Sardine Assessment Shows Cyclic Decline in Population
Pacific sardines are known for wide swings in their population: the small, highly productive species multiplies quickly in good conditions and can decline sharply at other times, even in the absence of fishing. Scientists have worked for decades to understand those swings, including a decline in the last few years that led to the Pacific Fishery Management Council's 
recommendation on April 13th to suspend commercial sardine fishing off the West Coast for the first time in decades..An updated stock assessment by NOAA Fisheries’ Southwest Fisheries Science Center (SWFSC) was the basis for the Council's action. Stock assessments are research tools that estimate the status and size of the sardine population. The Council uses the assessments to set fishing quotas.Models that support the sardine assessment combine NOAA data on past and current abundance of sardine eggs, larvae and mature fish with other data on sardine biology and fishery catches. The data on sardine abundance come from two SWFSC research vessel surveys conducted off the West Coast each year.These surveys employ two methods to estimate the current size of the sardine population. They use underwater acoustic equipment (like sonar) to estimate the size of fish schools, followed by the use of trawl nets to verify the species comprising the schools. Additionally, the surveys employ devices that measure the density of sardine eggs in the water as a gauge of sardine spawning. Scientists can then calculate how large the spawning population must be to produce the measured density of sardine eggs.These data feed a computer model to estimate sardine population trends and provide the foundation for projections of the total population of sardines off the West Coast in the next fishing year.“The assessment produced this year suggests that cool ocean water temperatures off the West Coast beginning around 2007 may have reduced the survival of juvenile sardine resulting in a population decline”, said Kevin Hill, a fisheries biologist who oversees the stock assessment for the SWFSC. The number of surviving young fish appears to have dropped to the lowest levels in recent history and has likely remained low in 2014. This has led to a steady decline in the fishable sardine stock biomass, which is defined as the total volume of sardines at least one year old. This is the measure the Council relies on when setting fishing quotas.“The environment is a very strong driver of stock productivity. If ocean conditions are not favorable, there may be successful spawning, but fewer young fish survive to actually join the population,” Hill said. “Small pelagic fish like sardine and anchovy undergo large natural fluctuations even in the absence of fishing. You can have the best harvest controls in the world but you’re not going to prevent the population from declining when ocean conditions change in an unfavorable way.”The current decline adds to a series of ups and downs that illustrate the boom-and-bust nature of sardine populations. The sardine biomass rose from about 300,000 metric tons in 2004 to a high point of more than 1 million in 2008 and is predicted to decrease to an estimated 97,000 metric tons by this coming July.Because of these swings in sardine populations, the Council’s management framework for sardines includes built-in mitigation measures and safeguards to exponentially reduce fishing pressure as the stock declines. One of these Council measures is a cessation in directed fishing on sardines when the biomass falls below 150,000 metric tons. “The fishing cutoff point is included in the guidelines adopted by the Council and is designed to maintain a stable core population of sardines that can jump-start a new cycle of population growth when oceanic conditions turn around,” Hill said.In the course of reviewing the 2015 updated assessment, it became evident that the final model used in the 2014 assessment did not correspond to the best fit to the data. The data were reanalyzed and a better fit to the 2014 model was achieved. This re-examination resulted in a lower 2014 biomass estimate of 275,705 metric tons, down from the previous estimate of 369,506 metric tons, which is still above the fishing cutoff value of 150,000 metric tons.The revised model applied to the 2015 assessment resulted in a biomass estimate of 97,000 metric tons, which is below the fishing cutoff. As a result, the Council decided to close the 2015-2016 sardine fishing season and requested that NOAA Fisheries close the remainder of the 2014-2015 sardine fishing season. The sardine population is presently not overfished and overfishing is not occurring; however, the continued lack of recruitment observed in the past few years could decrease the population, even without fishing pressure.The NOAA Ship Bell M. Shimada is currently conducting a new sardine survey off the West Coast to collect updated information on the size and location of the sardine stock. In addition, a large-scale 80-day survey this summer will collect data on sardine and whiting (hake) populations from the Mexican border to Canada. This new information will support the next stock assessment SWFSC prepares for the Council and NOAA fisheries managers.Learn more:Pacific sardine stock assessmentExecutive summary Full report In the Field: Spring Sardine Survey 2015Pacific Fishery Management Council Coastal Pelagic Species California Cooperative Oceanic Fisheries Investigations (CalCOFI)Video – Coastwide Sardine SurveyGreen Seas Blue Seas – Interactive Guide to the California Current For more information, please contact: Michael.Milstein@noaa.gov or Jim.Milbury@Noaa.gov (West Coast Regional Office Public Affairs), Dale.Sweetnam@noaa.gov (Southwest Fisheries Science Center) and Joshua.Lindsay@noaa.gov (West Coast Regional Office)
