Institute of Marine Research
Institute of Marine Research
News Article | April 17, 2017
Crude oil is an unruly soup of tens of thousands of different organic compounds, and this diversity makes it difficult to pick out individual molecules from the crowd for analysis using standard tools like mass spectrometry. Despite the vast quantities of crude oil used globally each day, much remains unknown about its chemical composition, which can vary dramatically from one oil field to the next. So a method that separates crude oil into a dozen fractions, based on their chemical properties, now promises to help measure levels of molecules that could trigger corrosion in a pipeline, or pinpoint the most toxic compounds in an oil spill (Anal. Chem. 2017, DOI: 10.1021/acs.analchem.6b04202). Fractionation is not a new approach to simplifying oil analysis. One of the most common methods, dubbed SARA, uses chromatography to split the oil into four broad classes: saturates, aromatics, resins, and asphaltenes. But this separation is largely based on the molecules’ solubilities in the solvent being used, and many chemical classes remain obscured within the mélange in each fraction. In contrast, the new method developed by Steven J. Rowland of the University of Plymouth and coworkers is particularly good at teasing apart polar compounds containing nitrogen, sulfur, or oxygen—often responsible for poisoning oil-processing catalysts—which conventional analytical methods struggle to identify. The procedure is not based on radical innovation: It relies on a series of columns filled with commercial ion exchange resins and silica, making the method reproducible, relatively simple, and inexpensive. “The real novelty is putting it all together,” says Ryan P. Rodgers, director of the Future Fuels Institute at Florida State University, who was not involved with the work. By deploying the separation columns in the right order and eluting the crude with a series of increasingly polar solvents, the method isolates molecules depending on how well their functional groups stick to each type of column. This yields fractions that are each dominated by a particular chemical class: sulfoxides, quinolines, carbazoles, fluorenones, and more. After analyzing each fraction with techniques such as gas chromatography-mass spectrometry (GC-MS), the team identified dozens of specific compounds. Some of them, such as thioxanthones, were previously unknown in crude oil. The method achieves “a better separation between different classes of chemicals,” says Sonnich Meier of the Institute of Marine Research. “It’s the best I’ve seen.” Meier has been working with Rowland’s team for the past three years, and plans to use the technique to single out the compounds in crude oil that are toxic to fish embryos. Polyaromatic hydrocarbons account for about 60% of oil’s toxicity, says Meier, but the culprits responsible for the remainder of the effect are unknown. “There are thousands of compounds in oil that we just ignore, because we’re not good at analyzing them,” he says. These data will feed into a new risk assessment on the potential exploitation of oil reserves in the Lofoten region of northern Norway, currently a matter of fierce debate in the country. Meanwhile, the oil industry increasingly wants to know the precise composition of a crude oil before investing billions in extracting and refining it. The world’s declining production of low-sulfur oil, known as sweet crude, means there is more reliance on crudes that contain higher proportions of heteroatoms and heavier compounds, requiring more refining and presenting new processing challenges, such as pipeline corrosion or blockages. The oil industry has expressed interest in the method, Rowland says.
News Article | April 17, 2017
More evidence has emerged to place European eels among other animals that use the Earth’s magnetic field to guide their migration, but the research methods used are causing controversy. A study published last week in Current Biology suggests eels generate a “magnetic map” of their surroundings that lets them read their location based on the field intensity, and use this map to find the Gulf Stream and catch a free ride to Europe. “We’re moving toward [magnetic sense] being the default hypothesis for how marine animals achieve their long-distance migrations,” says co-author Nathan Putman, a Florida-based biologist with the National Oceanic and Atmospheric Administration. “What was maybe viewed as an anomaly with sea turtles and salmon is now the hypothesis to beat.” Some scientists took issue with the study’s approach, however. Eels migrate twice in their lifetime: once as four inch–long larvae from the Sargasso Sea to coastal waters and rivers of Europe and Northern Africa, and again after maturing for a decade or more, when they return to the Sargasso to spawn and die. Since the 1970s, researchers have suspected eels could sense magnetic fields, and a 2013 study proposed the animals used a “magnetic compass” to orient using the North Pole. The new study suggests the eels have a more complete command of their location and direction. To test their hypothesis, researchers placed eels in a round, freshwater tank with 12 small chambers arranged like spokes around it, and a magnetic coil surrounding the whole apparatus. They simulated how it would have felt—magnetically speaking—for the eels to have been in four different locations along their larval migration route from the Sargasso to Europe. The eels chose which direction to swim by slithering over the barrier into one of the segments surrounding the central tank. Researchers tallied their choices and applied the data to a computer model of oceanic circulation. Based on the directions the eels would have gone in the Sargasso Sea, the researchers