Research Highlights
News & Insights
A marine chemist spends his time at home tinkering on a high-tech buoy in the basement, proving that being homebound doesn’t mean you can’t think big.
Ken Buesseler joins the hosts of Future Hindsight Podcast to talk about the safety of the Pacific Ocean, the natural occurrence of radioactivity in our environment, and a citizen scientist project for oceanic testing.
A decade of research since the Deepwater Horizon disaster has revealed how sunlight—its importance long understated in oil spill science—substantially alters petroleum floating at the sea surface.
News Releases

Novel analysis method may also be useful for monitoring volcanic activity
Researchers at Woods Hole Oceanographic Institution (WHOI), the University of California Los Angeles (UCLA) and their colleagues used a new geochemical tool to shed light on the origin of nitrogen and other volatile elements on Earth, which may also prove useful as a way to monitor the activity of volcanoes. Their findings were published April 16, 2020, in the journal Nature.
Nitrogen is the most abundant gas in the atmosphere, and is the primary component of the air we breathe. Nitrogen is also found in rocks, including those tucked deep within the planet’s interior. Until now, it was difficult to distinguish between nitrogen sources coming from air and those coming from inside the Earth’s mantle when measuring gases from volcanoes.
“We found that air contamination was masking the pristine ‘source signature’ of many volcanic gas samples,” says WHOI geochemist Peter Barry, a coauthor of the study.
Without that distinction, scientists weren’t able to answer basic questions like: Is nitrogen left over from Earth’s formation or was it delivered to the planet later on? How is nitrogen from the atmosphere related to nitrogen coming out of volcanoes?
Barry and lead author Jabrane Labidi of UCLA, now a researcher at Institut de Physique du Globe de Paris, worked in partnership with international geochemists to analyze volcanic gas samples from around the globe—including gases from Iceland and Yellowstone National Park—using a new method of analyzing “clumped” nitrogen isotopes. This method provided a unique way to identify molecules of nitrogen that come from air, which allowed the researchers to see the true gas compositions deep within Earth’s mantle. This ultimately revealed evidence that nitrogen in the mantle has most likely been there since our planet initially formed.
“Once air contamination is accounted for, we gained new and valuable insights into the origin of nitrogen and the evolution of our planet,” Barry says.
While this new method helps scientists understand the origins of volatile elements on Earth, it may also prove useful as a way of monitoring the activity of volcanoes. This is because the composition of gases bellowing from volcanic centers change prior to eruptions. It could be that the mix of mantle and air nitrogen could one day be used as a signal of eruptions.
This study was supported by the Deep Carbon Observatory and the Alfred P. Sloan Foundation. The research team also included colleagues David Bekaert and Mark Kurz from WHOI, scientists from several other U.S.-based universities, and from France, Canada, Italy, the United Kingdom and Iceland.
A new geochemical analysis method helps scientists understand the origins of volatile elements on Earth, and may also prove useful as a way of monitoring the activity of volcanoes, such as this one, Mount Etna on the east coast of Sicily, Italy. (Video by Peter Barry, © Woods Hole Oceanographic Institution)
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 www.whoi.edu.
Key Takeaways
- Nitrogen is the most abundant gas in Earth’s atmosphere, but it’s origin and how much is in Earth’s interior was previously unknown.
- A new method of nitrogen analysis of volcanic gases from around the world revealed more accurate measurements of volatile elements in Earth’s interior.
- This new method could be useful in monitoring the activity of volcanoes.
- Nitrogen in Earth’s mantle has most likely been there from the beginning of our planet.
Shelf sediments, freshwater runoff from rivers brings more carbon, nutrients to North Pole
A new study by researchers at Woods Hole Oceanographic Institution (WHOI) and their international colleagues found that freshwater runoff from rivers and continental shelf sediments are bringing significant quantities of carbon and trace elements into parts of the Arctic Ocean via the Transpolar Drift—a major surface current that moves water from Siberia across the North Pole to the North Atlantic Ocean.
In 2015, oceanographers conducting research in the Arctic Ocean as part of the International GEOTRACES program found much higher concentrations of trace elements in surface waters near the North Pole than in regions on either side of the current. Their results published this week in the Journal of Geophysical Research-Oceans.
“Many important trace elements that enter the ocean from rivers and shelf sediments are quickly removed from the water column,” explains WHOI marine chemist Matthew Charette, lead author of the study. “But in the Arctic they are bound with abundant organic matter from rivers, which allows the mixture to be transported into the central Arctic, over 1,000 kilometers from their source.”
Trace elements, like iron, form essential building blocks for ocean life. As the Arctic warms and larger swaths of the ocean become ice-free for longer periods of time, marine algae are becoming more productive. A greater abundance of trace elements coming from rivers and shelf sediments can lead to increases in nutrients reaching the central Arctic Ocean, further fueling algal production.
Key Takeaways
- Trace elements may increase with future Arctic melt releasing dissolved organic matter from permafrost thaw.
- Nutrient levels and productivity may increase in the Arctic, but loss of ice cover will continue to worsen overall warming as more heat is absorbed from the atmosphere.