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Scat may contain clues to marine mammals' Southern California deaths
Biologist Mark Lowry collects sea lion and elephant seal scat.(Brian van der Brug / Los Angeles Times)
By Louis Sahagun
Mark Lowry has collected sea lion and elephant seal scat from San Nicolas and San Clemente islands for more than three decades to track the long-term health of marine mammal life off the California coast.But the federal biologist's work has new meaning — and urgency — this year. Analyses of the specimens could solve the mystery of why so many young sea lions have been found dead and dying on Southern California beaches.Keeping a wary eye on a herd of elephant seals lolling on rocks perched over the pounding surf here on a recent weekday, Lowry put on rubber gloves and used a dinner spoon to scoop up piles of seal scat and plop them into plastic specimen bags.Lowry, a National Oceanic and Atmospheric Administration biologist, hoped the pungent material contained answers to why at least 2,250 dehydrated and underweight sea lions started showing up on local beaches in January — around the time he detected evidence of an unprecedented shift in the species' eating habits.Specifically, Lowry found what he described as "mystery stuff — gooey bits of substance you'd expect from a diet of jellyfish or tube worms."Sea lions are opportunistic predators that typically feed on mackerel, sardines, rockfish and market squid. But amid El Niño-like conditions and a dearth of fish and squid to prey on, they may be trying to sustain themselves on novel food sources, he said."These findings are preliminary," Lowry said. "But it could mean sea lions are starving and eating what little they can find to fill their stomachs up."There were 350 ailing sea lion pups stranded on local beaches in January, 850 in February and 1,050 in March, according to the latest numbers released by the National Marine Fisheries Service.The overall health of the California sea lion population, however, remains robust."The sea lion population is increasing at a rate of about 5.1% per year," said Lowry, who also conducts annual aerial surveys of California's pinniped populations. "In 1964, the sea lion population was about 30,000. Today, it is a tad over 300,000."Most of those sea lions breed on the wind-raked beaches of 3-mile-by-9-mile San Nicolas Island, the outermost of the eight Channel Islands and pinniped capital of the United States.
San Nicolas is populated by about 200 military and civilian residents. But for several months beginning in December and continuing into spring, it is breeding grounds for tens of thousands of California sea lions, elephant seals and harbor seals.Lugging his collecting gear and buckets down a sandstone bluff toward raucous herds of sea lions and elephant seals weighing as much as 3,000 pounds, Lowry, 64, said with a laugh, "This is field biology at its finest."Moments later, he was in his element, on his knees and harvesting seal scat on this desert isle used by the Navy to test the latest missile defense systems."If flies are interested in it, I'm interested," he said. "No joke."He aimed to collect 15 pounds of the stuff for analysis later in his La Jolla laboratory. That process involves soaking the samples in buckets of fragrant soapy water, then pouring them through wire-mesh seines to separate out bony particles that can determine the species, size and age of the fish and squid eaten."The value of Mark's data is enormous," said Doug Demaster, science and research director of NOAA's Alaska region fisheries. "Shifts in the diets of sea lions are among the earliest signals we get of impending El Niño events, which mean wholesale shifts of wind and storm patterns, and changes in the marine ecology."Beyond that, we all want to know why the number of dying sea lion pups on California's beaches has jumped from a few dozen a year to thousands in the past three months alone."Seals have altered their feeding habits several times over the last three decades, Lowry said. In the 1980s, for example, they were eating mostly anchovies and sardines. In the 1990s, they started going after squid. During El Niño events, they chase rockfish."The mystery stuff I'm finding now is altogether new," he said. "I intend to figure out exactly what it is."Lugging a 5-gallon bucket full of scat samples back to his pickup after a productive day of prospecting, Lowry smiled and said, "I have no plans to retire, and my bosses are very happy about that."
Seal scatBrian van der Brug / Los Angeles TimesBiologist Mark Lowry uses a large tablespoon to scoop up sea lion and elephant seal scat to track the long-term health of marine mammal life on San Nicolas Island.
