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right whales

Rare Drone video shows critically endangered North Atlantic right whales

May 10, 2021

May 10, 2021   During a joint research trip on February 28 in Cape Cod Bay, Mass., WHOI whale trauma specialist Michael Moore, National Geographic photographer Brian Skerry, and scientists from New England Aquarium, witnessed a remarkable biological event: North…

A checkup for the oceans reveals threats to human health

December 7, 2020

The health of the world’s ocean is in serious decline—and human health is suffering as a result. A comprehensive report from the Monaco Commission and co-authored by several WHOI researchers investigates the impacts of ocean pollution and recommends actions to safeguard human health.

Unicorns of the Arctic face a new potential threat

December 1, 2020

Narwhals and other marine mammals could be vulnerable to a new threat we’ve become all too familiar with: COVID-19

WHOI working to help save critically endangered North Atlantic right whales

November 10, 2020

North Atlantic right whales are in crisis. There are approximately 356 individuals remaining, and with over 80% bearing scars of entanglements in fishing line, the race to save this species is more critical than ever.

WHOI oceanographer completes epic Arctic mission

October 13, 2020

The largest Arctic science expedition in history has ended, with the return of the German icebreaker Polarstern to its home port of Bremerhaven more than one year after it departed Tromso, Norway.


Listening to fish with passive acoustics

September 30, 2020

Scientists at the Woods Hole Oceanographic Institution and NOAA Fisheries combine forces to adapt technologies used to detect marine mammals for fisheries management.

deep water corals

Why we explore deep-water canyons off our coast

September 16, 2020

WHOI biologist Tim Shank joins NOAA Fisheries, the National Centers for Coastal Ocean Science, the National Ocean Service, and the Mid-Atlantic Regional Council on the Ocean (MARCO) to study the ecological diversity and economic value laden in the 90 underwater canyons along the northeast U.S. continental shelf

Exploring the shipwrecks of Stellwagen Bank

August 21, 2020

Join us live 8/25-8/27, as WHOI and NOAA scientists partner with Marine Imaging Technologies to explore the living shipwrecks of this marine sanctuary. Send in your questions and have them answered in real time to learn more about the diverse marine communities that call these ships home

diver and kelp

Can Seaweed Fuel the Future?

August 13, 2020

Fuels generated from kelp could provide a low-emission alternative to fossil fuels, and WHOI is breeding new strains of kelp and developing autonomous robots to monitor kelp farms

seal eating fish

Scientists and fishermen team up to film seals in fishing nets

August 6, 2020

Seals find ease in taking a meal already ensnared in wall-like gillnets cast by fishermen, but at what cost? WHOI biologist Andrea Bogomolni works with the fishing community to record and observe this behavior with the hopes of mitigating marine mammal bycatch

News Releases

Tiny Protozoa May Hold Key to World Water Safety

December 9, 2010

Right now, it looks a little like one of those plastic containers you might fill with gasoline when your car has run dry. But Scott Gallager is not headed to the nearest Mobil station. The Woods Hole Oceanographic Institution (WHOI) biologist has other, grander plans for his revolutionary Swimming Behavioral Spectrophotometer (SBS), which employs one-celled protozoa to detect toxins in water sources.

Not only is he working on streamlining the boxy-looking contraption—eventually even evolving it into a computer chip—but he sees it as a tool to potentially  “monitor all the drinking water in the world.

“It has a unique utility.”

The SBS has been selected as a 2010 “Better World” technology by the Association of University Technology Managers, which was recently published in the association’s Better World Report.

Not bad for a concept the U.S. Department of Defense (DOD) once put on the back burner for a year and a half before finally funding the idea to detect toxins in water sources using the smallest of animals, the one-celled protozoa.  Working in collaboration with Robert Jaffe (Environmental Toxicology Laboratory), the SBS may be on the cusp of providing unprecedented assessment of the world’s water supplies.

The groundbreaking technique works by introducing protozoa into small chambers with water samples taken from municipal, industrial, or military water sources and comparing them to control samples. Any alteration of the protozoa’s swimming mechanics is a sign that water conditions have changed and chemical or biological contaminants—pesticides, industrial chemicals, or biological warfare agents—may be present.

A camera records the protozoa’s swimming patterns, triggering software developed by Gallager and his colleagues that interprets the water’s risk. The device then relays color-coded, traffic light-type signals to the user: green (safe); yellow (check the water further for safety); red (bad or deadly—do not drink the water).

SBS’s big advantage is that it provides virtually instantaneous feedback on the water supply’s safety, Gallager says. “It’s a very rapid approach to providing a continuous monitoring for the potential presence of toxins,” he says.

The project is based on Gallager’s work on examining the possible effects of climate change on the swimming behavior of microscopic plankton and builds on the Tetramitus Growth Inhibition Test developed by the Environmental Toxicology Laboratory (ETL), as described in Jaffe’s patent application of 2000. Gallager, Jaffe and former WHOI colleague Wade McGillis—now a professor at Columbia University’s Lamont-Doherty Earth Observatory further developed the premise that protozoa, with their unique methods of propelling themselves through water, might act as barometers of the health of their local underwater environment.

After the 9/11 attacks in 2001, Phil Speser alerted McGillis that the Defense Department had issued an RFP on October 23 stating DOD’s interest in techniques for monitoring water supplies. Gallager, McGillis and Jaffe submitted the protozoa proposal to DOD in 2002; “I didn’t hear back,” Gallager said. “I literally forgot about it.”

The following year, he received an e-mail from the Defense Department. “It said, ‘How do you want us to transfer the funds?’ he recalled. “It was nearly a million dollars.”

Petrel Biosensors Inc., a private company has licensed the technology for further development and commercialization. The company is attempting to raise about $2 million to further develop and fine-tune the SBS.

“Other, existing water tests with this spectrum of activity take from 24 to 72 hours to generate results and can cost anywhere from $50 to $250 per test,” says Bob Curtis, Petrel’s chief executive officer. “We estimate that the SBS will perform real-time biological testing and provide nearly instant feedback for just $1 or $2 per test.”

Commercial applications for the technology include monitoring of industrial wastewater discharge, security and quality of drinking water supplies, and the potential testing of water sources associated with hydraulic fracturing, or fracking, in the oil and gas industry

Curtis says Petrel is developing a range of fully automated sensing instruments that include desktop, portable, and hand-held units. The company is finalizing a business plan and intends to raise $2 million in investment funding to develop initial SBS systems for commercial launch.

In his WHOI lab, Gallager works to refine and fine-tune the science responsible for those impressive statistics. He uses up to three types of protozoa depending on the project—for example, one type may be good for fresh water and another for brackish water.

The digital camera records the creatures’ movement at 30 frames a second. The software tracks the protozoa’s course in two and three dimensions and evaluates about 50 features of their paths—showing almost immediately if the organisms are spiraling out of control or careening erratically around the tank.

The results are compared to those of the control sample of distilled water, yielding a statistical analysis that “tells you if toxins are present,” Gallager says, setting off the red, yellow, or green warning light. Further analyses of the swimming patterns, along with the water’s acidity levels and other variables, can help scientists determine the presence of specific kinds of toxins, he says, including pesticides and heavy metals such as cadmium or mercury. The system includes controls to prevent the reporting of false-positive and false-negative results.

The tiny animals “replenish themselves” for long periods, Gallager says, so he needs to change the protozoa supply only about every two months.

“It’s not a solved problem yet,” Gallager says of the SBS system. “It needs a couple of more generations to size down.” But ultimately—after SBS has been streamlined and perfected–he envisions a worldwide, real-time monitoring network with “four or five units in every reservoir in the world.” At any given time, he says, “Somebody at a central location could be monitoring all drinking water world wide.”

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

Innovative Tagging Technique May Help Researchers Better Protect Fish Stocks

August 7, 2007

Marine Protected Areas (MPAs) are often hailed as a way to halt serious declines in the abundance of marine species that have been over-fished. But even as nations begin to set aside protected parcels of ocean for marine reserves, the effectiveness of the approach as a fisheries management tool remains unclear.

Simon Thorrold, a fish ecologist from the Woods Hole Oceanographic Institution (WHOI), would like to put MPAs to the test with a novel technique for tagging fish.

Through a new research grant from the David and Lucile Packard Foundation, Thorrold and colleagues plan to use harmless chemical tags to track the dispersal of the larvae of coral reef fishes in the western Pacific Ocean. The Packard Foundation’s Conservation and Science Program has granted Thorrold and colleagues more than $480,000 for three years to study the population dynamics of grouper and snapper in the waters around the Great Barrier Reef and Papua New Guinea.

Through a new technique known as TRAnsgenerational Isotope Labeling (TRAIL), the researchers will introduce an artificial tag—a stable isotope of barium—into the tissues of mature female fish just before spawning. That chemical tag is then passed to the female’s offspring and becomes a chemical signature within the ear bones (otoliths) of the next generation of fish.

Researchers can then track the dispersal of the tagged larvae across reefs and large stretches of open ocean. This chemical tagging approach has been successfully tested in limited studies with clownfish and butterflyfish.

Now, Thorrold and colleagues want to attempt one of the first large-scale, empirical tests of the effectiveness of marine protected areas. The scientists will attempt to assess how far and how effectively the larvae spawned within protected areas are contributing to populations outside of their human-described borders.

Most management and conservation strategies assume that fish populations may be connected across broad areas, and that protecting them in one location will allow for sustainable fisheries outside of the reserve boundaries. But such theories are mostly untested and do not necessarily account for how long and how far larvae may or may not drift in the open ocean.

The new research program will be led by Thorrold, an associate scientist in the WHOI Department of Biology. Co-investigators include Glenn Almany, Geoffrey Jones, and Garry Russ of the ARC Centre of Excellence for Coral Reef Studies and James Cook University (Australia), and Rick Hamilton of The Nature Conservancy.

The David and Lucile Packard Foundation was created in 1964 by David Packard, cofounder of the Hewlett-Packard Company, and Lucile Salter Packard. The Foundation’s Conservation and Science Program seeks to protect and restore our oceans, coasts, and atmosphere, and to enable the creative pursuit of scientific research.

The Woods Hole Oceanographic Institution is a private, independent organization in Falmouth, 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 ocean’s role in the changing global environment.

Explorers to Use New Robotic Vehicles to Hunt for Life and Hydrothermal Vents on Arctic Seafloor

June 21, 2007

Scientists and engineers from the Woods Hole Oceanographic Institution (WHOI) have just completed a successful test of new robotic vehicles designed for use beneath the ice of the Arctic Ocean. The multidisciplinary research team will now use those vehicles to conduct the first search for life on the seafloor of the world’s most isolated ocean.

WHOI researchers have built two new autonomous underwater vehicles (AUVs) and a new tethered, remote controlled sampling system specifically for the difficult challenges of operations in the Arctic ice. They hope to discover exotic seafloor life and submarine hot springs in a region of the ocean that has been mostly cut off from other ecosystems for at least 26 million years.

The 30-member research team will depart on July 1 from Longyearbyen, Svalbard, for a rare expedition to study the Gakkel Ridge, the extension of the mid-ocean ridge system which separates the North American tectonic plate from the Eurasian plate beneath the Arctic Ocean.

The 40-day cruise on the Oden—a 108-meter long (354-foot) icebreaker operated by the Swedish Maritime Administration—will take researchers close to the geographic North Pole.

The research team for the Arctic Gakkel Vents Expedition (AGAVE) includes specialists in each field of deep-sea exploration, with scientists and engineers from the United States, Norway, Germany, Japan, and Sweden.

WHOI geophysicist Robert Reves-Sohn will serve as chief scientist. Fellow principal investigators include: Tim Shank, a hydrothermal vent biologist from WHOI; Hanumant Singh, a WHOI engineer and vehicle developer; marine chemist Henrietta Edmonds of the University of Texas at Austin, who sailed on the last research expedition to the Gakkel Ridge in 2001; Susan Humphris, a WHOI geochemist who has surveyed dozens of hydrothermal vent sites around the world; and Peter Winsor, a WHOI oceanographer who studies Arctic Ocean circulation and its implications for climate.

Major funding for the expedition and for vehicle development was provided by the National Science Foundation (NSF) and the National Aeronautics and Space Administration (NASA).

“This is an exciting opportunity to explore and study a portion of Earth’s surface that has been largely inaccessible to science,” said Reves-Sohn. “Any biological habitats at hydrothermal vent fields along the Gakkel Ridge have likely evolved in isolation for tens of millions of years. We may have the opportunity to lay eyes on completely new life forms that have been living in the abyss beneath the Arctic ice pack.”

Most of the instrumentation that researchers would normally use to study deep sea environments and organisms—such as the human occupied submersible Alvin or tethered vehicles—cannot be safely operated in the Arctic ice, which can easily crush most small vehicles. So researchers asked Singh and colleagues to design and develop three new vehicles from scratch.

During the July expedition, researchers will use the Puma AUV, or “plume mapper,” to sniff out the chemical and temperature signals of hot, mineral-rich fluids venting out of the ocean floor. Once Puma finds the source of venting, Singh and colleagues will send down the Jaguar AUV, which will use cameras and bottom-mapping sonar systems to image the seafloor. Finally, the CAMPER towed vehicle will be lowered to the seafloor to scoop or vacuum up rocks, sediments, and living creatures.

During a 10-day engineering trial in May and June 2007, all three vehicles were lowered through the Arctic ice and driven underwater, while engineers simultaneously tested acoustic communications techniques. The researchers were able to recover their vehicles from beneath the ice, which can be risky in the midst of moving floes that can quickly close the leads around an icebreaker.

“Anyone can deploy an AUV in the Arctic; the trick is getting it back,” said Singh, who will send his vehicles to the seafloor for 10 to 24 hours at a time during the Gakkel expedition. “In order to have a good day with autonomous vehicles, the number of recoveries must equal the number of launches.”

The Gakkel Ridge extends roughly 1,800 kilometers (1,100 miles) from north of Greenland toward Siberia. It is both the deepest ocean ridge—ranging from 3 to 5 kilometers (1.8 to 3 miles) beneath the ice cap—and the slowest spreading tectonic plate boundary anywhere on Earth. The ridge moves roughly one centimeter (1/3 inch) per year, about 20 times slower than most other ridges.

