tectonic plates form?

Melting and flowing

Oceanic plates are continuously forged at mid-ocean ridges, an undersea mountain chain created where the edges of two plates are separating. If you could sit right under a ridge, you would see rocks from the Earth’s mantle—the hot layer underlying the crust—melting and percolating up toward the seam between the two plates. The molten rock cools to form the crust. The new crust is pulled slowly out and away from the ridge as the two plates move apart, making room for molten mantle.

The upper part of the mantle also flows laterally along with that brittle crust, cooling and strengthening as it moves away from the ridge. Don’t get me wrong—this flowing upper mantle is still solid rock. The key here is time. For short (human-scale) amounts of time, the upper mantle behaves like a solid, but over millions of years, the hot stuff under the ridge can ooze along with the crust. It’s like silly putty: Hit it fast with a hammer and it shatters, but press it with your hand, slowly, and it just squashes. The plate as a whole is made of the crust plus that solid-flowing uppermost mantle. They move together as one rigid body, pushed out from the ridge over tens of millions of years.

Mantle flowing at the ridge has a lasting effect: It aligns crystals within the rocks in the upper mantle so that they point in the direction of the flow. That crystal alignment gets frozen into the plate as it moves away from the heat of the ridge. Imagine what happens if you drop a truckload of logs into a fast-flowing river. The logs will jostle and turn in the current until they all point downstream. These crystals do the same, only in a much slower kind of flow. We call this alignment of crystals a “fabric.” Like woven cloth, it has some directions built into it.

That crystal fabric is what makes sound waves travel faster east and west than north and south at our study site in the Pacific. How does that work? Well, think about one of those logs flowing in a river. It takes less force to split a log with the grain than it does to saw against the grain. We geophysicists say that logs are anisotropic: The log’s strength is not (an) the same (iso) if you turn (tropos) the log to a different orientation.

The speed of sound is also anisotropic: Sound travels faster with, rather than against, the grain. When mantle flow aligns crystals in rocks to point away from the ridge, sound traveling in that direction through the rocks will move faster. This anisotropic crystal fabric is a signature of plate formation that we have measured 70 million years later, out in the Pacific.

Cooling and cracking

But this isn’t quite the whole story. We’ve also measured how the sound speed changes at various depths beneath the seafloor, and crystal alignment doesn’t explain why east-west sound waves travel faster when they move through rocks deeper into the plate. To figure this out, we have to look past the ridge and see what happened to our plate between the time it formed and the present day.

The plate starts out hot at the mid-ocean ridge. Over time, the cold seawater sitting on top absorbs that heat, and the plate stiffens, densifies, and contracts. Tiny cracks form. You can see similar kinds of thermal contraction on roads and sidewalks. After a hard winter, cracks show up where the pavement shrank in the cold. In oceanic plates, thermal cracks tend to form parallel to the ridge.

These aligned cracks also create anisotropy. Sound waves traveling parallel to cracks aren’t affected by them, but waves that try to go perpendicularly or at an angle through the cracks are slowed down. The microscopic cracks that we think are in the upper mantle of the plate can partly cancel out the anisotropy of the crystal fabric from mantle flow.

But the deeper we go in our plate, the more overlying rocks increase pressure on the rocks below them, compressing the cracks and squeezing them shut. And that offers our best explanation for our observations: At shallow depths, the cracks counteract the crystal fabric, but as pressure increases deeper down, the cracks close and we see the full effects of crystal alignment.

Listening to the Earth

A lot happened to this ordinary oceanic plate over 70 million years. We’ve found traces of melting, mantle flow, cooling, and brittle cracking, all revealed by using the echoes of sound waves passing through the subsurface.

It’s pretty remarkable that we can decipher the story of a tectonic plate at this level. In the early days of plate tectonic theory, scientists went looking for anisotropy to provide evidence that plate spreading in the ocean was actually happening. Now, our measurements are good enough to see beyond that: Anisotropy encodes information about plate spreading and about other processes that alter the plate millions of years after the crystals first aligned at the ridge.

What else can we learn from anisotropy? Could we use it to reveal and map “currents” of rock flowing in Earth’s interior as we can for ocean currents? Not quite yet, but new measurements give rise to a new generation of questions, and as we listen more closely to the echoes reverberating through the Earth, maybe we’ll hear some of the answers about how the face of the planet we call home has formed and evolved.