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Broccoli, sardines, blueberries good for your eyes, says study
Found in blueberries, the pigment anthocyanin can help maintain cornea health. – AFP Relaxnews pic, April 2, 2015.
Anyone concerned with maintaining healthy eye function may want to add more broccoli, sardines and blueberries to their diet, according to the recommendations from an expert at Loyola University Chicago.
Several nutrients are essential to eye health, and some may even help to improve eyesight and prevent problems such as cataracts and macular degeneration.Dr James McDonnell, a paediatric ophthalmologist at the Loyola University Health System, has compiled a list of these nutrients and the foods that contain them.Omega-3: Protection from macular generation is yet another benefit of this remarkable fatty acid, which by now is well known to nutrition-savvy consumers. Good sources include oily fish (sardines, mackerel, etc.), flaxseed and canola oil.Astaxanthin: This pigment is a powerful antioxidant with the power to stave off cataracts and even blindness. Seaweed and wild salmon (not farmed) are among the top sources.Anthocyanins: These pigments, which range in colour from bright red to blue, can help maintain the health of the cornea and of the blood vessels throughout the eye. Blueberries and blackcurrants are rich in these colourful nutrients.Zeaxanthin: Found in dark leafy green vegetables such as broccoli, kale, collard greens and spinach, this nutrient may help reduce the risk of age-related macular degeneration.Vitamin D: Moderate sun exposure is one way to ensure an adequate supply of Vitamin D, and consuming fish oils, liver and egg yolks can provide an additional boost. Supplementing with Vitamin D3 has been shown to reduce retinal inflammation and even improve vision.Bioflavonoids: These antioxidants belong to the polyphenols family and may reduce the risk of cataracts and macular degeneration. They are found in citrus fruits, cherries, tea and even red wine.Beta-carotene: Found in carrots, sweet potatoes and butternut squash, this provitamin helps to improve night vision and to prevent dry eyes.Lutein: Supplementing with this carotenoid, which is found in organic eggs from pastured hens, may help prevent macular degeneration. – AFP Relaxnews, April 2, 2015.
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NW scientists discover Pacific fish surviving dead zones
Some species of Pacific Ocean rockfish have been found to survive in low-oxygen dead zones off the West Coast, while other species struggle significantly, researchers in Oregon and Washington reported in a recent study. (Cindy, Oregon Coast Aquarium)
GRANTS PASS -- Scientists say they have found that some fish can survive in low-oxygen dead zones that are expanding in deep waters off the West Coast as the climate changes.While the overall number and kinds of fish in those zones are declining, some species appear able to ride it out, according to a study published this month in the journal Fisheries Oceanography.The study focused on catches from 2008 through 2010 of four species of deepwater groundfish -- Dover sole, petrale sole, spotted ratfish and greenstriped rockfish.Catches of ratfish and petrale sole both declined in low-oxygen areas, while catches of greenstriped rockfish and Dover sole showed no changes. Dover sole are well-known for being adapted to low oxygen, but greenstriped rockfish are not.Oregon State University oceanographer Jack Barth, a co-author, says commercial fishermen will likely start taking oxygen levels into account as they decide where to tow their nets."It's rearranging that ocean geography," Barth said of the low-oxygen conditions. "If you go out to a spot where you've always gone before commercial fishing, and you don't catch what you expect, is it because the oxygen has gone low and things moved someplace else?"Dead zones were first noticed off Oregon in 2002, where they peaked in 2006, and have since spread to Washington and California waters.Some, such as where the Mississippi River flows into the Gulf of Mexico, are caused by agricultural runoff. On the West Coast, scientists have demonstrated they are triggered by climate change.North winds cause the ocean to turn over, drawing cold low-oxygen water up from the depths. Conditions get worse as tiny plants, known as phytoplankton, are drawn to the surface, where sunshine triggers a population explosion. As they die, they sink and use up more oxygen as they decompose.Underwater videos have shown crabs and other slow-moving bottom-dwellers in shallow waters die, but scientists from NOAA Fisheries Service and Oregon State wanted to know what happened to fish.NOAA Fisheries was already chartering fishing trawlers to do annual surveys of groundfish populations off the West Coast. They equipped the nets with oxygen sensors.Lead study author Aimee Keller, a fisheries biologist for the NOAA Fisheries Service's Northwest Fisheries Science Center in Seattle, said scientists ultimately want to see whether fish forced out of preferred habitats grow more slowly, are less successful reproducing, and whether other species adapted to low-oxygen conditions move in.The next step, she said, is to expand the surveys to include more commercially important species.Tim Essington, professor of fisheries at the University of Washington, was not part of the study but said it was significant for covering a large geographic area, and was consistent with what has been seen in estuaries. He added he expects fish to congregate along the edges of low-oxygen zones, where predators will be able to feed on less active fish inside the zone.NOAA oceanographer Bill Peterson, who was not part of the study, said there was no doubt that low-oxygen waters were expanding, but it was a slow process that would take decades to be felt.