At most mid-ocean ridges, Earth’s crust spreads apart, allowing hot magma from the mantle to come up and form new ocean crust. The enormous heat sparks chemical reactions between crustal rocks and the seawater that seeps down into them.

These chemical reactions produce hot, mineral-rich fluids that spew like geysers from seafloor vents, as well as massive deposits of minerals, such as copper and zinc. These hydrothermal fluids also contain chemicals that sustain rich communities of unusual life forms, which thrive via chemosynthesis, rather than photosynthesis.

Many geologists believed the Gakkel Ridge region would be too geologically cold to produce hydrothermal vents. And yet during a 2001 expedition, researchers found signs of such venting in the Arctic. Where there are vents, there may be unusual seafloor life forms.

“A few years ago, mid-ocean ridge and hydrothermal vent biologists came together and asked: ‘Where are the key places in the world to go to make big leaps in understanding biodiversity?’ The Gakkel Ridge was one of the top places,” said Shank, who plans to study the genetics of animals found during the expedition.

“The region has been mostly separated from the Atlantic and Pacific oceans for millions of years, so whatever lives there has since been evolving in relative isolation—much the way animals in Australia did,” Shank added. “We know that deep-sea Arctic fauna found away from vents are more than 70 percent different from all others around the world. So at hydrothermal vents we are likely to find completely new suites of species with never-before seen adaptations.”

Some scientists—including program managers and scientists from the NASA Astrobiology Program—have been keenly interested in the possibility that Gakkel Ridge may harbor life forms and environmental conditions consistent with primordial Earth or other watery planets.

“The origin of life discussion comes up because the rocks that are exposed on this very slow spreading ridge are not volcanic, but instead come directly from Earth’s mantle,” said Humphris. “The chemistry is very much like the volcanism that occurred on the primordial Earth. If you are thinking about origins of life, you’d like to have an area that is the closest analog to what was happening on the early Earth.”

In July 2001, WHOI researchers were part of the Arctic Mid-Ocean Ridge Expedition (AMORE) that produced the first detailed maps of the Gakkel Ridge and made the unexpected discovery that the ridge is volcanically active. Scientists also found that large sections of Earth’s mantle appear to be deposited directly onto the seafloor along the Gakkel Ridge.

The Gakkel Ridge expedition will be covered live on the web, allowing students, educators, and the general public to follow along with daily dispatches from the Arctic Ocean. The Dive and Discover web site brings students and teachers along on research field trips to read about science in action, while the Polar Discovery project uses photos and live phone calls from the Oden to allow museum visitors and the public to see the Arctic through the eyes of the explorers.

Support for the Gakkel Ridge expedition and for underwater vehicle development has been provided by the National Science Foundation’s Office of Polar Programs and Division of Ocean Sciences; the NASA Astrobiology Program; the WHOI Deep Ocean Exploration Institute; and the Gordon Center for Subsurface Sensing and Imaging Systems, an NSF Engineering Research Center.

The Woods Hole Oceanographic Institution is a private, independent organization in Falmouth, 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 ocean’s role in the changing global environment.

Sea Urchin Genome Yields New Understanding of “Chemical Defensome”

November 13, 2006

The Sea Urchin Genome Sequencing Consortium, a group of 240 researchers from more than 70 institutions in 11 countries, recently announced the sequencing of the California purple sea urchin, Strongylocentrotus purpuratus.  Three biologists from the Woods Hole Oceanographic Institution (WHOI) were among those participating in describing the sea urchin genes.  They helped to identify a large group of genes encoding proteins involved in protecting the sea urchin from toxic chemicals.

Reporting in the November 10 issue of the journal Science, the consortium researchers announced the high-quality “draft” sequence, covering more than 90 percent of the sea-urchin genome, and provided detailed descriptions of genes involved in a variety of biological processes ranging from immune function to sensory biology.  Those descriptions appear in 41 papers in the December 1 issue of the journal Developmental Biology.

The sea urchin genome contains over 814 million letters, spelling out 23,300 genes.  The WHOI scientists, in collaboration with researchers from Stanford University’s Hopkins Marine Station and several other institutions, identified over 400 of these genes that are part of the “chemical defensome,” an integrated network of genes and pathways that allow animals to mount an orchestrated defense against toxic chemicals.

The defensome genes include those for enzymes involved in biotransformation — the conversion of chemicals to less-toxic derivatives — as well as those encoding proteins involved in the expulsion of chemicals or their metabolites from cells.  Also included in the defensome are genes for proteins called transcription factors, which sense the presence of toxic chemicals and turn on the genes for biotransformation enzymes and transporters.

The defensome characterization was led by Jed Goldstone, a postdoctoral scholar in the WHOI Biology Department, and Amro Hamdoun of Stanford University, and also included two WHOI senior scientists, biologists Mark Hahn and John Stegeman.  For many years, the WHOI group has studied defensome genes in a variety of animals.  The sea urchin research provides the first comprehensive, genome-wide assessment of the defensome in any animal. The sea urchin defensome is notable because several of the gene families in it have undergone expansion in the sea urchin lineage, suggesting an especially important role for chemical defense in these animals.

The overall sequencing project was led by Drs. Erica Sodergren, George Weinstock, and Richard Gibbs at the Human Genome Sequencing Center at Baylor College of Medicine, and Drs. Eric Davidson and Andrew Cameron of the California Institute of Technology.

Sea urchins are echinoderms (Greek for “spiny skin”), marine animals that originated over 540 million years ago and include starfish, brittle stars, sea lilies, and sea cucumbers.  There was great interest in the sea urchin as a target for genome sequencing because these animals share a common ancestor with humans. That ancestor lived over 540 million years ago and gave rise to the Deuterostomes, the superphylum of animals that includes phyla such as echinoderms and chordates, the phylum to which humans and other vertebrates belong.  All Deuterostomes are more closely related to each other than they are to any other animals not included in the Deuterostome superphylum. For example, among sequenced genomes, the sea urchin genome is closer to the human genome than to genomes of flies and worms.

“Each genome that we sequence brings new surprises. This analysis shows that sea urchins share substantially more genes and biological pathways with humans than previously suspected,” said Dr. Francis S. Collins, director of the National Human Genome Research Institute at the National Institutes of Health. “Comparing the genome of the sea urchin with that of the human and other model organisms will provide scientists with novel insights into the structure and function of our own genome, deepening our understanding of the human body in health and disease.”

The comparison of the genes of the sea urchin to the human gene list shows which human genes are likely to be recent innovations in human evolution and which are more ancient. It also shows which human genes have changed slowly in the lineage from the ancestral Deuterostome animal and which genes are evolving rapidly in response to natural selection.

Although, as invertebrates, sea urchins have a radically different morphology from humans and other vertebrates, their embryonic development displays basic similarities, an important shared property of Deuterostome animals.  The evolutionary relationship to humans makes the sea urchin, with its many useful properties such as ease of isolation of eggs and sperm and transparent embryos, a valuable model to study the process of development and help understand human development. The development of the animal occurs through a complex network of genes, and the sea urchin is one of the main models for systems biology, the description of how the building blocks of an animal interact in time and space.

The chemical defensome described by the WHOI team and their colleagues may be especially important for protecting sea urchin embryos from toxic chemicals during embryonic development.  Indeed, the team found that many of the defensome genes are expressed, or “turned on,” in embryos.  In addition, based on comparisons with the previously sequenced genomes of other invertebrates and vertebrates, the researchers suggested that some defensome genes may have originally functioned as part of the complex network of developmental regulatory genes, and then later evolved their defensive roles.

The WHOI researchers were funded by grants from the National Institute of Environmental Health Sciences, at part of the National Institutes of Health.

Beaked Whales Perform Extreme Dives to Hunt Deepwater Prey

October 19, 2006

A study of ten beaked whales of two poorly understood species shows their foraging dives are deeper and longer than those reported for any other air-breathing species.  This extreme deep-diving behavior is of particular interest since beaked whales stranded during naval sonar exercises have been reported to have symptoms of decompression sickness. One goal of the study was to explore whether the extreme diving behavior of beaked whales puts them at a special risk from naval sonar exercises.

Scientists from the Woods Hole Oceanographic Institution (WHOI) teamed with colleagues from the University of La Laguna in Spain, the University of Aarhus in Denmark, Bluwest and the NATO Undersea Research Centre in Italy. The team studied Cuvier’s beaked whales (Ziphius cavirostris) and Blainville’s beaked whales (Mesoplodon densirostris) in Italian and Spanish waters using a non-invasive digital archival tag or D-tag developed at WHOI by one of the authors, engineer Dr. Mark Johnson.  Their findings are reported in the current online issue of the Journal of Experimental Biology.

The D-tag, about the size of a sandal,  has a variety of sensors to record sounds and movements, and is attached to the animals with four small suction cups using a handheld pole. It is programmed to release from the animal within a day and is recovered with help from a VHF radio beacon in the tag. The 3-6 Gbytes of audio and sensor data are then off-loaded to a computer for anaylsis.

Dr. Peter Tyack, a senior scientist in the WHOI Biology Department and lead author of the study, says they found some similarities with the much better studied sperm whales and elephant seals, but also some major differences. “These two beaked whale species make long, very deep dives to find food, and then make shallow dives and rest near the surface. By contrast, sperm whales and elephant seals can make a series of deep dives without the need for prolonged intervals between deep dives. We think that beaked whales return to the surface after deep dives with an oxygen debt and need to recover before their next deep dive.”

Tyack said the team’s analysis suggests that the normal deep diving behavior of beaked whales does not pose a decompression risk. “Rather, it appears that their greatest risk of decompression sickness would stem from an atypical behavioral response involving repeated dives at depths between 30 and 80 meters (roughly100 to 250 feet),” Tyack said. “The reason for this is that once the lungs have collapsed under pressure, gas does not diffuse from the lungs into the blood. Lung collapse is thought to occur shallower than 100 meters (330 feet), so deeper parts of the dive do not increase the risk of decompression problems. However, if beaked whales responded to sonars with repeated dives to near 50 meters (165 feet), this could pose a risk.”

The Cuvier’s beaked whales were tagged in June 2003 and 2004 in the Ligurian Sea off Italy, while the Blainville’s beaked whales were tagged in October 2003 and 2004 off the island of El Hierro in the Canary Islands. Both field sites were in deep water, between 700 and 2,000 meters (2,300 to 6,500 feet) with steep bottom topography. Tags were attached to seven Cuvier’s beaked whales and three Blainville’s beaked whales, and they remained attached to the whales for an average of 8 hours and 12 hours, respectively.

“Although this study was limited to ten animals, it provides the first detailed information available about the diving, acoustic, and movement behavior of two species of beaked whales,” Tyack said. “Shallow dives seem to be performed between deep dives, and both species dive very deep to hunt for prey. They seem to spend equal time ascending and descending in shallow dives, but take longer to ascend from deep dives.”

The slow ascent from deep dives is a major mystery. “Why don’t they stay longer at depth to feed, and then come up more rapidly?” Tyack said.  “Avoidance of decompression problems by slow ascent, as in scuba divers, cannot account for this behavior if the lungs of these breathhold diving marine mammals are collapsed at depths greater than 100 meters (330 feet).”

Very little is known about these two species of beaked whales since they spend little time on the surface and it is difficult to tag them.  The much better studied sperm whale can dive for more than one hour to depths greater than 1,200 meters (roughly 4,000 feet), but typically dives for 45 minutes to depths of 600-1,000 meters (1,968 to 3,280 feet). Elephant seals, another well known deep diver, can spend up to two hours in depths over 1,500 meters (nearly 5,000 feet), but typically dive for only 25-30 minutes to depths of about 500 meters (1,640 feet).  Marine mammals seem to have adapted to the effects of diving deep and optimizing their oxygen supplies.

The Cuvier’s beaked whales dove to maximum depths of nearly 1,900 meters (about 6,230 feet) with a maximum duration of 85 minutes, while the Blainville’s beaked whales dove to a maximum depth of 1,250 meters (4,100 feet) and 57 minutes in duration. The dives near 1,900 meters constitute the deepest confirmed dives reported from any air-breathing animal. While people often focus on the maximum dives of breathhold diving animals, breathhold divers are not at a track meet and it is the average of the deep foraging dives that is more important. Regular echolocation clicks and buzzes and echoes of what appears to be prey were recorded on the tags, suggesting the whales were hunting for food on the deep dives. The average foraging dive for Cuvier’s beaked whale went to a depth of 1,070 meters (about 3,500 feet) with a duration of 58 minutes, while the Blainville’s beaked whales dove to an average depth of 835 meters (2,740 feet) and 46.5 minutes in duration.  These represent the deepest and longest average dives reported for any breathhold-diving animal.

These two beaked whale species have been reported to mass strand during naval sonar exercises in the area.  It is unclear how these beaked whale species respond to the sonar sounds and whether their responses cause physiological changes that increase the risk that  they will strand and die.  This study suggests the paradoxical result that even though beaked whales are extreme divers, their normal diving behavior does not seem to put them at greater physiological risk for sonar exposure. Rather it suggests that physiological risk would stem from a specific behavioral response to the sonars.

“No matter what the precise cause of the strandings is, we need to develop effective mitigation strategies to reduce the accidental exposure of beaked whales to bay sonar,” Tyack said. “The information in this study provides critical data to design efficient acoustic and visual detection methods for these at-risk species of marine mammals.”

Funding for the tag development was provided by a Cecil H. and Ida M. Green Technology Innovation Award at WHOI and the U.S. Office of Naval Research. Funding for field work was provided by the Strategic Environmental Research and Development Program  (SERDP), the National Ocean Partnership Program, the Packard Foundation, the Canary Islands Government, and the Spanish Ministry of Defense. Fieldwork support was provided by BluWest, NATO Undersea Research Center, and the Government of El Hierro.

Island Ferries Take on Role of Research Vessels Collecting Data about Nantucket Sound

August 29, 2006

Ferries that connect Cape Cod and the islands of Martha’s Vineyard and Nantucket are taking on another role – research vessels.

