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Why some threatened corals swap ‘algae’ partners

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This image shows Caribbean star coral (Orbicella faveolata) with individual coral polyps showing different levels of bleaching during a warm summer bleaching event in summer 2014. Image taken off northern Florida Keys.
Credit: Rivah Winter

A new research study showed why threatened Caribbean star corals sometimes swap partners to help them recover from bleaching events. The findings are important to understand the fate of coral reefs as ocean waters warm due to climate change.

The University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science research team placed colonies of Caribbean star coral (Orbicella faveolata) in a heated tank for one to two weeks to replicate ocean conditions that would lead to both mild and severe coral “bleaching” — when corals turn white as a result of the loss of symbiotic algae living in their tissues. The corals, collected from waters off Miami, were then allowed to recover at two different water temperatures, below and above the local average, to see if they recovered with the same or different algal partners.

“Since ‘symbiont shuffling’ occurs in only some cases, we wanted to understand what drives this process and whether it could help corals adjust to climate change,” said Ross Cunning, a UM Rosenstiel School alumnus and lead author of the study. “We discovered that partner switching in Caribbean star corals is dependent upon the severity of the bleaching event and the temperature during recovery.”

The researchers discovered that severe bleaching and warmer water recovery temperatures caused corals to shuffle their symbionts in favor of more heat-tolerant algae, which belong to a group of symbionts called clade D, while mild bleaching and cooler recovery drove shifts toward the less heat-tolerant algae, in clade B. The study, published in the June 3 issue of the journal Proceedings of the Royal Society B, suggests that increases in heat-tolerant symbionts in the Caribbean star coral are greatest when bleaching is more severe and the recovery environment is warmer.

Corals depend on symbiotic algae to survive and build coral reefs. Increased ocean temperatures due to climate change can cause these symbiotic algae to be expelled from the coral, an event known as bleaching, which often leads to death. Climate change is one of the main threats to the Caribbean star coral (O. faveolata), which was were recently listed as a ‘threatened’ species under the U.S. Endangered Species Act.

“These findings help resolve a long-standing debate over why some corals switch partners after bleaching, while others do not,” said Andrew Baker, UM Rosenstiel School associate professor of marine biology and ecology and a Pew fellow in marine conservation. “They show that, as the oceans continue to warm and bleaching events become more severe, we might expect heat-tolerant symbionts to become a common feature of recovering reefs. Corals that can ‘buddy up’ with different algae might be more resistant to bleaching in the future.”

Two more recent studies, also conducted in Baker’s Coral Reef Futures lab at UM, showed how corals modify their symbionts in response to environmental changes. The first, published earlier this year in the journal Global Change Biology, showed how changes in symbiont partners following bleaching directly increased corals’ thermal tolerance. The second, published in the May issue of the journal Ecology, showed that, in addition to changing the types of algae they partner with, corals also fine-tune the number of algae they contain to deal with an ever-changing environment.

“Together, these studies suggest that that the rate of warming, timing between bleaching events, and severity of each bleaching event, will play an important role in determining coral survivorship,” said Baker. “We need to better understand these changes in order to accurately predict coral reef futures.”

Source: University of Miami Rosenstiel School of Marine & Atmospheric Science

Originally published here: www.sciencedaily.com/releases/2015/06/150604100915.htm

Posted June 8th, 2015.

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Leaping Snails!: Sea Snails May Lose Their Jumping Ability

The conch snail, which uses a strong foot to leap away from approaching predators, either stops jumping, or takes longer to jump, when exposed to the levels of carbon dioxide projected for the end of this century. (Credit: ARC Centre of Excellence in Coral Reef Studies)

Sea snails that leap to escape their predators may soon lose their extraordinary jumping ability because of rising human carbon dioxide emissions, a team of international scientists has discovered.

Lead author of the study published today, Dr Sue-Ann Watson from the ARC Centre of Excellence for Coral Reef Studies (Coral CoE) and James Cook University observed that the conch snail, which uses a strong foot to leap away from approaching predators, either stops jumping, or takes longer to jump, when exposed to the levels of carbon dioxide projected for the end of this century.