concluded the majority of the eels seemed to be swimming in the direction of what would have been the Gulf Stream from various points on their migration route. Some eel researchers have criticized the study because the authors didn’t use larval eels, but rather juveniles captured in in an estuary in the U.K., which had already completed their Europe-bound migration. “You could compare it to doing experiments on butterflies and expecting them to behave like caterpillars,” says Caroline Durif, a scientist at Norway’s Institute of Marine Research, who was not involved in the work but co-authored the 2013 study, which used adult eels captured as they started their return migration to the Sargasso Sea. Other scientists point out the impracticality of attempting such a test on larval eels, however, because of the difficulty of capturing them. Michael Hansen, a biologist at Aarhus University in Denmark who was not involved in the study, agrees the age of the eels is the largest potential source of error, but says the results make sense biologically, which convinces him it was not a major issue. “It would be almost impossible to do a study like this on eel larvae,” he says, simply because tiny, transparent eels are tough to gather in large numbers in the open ocean. “I think it would be unrealistic to do it any other way than they did.” Karin Limburg, a professor of environmental and forest biology at SUNY College of Environmental Science and Forestry who was also not involved in the work, agrees. The authors are “taking advantage of the fact that [with] eels, when they enter and colonize an estuary, you have a concentration of them,” she says. “If you were to try to sift through the Sargasso Sea for larval eels, you’d be out there till the cows come home. Odds of finding what you’re looking for are very low. I don’t see how they could have done it any other way.” Putman defends his study on similar grounds. “We picked that life stage of eel because it was what we could get our hands on: eels that had just moved from ocean habitats into estuaries,” he says. He and his colleagues say they were posing a question to the eels: “‘If you felt displaced back into the North Atlantic, where would you feel like you should go?’ We got lucky that they still had some remnant of their migratory behavior.” Durif also points out that simulating an oceanic migration in freshwater creates more potential for error. Putman argues that transferring eels caught in freshwater back to saltwater would add another variable to what was intended as a magnetic displacement test. “Only a change in the magnetic map conditions is necessary to elicit orientation responses from the eels,” he says.
News Article | May 4, 2017
© IMR On 10 January 2017, the new R/V Dr. Fridtjof Nansen arrived in Bergen for the first time, after the delivery of the Spanish shipyard Astilleros Gondan. The vessel, which is owned by the Norwegian Agency for Development Cooperation (NORAD) was built as part of the tripartite agreement between FAO, the Institute of Marine Research (IMR) and the Norwegian Agency for Development Cooperation (NORAD) to help developing countries improve their fisheries management. Now the vessel, equipped with the most up to date technology, is undergoing testing of equipment and functions before the first survey planned for the beginning of May 2017. An official naming ceremony will be held in Oslo, Norway, on 24 March 2017. More information available here.
News Article | May 4, 2017
Nansis, the Survey Information System for logging, editing and analysis of biological and environmental data from marine fisheries research surveys, has undergone a series of improvements since 2006 when the first version for Window was released. The software and the database which constitute the system are principally used to store and retrieve data for scientific or decision making purposes. Throughout the years, several updates were made to optimize software stability and performances, based on suggestions provided by the user group of fisheries scientists. From 27 to 31 October 2014, an early version 1.9 of Nansis was introduced and tested by a number of participants attending the Training of Trainers course on Nansis held at Casablanca, Morocco. The course, organized by the EAF-Nansen project, was to train scientist in the use of Nansis and in the meantime to test it. During the course, participants highlighted strengths and weaknesses of the software providing suggestions on suitable improvements. Based on feedback received a new series of enhancements was planned and an updated version is now available as public release. Nansis version 1.9 is meant to be a user-friendly tool with enhanced features. Indeed a wizard process easily lead users through a series of well-defined and simplified steps to successfully finalize the installation. The version 1.9 of the software was officially released on 17 May 2015, on the occasion of the Norwegian national day, both on the EAF-Nansen project Nansis page and the Institute of Marine Research Website. On the webpages technical details on the software and download are also available. We always strive to improve the quality and accuracy of Nansis. For this reason we warmly invite you to test version 1.9 of Nansis and provide us with your comments and suggestions at firstname.lastname@example.org. The Nansis software is shipped only with a dummy dataset to be installed. The software is compatible with the database already installed with many users and the datasets received from the surveys with Dr. Fridtjof Nansen, please refer to the help menu on how to import your data. To receive data from the Nansen program to use with the database please contact Inês Bernardes at CDCF using the data download form available from the web.