Woods Hole Oceanographic Institution (WHOI) biologist Scott Gallager and colleagues have installed a package of sensors on the 235-foot freight ferry Katama to measure water quality and to photograph plankton as the ferry crisscrosses the western side of Nantucket Sound year-round, several times daily.

“Hitchhiking science on a ferry provides a terrific opportunity for us to better understand how water quality and ocean life change over time,” Gallager said.  The measurements for the Nantucket Sound Ferry Scientific Environmental Monitoring System began in May.

With the interest and cooperation of the Woods Hole, Martha’s Vineyard and Nantucket Steamship Authority, which operates the ferry service between Cape Cod and the islands, Gallager and colleagues developed a sensor package to measure water temperature, salinity, oxygen, chlorophyll, and water clarity, and take images of plankton living in the water column. Real-time data from the sensors travel over a wireless connection to Gallager’s shore-based lab, where he and WHOI colleagues Steve Lerner, Emily Miller, Andrew Girard, Andy Maffei, and collaborator Kevin Fall from Intel Corporation make them available to scientists and the public on the project Web site,

The WHOI team will be installing another instrument package on the Steamship Authority ferry Eagle, which runs between Hyannis and Nantucket on the eastern side of Nantucket Sound. Their objective is to build up a detailed, continuous portrait of changing water conditions and plankton communities in Nantucket Sound over long time scales.

Nantucket Sound is a triangular area of coastal ocean between Cape Cod, Martha’s Vineyard, and Nantucket and is known for its changing water conditions and diverse marine life. The cold south-flowing Labrador Current nearby collides with warm water in the relatively shallow Nantucket Sound, creating a perpetual front just inside the eastern Sound. As water shifts with the wind and the tides, warm-water and cold-water species are thrust into the same space. Waters loaded with nutrients, from septic systems and runoff along the developed Cape Cod coastline, also mingle in the Sound with North Atlantic waters that have far fewer nutrients.

Gallager studies plankton, the tiny and abundant swimming animals that serve as food for coastal fish and marine mammals. The numbers and proportions of different plankton in coastal oceans change with the seasons and ocean conditions, and Gallager is interested in the processes and their time scales that control those changes.

The availability of plankton can make the difference between healthy and undernourished stocks of commercial finfish and shellfish. Storms, nutrient runoff from coastal development, and the warming of coastal ocean waters could drastically alter the types of plankton that flourish in Nantucket Sound, and therefore the quantity and quality of food for fish, marine mammals, and ultimately people.

“A long-term archive of how conditions change in Nantucket Sound could provide an early warning about the health and function of coastal regions important to our economy and our quality of life,” Gallager said.

The Nantucket Sound Ferry Scientific Environmental Monitoring System project is supported by the Woods Hole Sea Grant program.

Oceanus Magazine

Sea of Hazards

A Sea of Hazards

October 22, 2020

A Sea of Hazards

How researchers are safeguarding us from the perils of a changing ocean

By Evan Lubofsky | October 20, 2020

Illustration by Natalie Renier, WHOI Creative, © Woods Hole Oceanographic Institution

It had to have been the mussels.

Around 3:00am, the 62-year-old woman—who we’ll refer to as Diana to protect her identity—became nauseous a few hours after her midnight snack. The soup she ate was chock-full of freshly harvested mussels. Her nausea quickly turned to lightheadedness, vomiting, and mental confusion. Diana’s nervous system was under attack, and by the time she got to the hospital, the muscles responsible for speech became impaired, interfering with her ability to vocalize. In the ER, she felt like her throat was closing up, forcing doctors to put her on a ventilator until the next day when she recovered enough to be discharged.

This bout of shellfish poisoning (it was the mussels) happened just a few years ago, but human beings have suffered all sorts of maladies, from various types of fish, for centuries.

Women collecting shellfish in Lombok, Indonesia. (Photo by A. David South © Alamy) Women collecting shellfish in Lombok, Indonesia. (Photo by A. David South © Alamy)

“Human populations near the coast continue to increase, so the interactions people have with the ocean have become increasingly important from a public health perspective.” ~ John Stegeman, Woods Hole Oceanographic Institution

In the fourth century, Alexander the Great forbade his soldiers to eat fish before conquests, and in 1774, Captain James Cook fell ill while exploring the South Pacific. “I had almost lost the sense of feeling; nor could I distinguish between light and heavy bodies, of such as I had the strength to move; a quart-pot, full of water, and a feather being the same in my hand,” noted Cook, who was likely affected by potent neurotoxins in a toadfish he ate.

In the modern era, changes in global climate, warming ocean conditions, and other human-caused factors have rendered the ocean a sea of hazards. Harmful algal blooms (HABs), ocean pollutants, and marine pathogens are just a few of the dangers that increasingly threaten human health.

The problem is vast in scope. More than half the world’s population lives along the coast, and the global ocean blankets over 70 percent of the Earth’s surface. Billions of people rely on the oceans for protein-rich sustenance, for novel medications used to treat everything from breast cancer to malaria, and for physical and mental well-being. The question of how to make the oceans safer for human beings has spurred one of oceanography’s fastest growing areas of research, oceans and human health (OHH).

“Human populations near the coast continue to increase, so the interactions people have with the ocean have become increasingly important from a public health perspective,” says Woods Hole Oceanographic Institution’s John Stegeman. He is head of the Woods Hole Center for Oceans and Human Health, one of four such centers throughout the United States.
He and other researchers have been investigating the ocean’s most critical human health threats to understand them better and develop strategies aimed at minimizing impacts. A lot is riding on what they discover.
“The role oceanography plays in keeping people healthier and safer has never been as important as it is today,” Stegeman says. “Exposure to marine toxins and pollutants can lead to respiratory and cardiovascular problems and immune effects, underlying conditions that can make us more susceptible to emerging viruses like COVID-19.”

Harmful algal blooms

It was the ultimate avian attack: thousands of seemingly possessed seagulls, ravens, and other birds flocked furiously above hordes of people running for their lives.

A scene from the 1963 Hollywood horror classic, The Birds. The movie drew inspiration from a real-life situation in Monterey Bay, California where seabirds became disoriented and began slamming into homes after ingesting toxic algae. (Photo Courtesy of Universal Studios Licensing LLC) A scene from the 1963 Hollywood horror classic, The Birds. The movie drew inspiration from a real-life situation in Monterey Bay, California where seabirds became disoriented and began slamming into homes after ingesting toxic algae. (Photo Courtesy of Universal Studios Licensing LLC)

It may have come straight out of Hollywood, but the idea behind Alfred Hitchcock’s 1963 blockbuster movie The Birds may not have been so crazy after all. Hitchcock had seen a newspaper story in The Santa Cruz Sentinel describing a flock of crazed seabirds that “pelted the shores of North Monterey Bay” and began flying into objects as they regurgitated anchovies.

The seabirds—called sooty shearwaters—had snacked on anchovies from the bay where toxic algae had bloomed into dense patches near the surface. The algae produced a toxin called domoic acid which can cause confusion, disorientation, seizures, and even death. The toxins were taken up by plankton, which were eaten by the anchovies and then eventually the birds. Of all the ocean-related human health risks, harmful algal blooms (HABs) are among the most dire. Often referred to as “red tides,” these vast, swirling patches often put on a

dazzling show from space, but in the ocean, some produce toxins that can cause a range of human health problems, including neurological disorders, respiratory infections, paralysis, and death. One particular toxin, known as saxitoxin, is so baleful that it was declared a chemical weapon in 1993.

HABs occur when single-celled algae in the ocean accumulate, often due to interactions between their swimming behavior and the movement and structure of the water column. As microscopic algal cells multiply, they sometimes form visible “blooms” that discolor the water. Some blooms are small, localized events affecting bays and estuaries; others can affect larger stretches of coastline than a major hurricane.

In either case, the human health risks of HABs are substantial, and blooms are more common than ever before. In fact, scientists believe that there are more toxic algal species, more affected areas, and higher economical losses today than just 30 years ago.

“The HAB problem has been growing at a time when people are relying more than ever on the ocean for food, recreation, and commerce,” says Don Anderson, a senior scientist at WHOI and Director of the U.S. National Office for Harmful Algal Blooms. “This area of research has gone from just a handful of scientists in the 1970s to a national program that includes scientists from oceanography, ecology, engineering, economics, and human health studies. It’s a concerted national attack on the problem focused on figuring out where the blooms are, how toxic they are, and where they’re likely to show up in the future so we can help mitigate the risks to people.”

Moving target
Today, algal blooms have been reported in every coastal state throughout the U.S., and are occurring in places Anderson and other scientists never believed they could. “For years, we believed that HABs couldn’t show up as far north as the Arctic Ocean, but two years ago we began finding saxitoxin-producing organisms in huge numbers north of Alaska,” Anderson says. “And we’ve been finding them in extraordinary numbers, numbers that dwarf what we find in the Gulf of Maine.” A green phytoplankton bloom swirls across a section of the Baltic Sea in July 2018. (Image by Joshua Stevens and Lauren Dauphin, NASA Earth Observatory, using Landsat data from the U.S. Geological Survey and MODIS data from LANCE/EOSDIS Rapid Response) A green phytoplankton bloom swirls across a section of the Baltic Sea in July 2018. (Image by Joshua Stevens and Lauren Dauphin, NASA Earth Observatory, using Landsat data from the U.S. Geological Survey and MODIS data from LANCE/EOSDIS Rapid Response)

Warming sea temperatures and loss of sea ice in the Arctic have made the waters propitious for plankton producing the toxins. It’s become a major concern for indigenous people in the region who eat seabirds and marine mammals for sustenance.

“They ask us for advice about what is safe to eat, but we haven’t been able to provide a lot of guidance to date since it’s a new phenomenon up there,” says Anderson.

Anderson has partnered with the National Oceanic and Atmospheric Administration (NOAA) on a multi-year, $5 million research project aimed at studying the effects of HABs on marine mammals and other parts of the marine food web in the Arctic region. The researchers are particularly focused on the type of bloom that can cause paralytic shellfish poisoning. They want to understand how the toxins are moving through the food web, and what the exposure risks are to people and wildlife.

NOAA marine biologist Kathi Lefebvre, Anderson’s co-investigator on the project, notes that monitoring programs are already in place for commercial shellfish in the state of Alaska, but not for shellfish and marine mammals that people hunt and harvest on their own for survival.

“It’s a human health issue that people up there really care about. There’s a very intimate relationship between marine resources that are critical for survival and these remote communities,” says Lefebvre.

Lefebvre, Anderson, and Bob Pickart, a WHOI physical oceanographer, are working to document where algal blooms are, determine how they’re changing with climate conditions, and track toxicity levels in all layers of the food web. Last year, they collected phytoplankton, zooplankton, clam, worm, and fish samples at various sites to look for the presence of toxins and measure doses within the organisms. Members of Alaska Native communities are helping as well.

“We have partners out there in the remote communities who are collecting samples from subsistence-harvested bowhead whales, ice seals, and walruses,” says Lefebvre. “We can measure HAB toxins in those animals and see if the animals are suffering health consequences.”

It’s a solutions-oriented approach: The data will feed a quantitative model that correlates environmental conditions to bloom events and toxin accumulation in food webs. The model could ultimately be used to predict health impacts to marine wildlife.

WHOI scientist Don Anderson (center) gently guides an instrument known as a multi-corer as it’s lowered to the ocean bottom off the west coast of Greenland. The instrument takes eight individual sediment core samples from the bottom, which scientists use to look for the presence of seed-like cysts released by harmful algae. (Photo by Nicole D’Entremont, © Woods Hole Oceanographic Institution) Seeing cells
On a late afternoon in October 2016, Dan Ward, a shellfish farmer on Cape Cod, Mass. came home to some bad news. Government regulators had ordered his business, Ward Aquafarms, to shut down. The culprit was an algal bloom of a species found along the southern Massachusetts coast called Pseudo-nitzschia, which can cause Amnesic Shellfish Poisoning (ASP) leading to permanent short-term memory loss.

“The regulators immediately closed all harvesting,” Ward says. “Just like that, my business and the rest of the shellfishing industry along the south coast shut down.”

Ward knew his oysters, clams, and bay scallops would be fine. This particular species of Pseudo-nitzschia wasn’t a direct threat to shellfish. But it can produce a neurotoxin that accumulates in the shellfish and causes illness and even death in humans who eat them.

Ward Aquafarms sat idle for more than a month, but it turned out that the bloom hadn’t produced toxins that were harmful to people after all.

Ward immediately saw a need to actively monitor HABs around his shellfish beds. Knowing that WHOI was a leader in ocean engineering and technology solutions, he got in touch with Mike Brosnahan, a WHOI biologist who had been using a compact submersible camera system, the Imaging FlowCytobot (IFCB), to detect algal bloom species in the water.

“The sensor produces hundreds of thousands of images a day, allowing us to detect harmful species that produce toxins or kill farmed animals,” says Brosnahan. “And it can stay in the water for many months with basically zero maintenance.”

The instrument, which was originally developed by WHOI scientists Heidi Sosik and Rob Olsen for spying on phytoplankton populations, is roughly the size of a scuba tank and easily hangs off a dock or any structure in the water where monitoring is needed. Inside, the IFCB’s camera takes photos of individual phytoplankton cells at a rate of up to 12 per second. Automated image recognition algorithms identify and count the species.

“We can alert shellfish farmers to the presence of these harmful organisms and give them the opportunity to mitigate whatever damage might come from these blooms,” Brosnahan says.

At Ward’s farm on Cape Cod, the submerged camera system sends alerts when critical thresholds are reached for particular species so that Ward knows when to take action. This involves turning off the incoming water flow to his nursery, switching the system into recirculating mode so toxic water stays out, and turning on an air system to keep oxygen levels sufficient for the shellfish as he and his crew wait out the bloom.

“Once the threat is gone, we just turn the water back on and we’re back in business,” Ward says.