Dr Watson explains that increased carbon dioxide and ocean acidification levels disrupt a particular neurotransmitter receptor in the snail’s nervous system, delaying vital decision-making on escape. This leaves the snail more vulnerable to the poisonous dart of its slow-moving nemesis, the marbled cone shell. The effects may be quite profound. “Altered behaviours between predators and prey have the potential to disrupt ocean food webs,” Dr Watson said. While this study shows that disrupted decision-making with elevated carbon dioxide levels can occur in marine invertebrates, scientists have also observed similar effects before, in fish. Co-author Professor Göran Nilsson, from the University of Oslo, explains, “this neurotransmitter receptor is common in many animals and evolved quite early in the animal kingdom. So what this study suggests is that human carbon dioxide emissions directly alter the behaviour of many marine animals, including much of the seafood that is part of the human diet.” Professor Philip Munday, from the Coral CoE, says past studies on the effects of ocean acidification on animals mostly focused on what would happen to the shells of marine snails and other calcifying animals — how could shells be built and maintained in a more acidic environment? This study shows that they actually face the dual threat of both weaker shells and impaired behaviour. Professor Munday says it is critical to study and understand more about the extent of these behavioural disturbances. The big question now, he adds, is whether sea creatures can adapt fast enough to keep up with the rapid pace of rising carbon dioxide levels and ocean acidification. The article Marine mollusc predator-escape behaviour altered by near-future carbon dioxide levels by Sue-Ann Watson, Sjannie Lefevre, Mark I. McCormick, Paolo Domenici, Göran E. Nilsson and Philip L. Munday appears in Proceedings of the Royal Society B: Biological Sciences.
Originally published here: http://www.coralcoe.org.au/news/jumping-snails-left-grounded-in-future-oceans

Posted June 2nd, 2015.

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New Species of Flasher Wrasse

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The new species, a flasher wrasse, was named Parcheilinus rennyae in honor of ichthyologist Renny Hadiaty of the Indonesian Institute of Sciences (LIPI). (Photo courtesy of Conservation International)

By Jakarta Globe

Indonesian scientists working together with counterparts from the University of California have announced the discovery of a new species of fish in East Nusa Tenggara.

The new species was named Parcheilinus rennyae in honor of ichthyologist Renny Hadiaty of the Indonesian Institute of Sciences (LIPI).

“I’m deeply honored by this recognition, not only because it is such a beautiful fish species, but also because the lead author on the description is my close colleague and internationally renowned ichthyologist Gerald Allen,” said Hadiaty, the curator of fish collections at the Museum Zoologicum Bogoriense (MZB), in a statement released by Conservation International on Wednesday.

The description of the species — a flasher wrasse — was published in the year-end edition of aqua, International Journal of Ichthyology, the statement said.

Conservation International (CI) said that Hadiaty, in her 27-year career, has focused primarily on the taxonomy of freshwater fish in Indonesia, and has coauthored many papers with Allen, who now works for CI as a consultant.

The wrasse — a striking and colorful fish — is adding further conservation value to Komodo National Park and the surrounding reefs of southwest Flores, according to CI.

Tiene Gunawan, marine program director at Conservation International Indonesia, said that the new species therefore must be protected.

Although it is the seventeenth known species of flasher wrasse, CI said that the fish is unique in both its colors and the rounded shape of its dorsal and anal fins and tail.

“We’re delighted that one of our young local scientists, Ni Luh Astria Yusmalinda, was able to publish her first international journal paper based on her genetic analysis of this new species and its closest relatives,” Ngurah Mahardika, the hosting laboratory director of the Indonesian Biodiversity Research Center at Udayana University, said.

He also said that he deemed it particularly fitting that the new species be named after Renny and added that he hoped “this will highlight the spirit of strong scientific collaboration between Indonesian universities, conservation NGOs like Conservation International and the Indonesian Institute of Sciences.”

Flasher wrasses are popular among divers and underwater photographers because of their neon color patterns displayed as part of a daily mating ritual about one hour before sundown. Wrasses are brownish in hue the remainder of the day.

“We’re also hopeful that this new species will add to the tourism value of Komodo National Park and the surrounding reefs of southwest Flores,” Tiene Gunawan, marine program director at Conservation International Indonesia, said.