Transpolar Drift as a Source of Riverine and Shelf-derived Trace Elements to the Central Arctic Ocean (Journal of Geophysical Research: Oceans, 2020)

Click image to enlarge. Map of the USCGC Healy route during 2015 expedition in the Arctic Ocean as part of the International GEOTRACES program. (Illustration by Natalie Renier, © Woods Hole Oceanographic Institution)
“It’s difficult to say exactly what changes this might bring,” says Charette. “but we do know that the structure of marine ecosystems is set by nutrient availability.”
Nutrients fuel the growth of phytoplankton, a microscopic algae that forms the base of the marine food web. Generally speaking, more phytoplankton brings more zooplankton—small fish and crustaceans, which can then be eaten by top ocean predators like seals and whales.
Higher concentrations of trace elements and nutrients previously locked up in frozen soils (permafrost) are expected to increase as more river runoff reaches the Arctic, which is warming at a much faster rate than most anywhere else on Earth. While an increase in nutrients may boost Arctic marine productivity, Charette cautions that the continued loss of sea ice will further exacerbate climate warming, which will impact ecosystems more broadly.
“The Arctic plays an important role in regulating Earth’s climate, with the ice cover reflecting sunlight back to space, helping to mitigate rising global temperatures due to greenhouse gas emissions,” he adds. “Once the ice is gone, the Arctic Ocean will absorb more heat from the atmosphere, which will only make our climate predicament worse.”
A polar bear sighting off the U.S. Coast Guard Cutter Healy during the 2015 Arctic GEOTRACES expedition. The Arctic has experienced the highest degree of warming on the planet, causing sea ice to thin and recede. The region’s iconic polar bears rely on sea ice to hunt, travel and mate. (Video courtesy of Bill Schmoker PolarTrek teacher 2015 GEOTRACES Arctic expedition)
Funding for Arctic GEOTRACES was provided by the U.S. National Science Foundation, Swedish Research Council Formas, French Agence Nationale de la Recherche and LabexMER, Netherlands Organization for Scientific Research, and Independent Research Fund Denmark. The Arctic GEOTRACES expeditions were supported by the captains and crew of the USCGC Healy and the R/V Polarstern.
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 www.whoi.edu.
Scientists have long known that the ocean plays an essential role in capturing carbon from the atmosphere, but a new study shows that the efficiency of the ocean’s “biological carbon pump” has been drastically underestimated. (Video by Elise Hugus, UnderCurrent Productions, © Woods Hole Oceanographic Institution)
Every spring in the Northern Hemisphere, the ocean surface erupts in a massive bloom of phytoplankton. Like plants, these single-celled floating organisms use photosynthesis to turn light into energy, consuming carbon dioxide and releasing oxygen in the process. When phytoplankton die or are eaten by zooplankton, the carbon-rich fragments sinks deeper into the ocean, where it is, in turn, eaten by other creatures or buried in sediments. This process is key to the “biological carbon pump,” an important part of the global carbon cycle.
Scientists have long known that the ocean plays an essential role in capturing carbon from the atmosphere, but a new study from Woods Hole Oceanographic Institution (WHOI) shows that the efficiency of the ocean’s “biological carbon pump” has been drastically underestimated, with implications for future climate assessments.
In a paper published April 6 in Proceedings of the National Academy of Sciences, WHOI geochemist Ken Buesseler and colleagues demonstrated that the depth of the sunlit area where photosynthesis occurs varies significantly throughout the ocean. This matters because the phytoplankton’s ability to take up carbon depends on amount of sunlight that’s able to penetrate the ocean’s upper layer. By taking account of the depth of the euphotic, or sunlit zone, the authors found that about twice as much carbon sinks into the ocean per year than previously estimated.
The paper relies on previous studies of the carbon pump, including the authors’ own. “If you look at the same data in a new way, you get a very different view of the ocean’s role in processing carbon, hence its role in regulating climate,” says Buesseler.
“Using the new metrics, we will be able to refine the models to not just tell us how the ocean looks today, but how it will look in the future,” he adds. “Is the amount of carbon sinking in the ocean going up or down? That number affects the climate of the world we live in.”
In the paper, Buesseler and his coauthors call on their fellow oceanographers to consider their data in context of the actual boundary of the euphotic zone.
“If we’re going to call something a euphotic zone, we need to define that,” he says. “So we’re insisting on a more formal definition so that we can compare sites.”
Rather than taking measurements at fixed depths, the authors used chlorophyll sensors —indicating the presence of phytoplankton— to rapidly assess the depth of the sunlit region. They also suggest using the signature from a naturally-occuring thorium isotope to estimate the rate at which carbon particles are sinking.
Buesseler is a principal investigator with WHOI’s Ocean Twilight Zone project, which focuses on the little-understood but vastly important mid-ocean region. In a commentary published in Nature on March 31, Buesseler and colleagues call on the international marine research community to intensify their studies of the twilight zone during the upcoming United Nations Decade of the Ocean (2021-2030). Increased understanding of the twilight zone ecosystem and its role in regulating climate, the authors say, will lead to global policy to protect the area from exploitation.
Coauthors of the paper include: Phillip Boyd of University of Tasmania, Australia; Erin Black of Dalhousie University, Nova Scotia, and Lamont Doherty Earth Observatory, New York; and David Siegel, University of California, Santa Barbara.