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Trawling has “negligible” effect on soft-bottom
Petrale sole, a flatfish caught by trawling on soft-bottom seafloor. Credit: The Nature Conservancy
A groundbreaking new study recently conducted by California fishermen, The Nature Conservancy and CSU Monterey Bay indicates that bottom trawling only has a “negligible effect” on the seafloor and fish habitat in certain types of soft sea bottom.Trawling is continually criticised by environmental advocates for the damage it causes to rocky marine habitats and the long-lived animals that occur in them. However, important questions remain about the extent of any damage to sandy and muddy environments.During the three-year study, fishermen trawled patches of the ocean floor off Morro Bay. Those areas were analysed by underwater photos and video and compared with nearby areas that were untouched.Their peer-reviewed work, published in the Fishery Bulletin, found that California’s largely soft-bottom seafloor saw little lasting impacts from trawling with a small-footrope trawl.The researchers say that their study adds to a growing body of literature from around the world showing trawling impacts are context-dependent - the impacts depend on the type of gear used, the types of habitats trawled and how often trawling occurs.The scientists point out that their study does not imply that all soft-bottom habitats should be open to trawling; but, with new research and technology, "we can fine-tune our fishery regulations to protect truly vulnerable habitats."One of the researchers, Dr. James Lindholm has been studying marine ecosystems for 20 years and this autumn he will conduct a similar experiment off Half Moon Bay using trawling nets of different sizes. Commercial fishermen will also be involved.
Read the original post: www.worldfishing.net
NBCNews.com Replaces Reality, Regulation and History with Hyperbole
Original post: AboutSeafood.com | © 2015 National Fisheries Institute | Published with permission.
A story this week on NBCnews.com about the state of the seafood industry is packed with sensationalism and hyperbole, yet absent much of the real science, facts and figures that drive actual sustainability.To begin, U.S. fisheries are among the world’s best managed and most sustainable. Though not referenced by name a single time in this article, the National Oceanic and Atmospheric Administration, NOAA, regulates U.S. seafood with headquarters in Washington D.C., five regional offices, six science centers and more than 20 laboratories around the country and U.S. territories.Author John Roach, however, perpetuates doom and gloom throughout this piece, asserting “voids” left by cod, halibut and salmon that need to be filled by other fish. We’re guessing Mr. Roach isn’t aware that salmon shattered modern-day records in 2014, returning to the Columbia River Basin in the highest numbers since fish counting began at Bonneville Dam more than 75 years ago. Could you tell us again about that void?Mr. Roach also intones a narrative of sustainability disaster for popular predators like tuna but forgot to mention groups like the International Seafood Sustainability Foundation (ISSF), a coalition created through a partnership between WWF, the world’s leading conservation organization, and canned tuna companies from across the globe to insure the long-term conservation and sustainable use of tuna stocks. In an article that claims the sky is falling for species like tuna it’s odd that ISSF gets nary a nod or even a mention.Switching gears, Mr. Roach goes on to blame giant trawlers “armed” with technology and massive nets as part of the reason we’re “running low” on fish. As in any industry, technology gets better by the day, creating more efficient ways to do business. However, new technology is by no means exempt from standing national and global fishery regulations, such as catch-limits, by-catch laws, compliance, and so forth. To suggest that enhanced technology or “bigger or faster” boats are causing our fish supplies to dwindle ignores the impact of technology on sustainability and even regulatory oversight. There are pros and cons to every catch-method and there is no one-size-fits all solution to sustainability challenges but to blame technology without recognizing its contribution to solutions is folly.Hyperbolic rhetoric about sustainability continues to be discounted by legitimate fisheries experts in the scientific community. In fact, one “report” forecasting empty oceans by 2048 was challenged by a number of independent researchers who described the study that promoted the statistics as, “flawed and full of errors.” Including Ray Hilborn, a professor of aquatic and fishery sciences at the University of Washington in Seattle whose research into the study lead him to say, "this particular prediction has zero credibility within the scientific community.” After Hilborn’ s analysis the author of the original study himself explained that his research was not in fact predicting worldwide fish stock collapse at all but merely examining trends. Articles like this track along precisely with the discounted, overblown storyline that gave birth to the empty oceans by 2048 nonsense.Whether you’re a “natural optimist” or not, there is no question that seafood harvested from U.S. fisheries is inherently sustainable as a result of NOAA’s fishery management process and global fisheries management is far from the wild west scenario bandied about. Things aren’t perfect and there’s work to be done but the “game” is not “almost over” and those who suggest it is, willfully propagate that narrative not because it’s accurate but because bad news sells.