The scientists participating scientists were from the Indonesian Biodiversity Research Center, a collaborative initiative of Udayana University in Bali, the State University of Papua in Manokwari, Diponegoro University in Semarang, the University of California Los Angeles and Conservation International Indonesia.

Source: The Embassy of Indonesia

Posted June 2nd, 2015.

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Going Back to Where It All Began: Research on Eels’ History and Survival

An adult European eel Anguilla anguilla. (Credit: J. Schröder, GEOMAR)

The European eel is one of the world’s many critically endangered species. Comprehensive protection is difficult because many details of the eel’s complex life cycle remain unknown. In a multidisciplinary study, biologists and oceanographers at GEOMAR recently demonstrated the crucial influence of ocean currents on eel recruitment. They did so by using, among others, a state-of-the-art ocean model developed in Kiel, in combination with genetic studies. The study appears in the international journal Current Biology.

Smoked, fried or boiled — the European eel (Anguilla anguilla) has always been a popular fish in Europe. Even though people have consumed it for millennia, the origin of the eel has long been shrouded in mystery. While the fish spend most of their lives in fresh and coastal waters, spawning and the birth of the larvae take place in the Sargasso Sea in the central Atlantic Ocean, about 4500 km away from the European coastlines. “Because the observation of eels in the Sargasso Sea is scarcely possible, some details of the life cycle are still unknown” says biologist Miguel Baltazar-Soares, from GEOMAR Helmholtz Centre for Ocean Research Kiel.

In a multidisciplinary study recently published in the international journal “Current Biology,” biologists, geneticists and theoretical oceanographers at GEOMAR, together with colleagues from Hamburg, London, Belfast and Antofagasta (Chile), discovered a relationship between ocean currents and the variation in eel recruitment.

The study is based on a latest generation ocean model developed in Kiel. Originally it was used to simulate the effects of melting Greenland glaciers on the North Atlantic. “It has a resolution approximately ten times larger than the conventional ocean and climate models,” explains Prof. Dr. Arne Biastoch, a theoretical oceanographer at GEOMAR. “The new model allows us to understand even small-scale changes in the ocean, so we came up with the idea of using it for a simulation of eel migrations,” adds Miguel Baltazar-Soares, lead author of the new study.

The model simulation was run for 45 years, and in each of these years, the researchers seeded the Sargasso Sea with 8 million tiny drifting particles. “They represent the eel larvae which, for the first few years of their life, mainly drift with the currents,” says biologist Dr. Christophe Eizaguirre from GEOMAR, who initiated the study. External factors, like wind and weather conditions, were the same in the model as the conditions observed in each year from 1960 to 2005. “We were able to track how the larvae migrated to Europe. Only those who reached the European shelf seas within two years were considered viable. This also corresponds to eel life cycle,” explains Dr. Eizaguirre.

In fact, the eel recruitment in the model fluctuated significantly, mimicking the patterns reported across Europe. “In the early 1980s, for example, only a fraction of the larvae managed their way to Europe,” reports Professor Biastoch. The researchers found that small-scale, wind-driven ocean currents strongly determine the eel population fluctuation. Depending on the presence of regional currents in the Sargasso Sea, the larvae’s path to Europe was either extended and led to low recruitment or shortened leading to high recruitment in Europe. “We had not seen these flow changes in any of the older ocean models. But they seem to play a crucial role in the migration of the eel larvae,” explains Professor Biastoch.

Combining those discoveries with genetic analyses, the scientists found evidence that, contrary to what is typically thought, eels do not return to random locations in the Sargasso Sea to reproduce but rather return to where their mother spawned in particular locations within the Sargasso Sea. “This is a new finding — so far, it was assumed that the mating in the Atlantic takes place completely independent of the area of origin and future scientific expeditions will have to verify this result in situ ” says Baltazar-Soares.