Shellfish farmer Dan Ward pulls up an Imaging FlowCytobot (IFCB) from one of his shellfish beds in Falmouth, Massachusetts. The instrument takes up to 12 photos of plankton cells per second, and uses specialized algorithms to identify harmful algal species that produce toxins. (Photo by Daniel Hentz, © Woods Hole Oceanographic Institution) Turning back the tide
The Imaging FlowCytobot may be a field-proven tool in the fight against HABs, but mitigation requires more than monitoring. Bloom control strategies that can remove the offending cells and toxins from the water are also needed. Artificial reefs are one solution that’s showing promise.
The City of Bradenton Beach, Florida, in concert with an artificial reef company called Ocean Habitats, recently installed more than a dozen miniature artificial reefs below the Historic Bradenton City Pier to help ward off red tide, which invades the southwest Florida coastline each year. Shellfish and other organisms on the reefs filter water as they feed, and in the process, sift out red tide cells and impair the bloom’s ability to grow.

Other bloom control methods include spraying clay on affected waters. Clay latches onto algal bloom cells and as it carries them to the bottom, some of the cells are destroyed. Researchers are also injecting affected waters with nano-sized bubbles filled with ozone, which destroys HAB cells.

“These types of control measures are very much needed,” Anderson says, “since in the absence of a treatment, blooms can persist and continue to cause problems.” But he says that few of the current technologies are scalable to the point where they can help solve harmful algal bloom problems in small lagoons and across wide stretches of coastline. Also, not enough is known about the potential side effects of current bloom control methods. “We need to fully understand the environmental impacts of each approach to help make informed decisions,” Anderson says.

Marine pathogens
Aside from the occasional jellyfish sting, rogue wave, or shark sighting, going to the beach is generally considered a safe activity. But a more pervasive, invisible threat to public health is lurking on the shoreline: marine pathogens.

Harmful viruses, bacteria, and protozoa thrive in areas contaminated with human sewage, stormwater, or animal feces. They can infect swimmers’ eyes, ears, and wounds, but some infectious microbes come from bathers themselves. Hepatitis A, Salmonella, Legionella and Staphylococcus aureus are just a few good reasons to shower before and after swimming.

Microbes such as fecal coliform are widely used to indicate contamination in seawater, but “sentinel” species and habitats can also act as early warning systems for potential health risks. These “first responders” include sea grass beds, kelp forests, oyster and coral reefs, as well as marine mammals.

“Microbes are fantastic sentinels for human health and health of ecosystem in general,” says WHOI microbiologist Amy Apprill. “Marine life can alert us to potential problems, whether from harmful algal blooms or pathogens that might show up at the beaches.”

Andrea Bogomolni, who studied marine pathogens and viruses as a WHOI research associate, notes that marine mammals can also signal the alarm for potential human health risks.

“Because they’re mammals like us, seals, dolphins, and whales are the perfect indicator species for what we are putting into the ocean,” says Bogomolni, now a professor at the Massachusetts Maritime Academy and chair of the Northwest Atlantic Seal Research Consortium. “Balance in nature will include disease. It’s important to take a holistic view to see how perturbations affect the overall system, including our own health.” –Elise Hugus

Ocean pollutants

If psychotic birds weren’t strange enough, consider the case of the demented cats.

In the mid-1950s in Minamata, Japan, numerous domestic cats suddenly became possessed, screeching while having seizures and falling into Minamata Bay. Villagers, too, began experiencing strange symptoms: spasms, blurred vision, and even hearing loss.

In time, the ailment became so prevalent, it got a formal name: Minamata disease. The cause? Chisso Corporation, a local chemical manufacturer, had been dumping tons of mercury into the bay for more than thirty years via their wastewater.

Minamata disease patients at a rehabilitation center in 2016 in Minamata, Kumamoto, Japan. (Photo by The Asahi Shimbun © Getty Images)

Today, more than half-a-century later, environmental pollution—air, land, and water combined—is responsible for an estimated nine million premature deaths per year. In our oceans, pollution takes a variety of forms: toxic metals, industrial chemicals, and microplastics, to name a few. The pollutants stem from a variety of sources including factories, rivers, and the atmosphere, and are found everywhere from the high Arctic to the deepest trenches of the ocean.

“Ocean pollutants are a critical aspect of environmental pollution as a whole, given their ability to bioaccumulate and move through the marine food web,” says John Stegeman. “Despite the fact that some of these pollutants have been around for a long time, however, they are still not well understood or controlled. So they remain a vitally important part of Oceans and Human Health research.”

You are what you eat
It is common knowledge that vulnerable populations, such as pregnant women, should limit their intake of certain fish species to avoid excessive mercury consumption. This is because large predator fish like tuna can accumulate 10 million times as much mercury as the waters they swim in.

Mercury pollution stems from activities like burning coal, making cement, gold mining, and in the case of the Minamata disaster, chemical dumping. Scientists have a good handle on the associated human health effects: infant exposure to mercury can impair brain development and lead to poorer IQ, autism, ADHD, and learning disabilities; adult exposure increases the risk for dementia and cardiovascular disease.

But what scientists haven’t traditionally known much about is how the inorganic and relatively harmless form of mercury (Hg) gets converted in the ocean to its more dangerous and methylated form, methylmercury (MMHg). Methylmercury is a neurotoxin that is taken up by phytoplankton and then moves up the food chain, eventually bioaccumulating in the fish that end up on many dinner plates. Researchers think that knowing its origin may help identify sources that lead to contamination in the food chain.

Former WHOI biogeochemist Carl Lamborg and his colleagues investigated the chemistry behind the conversion and found that one of the likely culprits in the formation of methylmercury is a type of bacteria living in the sediments of certain coastal areas that are able to produce methylmercury through respiration.
The researchers also found high levels of methylmercury in the ocean’s midwater, a layer of water from 100 to 1,000 meters below the surface, also referred to as the ocean twilight zone. There, methylmercury levels spiked in low-oxygen zones, areas in the midwater where dissolved oxygen levels plummet. Celia Chen, a biologist at Dartmouth College and expert in toxic metals research, says that this is the result of anaerobic bacteria munching on carbon from dead phytoplankton that sinks to these depths.
“As the bacteria consumes the organic carbon, they respire and cause the oxygen to drop, making the conditions right for methylation to occur,” she says.

Climate change is an increasingly important factor in mercury contamination of the ocean. Chen and her colleagues are investigating the link between warming ocean temperatures and the uptake of methylmercury by fish through a series of lab experiments on both forage fish and crustaceans. They have found that the warmer the water, the hungrier the animals, and as their metabolic rates and food intake increased, so did their uptake of the toxic metal.

“As the ocean faces increasing climate pressures, it’s important to understand how mercury is acting in the marine environment and whether fish are bioaccumulating more of it,” says Chen. “That directly increases the health risk to people who eat seafood. After all, we are what we eat.”

One of today’s more worrisome pollutants in our oceans today ceased production in the U.S. during the late 1970s, when President Jimmy Carter was in office. PCBs—polychlorinated biphenyls—contribute to a host of human health problems including endocrine disorders, reduced male fertility, nervous system damage, and increased risk of cancer and cardiovascular disease. PCB exposure can also interfere with thyroid function and brain development.
Production of these chemicals, which began in 1929, grounded to a halt in 1977 as reports of the health effects went public. A federal ban in the U.S. went into effect two years later, but today, PCBs are still very much in the environment.

“Most of these chemicals are not biodegradable, so they continue to persist in the global ocean, bioaccumulating in top predators like Orca whales and seals, as well as fish that we eat,” says WHOI post-doc Nadja Brun, who works in Stegeman’s lab.

Brun has been investigating the neurological impacts PCBs can have on both animals and humans. In laboratory experiments on larval zebrafish, a biologically-relevant organism often used for biomedical studies, she and other members of Stegeman’s team exposed the fish to PCBs to see how the chemicals affected their swimming behavior.

The fish exhibited slower escape responses and, in some cases, none at all.

“Similar to humans, dopamine and serotonin are involved in these processes, so we can hypothesize that similar neurotransmitter effects could occur in humans as well and cause movement disorders,” says Brun. “By understanding the relationship between PCBs and these mechanisms, we can apply our knowledge to help come up with solutions, like the design of safer chemicals or possibly treatments to counteract the effects.”

Marine microplastics

As WHOI biologist Scott Gallager poked through the filthy mound of freshly dredged sea scallops with his shovel, he had a hunch: their guts would be loaded with tiny microplastics.

It was the summer of 2017, and Gallager was collecting adult scallops as part of a NOAA scallop survey in the Gulf of Maine. His thought was that microplastics were sticking to algal blooms at the ocean’s surface, and once the blooms decayed and sunk, they’d take the plastic bits down with them to where filter-feeding scallops would ingest them.

“Sea scallops are clearly a shellfish that a lot of people enjoy eating,” says Gallager. “So if this is happening, then maybe we should avoid eating shellfish during certain parts of the year.”

As ocean scientists work to fill remaining knowledge gaps about legacy ocean pollutants like mercury and PCBs, an emerging pollutant—marine microplastics—has been gaining a bigger share of the spotlight. According to a recent report, the amount of plastic entering the ocean annually could triple in the next two decades and by 2050, there could be more plastic than fish in our waters.

Plastics that get into the ocean often degrade into microplastics that are ingested by fish and shellfish and can go up the food chain to be ingested by humans. (Illustration by Natalie Renier, WHOI Creative © Woods Hole Oceanographic Institution)

WHOI toxicologist Mark Hahn, who leads the institution’s Marine Microplastics Initiative, says that microplastics “fit into the overarching category of industrial contaminants we release into the oceans that may come back to bite us through our consumption of seafood.” But he says it’s too early to tell.

“Although microplastics have emerged in the last decade as pollutants of grave concern, the human health impacts aren’t well understood,” says Hahn.

Tiny plastics, big investigation
Microplastics science is a tricky business. There’s uncertainty about the amount of microplastics in the ocean and how much marine organisms consume. And, there’s a seemingly endless number of sizes, thicknesses, and colors that today’s consumer-based plastics come in, and health effects can vary depending on the types of additives used.

Collin Ward, a marine chemist at WHOI, agrees with Hahn that the science hasn’t matured to the point where a clear link can be established between microplastics and environmental and human health.

“Microplastics are referred to as an ‘emerging’ pollutant for a reason,” says Ward. “There is so much foundational knowledge we don’t have that would be necessary to understand how risky this pollutant is versus others in the marine environment.”

Into the web
Like Gallager, other researchers have been investigating how microplastics get into the marine food web, and ultimately into humans. In a 2013 study, WHOI scientists, along with colleagues from the Marine Biological Laboratory (MBL), discovered tiny pits and grooves missing in plastic particles found in the ocean, suggesting that hungry microbes may be snacking on the material and, in turn, coating them with a biofilm that fish find appetizing.

But when a fish eats microplastics, do the microplastics remain inside that fish when we sit down for mealtime? The jury is still out. In a study published in July 2020 in the journal Marine Pollution Bulletin, researchers at the Helmholtz Centre for Polar and Marine Research fed young European sea bass feed laced with extremely high concentrations of microplastics for four months and found virtually no microplastic particles in the fish fillets.

“Even though we subjected the sea bass to extremely high microplastic pollution in comparison to their natural setting, in the end there were only one or two particles in every five grams of their fillets,” reports Sinem Zeytin, lead author of the study. “This, along with the fact that the fish grew very well and were in perfect health, tells us that the fish can apparently isolate and excrete these particles before they have a chance to penetrate their tissues.”

Terra incognita
Heather Leslie, a research scientist at Vrije Universiteit Amsterdam and a leading expert in microplastics, also acknowledges that a direct link between microplastic exposure and adverse human health outcomes has yet to be established. But she’s wary about claims suggesting that an absence of proof indicates an absence of risk. Last year, the World Health Organization (WHO) stated that “humans have ingested microplastics and other particles in the environment for decades with no related indication of adverse health effects” and that there is “no evidence to indicate a human health concern.” Statements like these worry Leslie.

“Many misinterpret this statement to mean there’s no health concern, but that is far from certain at this point,” she says. “No one’s done a human risk assessment yet.”

Leslie refers to this area of research as an analytical “terra incognita”—unexplored territory. She questions how “no risk” can be supported by “no data” and feels that we all should wait until the evidence is in before coming to a verdict about the risks to humans.

“It’s harder to tell a compelling story,” she says, “if all you can say is ‘we don’t know.’”
Leslie hopes to find more conclusive evidence soon. She and her colleagues are working on methods for measuring the amount of microplastics—or doses—in human bodies.

“No one has measured the actual doses of plastic particle pollution in our bodies yet, so we don’t know how much gets absorbed in the gut or lungs or taken up into the bloodstream,” says Leslie. “You can’t make any real hard claims about risk if you don’t know the exposure.”

She says that if we simply excrete the particles and they’re unable to get to target sites in the body where they cause toxicity, they may not be dangerous to us. “The fine and ultrafine fractions of plastic particles are thought to be more prone to be absorbed and could linger longer in the body, while bigger particles are more likely to pass through the GI tract,” says Leslie. “This is why it’s important to develop highly-sensitive methods to detect trace amounts of fine and ultrafine plastic.”

“In toxicology, we often say that the dose makes the poison,” says Jed Goldstone, a research specialist who has been studying marine toxins for nearly two decades at WHOI. “A handful of microplastics probably won’t matter, but if the estimates are correct, there are an awful lot of plastics out there,” he says. “But we haven’t known for sure because we haven’t had the technology.”

Fortunately, solutions are on the horizon. Ocean scientists and engineers are testing new technologies that can find and identify microplastics in the ocean in real time. This includes a new type of “flow-through” sensor that counts and sizes microplastics directly in water and can distinguish between plastics and biological particles such as copepods. WHOI scientist Anna Michel, whose lab is developing the solution, says the instrument can make this distinction by measuring the electrical properties of the plastics as they permeate through the sensor.

“This sensor operates continuously on a flow of water, so we envision turning it into a low-cost, field-going microplastic tool to help researchers capture the dynamics and fate of microplastics in aquatic environments,” she says.

» Learn more about WHOI’s Microplastics Initiative

An ounce of prevention

“Dad, are you going to eat that?”