Limburg K.E.,New York University |
Olson C.,University of Stockholm |
Walther Y.,Institute of Marine Research |
Dale D.,Cornell University |
And 2 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2011
Growing hypoxic and anoxic areas in coastal environments reduce fish habitat, but the interactions and impact on fish in these areas are poorly understood. Using "natural tag" properties of otoliths, we found significant correlations between the extent of Baltic Sea hypoxia and Mn/Ca ratios in regions of cod (Gadus morhua) otoliths corresponding to year 1 of life; this is associated with elevated bottom water dissolved manganese that increases with hypoxia. Elevated Mn/Ca ratios were also found in other years of life but with less frequency. We propose that cod exhibiting enhanced Mn/Ca ratios were exposed to dissolved manganese from hypoxia-induced redox dynamics in nursery areas. Neolithic (4500 B.P.) cod otoliths (n = 12) had lowlevels ofMn/Ca ratios, consistent with lowhypoxia, but a single otolith dated to the younger Iron Age had a distinct growth band with an elevated Mn/Ca ratio. Sr/Ca patterns reflecting changes in environmental salinity and temperature were similar in both modern and Stone Age otoliths, indicating consistent migration habits across time, and Ba/Sr ratios in modern cod otoliths indicate increasing use of a more saline habitat with age. Using elemental ratios, numerous existing archival collections of otoliths could provide the means to reconstruct hypoxia exposure histories and major patterns of fish movement near "dead zones" globally.
News Article | September 7, 2016
On the dock in Buenaventura, Colombia, the fisherman needed help identifying his catch. “I don’t have any clue what this is,” he said, holding a roughly 50-centimeter-long, grayish-brown fish. Gustavo Castellanos-Galindo, a fish ecologist, recalls the conversation from last October. “I said, ‘Well, this is a cobia, and it shouldn’t be here.’ ” The juvenile cobia had probably escaped from a farm off the coast of Ecuador that began operating earlier in 2015, Castellanos-Galindo and colleagues at the World Wildlife Fund in Cali, Colombia, reported in March in BioInvasions Records. Intruders had probably cut a net cage, perhaps intending to catch and sell the fish. Roughly 1,500 cobia fled, according to the aquaculture company Ocean Farm in Manta, Ecuador, which runs the farm. Cobia are fast-swimming predators that can migrate long distances and grow to about 2 meters long. The species is not native to the eastern Pacific, but since the escape, the fugitives have been spotted from Panama to Peru. The cobia getaway is not an isolated incident. Aquaculture, the farming of fish and other aquatic species, is rapidly expanding — both in marine and inland farms. It has begun to overtake wild-catch fishing as the main source of seafood for the dinner table. Fish farmed in the ocean, such as salmon, sea bass, sea bream and other species, are raised in giant offshore pens that can be breached by storms, predators, fish that nibble the nets, employee error and thieves. Global numbers for escapes are hard to come by, but one study of six European countries over three years found that nearly 9 million fish escaped from sea cages, according to a report published in Aquaculture in 2015. Researchers worry that these releases could harm wildlife, but they don’t have a lot of data to measure long-term effects. Many questions remain. A study out of Norway published in July suggests that some domesticated escapees have mated extensively with wild fish of the same species, which could weaken the wild population. Scientists also are investigating whether escaped fish could gobble up or displace native fish. Worst-case scenario: Escaped fish spread over large areas and wreak havoc on other species. From toxic toads overrunning Australia and Madagascar (SN Online: 2/22/16) to red imported fire ants in the United States, invasive species are one of the planet’s biggest threats to biodiversity, and they cost billions of dollars in damage and management expenses. Not every introduced species has such drastic effects, but invasives can be tough to eliminate. While researchers try to get a handle on the impact of farm escapes, farmers are working to better contain the fish and reduce the ecological impact of the runaways. Some countries have tightened their aquaculture regulations. Researchers are proposing strategies ranging from new farm designs to altering fish genetics. As aquaculture becomes a widespread means to feed the planet’s protein-hungry people, the ecological effects are getting more attention. If escapees weaken native wildlife, “we’re solving a food issue globally and creating another problem,” says population geneticist Kevin Glover of Norway’s Institute of Marine Research in Bergen. Norway, a top producer of marine fish, has done much of the research on farm escapes. Fish farming is big business. In 2014, the industry churned out 73.8 million metric tons of aquatic animals worth about $160 billion, according to a report in July from the Food and Agriculture Organization of the United Nations in Rome. Nearly two-thirds of this food comes from inland freshwater farms such as ponds, used in Asia for thousands of years. The rest is grown on marine and coastal farms, where farmed fish live in brackish ponds, lagoons or cages in the ocean. Freshwater fish can escape from pond farms during events such as floods. Some escapees, such as tilapia, have hurt native species by competing with and eating