This work was funded by: WHOI’s Ocean Twilight Zone project; NASA as part of the EXport Processes in the global Ocean from RemoTe Sensing (EXPORTS) program; the Ocean Frontier Institute at Dalhousie University; and the Australian Research Council.
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 www.whoi.edu.
Key Takeaways
- Using photosynthesis, phytoplankton floating on the ocean’s surface absorb carbon dioxide from the atmosphere. The depth of this sunlit layer affects the efficiency of the ocean’s “biological carbon pump” or ability to take up carbon.
- By measuring the depth of the ocean’s sunlit surface area, or “euphotic zone”, scientists found that the “biological carbon pump” is twice as efficient as previously estimated.
- Using this method could lead to more accurate climate models, such as those used by the Intergovernmental Panel on Climate Change, to set global climate policy.
- More study of the mid-ocean “twilight zone” will lead to better understanding of the biological carbon pump’s role in regulating climate and the productivity of fisheries.

Exclusive report
Value Beyond View: Illuminating the human benefits of the ocean twilight zone
Did you know that there’s a natural carbon sink—even bigger than the Amazon rainforest—that helps regulate Earth’s climate by sucking up to six billion tons of carbon from the air each year?
A new report from researchers at Woods Hole Oceanographic Institution (WHOI) reveals for the first time the unseen—and somewhat surprising—benefits that people receive from the ocean’s twilight zone. Also known as the “mesopelagic,” this is the ocean layer just beyond the sunlit surface.
The ocean twilight zone is a mysterious place filled with alien-looking creatures. The nightly, massive migration of animals from the zone to the surface waters to find food helps to cycle carbon through the ocean’s depths, down into the deep ocean and even to the seabed, where it can remain sequestered indefinitely.
“We knew that the ocean’s twilight zone played an important role in climate, but we are uncertain about how much carbon it is sequestering, or trapping, annually,” says Porter Hoagland, a WHOI marine policy analyst and lead author of the report. “This massive migration of tiny creatures is happening all over the world, helping to remove an enormous amount of carbon from the atmosphere.”
Exactly how much carbon is difficult to pinpoint because the ocean twilight zone is challenging to get to and is understudied. The WHOI Ocean Twilight Zone project, which launched in April 2018, is focused on changing that with the development of new technologies.
It’s estimated that two to six billion metric tons of carbon are sequestered through the ocean’s twilight zone annually. By comparison, the world’s largest rain forest sucks in only about 544 million metric tons of carbon a year—five percent of the world’s annual 10 billion metric tons of carbon emissions.
Using a range of prices for carbon, reflecting future damages expected as a consequence of a changing climate, this “regulating” service has an estimated value of $300 to $900 billion annually, Hoagland notes. Without the ocean’s ability to sequester carbon, atmospheric carbon dioxide levels could be as much as 200 parts per million higher than they are today (about 415 ppm), which would result in a temperature increase of about six degrees Celsius or 10.8 degrees Fahrenheit.
In addition to its role in the carbon cycle, the twilight zone likely harbors more fish biomass than the rest of the ocean combined, and it is home to the most abundant vertebrate species on the planet— the bristlemouth. While twilight zone fish are unlikely to ever end up on peoples’ dinner plates because of their small size and strange appearance, they do provide meals for larger, economically important fish, like tuna and swordfish, and for other top predators, including sharks, whales, seals, penguins, and seabirds.
The twilight zone’s biological abundance makes it an attractive target for commercial fishing operations. Ocean twilight zone animals could be harvested to produce fish meal to support the rapidly growing aquaculture industry and to provide fish oils for nutraceutical markets. Because the twilight zone is situated largely in unregulated international waters, there is concern that its potential resources could be subject to unsustainable exploitation.
The research team hopes that the report will be useful for decision makers, such as the United Nations delegates who will meet this spring in New York to continue developing a new international agreement governing the conservation and sustainable management of marine life on the high seas, in areas beyond the coastal waters managed by individual member States.
“We need to think carefully about what we stand to gain or lose from future actions that could affect the animals of the twilight zone and their valuable ecosystem services,” says Hoagland. “Increasing scientific understanding is essential if we are going to move toward a goal of the sustainable use of the resources.”
Read Frequently Asked Questions about the ocean twilight zone, or download the report.
This research is part of the Woods Hole Oceanographic Institution’s Ocean Twilight Zone Project, funded as part of The Audacious Project housed at TED.
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 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 www.whoi.edu.
Key Takeaways
- The ocean’s twilight zone provides benefits to humans that occur largely out of sight.
- Ocean twilight zone creatures remove two to six billion metric tons of carbon annually, comprising a regulating service worth $300 to $900 billion each year.
- Without the nightly animal migrations that help shuttle carbon to the deep ocean, atmospheric carbon dioxide levels could be as much as one-third more than they are today, which translates to an average temperature increase of about six degrees Celsius or 10.8 degrees Fahrenheit.
- Commercial interests are considering the harvest of twilight zone organisms as a source of proteins and lipids for expanding aquaculture and nutraceutical operations, which are expected to grow by 37 percent from 2016 to 2030.