It’s a question Stegeman has heard time and time again from his own kids during family seafood dinners over the years.

“When the kids were growing up and we’d sit down to eat at a local restaurant, I would regularly ask where their shellfish came from,” Stegeman says. “This gave me a sense for whether or not it may have been contaminated.”

Of course, not everyone has the same kind of “insider info” that the director of the Woods Hole Center for Oceans and Human health does. But the fact he eats shellfish is encouraging. He knows, however, that just because toxins may be below levels that are dangerous, it doesn’t mean they aren’t present.

“We just don’t know yet what the health impacts are when we’re exposed to low levels of toxins that are invariably present in the water,” he says.

We know that some of the guidelines that have been put in place for COVID-19 clearly work if we adhere to them. It’s really no different with marine toxins. Anything we can do to reduce our exposure will have profound effects on human health.”
~ Fred Tyson, program director, National Institutes of Health

It’s just one of many questions he and other scientists need to tackle to make our oceans safer for people. Continuing to study the hazards and monitor their effects will be essential to coming up with solutions, which might range from enacting legislation that limits mercury emissions from coal plants to designing plastics that are safer for people and the environment.

Fred Tyson, a program director with the National Institutes of Health, says that improving human health and safety in the ocean is principally about putting strategies in place that reduce human exposure and allow us to stay ahead of the curve—similar goals that frame the fight against COVID-19.

“We know that some of the guidelines that have been put in place for COVID-19 clearly work if we adhere to them,” Tyson says. “It’s really no different with marine toxins. Anything we can do to reduce our exposure will have profound effects on human health.”

Eleonora Van Sitteren

Experts Explore the Ocean-Human Health Link

October 8, 2020

Experts Explore the Ocean-Human Health Link

November 9, 2020

Eleonora Van Sitteren

Eleonora Van Sitteren

Guest Student, Lindell Lab

I work with the Lindell Lab group at WHOI on a selective breeding program with sugar kelps. These can be used as a carbon-neutral, sometimes even carbon-negative, highly nutritious food source, as well as a promising biofuel.

To make the farming process more efficient, the lab is tracking the genetics of the algae. But to farm kelp, you need something for it to attach to and grow on. However, not all life stages of kelp are able to adhere to these substrates as others can. So, my job is to figure out a better binder (glues, basically) that will help algae attach and allow them to grow.

Even if we fish more of the already depleted wild stocks out there, we will still need more food in the future to feed the growing global population. A lot of ocean space along the coast can be used to grow algae, which not only provides an important source of food but also improves the water quality and helps reduce the production of global carbon dioxide.

Interviewed by Daniel Hentz

Nadja Brun

Nadja Brun

Environmental Toxicologist, Postdoc, Stegeman Lab

In my research, I study how exposures to chemical pollutants called polychlorinated biphenyls, or PCBs, induce neurological disease. We just add PCBs to water in experiments with zebrafish. We can look at how these toxicants influence the development of the nervous system and fish behavior.

Many people don’t make the connection between studying fish and biomedical research, but to me, it’s obvious. A few years ago, scientists sequenced the whole genome of zebrafish. That’s when we realized how similar they are to humans. The researched showed that we share more than 80% of genes involved with diseases. And zebrafish have a major advantage: They develop externally. That means we can observe how they grow from a single cell to a fish that can hunt and avoid predators in just five days. And because the larvae are transparent, it’s easy to image cells and organs. We can make nerve cells, for example, fluorescent and examine whether they develop properly under the microscope.

Interviewed by Lexi Krupp

Neel Aluru

Neel Aluru

Associate Scientist, Biology

I study how juvenile organisms’ exposure to environmental stressors–things like manmade pollutants or toxins– can impact the risks of developing adverse health conditions as adults. In particular, I look at the packaging of DNA in the nucleus—a process known as epigenetics—and how it is involved in mediating these toxic effects. If you think of DNA like a piano, the pianist is the epigenetic process that determines which notes are played, or how genes are expressed. While epigenetic changes are part of normal development, environmental factors also have the power to impair an organism’s overall health. In humans, these variations have been linked to illnesses, such as Alzheimer’s disease and other neurodegenerative disorders.

We use zebrafish as a model because of its short generation time, which allows us to study the long-term and multi-generational effects of toxins within shorter timeframes. Understanding the effects and processes by which toxins alter their health is critical to determining the risks posed by environmental chemicals to human health.

Interviewed by Lexi Krupp

Svenja Ryan

Svenja Ryan

Physical Oceanographer, Postdoc, Ummenhofer Lab

As a physical oceanographer, I often have people ask me, “So how does your research affect my life right now?” Often, you can’t say anything other than, “It might affect your life in 50-100 years.” But with marine heatwaves, the current subject of my research at WHOI, you can draw more immediate connections to society.

Similar to atmospheric heatwaves, these are discrete events where regions of the ocean experience above-average temperatures (sometimes lasting years). A few of these events have had drastic effects on the ecosystems that give us food and support our economies. Just off our doorstep in New England in 2012, there was an unprecedented marine heatwave that led to massive problems in the local lobster fishery. Because temperatures started to warm up very early in the season, the lobster landing came unexpectedly. The supply chain couldn’t handle it, and the price of lobster dropped precipitously, throwing the whole economy for a loop.

In a way, these phenomena give us a glimpse at a more permanent future if we don’t manage the effects of climate change.

Interviewed by Daniel Hentz

Biology WHOI Perspectives Pollution
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.

Bioacoustic alarms are sounding on Cape Cod

December 5, 2019

Bioacoustic alarms are sounding on Cape Cod

How a WHOI/IFAW study on dolphin sounds could help decrease mass strandings on the cape

By Daniel Hentz  |  December 5, 2019

IFAW's Marine Mammal Rescue Team and volunteers respond to a  stranding of four common dolphins on Scussett Beach, Cape Cod in 2018- their 5000th response since the beginning of the Cape Cod Stranding Network. (Photo courtesy of © IFAW) IFAW’s Marine Mammal Rescue Team and volunteers respond to a stranding of four common dolphins on Scussett Beach, Cape Cod in 2018- their 5000th response since the beginning of the Cape Cod Stranding Network. (Photo courtesy of © IFAW)

The International Fund for Animal Welfare (IFAW) and its Marine Mammal Rescue Team in Yarmouth, Massachusetts have responded to a record high of more than 464 marine mammals stranded on Cape Cod since January this year. Researchers at Woods Hole Oceanographic Institution (WHOI) believe patterns from animal sound data may be the key to curbing these numbers.

For those sing-songy dolphins that captivate many, sound is more than play, it’s survival. Like humans calling in the night, dolphins use their high-pitched whistles to note their position in the water, or if they’re unlucky, on shore.

“It’s like calling your name out to your friends,” says Laela Sayigh, an animal behaviorist at WHOI. “When dolphins and whales are stressed, the most important thing is for them to stay in touch with their group mates.”

Back in the early 2000s, Sayigh’s colleagues, including fellow WHOI marine mammal expert Michael Moore, former northeast stranding coordinator Dana Hartley (NOAA) and necrospy coordinator Andrea Bogomolni (Cape Cod Stranding Network), suggested that there may be detectable changes in the vocalizations of distressed dolphins and whales that are about to strand on Cape Cod’s beaches. With funding from Woods Hole Sea Grant, Sayigh saw an opportunity to finally explore what Moore and her other colleagues were talking about.

In 2014, her team installed a passive underwater recorder, or soundtrap, in Wellfleet Harbor, a place notorious for mass strandings. Working with IFAW data, Sayigh was able to observe nuances in recorded whistles around the time of a stranding and contrast them with the sounds of individuals not in danger of the phenomenon.

What they discovered was an exciting correlation: a cacophony of distress calls recorded time and time again before documented stranding events. With enough data to codify this pattern, they could program an alert system to initiate response teams at the onset of a stranding event.

“It was certainly exciting from a biological perspective,” adds Sayigh.

But for members of IFAW’s marine stranding team, this research couldn’t come soon enough.

The Hook Within a Hook

From a bird’s-eye view, Cape Cod has an iconic fish hook shape. Indeed, the area’s appearance has become the symbol of countless vacation-themed shirts about deep-sea angling and summer fun. But for conservationists at IFAW, Wellfleet Harbor is the barb on that hook—and not in a pleasant way.

Drastic tidal changes of more than 13 feet over shallow sandbars make the narrow bay a virtual trap for the unwitting marine visitor. Add to this the rush hour of boat traffic, migratory patterns, and inclement weather, and it’s no wonder dolphins and whales can’t avoid this sandy fate.

For members of IFAW’s Marine Mammal Rescue Team, Cape Cod’s preeminent stranding response group, the work has never been easy. Everything from common dolphins and minke whales, to injured gray, harbor and harp seals, all take turns winding up on shore.

In the past 20 years since the response team’s inception, they have always expected each species to strand on a seasonal schedule, typically following migratory patterns. Such rotations made it a manageable endeavor for the modest six-to-eight-person response teams. But times have changed.

“Usually it’s a cycle for each species – often there is one species where strandings peak for the year­,” says Misty Niemeyer, the stranding coordinator for IFAW. “One year will be higher for harbor porpoises, another for harp seals… this year it’s everything at once.”

Of all these marine victims, Sayigh was most interested in studying the sounds of highly social creatures that regularly strand together. After all, more individuals should mean louder, clearer and more frequent signals. And no two species would be more suited for this study than the common and Atlantic white-sided dolphins.

In early 2012, more than 200 common and Atlantic white-sided dolphins stranded during an 80-day stretch, forcing IFAW into a 24/7 operation.

“We got to the point where we would wake up and just drive to Wellfleet,” says the organization’s research coordinator, Kathryn Rose. “We wouldn’t even wait for a call.”

In the past ten years, IFAW has logged 139 mass strandings involving the two species, totaling more than 668 individuals. More than 71 of these events occurred during WHOI’s research period. It was clear: the species’ proneness to mass strand made them the most suitable subjects to observe. Identifying and logging every dolphin whistle, however, would be a lofty goal.

The Art of Whistle Detection

In their nearly four years of research, Sayigh’s team collected more than 6,287 hours of recordings. Altogether, that’s more than 261 days of audio.

The tools they used are modest to say the least: a pair of headphones and an audio visualization called a spectrogram, generated by a software program called Raven. Chief among Sayigh’s other assistants were former students Sam Walkes from Bowdoin College and Seth Cones of Ohio University (and a current doctoral student in the MIT/WHOI joint program) who in one summer scanned through a big chunk of the data collected between 2014 and 2018.

Laela Sayigh tags dolphin whistles collected from Wellfleet Harbor on her computer using a program called Raven (Photo by Daniel Hentz, © Woods Hole Oceanographic Institution)

“There’s no [reliable] way of putting in files of whistles from [whale or dolphin] species and training the computer to look and count for them,” says Cones. “Until then, it’s all manual.”

Cones, who began the project as a summer intern in 2017, is just now finishing the final year of data analysis. In that time, he’s tagged and analyzed more than 124 hours of the aquatic calls, scientifically known as signature whistles. On a monitor, these whistles appear like scribbles on an Etch-A-Sketch, but with an unmistakable pattern and cadence, some with high peaks and low valleys.

“We have to use visual representations of the sound, because our human ears can’t manage those higher frequencies,” notes Sayigh.

Frame by frame, 30 seconds at a time, Sayigh, Walkes, Cones and a cadre of supporting scientists scrolled through the endless static of Harbor ambience, humming boats, and curious wildlife to count the rare marks of whistles—a sound needle in an auditory haystack.

Sayigh even incorporated a small group of budding scientists from the Girls in Science program (video here) to help teach them about marine mammal vocalizations, while also expediting the search for these elusive calls.

Some days of audio were so dense with sound that they required an additional four days just for analysis, recalls Cones. In spite of this, the cohort still maintains an untampered excitement. Now zooming in, any feature from the peaks, valleys or breaks in each whistle could be another clue into the early warning signs of a potential stranding. One important difference in any of these patterns could mean saving scores of dolphins.

“There’s got to be something else in [the dataset] that we’re missing,” notes Cones. “It’s like a puzzle.”


The Future of Conservation

By combining soundtraps with computers that are coded to recognize the auditory cues of mass strandings, Sayigh believes we may be close to a future where an SMS text alert could notify rescue teams at IFAW to respond preemptively to strandings.

“I’m optimistic and hopeful that [the data] will help with mass stranding event detection, but we’d need more data to feel comfortable,” says Sayigh. This will mean identifying more than just occurrences of these whistles, but how far apart they occur from one another, and the window of opportunity to act once a detection is made.

And if there’s any one salient thing to know about marine mammal rescues, it’s that they’re time-sensitive.

On shore, marine mammals suffer the alien effect of gravity—their weighty figures sinking into the sharp edges of shells in the mudflat. The added stress of chilling winter winds or the pounding summer sun make an already uncomfortable experience a living horror. In large enough sizes, these mass strandings can overwhelm even the most experienced rescue teams.

On the clock to relocate sometimes dozens of individuals at a time—each weighing several hundred pounds—it is inevitable that some animals do not survive. In the last decade, nearly 20 percent of mass stranded dolphins found alive succumbed to exhaustion or sickness and died, or had to be euthanized.

“A lot of what we learn is from the animals that don’t make it,” says Niemeyer. “But compassion fatigue is a real thing.”

For Niemeyer, an alert system means the difference between herding live animals out of the bay with skiffs and motor boats, or sampling scores of dead ones in the Yarmouth facility’s mobile necropsy lab trailer.

But this isn’t the first time IFAW has stood behind bold conservation initiatives.

In 2010, NOAA approved the organization’s plan to affix tags to individually stranded dolphins scheduled for release. The tags reported the dolphins’ position by satellite, and IFAW’s teams discovered the individuals had indeed survived and reunited with their pods.

“We debunked the myth that animals couldn’t meet up with their pod and survive [after a stranding],” says Niemeyer.

More than anything, Niemeyer stresses the importance of public awareness. For her and Sayigh, Cape Cod can be ground zero for an automated alert system that could benefit other mass stranding hotspots worldwide—places like New Zealand and Australia, and even parts of the U.K., where dolphins and whales have been beaching for millennia.