The ultimate fate of eels making the long migration from the Sargasso Sea to the continental waters of Europe is still very difficult to predict, even using state of the art techniques. Indeed, from the 1960s to the 1980s, the results of the computer simulation matched up well with the observed occurrence of young eels reaching the European coasts. After that, however, the status of eel populations seems to be disconnected from the climatic influences in the Atlantic. “Since then fishing pressure, habitat destruction in European rivers and diseases appear to play an increased role” said Baltazar-Soares. Today, the European eel is on the list of endangered species and biologists, managers, fishers and politicians across the continent are working together to conserve eels and the valuable fisheries they support.

Although the current study does not solve all the lifestyle mysteries of the eel, “it clearly shows that not only biological, but also climatic, oceanographic and genetic conditions must be taken into account for a meaningful management of fish stocks,” says Dr. Eizaguirre who has recently relocated from Kiel to Queen Mary, University of London. And for co-author Arne Biastoch the study illustrates the potential that lies in the interdisciplinary cooperation between biologists and oceanographers: “The ocean models are becoming more and more accurate. This offers a great opportunity for reassessing the threats to marine organisms and understanding their fundamental biology.”

 

Originally published here: http://www.geomar.de/en/news/article/aale/

Posted June 2nd, 2015.

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“Reforesting” a Reef: A Reef Gets a Seaweed Transplant

 

Transplanted seaweed is attached to a reef by a team member. Credit: Image courtesy of University of New South Wales

Marine ecologists in Sydney have successfully restored a once thriving seaweed species, which vanished along a stretch of the city’s coastline during the 1970s and 80s when there were high levels of sewage.

A team of researchers from UNSW, the Sydney Institute of Marine Science and the NSW Department of Primary Industries has transplanted fertile specimens of the missing crayweed (Phyllospora comosa) onto two barren reef sites where it once grew abundantly.

They took seaweed from Palm Beach and Cronulla and transplanted it to Long Bay and Cape Banks. Their results are reported in the journal PLOS ONE.

“Seaweeds are the ‘trees’ of the oceans, providing habitat structure, food and shelter for other marine organisms, such as crayfish and abalone,” says lead author, Dr Alexandra Campbell, from the UNSW Centre for Marine Bio-Innovation.

“The transplanted crayweed not only survived similarly to those in natural populations, but they also successfully reproduced. This creates the potential for a self-sustaining population at a place where this species has been missing for decades,” she says.

Large brown seaweeds — known as macroalgae — along temperate coastlines, like those in NSW, also encourage biodiversity and are important to the region’s fishing and tourism industries.

However, these seaweed ecosystems face increasing threats of degradation due to human impacts and ocean warming. The authors say the potential environmental and economic implications of losing these habitats would be comparable to the more highly publicised loss of Australia’s tropical coral reefs.

In 2008, researchers from UNSW and the NSW Department of Primary Industries (DPI) showed that a 70 km stretch of this important habitat-forming crayweed had vanished from the Sydney coast decades earlier, coinciding with a period known for high levels of sewage.

Despite improved water quality around Sydney after the introduction of better infrastructure in the 1990s, which pumped sewage into the deeper ocean, the 70 km gap of depleted ‘underwater forest’ — between Palm Beach and Cronulla — has never been able to recover naturally.

Now, with some well-executed intervention, it looks as though this habitat-forming crayweed could make a successful comeback in Sydney’s coastal waters.

“This is an environmental good news story,” says research supervisor UNSW Professor Peter Steinberg, Director of the Sydney Institute of Marine Science.

“This kind of restoration study has rarely been done in these seaweed-dominated habitats, but our results suggest that we may be able to assist in the recovery of underwater forests on Sydney’s reefs, potentially enhancing biodiversity and recreational fishing opportunities along our coastline.”

The researchers say their results could provide valuable insights for restoring similar macroalgae marine ecosystems in Australia and globally, but further research is needed to understand the complex processes that affect recruitment and survival.

This project was funded in part by a grant from the NSW Recreational Fishing Trust.

 

Originally Published here: http://newsroom.unsw.edu.au/news/science/bald-reef-gets-seaweed-transplant

Posted June 2nd, 2015.

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A Look Into the Mysterious Life of Juvenile Sea Turtles

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Credit: Jim Abernethy

Small satellite-tracking devices attached to sea turtles swimming off Florida’s coast have delivered first-of-its-kind data that could help unlock they mystery of what endangered turtles do during the “lost years.”