- The loss of the carbon sequestration service as a consequence of a changing climate or the overfishing of twilight zone animals could amount to significant mitigation and adaptation costs (estimated in the hundreds of billions to trillions of dollars) by the end of the century.
Microorganisms play important roles in the health and protection of coral reefs, yet exploring these connections can be difficult due to the lack of unspoiled reef systems throughout the global ocean. A collaborative study led by scientists at the Woods Hole Oceanographic Institution (WHOI) and the Centro de Investigaciones Marinas – Universidad de La Habana (CIM-UH) compared seawater from 25 reefs in Cuba and the U.S. Florida Keys varying in human impact and protection, and found that those with higher microbial diversity and lower concentrations of nutrients and organic carbon—primarily caused by human activities—were markedly healthier.
“Human impacts such as overfishing and pollution lead to changes in reef structure,” says WHOI graduate student Laura Weber, lead author of the paper. A healthy reef provides home to a diverse group of marine animals, including herbivores that in turn help control algal growth. “Removal of algae grazers such as herbivorous fish and sea urchins leads to increases in macroalgae, which then leads to increased organic carbon, contributing to the degradation of coral reefs,” Weber adds.
Key Takeaways:
- Offshore and highly-protected reefs are healthier than nearshore reefs with less protection from human impacts.
- Reefs with lower nutrient runoff and carbon from industrial activities are markedly healthier.
- More species of microbes were found on healthier Cuban reefs than impacted Floridian reefs.
Researchers sampled seawater from each site and measured nutrients as well as a suite of parameters that offer insights into the microbial community. They found a notable difference between the heavily protected offshore reefs in Cuba and the more impacted nearshore ones in the Florida Keys.
Jardines de la Reina (Gardens of the Queen), the largest protected area in the Caribbean, is a complex ecosystem of small islands, mangrove forests, and coral reefs located about 50 miles off the southern coast of Cuba. These highly-protected offshore reefs provide habitat and feeding grounds for large numbers of fish, including top predators like sharks and groupers. Here, researchers found low concentrations of nutrients, and a high abundance of Prochlorococcus—a photosynthetic bacterium that thrives in low nutrient waters.
“Cuba does not have large-scale industrialized agriculture or extensive development along most of its coastline,” says Patricia González-Díaz, Director of CIM-UH and co-author of the study. “So there is not a lot of nutrient run-off and sedimentation flowing on to the reefs.” Additionally, the reefs of Jardines de la Reina may be further buffered from impacts by the mangroves and seagrass meadows that lie between the island of Cuba and the reef system of Jardines de la Reina.

Nearshore reefs in the heavily-impacted Florida Keys show unhealthier corals and less marine life. This mountainous star coral (Orbicella faveolata) from offshore Summerland Key shows patches of dead coral, now overgrown with algae. (Photo by Amy Apprill, ©Woods Hole Oceanographic Institution)
Conversely, seawater from the more accessible reefs of Los Canarreos, Cuba—which are more impacted by humans through subsistence and illegal fishing, tourism, and the diving industry—and the nearshore reefs in the Florida Keys both contained higher organic carbon and nitrogen concentrations.
The study demonstrates that protected and healthier offshore Cuban reefs have lower nutrient and carbon levels, and microbial communities that are more diverse with abundant photosynthetic microbes compared to the more impacted, nearshore reefs of Florida. This work suggests that the offshore nature and highly protected status of reefs in Jardines de la Reina have played a role in keeping these reefs healthy by being far from or minimizing human impacts. These findings may aid resource managers in decision making to protect and restore Caribbean coral reefs in the face of habitat and climate-based change.
The study was published in the journal Environmental Microbiology on December 13. Co-authors of the paper include colleagues from CIM-UH, Universidad Nacional Autónoma de México, Phillip and Patricia Frost Museum of Science, Mote Marine Laboratory, and the University of California, Santa Barbara. For more information, visit Amy Apprill’s lab.
Funding for this work was provided by OceanX and the National Science Foundation.
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 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 www.whoi.edu.
Researchers at Woods Hole Oceanographic Institution (WHOI) successfully conceived and tested a portable device, DISCO, that performed the first in situ measurements of a highly reactive type of oxygen, known as superoxide, which may play an integral role in the health of coral reefs. Their findings were published as an early view article on Oct. 29 in the journal of Environmental Science and Technology.
Superoxide is a reactive chemical that is a byproduct within all respiring and photosynthesizing organisms. This unstable form of oxygen, or reactive oxygen species (ROS), is prone to stealing or giving electrons. As a consequence, superoxide has been known to catalyze chemical reactions that can lead to cancer and other diseases—one of the many reasons today’s diets stress incorporating antioxidant-rich foods, such as blueberries, nuts or dark chocolate. However, in many organisms, including corals, the nature of superoxide may be more complicated.
“It used to be that [superoxide] was only considered toxic,” says WHOI marine chemist Colleen Hansel, a coauthor of the study. “But we know now that it’s used for a lot of beneficial processes. In fungi, plants and even animals, superoxide is important for an organism’s immune response [for example]. That [logic] hasn’t really transferred over into marine life yet.”