wild fish. But sea farming has its own set of problems. The physical environment is harsh and cages are exposed to damaging ocean waves and wind, plus boats and predator attacks. Salmon is one of the most heavily farmed marine fish. In some areas, the number of farmed salmon dwarfs wild populations. Norway’s marine farms hold about 380 million Atlantic salmon, while the country’s rivers are home to only about 500,000 wild spawning Atlantic salmon. In the four decades that farmers have been cultivating Atlantic salmon, farmed strains have diverged from their wild cousins. When both are raised in standard hatchery conditions, farm-raised salmon can grow about three to five times heavier than wild salmon in the first year of life. Salmon raised in farms also tend to be less careful; for instance, after being exposed to an artificial predator, they emerge more quickly from hiding places than wild fish. This risky behavior may have arisen partly because the fish haven’t faced the harsh challenges of nature. “The whole idea of a hatchery is that everything gets to survive,” says Philip McGinnity, a molecular ecologist at University College Cork in Ireland. Farmed fish don’t know better. These differences are bad news for hybrid offspring and wild fish. In early experiments, hybrid offspring of farmed and wild salmon tended to fare poorly in the wild. In the 1990s, McGinnity’s team measured these fish’s “lifetime success” in spawning rivers and the ocean. Compared with wild salmon, hybrid offspring had a lifetime success rate about a fourth to a half as high. Around the same time, a team in Norway found that when wild fish swam with farmed fish in their midst, the number of wild offspring that survived long enough to leave the river to head to the ocean was about one-third lower than expected, perhaps because the fast-growing farmed offspring gobbled a lot of food or claimed territory. “There was truly reason to be concerned,” says Ian Fleming, an evolutionary ecologist at Memorial University of Newfoundland in St. John’s, Canada, who was part of the Norway team. Recent work supports the idea that farmed fish could crowd out wild fish by hogging territory in a river. In a study published last year in the Journal of Fish Biology, researchers found that the survival rate of young wild salmon dropped from 74 to 53 percent when the fish were raised in the same confined stream channels as young farmed salmon rather than on their own. When the channels had an exit, more wild fish departed the stream when raised with farmed salmon than when raised alone. “These are fish that give up the territory and have to leave,” says study coauthor Kjetil Hindar, a salmon biologist at the Norwegian Institute for Nature Research in Trondheim. To find out how much escaped fish had genetically mingled with wild fish, Glover’s team obtained historical samples of salmon scales collected from 20 rivers in Norway before aquaculture became common. The researchers compared the DNA in the scales with that of wild salmon caught from 2001 to 2010 in those rivers. Wild salmon in five of the 20 rivers had become more genetically similar to farmed fish over about one to four decades, the team reported in 2013 in BMC Genetics. In the most affected population, 47 percent of the wild fish’s genome originated from farmed strains. “We’re talking about more or less a complete swamping of the natural gene pool,” Glover says. Imagine buckets of paint — red, blue, green — representing each river, he says, and pouring gray paint into each one. Interbreeding was less of an issue where wild fish were plentiful. The farmed fish aren’t good at spawning, so they won’t mate much if a lot of wild competitors are present. But in sparse populations, the farm-raised salmon may be able to “muscle in,” Glover says. A larger study by Hindar’s team, published in July in the ICES Journal of Marine Science, showed that genetic mixing between wild and farmed salmon is happening on a large scale in Norway. Among 109 wild salmon populations, about half had significant amounts of genetic material from farmed strains that had escaped. In 27 populations, more than 10 percent of the fish’s DNA came from farmed fish. What does that mean for the offspring? Each salmon population has adapted to survive in its habitat — a certain river, at a specific temperature range or acidity level. When farmed fish mate with wild fish, the resulting offspring may not be as well-suited to live in that environment. Over generations, as the wild population becomes more similar to farmed salmon, scientists worry that the fish’s survival could drop. Scientists at several institutions in Norway are exploring whether genetic mixing changes the wild salmon’s survival rates, growth and other traits. Making a definitive link will be difficult. Other threats such as climate change and pollution also are putting stress on the fish. If escapes can be stopped, wild salmon may rebound. Natural selection will weed out the weakest fish and leave the strongest, fish that got a lucky combination of hardy traits from their parents. But Glover worries that, just as a beach can’t recover if oil is spilled every year, the wild population can’t rally if farmed fish are continually pumped in: “Mother Nature cannot clean up if you constantly pollute.” In places where the species being farmed is not naturally abundant, researchers are taking a look at whether escapes could upset native ecosystems. For instance, European sea bass sometimes slip away from farms in the Canary Islands, where (except for a few small populations on the eastern end) the species doesn’t normally live. In February 2010, storms battered cages at the island of La Palma, “like a giant tore up all the nets,” says Kilian Toledo-Guedes, a marine ecologist at the University of Alicante in Spain. About 1.5 million fish — mostly sea bass — reportedly swam free. A couple of weeks later, the number of sea bass in nearby waters was “astounding,” he says. “I couldn’t see the bottom.” Sea bass density in waters near the farm was 162 times higher than it had been at the same time the previous year, his team reported in 2014 in Fisheries Management and Ecology. Fisheries data showing a spike in catches of sea bass by local fishermen that January also suggested that large unreported escapes had occurred before the storm. Despite being raised in captivity, where they are fed pellets, some of the farmed fish learn to hunt. The researchers found that escaped sea bass caught four months after the 2010 farm breakdown had eaten mostly crabs. Sea bass from earlier escapes that had been living in the wild for several years had eaten plenty of fish as well. The results, reported in 2014 in Marine Environmental Research, suggest that escapees start by catching easy targets such as crustaceans and then learn to nab faster-moving fish. So far, though, scientists have not seen clear signs that the escapees damaged the ecosystem. The density of sea bass around La Palma had fallen drastically by October 2010 and continued to decline the next year, probably because some fish couldn’t find enough to eat, while others were caught by fishermen or predators, according to a 2015 study by another team in the Journal of Aquaculture Research & Development. Catches of small fish that sea bass eat, such as parrot fish, did not drop significantly after the 2010 escape or after a similar large escape in 1999, says study coauthor Ricardo Haroun, a marine conservation researcher at the University of Las Palmas de Gran Canaria in Spain. While he agrees that the industry should try to prevent escapes, he sees no evidence that the runaways are suppressing wild species. If the escaped fish can breed and multiply, the risk of harming native species rises. In a study published in Marine Ecology in 2012, Toledo-Guedes and colleagues reported finding sexually mature sea bass around the central island of Tenerife. But Haroun says the water is too warm and salty for the fish to reproduce, and his team did not see any juveniles during their surveys of La Palma, nor have they heard any reports of juveniles in the area. Toledo-Guedes says that more extensive studies, such as efforts to catch larvae, are needed before reproduction can be ruled out. Similarly, researchers can’t predict the consequences of the cobia escape in Ecuador. The water is the right temperature for reproduction, and these predators eat everything from crabs to squid. Castellanos-Galindo believes that farming cobia in the area is a mistake because escapes will probably continue, and the fish may eventually form a stable population in the wild that could have unpredictable effects on native prey and other parts of the ecosystem. He points to invasive lionfish as a cautionary tale: These predators, probably released from personal aquariums in Florida, have exploded across the Caribbean, Gulf of Mexico and western Atlantic and are devouring small reef fish. The situation for cobia may be different. Local sharks and other predators will probably eat the escapees, whereas lionfish have few natural predators in their new territory, argues Diego Ardila, production manager at Ocean Farm. Milton Love, a marine fish ecologist at the University of California, Santa Barbara, also notes that lionfish settle in one small area, but cobia keep moving, so prey populations might recover after the cobia have moved on. Not all introduced species become established or invasive, and it can take decades for the effects to become apparent. “Time will tell what happens,” says Andrew Sellers, a marine ecologist at the Smithsonian Tropical Research Institute in Panama City. “Basically, it’s just up to the fish.” Once fish have fled, farmers sometimes enlist fishermen to help capture the escapees. Professional fishermen caught nearly one-quarter of the sea bass and sea bream that escaped after the Canary Islands breach. On average, though, only 8 percent of fish are recaptured after an escape, according to a study published in June in Reviews in Aquaculture. Given the recapture failures, farmers and policy makers should focus on preventing escapes and maintaining no-fishing zones around farms to create a “wall of mouths,” local predators that can eat runaway fish, says coauthor Tim Dempster, a sustainable aquaculture researcher at the University of Melbourne in Australia. Technical improvements could help. The Norwegian government rolled out a marine aquaculture standard in 2004 that required improvements, such as engineering nets, moorings and other equipment to withstand unusually strong storms. Compared with the period 2001–2006, the average number of Atlantic salmon escaping annually from 2007–2009 dropped by more than half. Ocean Farm in Ecuador has tightened security, increased cage inspections and switched to stronger net materials; no cobia have escaped since last year’s break-in, says Samir Kuri, the company’s operations manager. Some companies raise fish in contained tanks on land to avoid polluting marine waters, reduce exposure to diseases and control growth conditions. But the