For now, it seems the ethos of Cape Cod—it’s undeniable connection to marine life—continues to drive support for WHOI’s and IFAW’s collaborative research, sometimes in strange and subtle ways.

In 2015, IFAW representatives attended Wellfleet’s annual Oyster Fest to promote knowledge of strandings in a place commonly afflicted by the issue. It was poignant that the attendees, including research coordinator Kathryn Rose, had to leave to meet Niemeyer in response to a stranded dolphin along the harbor sandbar. An early departure was, after all, an appropriate (albeit unplanned) advertisement of IFAW’s work.

Back then, Cape Cod’s lone highway was clogged with carefree festival-goers coming and going from Wellfleet. But the kindness of several police officers called in by the festival’s organizers made for an unconventional scene: the blare of police sirens, making way for a gurneyed dolphin in a trailer.

“There are so many cumulative impacts on these species. Some are obvious like entanglements in fishing gear and vessel strikes, but a lot of them are not so obvious… there’s ocean noise, climate change, contaminants, algal blooms, I could go on and on,” says Niemeyer. “There’s a lot we can’t fix – we’ll never eliminate strandings ­– but this could have a significant impact and save more animal lives.”

The bioacoustics research project was made possible with funding from the Woods Hole Sea Grant in Woods Hole, Massachusetts and collaborative support from the International Fund for Animal Welfare in Yarmouth, Massachusetts. This story’s map visualization was rendered using data generously provided by IFAW’s Marine Mammal Rescue Team. To learn more about Laela Sayigh’s research on bioacoustics check out the Girls in Science Program video above, where she was featured as a leading scientist and mentor.


The Rise of Orpheus

October 8, 2019

The Rise of Orpheus

WHOI’s new hadal robot moves one step closer to exploring the limits of life on Earth and beyond

By Evan Lubofsky | October 8, 2019

Orpheus, an autonomous underwater vehicle (AUV), is deployed off the New England continental shelf during one of several dives from the R/V Neil Armstrong in September 2019. Designed by WHOI lead engineer Casey Machado and WHOI deep-sea scientist Tim Shank in collaboration with NASA’s Jet Propulsion Laboratory, Orpheus is a critical component of WHOI’s HADEX deep ocean exploration program. (Video by Evan Kovacs, Marine Imaging Technologies, LLC / Courtesy of Woods Hole Oceanographic Institution)


Just as the first jaw-dropping images of deep-sea tubeworms and clams changed our understanding of life when hydrothermal vents were discovered in the 1970s, exploring the hadal zone—the deepest region of the ocean (named after Hades, king of the underworld realm in Greek mythology)—may yield new clues about the limits of life on Earth, and possibly beyond.

This is according to Tim Shank, a deep-sea biologist at Woods Hole Oceanographic Institution (WHOI), who is on the R/V Neil Armstrong headed to a vast, underwater canyon along the New England continental shelf. There, he and his team will field test Orpheus, a bright-orange ocean robot that he and WHOI engineer Casey Machado designed to explore this dark and mysterious layer of the ocean.

“Hadal trenches are among the least explored environments on our planet,” says Shank, who heads up the institution’s HADEX (short for Hadal Exploration) deep ocean exploration program. “We know very little about what species live down in these habitats, what the biological diversity looks like, and how life there has evolved to withstand and thrive under extreme conditions.”

Orpheus, named after one of the legendary figures in Greek Mythology who made it to the underworld and back, represents a new class of autonomous underwater vehicle (AUV) that Shank says will enable access to explore this last frontier on Earth.

WHOI’s hadal vehicle was named after the ancient Greek hero Orpheus, a musician, poet, and prophet who made it to the underworld and back. (Image by Wikimedia Commons)

WHOI’s hadal vehicle was named after the ancient Greek hero Orpheus, a musician, poet, and prophet who made it to the underworld and back. (Image by Wikimedia Commons) WHOI’s hadal vehicle was named after the ancient Greek hero Orpheus, a musician, poet, and prophet who made it to the underworld and back. (Image by Wikimedia Commons)

The ‘what’s down there?’ question is key, but his interest in this unknown universe six miles beneath the ocean’s surface runs far deeper.

“Certain novel adaptations that enable species to exist under hadal conditions could lead to promising medical treatments, and offer clues about the rise and evolution of life itself,” says Shank.

He adds that if Orpheus is successful in withstanding the extreme pressures of the deep, the technology could be leveraged to explore ocean worlds beyond Earth with similar environments, like Europa and Enceladus, the moons of Jupiter and Saturn, respectively.

Pushing the limits

The seas are calm as Neil Armstrong draws closer to a steep-sided submarine valley known as Veatch Canyon. There, Orpheus will make its first of three dives in the open ocean, a place it hasn’t been to since 2018 when Shank and his team conducted initial field tests of the vehicle aboard OceanX’s vessel, the M/V Alucia. The expedition is an incremental yet vital step in the robot’s formative stages, one aimed at garnering confidence in the vehicle’s capabilities before it makes its plunge into full-ocean depth territory in 2020.

Machado pops into the garage holding a medicine-ball-sized glass sphere. Inside is a tangle of colorful wires and cables—the circuitry of the robot’s nervous system. She and WHOI electrical engineer John Bailey spent the last half hour running it through a series of diagnostics in the ship’s main lab next door. It is now time to reattach Orpheus’s brain

WHOI deep-sea biologist Tim Shank has his game face on as the R/V <i>Neil Armstrong</i> heads to Veatch Canyon along the New England continental shelf. There, <i>Orpheus</i> will make a series of three dives into the open ocean, a critical incremental step in the robot’s formative stages. (Photo by Colin Reed, Woods Hole Oceanographic Institution) WHOI deep-sea biologist Tim Shank has his game face on as the R/V Neil Armstrong heads to Veatch Canyon along the New England continental shelf. There, Orpheus will make a series of three dives into the open ocean, a critical incremental step in the robot’s formative stages. (Photo by Colin Reed, Woods Hole Oceanographic Institution)

to its body (roughly the size and shape of a mechanical bull), which is covered in a thick layer of off-white syntactic foam. The foam—donated by filmmaker and ocean explorer James Cameron—was fabricated to withstand pressures that are more extreme than those found at the full 11,000-meter (36,000-foot) depth of the ocean. Cameron had used the custom-designed material in his own human-occupied hadal vehicle, Deepsea Challenger.

Orpheus bridges a critical gap in our nation’s ability to access and explore the deepest parts of our ocean,” says Cameron. “I’m thrilled that the technological legacy of the Deepsea Challenger is at the core of this new developing fleet of hadal AUVs.”

WHOI mechanical engineer Casey Machado sits in the ship’s staging bay before Orpheus’ first plunge of the expedition. The vehicle’s electronics are housed in a glass sphere, shown in the foreground, which can tolerate the extreme pressure of the deep, and is one of many cost-saving measures that went into the vehicle’s design. (Photo by Evan Lubofsky, Woods Hole Oceanographic Institution) WHOI mechanical engineer Casey Machado sits in the ship’s staging bay before Orpheus’s first plunge of the expedition. The vehicle’s electronics are housed in a glass sphere, shown in the foreground, which can tolerate the extreme pressure of the deep, and is one of many cost-saving measures that went into the vehicle’s design. (Photo by Evan Lubofsky, Woods Hole Oceanographic Institution) WHOI mechanical engineer Casey Machado sits in the ship’s staging bay before Orpheus’ first plunge of the expedition. The vehicle’s electronics are housed in a glass sphere, shown in the foreground, which can tolerate the extreme pressure of the deep, and is one of many cost-saving measures that went into the vehicle’s design. (Photo by Evan Lubofsky, Woods Hole Oceanographic Institution) WHOI mechanical engineer Casey Machado sits in the ship’s staging bay before Orpheus’ first plunge of the expedition. The vehicle’s electronics are housed in a glass sphere, shown in the foreground, which can tolerate the extreme pressure of the deep, and is one of many cost-saving measures that went into the vehicle’s design. (Photo by Evan Lubofsky, Woods Hole Oceanographic Institution)

Using glass to house the electronics is one of many cost-saving measures Machado and her team have taken to minimize the financial risks associated with a catastrophic vehicle failure—one that the punishing pressures of the deep could cause. Nereus, a hadal robot prototype developed at WHOI in 2011, imploded after reaching a depth of 10,000 meters in the Kermadec Trench northeast of New Zealand in 2014. From Machado’s perspective, Orpheus represented a chance to scale things down.

A polynoid polychaete worm ambles over the seafloor at a depth of more than 10,000 meters in the Kermadec Trench in 2014. Tracks and trails of undiscovered animals are etched into the seafloor below. (Video by Tim Shank, Woods Hole Oceanographic Institution) A polynoid polychaete worm ambles over the seafloor at a depth of more than 10,000 meters in the Kermadec Trench in 2014. Tracks and trails of undiscovered animals are etched into the seafloor below. (Video by Tim Shank, Woods Hole Oceanographic Institution)

“I did a cost analysis and tried to come up with the most cost-effective ways to do everything we really needed to do,” says Machado. “The philosophy was, everything on the vehicle had to be super-necessary or it wasn’t included.”

Shank says another reason for the cost-conscious design of Orpheus relates to one of the HADEX program’s key goals: having a fleet of low-cost, full-ocean depth vehicles. “We want an armada of these vehicles down there,” he says.

Collectively, the ocean’s hadal zone covers an area about as large as Australia—that’s a lot of space to cover. Shank says the idea is that, rather than relying on a single vehicle that costs millions of dollars, there could be twenty or more lower-cost robots exploring hadal trenches cooperatively. A second vehicle—Eurydice—has already been built to help cover more of the hadal zone in less time.

Cool your jets

A blender-like sound cuts through the air, then stops, and then whirs again. Russell Smith, a young engineer from NASA’s Jet Propulsion Laboratory (JPL), enters the garage, where the scent of ship diesel hangs in the air. With his space-gray Macbook, he starts toggling the robot’s thrusters on and off. He completes the sweep and moves on to the lights and other functions, making sure all systems are a go for Orpheus’s first dive.

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)

JPL engineers have been collaborating with WHOI on the Orpheus project since 2017. They’re interested in autonomous vehicles that can withstand the pressures at the bottom of the ocean, an environment that Smith says is a good analog to the pressures that exist in ocean worlds beyond Earth. He and his colleagues are writing software that will allow the robot to build three-dimensional maps of the seafloor by stitching together images of features it sees, such as rocks and clams. These terrain maps will enable Orpheus to navigate the deep, and independently recognize features along the seafloor that may be of scientific interest to Shank and others.

“The big trick here is that the bottom of the ocean is super murky and dark and there’s a lot of stuff floating around in the way,” says Smith. “There’s a lot of visual distortion that you have to get rid of to create the maps, so it’s really challenging from that perspective.”

Dunk tests

Orpheus is hanging off Neil Armstrong’s crane hoisted a dozen feet above the Atlantic. The winch motor groans as Orpheus is gently eased into the blue water. The blur of its orange body becomes obscured as the robot is tethered 10 meters below the surface. It’s not very deep for a hadal vehicle, but enough to get the robot’s systems wet to ensure nothing is malfunctioning.

An hour later, the ship’s crane starts whining again as Orpheus is hauled up from the sea. On deck, it’s gently placed onto a dolly and carted back to the garage, where Machado and Bailey begin working the robot over in pit-crew fashion.

The next day, just as Orpheus is supposed to take another dunk, the sky goes from a yawn to a tantrum as a squall rolls in. Heaving seas crash over the side of Neil Armstrong as the ocean surface becomes lined with a scrim of angry indigo ribbons. A few hours later, the storm moves out and Orpheus completes dive #2. So far, so good.

The Armstrong crew begins lowering Orpheus into the Atlantic Ocean for one of the three dives planned for the expedition. (Photo by Emiley Lockhart, Woods Hole Oceanographic Institution)

The <i>Neil Armstrong</i> crew begins lowering <i>Orpheus</i> into the Atlantic Ocean for one of the three dives planned for the expedition. (Photo by Emiley Lockhart, Woods Hole Oceanographic Institution) The Neil Armstrong crew begins lowering Orpheus into the Atlantic Ocean for one of the three dives planned for the expedition. (Photo by Emiley Lockhart, Woods Hole Oceanographic Institution)

The pressure to adapt

The extreme pressures of the deep may have forced hadal robots to evolve, but the real adaptations have occurred within deep-sea animals themselves. Taylor Heyl, a deep-sea biologist in Shank’s lab, says some of the most novel adaptations relate to how certain hadal creatures seem to correct for poorly-functioning proteins.

“The high pressures can make cells too small for proteins to work properly,” she says. “Some species have adapted by using enzymes called piezolytes that surround water molecules to increase space inside their cells and counteract the pressures.”

Shank says that when proteins become dysfunctional in humans, the result is often disease, such as Alzheimer’s. So, he wants to take a closer look at what’s controlling the protein stability of hadal animals by bringing them up from the deep and comparing their genomes with those of healthy people and those afflicted with disease.

“There’s a strong genetic basis for use of these hadal animals in society,” he says, “so we need to look at these adaptations on a genetic level.”

Going deeper

Today, Orpheus will plunge more than 1,600 meters into Veatch Canyon—the deepest it’s ever gone. If all goes to plan, it will explore for a few hours and make it back up by dinnertime.

The dinner menu on the board outside the mess hall looks good—grilled mahi, roasted mixed vegetables, tossed salad, as does the weather. But no one seems to be thinking about either right now: at this point, it’s all about robot readiness.

Machado is in the staging bay pumping fluid into a junction box of wires inside the robot’s glass housing. It’s a curious sight that runs counter to the general principle of keeping circuitry dry.

“Mineral oil compensates for depth, so we use it to protect the electronics from the extreme pressures rather than physical housings, which add weight,” she says.

Once again, Orpheus is hoisted above the water by crane and slowly submerged. As the safety line is cut, the robot is swallowed whole by the canyon. The engineers head straight to the ship’s computer lab, where Shank is stationed, to get an early view of the mission. The robot is dropping 30 meters per minute, and should be at the bottom within an hour.