Hansel and her team investigated the chemical’s interaction with symbiotic microorganisms that inhabit coral reefs. Preliminary evidence suggests that while corals may not be immune to superoxide’s toxic effects when it reaches high concentrations inside their cells, they may also be employing the chemical outside their cells for beneifical reasons, such as a defense against marine infections––some of which may be spurred on by warmer ocean temperatures.
“Superoxide to organisms reflects like a kind of Goldilocks effect,” says Kalina Grabb, the study’s lead author and WHOI-MIT Joint Program student in Hansel’s lab. “You don’t want too much because it can lead to oxidative stress, but you don’t want too little because it’s essential for physiological functions.”
Until recently, the ephemeral nature of superoxide has made it incredibly difficult to sample in the marine environment– the chemical only lasts mere minutes in seawater. This traditionally left no time to transfer water samples to a lab for adequate analysis. At the same time, other boat-borne systems were cumbersome to operate and could only be used in very select environments.
To overcome these limitations, WHOI engineer Jason Kapit and WHOI scientist Scott Wankel worked closely with Hansel and her lab to develop the world’s first portable DIver-operated Submersible Chemiluminescent SensOr, or DISCO. With it, they were able to sample superoxide concentrations in real time during a 2017 research trip to Cuba’s pristine reef system, Jardines de la Reina.
The boxy handheld device comprises a water-sealed battery and a tablet screen that scuba divers can operate at depth. Inside, fluidic pumps uptake the invisible chemical as corals produce it. DISCO then adds a chemical to the mixture that reacts with superoxide to create measurable light, read by an onboard sensor. Armed with these tools, DISCO detected notable differences in superoxide levels between species of corals in its first field test.
“Now, we want to be able to get at the why,” adds Hansel. “Why are they purposely making superoxide and is this helping the coral or is it related to stress in some way?”

WHOI scientist Colleen Hansel scuba-dives to corals in Cuba’s Gardens of the Queen reefs with the first model of DISCO, which stands for DIver-operated Submersible Chemiluminescent sensOr. (Photo by Ashlee Lillis, © Woods Hole Oceanographic Institution)
Since its inception, DISCO has been reengineered to become even more portable and lightweight. In 2018, Hansel, Wankel and Kapit collaborated on another iteration of the device, this time at roughly half the size and weight of its predecessor. The team has also adapted DISCO into a deep-sea version known as SOLARIS to accompany WHOI’s human-occupied submersible, ALVIN. In October 2019, they were able to use SOLARIS to detect superoxide produced by corals at 1,300 meters deep (~4,200 feet) along the Davison Seamount off the coast of central California.
“We are already talking about what we can do next with this technology,” says Hansel. “How can we build new sensors that incorporate other reactive oxygen species to fully understand their role in organismal health and ocean chemistry? I don’t see an end in sight.”
Also collaborating on the paper were Scott Wankel, Jason Kapit, Kevin Manganini and Amy Apprill of Woods Hole Oceanographic Institution, and Maickel Armenteros from Universidad de La Habana.
The research was funded by Schmidt Marine Technology Partners (G-1801-57385; to CMH), the National Science Foundation Graduate Research Fellowship Program (to KCG), and the Dalio Foundation’s Ocean Initiative (now ‘OceanX’) (to AA). The research was conducted in the Jardines de la Reina, Cuba, in accordance with the requirements of the Republic of Cuba, conducted under permits NV2370 and NV2568 issued by the Ministerio de Relaciones Exteriores (MINREX). This research was also conducted in accordance with a memorandum of understanding between the National Center of Protected Areas (CNAP) of the Ministry of Science, Technology and Environment (CITMA) in Cuba and the Woods Hole Oceanographic Institution in the USA.
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 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 www.whoi.edu.
Symbiotic algae living inside corals provide those animals with their vibrant color, as well as many of the nutrients they need to survive. That algae, and other microbes within the bodies of corals, have been extensively studied—yet until now, researchers have largely ignored the microbial communities just outside of the coral colonies. A new study from scientists at the Woods Hole Oceanographic Institution (WHOI) has begun to describe and catalogue microbes that live just a few centimeters from the surface of corals, laying the groundwork for future studies. The researchers’ work published May 21 in the journal Limnology and Oceanography.
“Microbes are everywhere on reefs. There’s roughly a million of them in a single milliliter, which is about 20 drops, of seawater. But we don’t yet have a good sense of the microbial population that exists right next to corals,” says Laura Weber, lead author of the study and a PhD student in the joint WHOI-MIT program. “There’s some evidence from previous studies that corals may be surrounded by unique microbial cells, but many questions are still unanswered. Do these cells differ with coral species or reef site? How might they function?” she says.
To begin to chip away at those questions, Weber and her colleagues focused on sampling the seawater surrounding Caribbean corals across multiple reefs. Weber thinks that microbes immediately next to the corals could play a role in breaking down waste products from the colonies, introducing new nutrients and potentially letting symbiotic algae or pathogens into the corals themselves.
Along with her PhD advisor, Amy Apprill, Weber traveled to a protected coral reef system called the “Jardines de la Reina,” located amid a string of remote islands near the southern coast of Cuba. Once there, Weber teamed with local Cuban scientists Patricia Gonzalez-Díaz and Maickel Armenteros to dive on the reefs and collect dozens of small samples from the water near five different species of coral.