industry is largely reluctant to adopt this option until costs come down. The money saved from reducing escapes probably wouldn’t make up for the current start-up expense of moving to land. The 242 escape events analyzed in the 2015 Aquaculture study cost farmers about $160 million. By one estimate, establishing a land-based closed-containment farm producing about 4,000 metric tons of salmon annually — a small haul by industry standards — would cost $54 million; setting up a similar-sized sea-cage farm costs $30 million. Another solution is to raise fish that have three sets of chromosomes. These triploid fish, produced by subjecting fertilized eggs to a pressure shock, can’t reproduce and therefore wouldn’t proliferate or pollute the wild gene pool. “The only ultimate solution is sterility,” Norway’s Glover says. “Accidents happen.” Escaped triploid salmon are less likely to disrupt mating by distracting females from wild males, the researchers wrote in Biological Invasions in May. But triploid fish don’t grow as well when the water is warmer than about 15° Celsius, and consumers might be reluctant to accept these altered salmon. Although the ecological effects of fish farm escapes may take a long time to play out, most researchers agree that we shouldn’t take chances with the health of the oceans, which already face threats such as climate change, pollution and overfishing. With the aquaculture industry expanding at about 6 percent per year, farmers will have to keep improving their practices if they are to stay ahead of the runaway fish. This story appears in the September 17, 2016, issue of Science News with the headline, "Runaway fish: Escapes from marine farms raise concerns about native wildlife."
News Article | March 4, 2016
For a few weeks in early fall, Georges Bank — a vast North Atlantic fishery off the coast of Cape Cod — teems with billions of herring that take over the region to spawn. The seasonal arrival of the herring also attracts predators to the shallow banks, including many species of whales. Now researchers from MIT, Northeastern University, the Institute of Marine Research in Norway, and the National Oceanic and Atmospheric Administration, have found that as multiple species of whales feast on herring, they tend to stick with their own kind, establishing species-specific feeding centers along the 150-mile length of Georges Bank. The team’s results are published today in the journal Nature. Based on acoustic data they collected in the region in 2006, the researchers identified and mapped the calls of various whales, and discovered a clear grouping of species within the dense herring shoals: Humpback whales congregated in two main clusters, at either end of the spawning grounds, while minke, fin, and blue whales set up feeding territories in the space in between. In general, calls from each whale species increased dramatically at nighttime, when herring tended to form extremely dense shoals. During the day, these whale calls dissipated, as herring scattered throughout the seafloor. These results represent the first time that scientists have observed such predator and prey interactions over a large marine region. “It’s known that different marine mammal species will eat fish, but no one has mapped their simultaneous feeding distributions over these huge scales,” says Purnima Ratilal PhD ’02, associate professor of electrical and computer engineering at Northeastern University. “Maybe there is some territorialism going on, or maybe they are preferentially selecting these locations based on their different foraging mechanisms. That’s material for new research.” Ratilal and her husband, Nicholas Makris, professor of mechanical engineering at MIT, along with their students, are co-authors of the paper. In 2006, Makris and Ratilal led a two-week cruise to Georges Bank, initially to track and study the behavior of populations of herring, which can number in the billions within a single shoal. The team had developed a remote-sensing system that uses acoustics to instantaneously image and continuously monitor fish populations over tens of thousands of square kilometers. Unlike conventional technologies, their system uses the ocean as a waveguide through which acoustic waves can travel over much greater distances, to sense the marine environment. To get a much wider, more detailed view of the herring populations, Makris and Ratilal deployed 160 hydrophones during their 2006 cruise, towing the array, like a “big acoustic antenna,” in and around Georges Bank. Using their ocean acoustic waveguide sensing technique, they mapped the evolving shoals over the two-week period in October. During that cruise, the group remembers hearing distinct sounds coming through the ship’s hull. “We were hearing these strange haunting sounds in the galley, like an upsweep, then a down-sweep,” Makris recalls. “Purnima recognized these were whale calls, and had all the characteristics of a classic humpback song. At that point she started the research that led to the current paper in Nature, which she spearheaded.” Makris notes that such whale calls have been heard through the hulls of ships for thousands of years. “The Patogonian Indians even had a name for them: 'Yakta,’” Makris says. “People had been listening to these sounds for a very long time, and it’s really this century that we’re starting to localize and observe their behavior.” The group continued looking through the data, even after they had analyzed them for herring signals, to look this time for whale calls. The team