Bottom trawling gets a bum rap, CSUMB study finds.
Nic CouryLocal petrale sole, like this dish at the former Alvarado Fish & Steakhouse, may be a more sustainable fish than we thought.
Bottom trawling—dragging nets along the sea floor to catch species like halibut and sanddabs—isn't always the destructive fishing method it's made out to be, according to a collaborative study by fishermen, The Nature Conservancy and CSU Monterey Bay.The study, published in National Marine Fisheries Service's Fishery Bulletin, found that not all sea floors are created equal. The "soft" sea floor (mostly mud and sand) that comprises up to 85 percent of the continental shelf off the California coast may be able to recover quickly from small footrope trawl gear, the study concludes. Yet most of the state waters and much of the federal waters are closed to bottom trawling."Our study adds to a growing body of literature from around the world showing trawling impacts are context dependent—they depend on the type of gear used, the types of habitats trawled and how often trawling occurs," a press release states. "Trawling in rocky areas with long-lived corals will likely have more long-lasting impacts than trawling in soft-bottom habitats that may be less vulnerable and can recover more quickly."Monterey Bay Aquarium's Seafood Watch guide, which has long shunned much of Monterey Bay's own local catch because it viewed bottom trawling as environmentally unfriendly, is now picking up on that more nuanced approach. The updated Seafood Watch guide upgraded 21 species of West Coast groundfish from red (avoid) to yellow (good alternative) or green (best choice) rankings, as the Weekly reported last fall.Also promising: next-generation light-trawl gear that floats just above the sea floor instead of dragging. Environmental Defense Fund consultants Huff McGonigal and David Crabbe developed the technology to allow fishermen to "fish a wider area, travel faster, reduce fuel costs by a quarter and preserve bottom-dwelling fauna," as the Weekly reported in 2013.
Read the original post: MontereyCountyWeekly.com | by Kera Abraham
Chemical clues in fossil shells may help us understand today's ocean acidification
By: Brendan Bane As atmospheric CO2 levels rise, so too do those in the sea, leading to ocean acidification that outpaces that of any other time in tens of millions of years. Some effects of ocean acidification are imminent, like the fact that calcified organisms such as corals and shellfish will have access to less and less of the chemical components they need to build their shells and skeletons. Other outcomes are less clear, and scientists wanting to predict what may come of our quickly acidifying waters are looking to past climatic events that were similar to our own.One such event, the Paleo-Eocene Thermal Maximum (PETM), which occurred 56 million years ago, is likely our closest analog to modern ocean acidification. Researchers who refer to the PETM as a case study have long suspected that ancient waters acidified then, but until recently, they never had physical evidence of it actually happening. Then just this past year, researchers uncovered the PETM's chemical chronology encrypted in the shells of fossilized plankton, called foraminifera, and learned that the two timelines aren't entirely similar; today's surface ocean is acidifying ten times faster than it did during the PETM. Their findings were published in Paleoceanography in June, 2014.Penman (the lead author) offered this image of himself (center), Richard Norris (Scripps) and Pincelli Hull (Yale) inspecting sediment cores from the PETM while aboard a scientific drilling vessel.Penman (the lead author) offered this image of himself (center), Richard Norris (Scripps) and Pincelli Hull (Yale) inspecting sediment cores from the PETM while aboard a scientific drilling vessel. Photo credit Donald Penman."While foraminifera are alive, they incorporate the chemistry of the water into their shells," said Bärbel Hönisch, associate professor of earth and environmental sciences at Columbia University and coauthor of the study. "When they die, they take that information with them into the sediment."Hönisch and several other scientists analyzed the chemical composition of fossilized foraminifera embedded in "nannofossil ooze," a section of rock particularly rich with tiny fossilized organisms, which they drilled out of sub-ocean sediment near Japan.Foraminifera, like coral and shellfish, pull carbonate ions from the surrounding seawater to build their shells. In a way, the chemical composition of these shells acts as a snapshot of the chemical composition of the water the foraminifer lived