The afternoon flies and suddenly it’s approaching 5:00 p.m. Orpheus has been surveying the submarine canyon like a grasshopper, landing on one spot, capturing video, and then jumping up and flying over to the next spot. One of the monitors in the computer lab shows the vehicle at a depth of 1,623 meters. According to Smith’s mission script, is expected to ignite a burn wire twelve minutes from now that will cause its weights to drop and the vehicle to surface.

Twelve minutes pass. The 1,623-meter figure on the monitor doesn’t budge. Orpheus is on the bottom of the ocean, and it isn’t moving. The scientists and engineers watch with baited breath.

Shank is pensive as he stares at the screen. He and Machado know this feeling all too well. Losing this vehicle would be a crushing blow to the HADEX program, which has gained considerable momentum since Orpheus was built.

It’s a tense night on the Neil Armstrong as Shank and Machado anxiously await Orpheus’s return to the surface. It’s a tense night on the Neil Armstrong as Shank and Machado anxiously await Orpheus’s return to the surface. (Photo by Taylor Heyl, Woods Hole Oceanographic Institution)

Did the batteries die? Did the robot get snagged in a fishing net or line? Will the sweeping canyon currents make Orpheus an irretrievable runaway vehicle? Heyl glances over at Shank, sees his lost expression, and can’t muster much beyond, “Take four deep breaths, please.”

Machado takes a shot at some much-needed humor. She asks if Eurydice, Orpheus’ twin robot, becomes the new Orpheus if the vehicle doesn’t come back up. The half joke is met with silence as she leaves the control room to re-examine the mission scripts and see if anything seems amiss.

Hadal mysteries

There are mysteries of the deep, and then there are stumpers. For example, how does organic matter get from the ocean’s surface all the way down to the hadal zone? According to Shank, there is a lot of organic material down there even though there shouldn’t be. For example, if you toss a fish overboard, other fish start eating it as it makes its way down. Microbes typically munch on the remainder so by the time the remains get to the deep ocean, there should be very little, if anything, left.

The hadal zone may be rich in organic matter, but scientists still don’t know the full variety of food sources that exist down there or what sustains its organisms.

Nereus, a hadal robot prototype developed at WHOI in 2011, captured imagery of sea life at more than 8,000 meters deep during a 2014 cruise to the Kermadec Trench. (Video by Tim Shank, Woods Hole Oceanographic Institution)

Heyl says another mystery is whether hadal animals found in different trenches are biologically connected. “We’re not certain if they’ve evolved independently of one another given the miles of separation between certain trenches, or if certain species populations are possibly connected through dispersal mechanisms,” she says. “So, we ultimately want to investigate this at the molecular level to determine if species are genetically distinct across different trenches.”


The robot stays down. At this point, no one will know anything until 7:15 pm, when a second failsafe—a tiny galvanic latch that supports the vehicle’s weights—will dissolve from corrosion. That should cause the robot to rise up like a hot air balloon, but if the vehicle is snagged, all bets are off.

With that fear in mind, Shank heads out to the deck to confer with Armstrong captain Kent Sheasley. It turns out, the captain has experience in “lassoing” instruments on the seafloor using cable spooled on the ship’s winch.

Seven o’clock rolls around. The waiting game has been painful, so even those who aren’t hungry hit the mess for their last supper. The air of tension on the ship is inescapable.

A readout of <em>Orpheus</em>’s location and depth appears on monitors in the <em>Neil Armstrong</em>’s computer lab. (Photo by Tim Shank, Woods Hole Oceanographic Institution) A readout of Orpheus’s location and depth appears on monitors in the Neil Armstrong’s computer lab. (Photo by Tim Shank, Woods Hole Oceanographic Institution)

Fifteen more minutes pass, and just when the latch is expected to separate and free the robot, the 1,623-meter figure stays etched on the screen.

Then, a few seconds later, the readout miraculously refreshes.




Orpheus is rising.

Word gets around the ship fast. Forty-five minutes later, the robot pops out of the water and is greeted with cheer on deck. Without hesitation, the vehicle is hauled up and shuttled back to the staging bay, where a symphony of socket wrenches fills the air as the engineers begin working Orpheus over to investigate why it got stuck.

A view from below

Heyl grabs a memory card from one of the robot’s cameras, and she and Shank head into the main lab to watch footage of Orpheus’ last few hours on a laptop. A crowd gathers around. Orpheus is making its way down the canyon, kicking up plumes of sediment with each turn along it’s programmed track. Then, it’s flying just above the seafloor, spying on what looks like an underwater desert of single-celled creatures known as xenophyophores. Occasional sea spiders and eels wriggle their way in and out of the otherworldly landscape.

The creatures on the monitor are quickly recognizable to Shank and Heyl, but it may be a whole different story next year when they send Orpheus to the bottom of the Mariana Trench in the western Pacific Ocean—the deepest point in the ocean that extends down 11,000 meters.

Shank, Heyl, and others huddle around a laptop to watch video footage of Orpheus during its last few hours exploring Veatch Canyon. (Video by Evan Kovacs, Marine Imaging Technologies, LLC / Courtesy of Woods Hole Oceanographic Institution)

“We need access to the animals there so we can get their genomes and start looking at their adaptations on a genetic level,” says Shank, with contagious excitement. “The societal relevance here is just so strong—I think it could be a complete game changer for understanding life as we know it today.”

Within 30 minutes, Orpheus discovers a patch of deep-sea mussels embedded in the soft sediment, indicating a cold seep—a chemosynthetic community that relies on methane as a food source. It’s similar to the type of chemo-communities Shank and Heyl will be looking for in the hadal zone.


Movie time is over. Shank heads back to the garage to reconnect with Machado and Bailey. They tell him that Orpheus’ batteries died at the bottom of the canyon. The thrusters were the main culprits; they had been programmed to run full throttle during the entire mission to compete with the tough currents until, ultimately, the vehicle ran out of juice.

“We pushed the boundaries of what we asked Orpheus to do,” says Shank. “And, we picked a really complex place with rough terrain to see how hard it could run. It’s exactly what these trials are for.”

In the end, he says the team learned more from the batteries failing than they would have if everything went smoothly. Which is good, because as Orpheus searches for life at 36,000 feet deep in Mariana Trench next year, it’ll need all the juice it can get.

Hadex Program Underwater Vehicles Ocean Life

Blue shark

A tunnel to the Twilight Zone

August 2, 2019

A tunnel to the Twilight Zone

Blue sharks ride deep-swirling currents to the ocean’s midwater at mealtime

By Evan Lubofsky | August 2, 2019

Video by Camrin Braun, University of Washington and Tane Sinclair-Taylor, James Cook University.

When you’re hungry, wouldn’t it be nice to just slip into a tunnel that rushes you off to a grand buffet? It sounds like something Elon Musk might dream up, but it turns out, certain species of sharks appear to have this luxury.

Last year, researchers at Woods Hole Oceanographic Institution (WHOI) and the Applied Physics Lab at the University of Washington (UW) discovered that when white sharks are ready to feast, they ride large, swirling ocean currents known as eddies to fast-track their way to the ocean twilight zone—a layer of the ocean between 200 and 1000 meters deep (656 to 3280 feet) containing the largest fish biomass on Earth. Now, according to a new study in Proceedings of the National Academy of Sciences (PNAS), scientists are seeing a similar activity with blue sharks, which dive through these natural, spinning tunnels at mealtime. The eddies draw warm water deep into the twilight zone where temperatures are normally considerably colder, allowing blue sharks to forage across areas of the open ocean that are often characterized by low prey abundance in surface waters.

To track their movements, the researchers tagged more than a dozen blue sharks off the Northeast Coast of the U.S. and monitored them for a period of nine months. According to Simon Thorrold, a senior scientist at WHOI and co-author of the study, each shark was “double tagged” on their dorsal fins; one tag monitored ocean temperatures and depth as the sharks moved through the ocean and the other tag tracked their location. This double-tagging strategy allowed the scientists to reproduce the three-dimensional tracks of the sharks with the resolution and accuracy needed to link their movements to the positions of ocean currents like eddies.

Animation by Natalie Renier, Woods Hole Oceanographic Institution

Data relayed from the tags via satellite to labs at WHOI and UW revealed that the sharks spent a good portion of their days diving these warm-water tunnels to the ocean twilight zone hundreds of meters below the surface. There, they’d spend an hour or so foraging before swimming back to the surface to warm up before diving again.

Simon Thorrold Satellite tags like this one displayed by WHOI biologist Simon Thorrold are giving scientists an unprecedented ability to follow sharks and understand their habitats and behavior. The information is essential for determining management strategies to ensure that the sharks are not overfished. (Photo by Tom Kleindinst)

Dives were less frequent at night, when many twilight zone animals make their daily migration from the ocean’s mid-water to the surface. According to Camrin Braun, an ocean ecologist at UW and lead author of the study, a trip to the twilight zone at night isn’t really worth it for hungry blue sharks since their “deep ocean buffet” isn’t particularly well stocked after dark.

“Sharks are all about opportunity, so with fewer prey items down there at night, they’re just not going to make the trip,” he said. “Going down there is costly for them from an energetic and metabolic standpoint.”

tagging a shark University of Washington ocean ecologist Camrin Braun and his colleagues tagged sharks to track them as they dove warm-water eddies to the ocean twilight zone to forage. (Photo by Tane Sinclair-Taylor, James Cook University)

Braun, who conducted the research as a PhD student in the MIT-WHOI Joint Program in Oceanography before working at UW, says that the behavior of the blue sharks was generally similar to that of the white sharks tracked in the previous study. However, the two species had different preferences when it came to water temperature. White sharks, which are warm-blooded animals, used a combination of warm- and cold-water eddies as a conduit to the twilight zone, while blue sharks—a cold-blooded species—relied exclusively on warm-water eddies.

“Blue sharks can’t regulate their body temperature internally to stay warmer than the ambient seawater like white sharks can, so they need to control it behaviorally,” said Braun. “We think this is why they show a clear preference for the warm-water eddies—it removes a thermal constraint to deep diving.”

In general, when it comes to the secret lives of large apex predators like sharks, scientists know relatively little. This research, according to Thorrold, helps fill important knowledge gaps about where they go and why, which can inform decision making on where to implement marine protected areas to conserve them. And, the work underscores the importance of the ocean twilight zone as a critical biomass resource.

“The twilight zone is vulnerable to overfishing,” he said. “If we’re harvesting low-value fish there at the expense of high-value fish like blue sharks and other pelagic predators, that’s probably not a good tradeoff.”

Ocean Twilight Zone Imaging Biology Department

The Deep-See Peers into the Depths

The Deep-See Peers into the Depths

February 20, 2019

In the ocean’s shadowy depths lies one of the Earth’s last frontiers: the ocean twilight zone. It’s a vast swath of water extending throughout the world’s oceans from 650 to 3,280 feet (200 to 1,000 meters) below the surface, and it abounds with life: small but fierce-looking fish, giant glowing jellies, and microscopic animals that feed marine life higher up the ocean’s food web.

This cold, dark, remote region of the ocean has remained largely unexplored, but a team of scientists and engineers from Woods Hole Oceanographic Institution have pioneered an ambitious new vehicle to blaze a trail into this ocean wilderness. Known as the Deep-See, it is a modern-day, subsea Conestoga wagon filled with a remarkable array of instruments designed to illuminate the ocean’s mysterious interior and reveal how many and what kinds of animals live there.

“To date, scientists have used several methods to explore the midwater depths, but each had its pros and cons,” said WHOI marine biologist Larry Madin. Acoustic sonars could detect masses of animals that reflected sound well, but they usually couldn’t distinguish individual species. Nets could bring back some intact animals, but they often squished the more gelatinous ones and missed those that were very small or could get out of the way. And cameras weren’t so effective at capturing images of animals that were sparsely distributed, moving, and often small or transparent.

“The aptly named Deep-See combines complementary imaging systems that promise to detect a broad range of organisms,” Madin said. It is towed behind a research ship from an electro-optical cable that can transmit power and data between the ship and the vehicle in real time. And it’s big, weighing 2,500 pounds (1,250 kilograms) and measuring about 16 feet (5 meters).

“It has plenty of room for all kinds of acoustic sensors and optical sensors—that’s another fancy word for cameras,” said WHOI acoustic oceanographer Andone Lavery, the lead scientist on the Deep-See project. “This particular combination has never been used before to study the twilight zone.”

The platform’s sophisticated acoustic and imaging systems include:

  • broadband, split-beam sonars to detect, count, track, and identify animals
  • a holographic laser-based camera to capture 3-D images of tiny plankton
  • a specialized stereo camera-and-lighting system to photograph jellyfish and other large animals
  • sensors to measure seawater properties, such as temperature, salinity, and dissolved oxygen
  • a sampler to collect DNA signatures of ocean twilight zone animals

WHOI mechanical engineer Kaitlyn Tradd helped to design and build the vehicle in three sections, or modules: the forward optics module for the cameras and lights, the middle acoustics module for sonars, and the aft module—the tail—for hydrodynamic stability and space to hold additional sensors and equipment.

“The three separate modules also allow us flexibility when it comes to how we configure the vehicle for a given scientific objective,” Tradd said. “The modules easily bolt together, and new sections can be developed and added should the need arise.”

As novel as the Deep-See is, many of its cutting-edge systems are built on decades of technology development and basic science research by WHOI engineers and scientists.

The early days of broadband acoustics

Lavery began working with sonar systems when she was just out of graduate school, and she quickly discovered that using sound to identify and count animals in the ocean is a tricky business.

A typical echosounder or “fish finder” works something like an acoustic flashlight, transmitting a single-frequency beam of sound into the water below a ship. Sound waves reflect off fish and other organisms, creating an echo that a receiver on the echosounder can detect. Many common fish, with their gas-filled swim bladders, provide readily detectable targets.

But what scientists really want to be able to do, says Lavery, is to tell how big the target animals are and how many there are—in other words, does the returning echo represent a single large fish or dozens of tiny zooplankton?

“When you have a single sound frequency, it’s really hard to tell,” Lavery said. “Because there are lots of different combinations of organisms that can give you a similar echo.”