This research was funded by the National Science Foundation, an NSF Graduate Research Fellowship, the J. Seward Johnson Fund, a Paul McDonald Fye Graduate Fellowship in Oceanography, and a Charles D. Hollister Graduate Student Fellowship. 

Unearthing Long-Gone Hurricanes

Unearthing Long-Gone Hurricanes

March 16, 2018

On Aug. 30, 2017, as the morning sun rose over the dusty savanna of West Africa, few were aware that the rustling breeze announced the birth of a terrifying but still unknown event. Who amongst us would recognize the gentle stirring of a giant yet to be?

It is here, over these rolling yellow grasslands, where the beginnings of some hurricanes come to life. Hot, dry air from the Sahara Desert collides with cool, wet air from the Gulf of Guinea, tucked under the big northwest bulge of the African continent. In the seam between these high- and low-pressure air systems, winds arise and blow westward toward the Atlantic in a powerful stream known as the African Easterly Jet.

This jet is highly unstable. It undulates north and south and north again. Bands of thunderstorms break off from the swerving jet and follow our jet into the Atlantic Ocean. There, a combination of moist air, warm ocean temperatures, and Earth’s rotation converge to provide all the ingredients to fuel a hurricane. All you need is some initial atmospheric disturbance—a band of thunderstorms perhaps—to trigger it. That’s what happened on Aug. 30 to give rise to tropical storm Irma.

The whole world knows what happened next. Irma moved westward, gathered energy from the warm moist air over the ocean, and intensified to Category 5 strength with wind speeds greater than 175 miles per hour. Irma left a trail of destruction in her wake, devastating Barbuda, the Virgin Islands, the Bahamas, and the Florida Keys.

But that’s not all it left behind.

As hurricanes such as Irma approach islands in the Caribbean, their strong winds generate huge waves that pick up large coarse-grained sand particles from the ocean floor and fling them into coastal lakes or lagoons. As the storms pass, the suspended particles drift back to the seafloor of these sheltered coastal basins and stay there, preserved in these tranquil environments for thousands of years.

That’s where I come in. I’m a graduate student pursuing my Ph.D. degree in the MIT-WHOI Joint Program in Oceanography. I work in the Coastal Systems Group at Woods Hole Oceanographic Institution, where we uncover the locations of these coastal basins and bring back some precious sediments that contain clues of past hurricanes. We follow the sedimentary evidence left behind from storms such as Irma to reconstruct the history of when and where hurricanes have struck over recent millennia.

Jousting for sediment cores

In pursuit of this goal, I found myself coated in sunscreen aboard a small pontoon boat crammed with equipment and other scientists headed toward the coast of Long Island in the Bahamas in 2016. This is the same Long Island that, one year later, would be ravaged by Hurricane Irma.

We may have seemed a comical lot. Strapped to our pontoon boat were thirty-foot-long aluminum tubes extending far beyond the bow of the boat, giving us the appearance of a vessel in search of a jousting opponent.

We used these tubes to extract sediment cores from the seafloor. We lowered the tubes to the ocean bottom, vibrated them into the sediment with the help of a powerful motor, and brought up tubes of intact sediment that ranged between thirty and sixty feet long. A longer tube reaches deeper into the sediment. The farther it goes down, the further back in time we can reach. So we always think big, bringing the longest tubes we can purchase and transport.

Lowering a tube to the seafloor often takes more than an hour of straining under the sweltering hot sun of the Caribbean, and bringing up an intact tube isn’t always guaranteed. If we drive the barrel too far into the sediments and strike the bedrock underneath, the pressure on the pullout can be too great for our small vessel or for the aluminum tube. Many times the pressure on pullout shears the tube in half, and we bring up an empty tube. And, of course, there is always the constant fear that the pullout might sink our boat.

We were searching for a “blue hole”—a big round patch of deep blue water surrounded by a contrasting expanse of sunlit turquoise water common on the shallow banks of the Bahamas. The blue hole gets its color and its name from the extraordinarily deep hole in the seafloor beneath it. Blue holes were once underground limestone caves that formed above water when sea levels dropped during the last ice age.

Over time, these caverns collapsed, carving out deep holes in the ground. When the ice sheets thawed and sea levels rose, the caves were submerged, creating ideal basins for capturing coarse-grained particles swept in by overlying storm waves. They also provide  a sheltered environment to preserve the particles as sand layers on their bottoms.