developed a technique to sift through the acoustic data for interesting signals — a method called passive ocean acoustic waveguide remote sensing (POAWRS). Through the years, the team gathered research on the characteristics of certain whale species’ calls and looked for these characteristics in their acoustic data. They eventually identified several hundred thousand calls, mostly along the northern edge of Georges Bank. “Different marine mammals in the ocean produce different sounds, sort of related to their size,” Ratilal says. “Humpbacks have a distinct song, while some species of tooth whales can sound like birds chirping.” “Fin whale calls, on the other hand, are in the register of a bass guitar,” Makris adds. The researchers located the source of each call by triangulation and other methods unique to waveguides, and found that the call rates of four main species of whales observed — humpback, sei, minke, and blue — tended to go up significantly at night, possibly in response to the increasing number of herring. “Spawning herring typically don't form big shoals during daytime because it’s too risky they can get caught more easily,” Makris notes. “So they form just as the sun goes down. That’s when the whale calls start going wild and begin to come from on top of the shoals.” These calls were concentrated in species-specific “hotspots,” with humpback whale calls bookending the other three species, all along the northern length of Georges Bank. The group found that humpbacks in particular emitted a distinct pattern of calls that may indicate a cooperative feeding ritual, which others have observed. “The whales will circle the herring, and then one will blow a bubble to contain the fish group, and another will scream and scare the fish into a tight ball,” Ratilal says. “Then another will give a signal, and they’ll all come up with their jaws open.” Jeff Simmen executive director of the Applied Physics Laboratory at the University of Washington, says that for the most part, technologies used to observe marine ecosystems are unable to localize fish and marine mammals at the same time. In contrast, Makris and Ratilal’s approach “provides unusual insight into the macroscopic behavior of marine populations.” “In short, the methodology provides a new and grand view of marine populations that will lead to completely new perspectives about the marine ecosystem, perhaps in a similar way that the enhanced views from the Hubble Space Telescope have changed our perspectives on the universe,” Simmen says. Going forward, the team hopes to tease out more marine behaviors in their dataset. “With this technology, you can really sense a lot of things,” Makris says. “Fish and marine mammals are just two examples.” Ratilal adds, “There are quite a few other interesting phenomena in our dataset.” This research was supported, in part, by the Ocean Acoustics Program of the Office of Naval Research, the National Science Foundation, the National Oceanographic Partnership Program, the Alfred P. Sloan Foundation, and is a contribution to the Census of Marine Life.
News Article | December 15, 2015
For a second straight year, the Arctic is warming faster than any other place in the world, and walrus populations in the area’s Pacific and Atlantic ocean regions are thinning along with the ice sheets that are critical for their survival, researchers reported Tuesday. Overall, the outlook for the frozen top of the world is bleak, according to the annual Arctic Report Card: 2015 Update released by the federal National Oceanic and Atmospheric Administration. Since the turn of the last century, it said, the Arctic’s air temperature has increased by more than 5 degrees due to global warming. Warmer air and sea temperatures melt ice that in turn expands oceans and causes sea-level rise, which scientists say presents a danger to cities along the entire Atlantic coast, from Miami to Washington to Boston. Walrus and other arctic mammals that give birth on ice sheets are struggling with the change, and fish such as cod and Greenland halibut are swimming north from fishermen and animals that feed on them in pursuit of colder waters. [The Arctic keeps warming. And polar bears are feeling the heat] NOAA chief scientist Richard Spinrad said changes in the Arctic portend changes that are likely to spread to the wider world — higher air temperatures, longer hot seasons, anomalous weather spikes and fish fleeing north only to be replaced by new species swimming from areas south. “The conclusion that comes to my mind is these report cards are trailing indicators of what’s happening in the Arctic. They can turn out to be leading indicators for the rest of the globe,” Spinrad said. The annual average surface-air temperature over the period of the report, between October 2014 and September 2015, was nearly 2.5 degrees higher than the time period scientists use as a baseline to compare temperatures, 1981 to 2010. As a result, Alaska was warmer in fall 2014 and winter this year, when the snow pack that usually melts to replenish rivers and moisten the earth was extremely low. Lightning strikes on dry land sparked that state’s second-worst wildfire season in its history. According to the NOAA report card, “the 2015 spring melt season provided evidence of earlier snow melt across the Arctic” because of the increased warmth. As of early July, the Arctic melt included more than half of the region’s ice sheet for the first time “since the exceptional melt of 2012.” The length of the melt season was up to 4o days longer than that of