“The Cuban reefs provided a perfect opportunity for this study. Because they’re so remote, there’s limited impact from human activities,” says Apprill, a coral reef ecologist at WHOI and senior author on the paper. A majority of the reef system was established as a marine protected area by the Cuban government in 1996, so fishing is prohibited and diving tourism is restricted. “The Cuban scientists we collaborated with are also doing research that complements our own. They have extensive knowledge of their marine environment, and provided access to research permits, which was a clear advantage when planning sites for cruises,” Apprill adds.
Once the samples were back in the US, Weber analyzed the genetic material of the microbes inside them to figure out which species were present. She found that different types of coral did indeed have different microbial communities living near them. ”We started finding cool species-specific trends,” Weber says. “I didn’t think we would see any differences at all—but it turned out that in some areas, the bacterium Endozoicomonas, which lives symbiotically with corals, was actually enriched in the seawater closer to corals compared to the surrounding reef water. That means the region adjacent to corals could be important for attracting symbionts to a coral’s surface, or it could represent a region where corals shed their symbionts.”
In addition to understanding which microbes are living next to corals, Weber and Apprill also looked at the microorganisms’ potential ecological functions. They found that the seawater microbes contained genes that let them interact with the coral surface, suggesting that there may be important interactions between seawater microorganisms and the coral surface.
“Scientists have been working for a while now to understand the role of microorganisms in reef environments and within coral colonies. But now we have evidence that demonstrates a possible relationship between seawater microbes and coral symbionts. That gives us some clues to how they find and infect coral colonies, and how they might impact the health of the corals. It’s very exciting,” Weber says.
This project was funded by the Dalio Explore Fund, which supports scientific research at WHOI. The fund is part of Dalio Philanthropies’ larger commitment to ocean exploration and discovery, including the new OceanX initiative.
“We are thrilled to support WHOI’s scientific research efforts through the Dalio Explore Fund,” said Vincent Pieribone, Vice Chairman, OceanX. “The findings from this mission will help reveal the secret lives of coral, how their microbiome – similar to ours – supports good health, and how, when they are at an imbalance, corals, like humans, can become sick.”
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 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 www.whoi.edu.
Two years ago an international team of scientists visited Costa Rica’s subduction zone, where the ocean floor sinks beneath the continent and volcanoes tower above the surface. They wanted to find out if microbes can affect the cycle of carbon moving from Earth’s surface into the deep interior. According to their new study in Nature, the answer is affirmatively—yes they can.
This groundbreaking study, published in Nature, shows that microbes consume and – crucially – help trap a small amount of sinking carbon in this zone. This finding has important implications for understanding Earth’s fundamental processes and for revealing how nature can potentially help mitigate climate change.
At a subduction zone there is communication between Earth’s surface and interior. Two plates collide and the denser plate sinks, transporting material from the surface into Earth’s interior. Showing that the microbes at the near-surface are playing a fundamental role in how carbon and other elements are being locked up into the crust provides a profound new understanding of Earth processes and helps researchers model how Earth’s interior may develop over time.
“What we’ve shown in this study is that in areas that are critically important for putting chemicals back down into the planet – these big subduction zones – life is sequestering carbon,” said Chris Ballentine, Head of the Department of Earth Sciences at the University of Oxford and a co-author of the paper. “On geological timescales life might be controlling the chemicals at the surface and storing elements like carbon in the crust.”
This is the first evidence that subterranean life plays a role in removing carbon from subduction zones. It has been well established that microbes are capable of taking carbon dissolved in water and converting it into a mineral within the rocks. The research showed that this happens on the large scale across a subduction zone. It is a natural CO2 sequestration process which can control the availability of carbon on Earth’s surface.
“We found that a substantial amount of carbon is being trapped in non-volcanic areas instead of escaping through volcanoes or sinking into Earth’s interior,” said Peter Barry, WHOI marine chemist and lead author of the paper. Barry carried out the research while at the Department of Earth Sciences, Oxford University.
“Until this point scientists had assumed that life plays little to no role in whether this oceanic carbon is transported all the way into the mantle, but we found that life and chemical processes work together to be the gatekeepers of carbon delivery to the mantle.”
During the 12-day expedition, the 25-person group of multi-disciplinary scientists collected water samples from thermal springs throughout Costa Rica. Scientists have long predicted that these thermal waters spit out ancient carbon molecules, subducted millions of years before. By comparing the relative amounts of two different kinds of carbon – called isotopes – the scientists showed that the predictions were true and that previously unrecognized processes were at work in the crust above the subduction zone, acting to trap large amounts of carbon.
Following their analyses, the scientists estimated that about 94 percent of that carbon transforms into calcite minerals and microbial biomass.
The researchers now plan to investigate other subduction zones to see if this trend is widespread. If these biological and geochemical processes occur worldwide, they would translate to 19 percent less carbon entering the deep mantle than previously estimated.
The research is part of the Deep Carbon Observatory’s Biology Meets Subduction project. The interdisciplinary team included 25 researchers from six nations belonging to each of the Deep Carbon Observatory (DCO) Science Communities: Deep Life, Extreme Chemistry and Physics, Reservoirs and Fluxes, and Deep Energy.