in. When water grows increasingly acidic, foraminifera replace whole carbonate molecules with borate molecules. When the scientists of this study inspected the boron composition of shells from plankton that died during the PETM, they learned not only how acidic the ocean was at the time, but also how quickly its chemistry shifted and how long it stayed that way."Acidification during the PETM was relatively rapid," said oceanographer Richard Zeebe of the University of Hawaii at Manoa, another coauthor of the study, "but it was also sustained. The whole event took a very long time." A massive surge in atmospheric carbon, its cause still unknown, warmed the globe by four to eight degrees and dropped the ocean's pH by about 100 percent. Conditions remained that way for approximately 70,000 years. These environmental changes triggered many biological ones. Seafloor-dwelling foraminifera suffered mass extinction while another type of tiny aquatic organism, dinoflagellates, thrived and expanded.Foraminifera like the one pictured above record their environment's chemistry in calcium carbonate shells, essentially leaving a trail of chemical breadcrumbs for future investigators. Photo by Howard Spero.Foraminifera like the one pictured above record their environment's chemistry in calcium carbonate shells, essentially leaving a trail of chemical breadcrumbs for future investigators. Photo by Howard Spero.Although the PETM ocean did acidify quickly, it happened ten times slower than what's happening today. Our ocean's pH has dropped from 8.2 to 8.1 in the last 150 years, an amount that took a few thousand years in the PETM. Scientists predict the drop will only continue, with the seas reaching a pH of 7.8 to 7.9 by 2100. That change was and continues to be fueled by manmade carbon being pumped into the atmosphere and subsequently absorbed by the ocean.In understanding how to compare the two events and what outcomes will emerge from modern acidification, rate is key."In any aspect of environmental change, particularly global change, rate matters" said lead author Donald Penman of the University of California Santa Cruz. Natural buffers like deep seawater mixing likely mitigated acidification during the PETM. But those same buffers will surely be outpaced by today's heightened rate. "If you put carbon dioxide into the ocean faster than its natural processes can deal with it," Penman said, "then they don't do you any good."Marine animals will also be challenged by the speed at which their environment is changing. "We know that organisms and ecosystems can adapt and evolve to slow changes as they have throughout earth's history," Penman said. "However, when you invoke the same change over a shorter time, then you can outstrip organisms' ability to evolve with that change. Species go extinct, and marine ecosystems change dramatically, perhaps irrecoverably."The researchers noticed that extinctions occurred during the PETM even at a pH change rate of 0.1 per thousands of years – which may not bode well for today's foraminifera."The fact that some organisms went extinct during the PETM puts our current activities in perspective," said Hönisch. "If the organisms died then, it is even more likely that some organisms will die now."With a clearer picture of the PETM painted, researchers can begin to draw more detailed analogies between the two events, and hopefully catch any drastic environmental changes before they surprise us."Now that we have [ocean acidification during PETM] quantified," Penman said, "we can begin to make calculations of how much and how quickly carbon was emitted during the PETM. This will help us disentangle what sources of carbon and feedbacks were in operation during the PETM, and whether or not they are something we need to worry about in the future."
Penman (the lead author) offered this image of himself (center), Richard Norris (Scripps) and Pincelli Hull (Yale) inspecting sediment cores from the PETM while aboard a scientific drilling vessel. Photo credit Donald Penman.
Foraminifera like the one pictured above record their environment's chemistry in calcium carbonate shells, essentially leaving a trail of chemical breadcrumbs for future investigators. Photo by Howard Spero.
Citations:Penman, D. E., Hönisch, B., Zeebe, R. E., Thomas, E., & Zachos, J. C. (2014). Rapid and sustained surface ocean acidification during the Paleocene‐Eocene Thermal Maximum. Paleoceanography.Hönisch, B., Ridgwell, A., Schmidt, D. N., Thomas, E., Gibbs, S. J., Sluijs, A., ... & Williams, B. (2012). The geological record of ocean acidification. science, 335(6072), 1058-1063.
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