the average northwestern, northeastern and western regions, the report said. This year’s findings are largely consistent with the dire findings last year. Dozens of scientists from across the world contribute to the report card, including those from U.S. Naval Research and the Army Corps of Engineers, the Institute of Marine Research in Norway, Knipovich Polar Research Institute of Marine Fisheries and Oceanography in Russia and University of Victoria in Canada. [A stunning five million acres have burned in Alaskan wildfires this year] The report cards’ year-to-year consistency will help scientists establish whether they are watching a weather anomaly in a key part of the world or an established trend. “What you see here is stronger confirmation,” Spinrad said. A separate study focusing on Alaska’s North Slope, which was presented late Tuesday at the fall meeting of the American Geophysical Union, estimates that the permafrost there will decline rapidly over time because of rising temperatures. Vladimir Romanovsky, head of the Permafrost Laboratory at the University of Alaska Fairbanks, said thinning permafrost is already causing roads and houses built on it to crumble. “Under these conditions, the permafrost will become unstable beneath any infrastructure such as roads, pipelines and buildings,” Romanovsky said. “The result will be dramatic effects on infrastructure and ecosystems.” Another researcher at the university, Santosh Panda, said permafrost that covers virtually all of five national parks as large collectively as South Carolina could decline by 10 percent within the next 35 years. “Permafrost degradation is going to touch the whole landscape through changes in water distribution, slope failures and changes in vegetation that will affect wildlife habitat and the aesthetic value of the parks,” Panda said. In the Arctic, the age of ice generally defines the region’s health. Older ice is thicker, more resilient and resistant to atmospheric changes, and better at supporting mammals. Younger ice is thin and vulnerable to collapse. Yet in nearly all Arctic regions, sea ice is decreasing, the report said. In 1985, 85 percent of the region’s ice qualified as old. In March, that fell to 30 percent. “This is the first year that first-year ice dominated the ice cover,” it notes. “Sea ice cover has transformed from a strong, thick pack in the 1980s to a more fragile, thin and younger pack in recent years.” [The collapse of the Antarctic ice sheet is underway and unstoppable, but will take centuries] Walruses are starting to teem on land as the ice fades, exposing their young to frequent trampling events. Walruses mate on the edges of ice, and females prefer giving birth and raising pups on old ice, which they use as a base to reach feeding grounds. Now many are on land, and the long path to the feeding areas are filled with animals that prey on them, such as sharks and orcas. That is further reducing walrus numbers, the U.S. Fish and Wildlife Service concluded in its section of the report. Ice melt “is already a pervasive threat” to walrus, the agency’s researchers said, but how much of a threat depends on the ability of animals to adapt to change, tolerate it or flee it for more suitable habitat. Scientists estimate that Pacific walrus populations have fallen by half as a result of declining sea ice and hunting. The Atlantic stock, reduced by 80 percent through unregulated hunting between 1900 and 1960, is unknown, but estimates put the population at 25,000. The world just adopted a tough new climate goal. Here’s how hard it will be to meet Holding warming under two degrees Celsius is the goal. But is it really attainable? For more, you can sign up for our weekly newsletter here, and follow us on Twitter here.
Petchey O.L.,University of Sheffield |
Belgrano A.,Institute of Marine Research
Biology Letters | Year: 2010
The sizes of individual organisms, rather than their taxonomy, are used to inform management and conservation in some aquatic ecosystems. The European Science Foundation Research Network, SIZEMIC, facilitates integration of such approaches with the more taxonomic approaches used in terrestrial ecology. During its 4-year tenure, the Network is bringing together researchers from disciplines including theorists, empiricists, government employees, and practitioners, via a series of meetings, working groups and research visits. The research conducted suggests that organismal size, with a generous helping of taxonomy, provides the most probable route to universal indicators of ecological status. © 2010 The Royal Society.
Cardinale M.,Institute of Marine Research |
Svedang H.,Swedish Institute for the Marine Environment
Marine Ecology Progress Series | Year: 2011
The Baltic Sea ecosystem is hypothesized to have undergone a regime shift during the last 3 decades, altering its functioning and the composition of its zooplankton and fish communities. The new stable state has been considered as 'cod hostile' due to reduced spawning success in cod, as well as increased predation on and declining food sources for cod larvae. Nonetheless, the eastern Baltic cod stock has recently recovered after more than 2 decades of low biomass and productivity. The recovery was mainly driven by a sudden reduction in fishing mortality and occurred in the absence of any exceptionally large year classes. The recovery of the cod stock during a 'cod-hostile' ecological regime indicates that fisheries are the main regulator of cod population dynamics in the Baltic Sea. © Inter-Research 2011.