The “lost years” refers to the time after turtles hatch and head to sea where they remain for many years before returning to near-shore waters as large juveniles. The time period is often referred to as the “lost years” because not much has been known about where the young turtles go and how they interact with their oceanic environment — until now.

“What is exciting is that we provide the first look at the early behavior and movements of young sea turtles in the wild,” said UCF biologist Kate Mansfield, who led the team. “Before this study, most of the scientific information about the early life history of sea turtles was inferred through genetics studies, opportunistic sightings offshore, or laboratory-based studies. With real observations of turtles in their natural environment, we are able to examine and reevaluate existing hypotheses about the turtles’ early life history. This knowledge may help managers provide better protection for these threatened and endangered species.”

Findings from the study appear today in the journal Proceedings of the Royal Society B.

A team of scientists from the UCF, Florida Atlantic University, University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, and University of Wisconsin, tracked 17 loggerhead turtles for 27 to 220 days in the open ocean using small, solar-powered satellite tags. The goal was to better understand the turtles’ movements, habitat preferences, and what role temperature may play in early sea turtle life history.

Some of the findings challenge previously held beliefs.

While the turtles remain in oceanic waters (traveling between 124 miles to 2,672 miles) off the continental shelf and the loggerhead turtles sought the surface of the water as predicted, the study found that the turtles do not necessarily remain within the currents associated with the North Atlantic subtropical gyre. It was historically thought that loggerhead turtles hatching from Florida’s east coast complete a long, developmental migration in a large circle around the Atlantic entrained in these currents. But the team’s data suggest that turtles may drop out of these currents into the middle of the Atlantic or the Sargasso Sea.

The team also found that while the turtles mostly stayed at the sea surface, where they were exposed to the sun’s energy, the turtles’ shells registered more heat than anticipated (as recorded by sensors in the satellite tags), leading the team to consider a new hypothesis about why the turtles seek refuge in Sargassum. It is a type of seaweed found on the surface of the water in the deep ocean long associated with young sea turtles.

“We propose that young turtles remain at the sea surface to gain a thermal benefit,” Mansfield said. “This makes sense because the turtles are cold blooded animals. By remaining at the sea surface, and by associating with Sargassum habitat, turtles gain a thermal refuge of sorts that may help enhance growth and feeding rates, among other physiological benefits.”

More research will be needed, but it’s a start at cracking the “lost years” mystery.

The findings are important because the loggerhead turtles along with other sea turtles are threatened or endangered species. Florida beaches are important to their survival because they provide important nesting grounds in North America. More than 80% of Atlantic loggerheads nest along Florida’s coast. There are other important nesting grounds and nursing areas for sea turtles in the western hemisphere found from as far north as Virginia to South America and the Caribbean.

“From the time they leave our shores, we don’t hear anything about them until they surface near the Canary Islands, which is like their primary school years,” said Florida Atlantic University professor Jeannette Wyneken, the study’s co- PI and author. “There’s a whole lot that happens during the Atlantic crossing that we knew nothing about. Our work helps to redefine Atlantic loggerhead nursery grounds and early loggerhead habitat use.”

Mansfield joined UCF in 2013. She has a Ph.D. from the Virginia Institute of Marine Science and a master’s degree from the Rosenstiel School of Marine and Atmospheric Science at the University of Miami. She previously worked at Florida International University, through the Cooperative Institute for Marine and Atmospheric Studies (CIMAS) in association with the National Oceanographic and Atmospheric Administration and the National Marine Fisheries Services. She was a National Academies NRC postdoctoral associate based at NOAA’s Southeast Fisheries Science Center, and remains an affiliate faculty in Florida Atlantic University’s biology department where Wyneken is based.

With colleagues at each institution Mansfield conducted re

search that has helped further the understanding of the sea turtle “lost years” and sea turtle life history as a whole. For example she and Wyneken developed a satellite tagging method using a non-toxic manicure acrylic, old wetsuits, and hair-extension glue to attach satellite tags to small turtles. Tagging small turtles is very difficult by traditional means because of their small size and how fast they grow.