WHOI acoustical oceanographer Tim Stanton is all too familiar with that problem. He spent more than 20 years bouncing sound waves of all different frequencies off individual organisms in test tanks. Lavery joined his efforts when she first came to WHOI as a postdoctoral researcher.

“We put one organism at a time in the test tank,” Stanton said—from large fish all the way down to a tiny swimming snail the size of a head of pin. To keep the snail in front of the beam of sound, Stanton restrained it with an acoustically transparent tether: a human hair.

“We did this both on land and on the deck of a ship, collecting nothing but live, pristine organisms, and making these series of measurements,” Stanton said.

Through that painstaking process, Stanton and Lavery were able to identify each species’ unique acoustic “signature”—the strength of the sound waves bouncing back off an organism at various frequencies. These included high-frequency sound waves—the kind needed to detect smaller crustaceans such as copepods and krill.

In the early 2000s, Stanton and Lavery started testing their lab-based signatures in the open ocean, working with seagoing acoustic systems that could transmit and receive sound at not just a single frequency, but at several different ones, or across a whole spectrum at once. They showed that different sound waves returned from different organisms, proving that this so-called broadband approach could distinguish and count animals in the open ocean.

For them, it was like going from getting information from only one radio station, then from several, then from all the stations across the entire FM dial.

Building on the BIOMAPER

One predecessor to the Deep-See was a ship-towed vehicle developed at WHOI called the Bio-Optical Multifrequency Acoustical and Physical Enviromental Recorder, or BIOMAPER-II. It was equipped with transducers that transmitted sound at 43 kilohertz (kHz), 120 kHz, 200 kHz, 420 kHz, and 1,000 kHz.

BIOMAPER-II had a lot of high-frequency acoustics on it,” said WHOI biologist Peter Wiebe, who led its development. “That meant it could detect not just fish, but tiny plankton that can only be detected at higher frequencies.”

However, BIOMAPER-II could only descend to 300 meters—not deep enough to be useful in the ocean twilight zone. In contrast, says Lavery, the Deep-See can descend to 2,000 meters and transmit sound across frequencies from 1 to 500 kHz.

“One of the big advantages of the Deep-See,” said WHOI scientist and engineer Dana Yoerger, “is that it puts high-frequency acoustics right down into the twilight zone. You can’t use high frequencies from a ship because they are quickly absorbed in seawater, long before they can reach the twilight zone.”

But having a small library of laboratory-derived acoustic signatures isn’t sufficient. The signatures for most already-identified twilight zone animals remain unknown, let alone for the species yet to be discovered. In addition, scientists need to ground-truth the acoustic data by seeing with their own eyes what the sonar systems are detecting. From a ship, without a submarine, they have only two options: cameras and nets.

The next generation of cameras

BIOMAPER-II had several bio-optical sensors and a video plankton recorder, or VPR—a kind of underwater microscope that could capture high-resolution images of tiny particles and plankton from 50 microns (0.002 inches) up to a few centimeters (about an inch and half) in size. The Deep-See improves on its predecessor with two camera systems capable of capturing images of the organisms detected by its acoustic arrays: one holographic, one stereo.

The first is a small-area, holographic camera system, developed by emeritus WHOI biologist Cabell Davis at the marine technology company he founded, Seascan. The camera system is analogous to the BIOMAPER-II’s VPR, “but it uses lasers to take detailed, 3-D images of tiny plankton in their natural environment without disturbing them,” said engineer Cliff Pontbriand, who worked on the camera at WHOI. To do that, the holographic system sends out a laser beam with a diameter of 1.5 inches (3 centimeters)—about seven times per second—from a transmitter on one side of the Deep-See’s front frame to a receiver 3.3 feet (1 meter) away on the other side of the frame.

The Deep-See’s stereo camera system also builds on an earlier technology, known as the Large Area Plankton Imaging System, or LAPIS, which Madin and colleagues developed more than a decade ago.

“The original LAPIS was really a proof-of-concept to provide images of larger organisms than the VPR could,” Madin said. Special strobe lights provided illumination for the LAPIS cameras, allowing them to “see” in dark ocean water down to 1,640 feet (500 meters) and capture low-resolution, black-and-white images of both opaque animals such as krill and transparent ones such as jellyfish and salps.

“The trick is in the lighting, which needs to be reflected for opaque targets but refracted—from beside or slightly behind—for transparent ones,” Madin said.

The Deep-See contains a next-generation LAPIS camera system. It images a 1-square-meter swath of water using a more versatile LED-based lighting array rather than power-hungry strobes, and it produces 24-megapixel images instead of 1-megapixel ones. The higher-resolution image quality makes it easier for scientists to identify twilight zone animals and even study some of their behavior.

Genetic evidence

To complement its acoustic arrays and camera systems, Deep-See carries a host of sensors that measure seawater characteristics, such as temperature, salinity, dissolved oxygen concentrations, and the amount of light available to marine plants.

In addition, a sampler aboard the Deep-See collects filtered seawater containing genetic material from organisms living in it. Using cutting-edge gene-sequencing technology, WHOI biologist Annette Govindarajan is analyzing the water for this environmental DNA, or eDNA, seeking genetic evidence of life.

“Environmental DNA will allow us to detect evidence of twilight zone animals, including those missed by other sampling methods,” Govindarajan said.

Even with its combination of acoustics, imaging, environmental sensors, and water sampling capabilities, the Deep-See will not tell researchers everything they want to know about the twilight zone. To really understand this little-known region of the ocean, scientists will need to combine data from the Deep-See with information gleaned from traditional net tows and gathered by new underwater robotic systems such as the Mesobot. Using a multifaceted approach, Lavery says, should make it possible to reveal more accurately the abundance and diversity of animals in the twilight zone and to understand their behavior. It will also help determine how that behavior affects the ocean’s chemistry, including the transfer of the greenhouse gas carbon dioxide from the atmosphere to the deep ocean, which has huge ramifications for Earth’s climate.

“No system is foolproof,” Lavery said. “But I think that with Deep-See’s combined capabilities, we can begin to get at some pretty important questions.”

The Deep-See had its first sea trials in August 2018, on WHOI’s first ocean twilight zone expedition. The nine-day cruise aboard the National Oceanic and Atmospheric Administration’s research vessel Henry B. Bigelow was a collaborative mission with NOAA’s Northeast Fisheries Science Center and the University of Connecticut. The Bigelow navigated beyond New England’s continental shelf to the deeper waters of the northwest Atlantic Ocean, where the vehicle’s unique combination of instruments collected more than 22 terabytes of data.

On its first foray into the twilight zone, the Deep-See has already challenged scientists’ previous understanding of life in the deep ocean. Earlier acoustic explorations suggested that twilight zone animals were concentrated in one or more dense layers. However, because most of these early acoustic systems operated at lower frequencies and were mounted on the ship’s hull, the sound scattering they detected was mainly from animals with internal gas bubbles, such as swim bladders in fish or gas-filled chambers in jellies that help them float. Many organisms, especially ones not containing gas bubbles, were acoustically invisible.

The more perceptive Deep-See was able to detect twilight zone animals with and without gas bubbles, spanning a diverse range of species—and found that they were spread throughout the twilight zone at all depths.

“That was really surprising,” Lavery said. “I’m eager to find out what the Deep-See will reveal to us next.”

Funding for the development of Deep-See came from the National Science Foundation.

Do Microplastics in the Ocean Affect Scallops?

Do Microplastics in the Ocean Affect Scallops?

January 24, 2019

WHOI scientist Scott Gallager is making field observations and conducting lab experiments to explore the possible effects of microplastics in the ocean on marine organisms. Specifically, he’s looking at sea scallops at different life stages to determine if the tiny plastic fragments they ingest when filtering seawater stunt their growth. The work is part of WHOI’s Marine Microplastics Initiative, which is aimed at understanding the fate of “hidden” microplastics in the ocean and their impacts on marine life and human health. 

Q: Why did you choose scallops for this study?

A: Scallops are the most valuable fishery in the United States, with an estimated $750 million harvested annually. If microplastics are hampering them in any way, we need to know that now. We are collecting adult scallops offshore from Delaware to Georges Bank and finding plenty of microplastics in their guts. In addition, sea scallops are shellfish that many people like to eat. So there could be a potential risk for humans as well, particularly for shellfish where the entire animal is consumed.

Q: How does the lab experiment work with larval scallops?

A: First, we grind down larger pieces of plastics into irregularly shaped and sized particles, which is what you’d find under natural conditions in the ocean. The smaller we can make the particles, the better, since we’re feeding them to scallop larvae that are less than 90 microns in size. Then, we fill 10 different beakers of seawater with various concentrations of microplastics and place millions of larvae—just a few days old—into them. We’re exposing the larvae to microplastic concentrations that we think may interfere with their physiology, and to concentrations that we think will not. Often, when scientists do experiments like this, they expose the larvae to extremely high levels of microplastics, which you’d never see in the ocean. But we want to use concentrations that are environmentally relevant, so that we can assess if the health risks are actually real.

Q: Once the larvae ingest plastics, how can you tell if the plastics are affecting the growth rates?

A: We look at the larvae after their shells begin to develop using polarized light microscopy. That allows us to see very distinct patterns that indicate correct shell thickness and formation. If we see that the patterns are distorted in any way, it’s a good indication that the shell is not properly forming. 

Q: Is shell formation the only indicator?

A: It’s one of the key indicators of scallop growth, but we’re also looking for the formation of lipid droplets, which is a storage compound the larvae use to concentrate energy during metamorphosis when they cannot feed for a few days. They rely on those lipid reserves to survive. Using spectroscopy, we can measure the size and volume of the lipid droplets inside the newly formed shells and from there, determine how much lipid they are storing.

Q: What happens if you detect impaired shell growth and/or a lack of lipids?

A: If we do see signs of inhibited growth, we can look at what microplastic concentration levels those animals were exposed to and relate those to levels found in the environment.

We’ll be following these scallops all the way throughout their larval stage, which lasts about 40 days, and then running additional experiments in the future to track potential microplastic impacts during their sensitive juvenile and adult stages as well.

This work will ultimately help determine if there are health risks associated with microplastics that we need to be concerned about.

For more information about WHOI’s Marine Microplastics Initiative, visit

To Tag a Squid

To Tag a Squid

January 3, 2019
Junk Food

Junk Food

December 17, 2018

An estimated eight million tons of plastics enter our oceans each year, yet only one percent can be seen floating at the surface. This is the third in a three-part series of stories about how researchers at Woods Hole Oceanographic Institution are trying to understand the fate of “hidden” microplastics and their impacts on marine life and human health.

Microplastics may appear tiny—most are smaller than the fingernail on your pinky—especially when compared to larger plastics floating around the ocean such as bottles and bags. But as small as they are, a single particle is big enough to provide housing for thousands of microorganisms that cling to them. Together, they form communities of what some scientists refer to as the “Plastisphere” of the ocean.

Plastic bits may seem like one of the ocean’s stranger habitats, but they provide available real estate for microbes. As they drift through the ocean for a while, they act as tiny rafts on which bacteria and algae can hitch a ride and settle down and form colonies.

Plastic particles might also provide a microbial food court. They may not sound appetizing to us, but it’s possible that microbes may eat them. In a 2013 study looking at the microbial colonization of plastic marine debris, scientists from Woods Hole Oceanographic Institution and the Marine Biological Laboratory placed microplastics collected from the ocean under high-powered microscopes. They found not only diverse communities of microbes living on the them, but also chunks of material or “pits” missing from the fragments. Scientists, however, stress that more evidence is needed to confirm whether microbes consume plastics.

Over time, the microbes form a biofilm coating on the microplastic fragments. Scientists believe this entices fish, which may not know the difference, to gulp down food-covered microplastics and push them further up the food chain.

Scallops, for example, ingest plastic particles as they filter seawater. In recent years, deep-sea scallops collected during surveys off Cape Cod,  Mass., showed traces of microplastics in their guts, according to WHOI scientist Scott Gallager.

“Once we dissected them and scanned their gut contents,” explained Gallager, “we saw that these animals had ingested microplastics. In fact, we discovered six different types of polymers in these scallops.”

While the associated health impacts to sea scallops aren’t yet clear, there is reason to think that microplastics and marine life aren’t a good mix in general. For example, a 2018 study investigated the link between plastic waste and disease risk in more than 120,000 reef-building corals throughout the Asia-Pacific region and found that the likelihood of diseases increases from 4 percent to a whopping 89 percent when corals are in contact with plastic.

If it turns out that microplastics are dangerous for shellfish and other types of marine animals, what does that mean for seafood lovers? Plastics may contain phthalates, bisphenol A, and other toxic chemicals used in manufacturing processes. These additives can change the properties of plastic items in different ways. They can make your soda bottle more rigid and your pen more flexible. Microplastics also suck up harmful chemicals from the environment, such as polychlorinated biphenyls (PCBs), which have been directly linked to human health problems.

According to Amy Apprill, a microbial ecologist at WHOI, there’s also speculation that some of the microbes residing on microplastics are pathogens. “That can spell trouble for marine animals and possibly humans that consume plastics,” she said.

But Mark Hahn, a toxicologist at WHOI, says there’s a lot of controversy around the question of how dangerous microplastics are. Some feel the risk is trivial compared to the risks from exposure to other environmental stressors, whereas others see exposure to microplastics as an urgent problem.

To settle the score, Hahn feels it will be important to first determine which types of microplastics we’re most concerned about and then determine how much of them is being ingested by marine animals, including seafood.

“By combining these two pieces of information, we can assess the risks for marine animals and humans” he said.

For now, however, Hahn says there are a lot of unknowns.

“Are microplastics taken up and internalized in humans, or do they pass right through the gut?” Hahn asked. “And what is the relative contribution of seafood versus other sources of microplastics we’re exposed to? We inhale microplastic particles all the time. There are still many more questions than answers.”

For more information about WHOI’s Marine Microplastics Initiative, visit

Other Oceanus stories in this series:

Part 1: Sweat the Small Stuff

Part 2: Tracking a Snow Globe of Microplastics