Watch this video for a glimpse of the 2017 field campaign, including the final descent into Póas Volcano’s active crater. Credit: Deep Carbon Observatory/CoLab Productions
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 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 www.whoi.edu.
Two new studies have shown that sunlight transforms oil on the ocean surface more significantly and quickly than previously thought. The phenomenon considerably limits the effectiveness of chemical dispersants, which are sprayed during oil spills to break up floating oil and reduce the amount of oil that reaches coastlines.
A research team led by Woods Hole Oceanographic Institution (WHOI) found that sunlight chemically alters crude oil floating on the sea surface within hours or days. In a follow-up study the team reported that sunlight changes oil into different compounds that dispersants cannot easily break up. The results of these two studies could affect how responders decide when, where, and how to use dispersants.
The related studies were published on February 20, 2018, in the Journal Environmental Science & Technology and today (April 25, 2018) in the journal Environmental Science & Technology Letters.
“It has been thought that sunlight has a negligible impact on the effectiveness of dispersants,” said Collin Ward, a scientist at WHOI and lead author of both studies. “Our findings show that sunlight is a primary factor controlling how well dispersants perform. And because photochemical changes happen fast, they limit the window of opportunity to apply dispersants effectively.”
Dispersants contain detergents, not unlike those people use to wash dishes, which help break oil into small droplets that can become diluted in the ocean, and/or are eaten by microbes before the oil can be swept to sensitive coastlines. But to do their work, the detergents (also known as surfactants) first need to mix with both the oil and water—and oil and water, famously, don’t mix.
To overcome this barrier, dispersants contain an organic solvent that helps the oil, detergents, and water to mix. Only once this key step occurs can the surfactants do their work to break oil into droplets. But sunlight hinders this key step, the new studies show.
Before dispersants can even be applied, light energy from the sun is already breaking chemical bonds in oil compounds—splitting off atoms or chemical chains and creating openings for oxygen to attach. This photo-oxidation process (also known as photochemical “weathering”) is similar to the process that causes paint on your car or colors on your clothes to fade if they are left out in the sun for too long.
To date, tests to determine dispersants’ effectiveness used only “fresh” oil that hadn’t been altered by sunlight. In the new studies, the researchers conducted extensive lab tests exposing oil to sunlight. They showed that sunlight rapidly transforms oil into residues that are only partially soluble in a dispersant’s solvent. That limits the ability of detergents to mix with the photo-oxidized oil and break the oil into droplets.
The finding suggests that responders should factor in sunlight when determining the “window of opportunity” to use dispersants effectively. That window will be far shorter than previously thought on sunny days than it would on cloudy days.
“This study challenges the paradigm that photochemical weathering has a negligible impact on the effectiveness of aerial dispersants applied in response to oil spills,” Ward said. “Sunlight rapidly alters oil into compounds that dispersants can’t easily break up into droplets. So photochemical weathering is a critical factor that should be considered to optimize decisions on when to use dispersants.”
In laboratory experiments in the 1970s, scientists showed that light alters the chemistry of oil, but the findings could not be applied to large-scale oil spills in the ocean. This was largely because in most spills, the oil quickly flowed away from the scene before it could be sampled. The long-duration flow from the 2010 Deepwater Horizon disaster provided a unique opportunity: Because oil floated on the sea surface for 102 days, it gave officials a chance to collect oil while it was floating on the sunlit sea surface.
The WHOI scientists obtained and tested samples of Deepwater Horizon oil that was skimmed from the surface almost immediately after it surfaced and was exposed to sunlight. They found that the longer the oil floated on the sunlit sea surface, the more the oil was photo-oxidized. They estimated that half of the spilled oil had been altered within days.
The next step was to test how the photo-oxidized oil would respond to dispersants. The scientists tested fresh unaltered Deepwater Horizon oil that was collected directly from the broken riser pipe on the seafloor. They meticulously controlled laboratory conditions to prevent temperature changes, evaporation, light infiltration, and other factors, and they exposed the oil to increasing durations of light. Cassia Armstrong, a guest student from Trinity College, played a key role in conducting these tests and is an author of the paper.
The WHOI scientists also closely collaborated with Robyn Conmy, one of the U.S. Environmental Protection Agency’s leading experts on developing new technologies for responding to oil spills. To conduct tests on the effectiveness of dispersants, the EPA uses a specific method and custom-designed glassware, which Conmy loaned to the WHOI scientists for their experiments.
Results of the experiments showed that light rapidly photo-oxidized the fresh oil, changing it into compounds that reduced the effectiveness of dispersants by at least 30 percent in a few days.
Next the scientists teamed with Deborah French McCay, an internationally recognized oil spill modeler at RPS ASA, a science and technology consulting firm in Rhode Island. They simulated conditions that might have occurred during the Deepwater Horizon spill, including a range of wind speeds and sunlight levels. Then they superimposed the actual 412 flight lines of planes that sprayed dispersants during the crisis.
The results showed that under average wind and sunlight conditions, the majority of dispersant applications would not have achieved even the minimum effectiveness levels designated by the EPA, because they targeted photochemically weathered oil. Even under the best-case scenarios for aerial dispersant spraying—cloudy weather (which would limit photochemical weathering) and high-wind conditions (which would transport oil farther from the spill area before sunlight transformed it)—dozens of aerial dispersant applications still would not have achieved EPA-designated effectiveness levels.