 

Published on http://www.sciencedaily.com/releases/2014/03/140304215610.htm based on materials from Proceedings of the Royal Society B: Biological Sciences (http://rspb.royalsocietypublishing.org/content/281/1781/20133039).

Posted June 2nd, 2015.

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Birds of a Feather Flock (Or in this Case, Fish of a Scale Swim) Together

Credit: Image courtesy of Polytechnic Institute of New York University

Brooklyn, New York— Recent studies from two research teams at the Polytechnic Institute of New York University (NYU-Poly) demonstrate how underwater robots can be used to understand and influence the complex swimming behaviors of schooling fish. The teams, led by Maurizio Porfiri, associate professor of mechanical and aerospace engineering at NYU-Poly, published two separate papers in the journalPLOS ONE.

These studies are the latest in a significant body of research by Porfiri and collaborators utilizing robots, specifically robotic fish, to impact collective animal behavior. In collaboration with doctoral candidate Paul Phamduy and NYU-Poly research scholar Giovanni Polverino, Porfiri designed an experiment to examine the interplay of visual cues and flow cues—changes in the water current as a result of tail-beat frequency—in triggering a live golden shiner fish to either approach or ignore a robotic fish.

They designed and built two robotic fish analogous to live golden shiners in aspect ratio, size, shape, and locomotion pattern. However, one was painted with the natural colors of the golden shiner, the other with a palette not seen in the species. The researchers affixed each robot to the inside of a water tunnel, introduced a live golden shiner fish, and observed its interactions with the robot. While the robot’s position remained static, the researchers experimented with several different tail-beat frequencies.

“When the fish encountered a robot that mimicked both the coloration and mean tail-beat frequency for the species, it was likeliest to spend the most time in the nearest proximity to it,” Porfiri said. “The more closely the robot came to approximating a fellow golden shiner, the likelier the fish was to treat it like one, including swimming at the same depth behind the robot, which yields a hydrodynamic advantage,” he explained.

While flow cues created by tail-beat frequency proved to be a critical trigger for shoaling behavior, coloration proved slightly dominant. “Even at tail-beat frequencies that were less than optimal for the live fish, the shiners were always more drawn to the naturally colored robot,” Porfiri added.

Robot speed and body movement were the main focus of another study, also published in PLOS ONE, in which Porfiri teamed with NYU-Poly postdoctoral fellow Sachit Butail and graduate student Tiziana Bartolini. This time, the subject was the zebrafish, and the robot was a free-swimming unit with the coloration, size, aspect ratio, and fin shape of a fertile female member of the species.

The researchers placed the robot in a shared tank with shoals of live zebrafish, aiming to determine if the fish would perceive the robot as a predator, and whether visual cues from the robot could be used to modulate the fishes’ social behavior and activity. The team used a remote control to drive the robot in a circular swimming pattern, while varying its tail-beat frequency. For comparison purposes, they also exposed the fish to the robot in a fixed position, beating its tail.

Experiments showed that while the zebrafish clearly did not perceive the swimming robot as one of their own—they maintained greater distance from the robot than they did to each other—the robot was still an effective stimulus for modulating their social behavior. When the robot was held still in the tank, the live fish showed high group cohesion, along with a strong polarization—meaning the fish were likely to be close to each other and oriented in the same direction. As the robot’s tail-beat frequency increased, it had a profound impact on the group’s collective behavior, causing a spike in the cohesion and a small but detectable decrease in polarization—the fish largely milled together and even matched their speeds to that of the robot as it reached a certain tail-beat frequency.

“This shows us that the fish are responding to more than one stimulus—it’s not just the flow cues, it’s the combination of visual and flow cues that influence the collective response,” Porfiri said.

Porfiri is a leading researcher in the field of ethorobotics—the study of robot-animal interaction. Studies like these advance multiple areas of science, including the development of an experimental animal model based on lower-order species such as fish, with robots providing a consistent, infinitely reproducible stimulus. The use of robots to influence collective animal behavior is also viewed as a potential means to protect marine wildlife, including birds and fish, in the wake of environmental hazard.

This research was supported by the National Science Foundation and the Mitsui USA Foundation.

Source: Polytechnic Institute of New York

Posted June 2nd, 2015.

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