The dream team

We steered our pontoon boat over the center of a blue hole, and our team burst into action. “Teamwork makes the dream work!” repeated Pete van Hengstum, one of our collaborators, from Texas A&M University of Galveston.

It takes a small platoon of scientists and students to make coring blue holes successful. In this case, one team stayed aboard the pontoon boat to set up the coring equipment and begin the process of pulling up aluminum tubes full of sweet, sweet mud. I joined the second team ferrying cores ashore where we began processing them. The not-so-simple act of bringing up cores from the bottom of the blue hole is only the beginning of the battle.

A thirty-foot-long barrel full of mud can weigh more than 300 pounds, making it impossible for a single person or a small team of people to move it great distances. My team needs to cut it down to a more manageable size.

Once we dragged a core on shore, we set upon it with hacksaws to cut it into smaller sections and with caps and electrical tape ready to seal the tops. Sometimes air in the tubes caused sediment to explode out of the incisions we cut—and that, of course, spurred another frenzy as we all attempted to cap the core section before we lost any of our precious mud.

At the end of the day, we had collected four or five cores from the site, cut and labeled them, and readied them for shipment back to the lab at Woods Hole Oceanographic Institution where I would analyze them. We hoped that they would tell us how often hurricane events such as Irma struck the Bahamas over the past two thousand years.

Library of sediment

I often remark that I have the best job in the world. Not many people can say they get paid to play with mud every day.

Back in the lab, I spend my days perusing our library of sediments. Conventional libraries consist of shelves and shelves of books telling stories of the world. Our sediment library takes an unconventional approach to storytelling. It is filled with shelves and shelves of sediment cores extracted from icy Greenland to the jungles of Fiji.

The cores in our library tell stories of the past—in particular what the climate was like long before these regions were settled by populations who recorded history. Our cores from Long Island in the Bahamas joined this collection, providing a glimpse of hurricane activity extending long before Europeans sailed across the Atlantic to colonize these island locations.

When we split the sediment cores from Long Island in half, they displayed a distinct orderly beauty. Layers upon layers of golden carbonate sediment lay perfectly compacted on top of one another.

To uncover what each layer tells us, I removed centimeter-wide chunks of sediment from the core and ran these samples through a fine-meshed sieve. The finer-grained particles pass through, leaving the coarser sand particles. I hunted down the sandiest layers in my sediment cores, the layers that represent hurricanes passing Long Island.

Getting the timing right

But how can we tell when these hurricanes passed by? To put an age on every sediment layer, I pulled small specks of mangrove leaves out of sections of the cores. These leaves—also blown into the blue hole by hurricanes—contain radiocarbon, a naturally occurring radioactive isotope of carbon (14C) that resides in every living thing on Earth.

When a mangrove leaf dies and falls into a blue hole, its radiocarbon begins to decay at a measurable rate until it becomes the stable carbon isotope (12C). I am lucky to have, within walking distance of my lab, the National Ocean Sciences Accelerator Mass Spectrometry Facility (NOSAMS) at WHOI, where colleagues can measure the ratio of 14C to 12C isotopes in my samples and determine how long ago my mangrove leaves drifted into the blue holes.

Together, the combination of grain size data and radiocarbon dates from mangrove leaves revealed a record of dramatic changes in hurricane strikes over Long Island over the past seven centuries. From the 1400s to 1600s, hurricanes struck Long Island time after time, knocking layer after layer of sand into the blue hole. The same high level of activity is true for the present. Over the past two hundred years, Long Island has been battered by an average of six storms per century.

During the 17th century, however, hurricane activity on Long Island virtually shut down. Only one or two storms hit the island.

What could have caused this hiatus in hurricane activity that lasted almost a century? We are still trying to puzzle that out.

Is there some perfect combination of ocean or land temperatures, wind patterns over the West African savanna, or additional conditions that spin up large numbers of hurricanes in the Atlantic? Will Earth’s changing climate shift the formula? Only more work and more records will tell.

Years from now, researchers may core a blue hole and find sand deposited by Irma in 2017. But that hurricane is already known. We are uncovering the long history of unknown hurricanes—paleohurricanes. That history will help us piece together the complex equation that spawns modern hurricanes and help us predict how often they will occur and how strong they may be in the future.

Funding for this research came from the Dalio Explore Fund, the National Science Foundation, the National Science Foundation Graduate Research Fellowship Program, and Woods Hole Sea Grant.