“We assembled a team that combined the expertise of academia, government, and industry,” explained Christopher Reddy, marine chemist at WHOI. “In future oil spill crises, the community needs the same kind of cooperation and collaboration to efficiently make the wisest decisions on how to respond most effectively.”
“This study shows how important it is to do the most basic research on chemical reactions that take place in the environment,” said Henrietta Edmonds, a program director in the National Science Foundation’s Division of Ocean Sciences, which funded the research. “The results help us learn how to effectively respond to oil spills.”
The Gulf of Mexico Research Initiative and the DEEP-C (Deep Sea to Coast Connectivity in the Eastern Gulf of Mexico) consortium also funded this research.
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 www.whoi.edu.
Scientists have found lingering radioactivity in the lagoons of remote Marshall Island atolls in the Pacific Ocean where the United States conducted 66 nuclear weapons tests in the 1940s and 1950s.
Radioactivity levels at Bikini and Enewetak Atolls were extensively studied in the decades after the testing ended, but there has been relatively little work conducted there recently. A team of scientists from Woods Hole Oceanographic Institution (WHOI) reported that levels of radioactive cesium and plutonium have decreased since the 1970s, but these elements continue to be released into the Pacific Ocean from seafloor sediments and lagoon waters.
The levels of plutonium are 100 or more times higher in lagoon waters compared to the surrounding Pacific Ocean and about two times higher for a radioactive form of cesium. Despite these enrichments, they do not exceed U.S. and international water quality standards set to protect human health, the scientists reported Oct. 30, 2017, in the journal Science of the Total Environment.
To determine the source of these radionuclides in lagoon waters, the WHOI scientists measured the amounts and flow of radioactive material entering the ocean from groundwater seeping from the islands. They found that groundwater was a relatively low source of radioactivity.
In particular, they found that radioactive groundwater was not leaking much from beneath one suspected potential source: the Runit Dome on the island of Runit—a massive 350-foot-wide concrete lid that covers 111,000 cubic yards of radioactive soil and debris that were bulldozed into a bomb crater and sealed over. It was constructed in the late 1970s by the U.S. government to contain contaminated waste from the nuclear tests. The bottom of the Runit Dome is not lined and below sea level, so scientists and others have been concerned that tidal action could move water through the buried radioactive material and bring it out to sea.
“The foundations of these island atolls are ancient coral reefs that have the porosity of Swiss cheese, so groundwater and any mobilized radioactive elements can percolate through them quite easily,” said WHOI geochemist Matt Charette. Though that does not seem to be happening now, the scientists advise that the Runit Dome area should be continuously monitored as sea level rises and the dome deteriorates.
Using isotopes of plutonium that act like a fingerprint to pinpoint sources, the WHOI scientists found that the seafloor sediments around Runit Island seem to be contributing about half of the plutonium to the lagoon. “Additional studies examining how radioactive plutonium moves through the environment would help elucidate why this small area is such a large source of radioactivity,” Buesseler said.
The WHOI scientists who conducted the study and wrote the report included Ken Buesseler, Matthew Charette, Steven Pike, Paul Henderson, and Lauren Kipp. They sailed to the islands aboard the research vessel Alucia on an expedition funded by the Dalio Explore Fund.
The team collected sediments from the lagoon with poster tube-sized collectors that were inserted by divers into the seafloor’s sediments, filled with mud, capped. Back in WHOI laboratories, the cores were sliced into layers and analyzed to reveal a buried record of local fallout from the nuclear tests. The scientists also collected and analyzed samples of lagoon waters .
On the islands, they collected groundwater samples from cisterns, wells, beaches, and other sites. They analyzed these samples for the levels of radioactive cesium and plutonium from weapons tests. For the first time on these islands, the scientists also measured isotopes of radium, a naturally occurring radioactive “tracer” that give scientists key information to determine how much and how fast groundwater flows from land into the ocean.
The WHOI research team also compared the radioactive contamination at the Marshall Islands to the contamination found today near Fukushima in Japan in the aftermath of the Dai-ichi Nuclear Power Plant disaster. “In contrast to Fukushima, where cesium is the most abundant radionuclide of concern, in these atolls, the focus should be on plutonium, given its significantly high levels,” said WHOI radiochemist Ken Buesseler.
The U.S. conducted 66 nuclear weapons tests between 1946 and 1958 at Bikini and Enewetak Atolls, each a ring of low-lying reef islands that surrounds a larger lagoon. Bikini has 26 islands; Enewetak had 42 islands, but three were bombed out of existence. They became known as the western part of the “U.S. Pacific Proving Grounds.”
Bikini and Enewetak are among 29 atolls that make up the Republic of the Marshall Islands, located in the equatorial Pacific, about 2,500 miles west of Hawaii. The collective land area of the thousands of small islands is equivalent to the area of Washington, D.C. but they are spread across an ocean area that exceeds the size of Alaska.
The work holds particular significance to the atolls’ indigenous populations which were evacuated before the tests and thus far have only been allowed to return to one small island in the Enewtak Atoll.
This research was funded by the Dalio Foundation and the Dalio Explore Fund.
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 www.whoi.edu.