November Takes a Bite Out of 'the Blob'
Warm expanse that heated up West Coast waters is beaten, but not yet broken
The so-called “blob” of infamous warm ocean waters that has gripped the West Coast and shaken up its marine ecosystems in the past two years is battered, but not dead yet, NOAA scientists report.
Strong winds blowing south from Alaska toward California dominated the West Coast through much of November, bringing cold air and some new upwelling of deep, cold water that weakened the warm patches that had long made up the blob, said Nathan Mantua, leader of the Landscape Ecology Team at NOAA Fisheries’ Southwest Fisheries Science Center in Santa Cruz, California. Patches of ocean that had been as much as 2 to 3 degrees C warmer than average in October have now dropped sharply to around 0.5 to 1.5 degrees C above average. Some areas along the Northern California Coast have even dropped to slightly below average temperatures for this time of year, he said.
Sea surface temperature maps from early November and early December illustrate decline of the large patches of warm water off the West Coast that have become known as “the blob.” The maps chart the difference between current and average sea surface temperatures, with darker red illustrating temperatures farther above average.
The blob has become one of the best-known temporary features of the world’s oceans, a big red expanse on temperature maps that has earned headlines in the New York Times and other outlets around the world. It has also become one of the hottest topics in climatology and oceanography, with scientists looking for possible links to climate change and the California drought; shifting distributions of marine species; and the unprecedented harmful algal bloom that has encompassed the West Coast, shutting down crabbing and clamming for months.The one main exception to the blob’s decline is a narrow band of still-warm water along the coast from Southern California to San Francisco that remains about 3 degrees C above normal for this time of year. But the band may also be an early signal of the arrival of El Niño-related ocean currents, which are expected to cause more warming along the Pacific Coast in the next few months, Mantua said.
A close-up of sea surface temperatures off the West Coast, with red illustrating areas warmer than average and blue representing areas below average.
Research scientist Nick Bond of the NOAA Joint Institute for the Study of the Atmosphere and Ocean at the University of Washington originally coined the term, “the blob,” to describe the warm expanse. He said climate models agree the strip of warm water will remain along the West Coast, perhaps helping the blob hang on. He figures that the conditions might continue “well into 2016, and be of great enough magnitude to matter to marine ecosystems. How much is the big question.”“Unusually warm temperatures still dominate the Pacific between Hawaii and the West Coast, but the amount of warmth is lower now than it has been for most of the past two years,” Mantua said. “As we get into the winter months, the expected El Niño influence on North Pacific weather and ocean currents includes more dramatic changes in West Coast ocean temperatures that will likely include coastal warming and offshore cooling.”Previous articles
A Remarkable Warming of Central California’s Coastal Ocean (Jul 30, 2014)Unusual North Pacific Warmth Jostles Marine Food Chain (Sep 8, 2014)Oncoming El Niño Likely to Continue Species Shakeup in Pacific (Oct 1, 2015)
Contact: SWFSC Fisheries Ecology Division, Landscape Ecology Team
Current conditions: What's happening now?
Below are the most recent sea surface temperature anomaly maps for the U.S. West Coast and the Northeast Pacific. These images are generated live from a data server, so they make take a few seconds to display.
Read the original story: https://swfsc.noaa.gov/
Fish Stocks Are Declining Worldwide, And Climate Change Is on the Hook
For anyone paying attention, it’s no secret there’s a lot of weird stuff going on in the oceans right now. We’ve got a monster El Niño looming in the Pacific. Ocean acidification is prompting handwringing among oyster lovers. Migrating fish populations have caused tensions between countries over fishing rights. And fishermen say they’re seeing unusual patterns in fish stocks they haven’t seen before.Researchers now have more grim news to add to the mix. An analysis published Monday in the Proceedings of the National Academy of Sciences finds that the ability of fish populations to reproduce and replenish themselves is declining across the globe.“This, as far as we know, is the first global-scale study that documents the actual productivity of fish stocks is in decline,” says lead author Gregory L. Britten, a doctoral student at the University of California, Irvine.Britten and some fellow researchers looked at data from a global database of 262 commercial fish stocks in dozens of large marine ecosystems across the globe. They say they’ve identified a pattern of decline in juvenile fish (young fish that have not yet reached reproductive age) that is closely tied to a decline in the amount of phytoplankton, or microalgae, in the water.“We think it is a lack of food availability for these small fish,” says Britten. “When fish are young, their primary food is phytoplankton and microscopic animals. If they don’t find food in a matter of days, they can die.”The worst news comes from the North Atlantic, where the vast majority of species, including Atlantic cod, European and American plaice, and sole are declining. In this case, Britten says historically heavy fishing may also play a role. Large fish, able to produce the biggest, most robust eggs, are harvested from the water. At the same time, documented declines of phytoplankton made it much more difficult for those fish stocks to bounce back when they did reproduce, despite aggressive fishery management efforts, says Britten.When the researchers looked at plankton and fish reproduction declines in individual ecosystems, the results varied. In the North Pacific — for example, the Gulf of Alaska — there were no significant declines. But in other regions of the world, like Australia and South America, it was clear that the lack of phytoplankton was the strongest driver in diminishing fish populations.“When you averaged globally, there was a decline,” says Britten. “Decline in phytoplankton was a factor in all species. It was a consistent variable.”And it’s directly linked to climate change: Change in ocean temperature affects the phytoplankton population, which is impacting fish stocks, he says.Food sources for fish in their larval stage were also a focus of research published earlier this summer by Rebecca Asch, now a postdoctoral research associate at Princeton University. Asch studied data from 1951 to 2008 on 43 species of fish collected off the Southern California coast and found that many fish have changed the season when they spawn. When fish spawned too early or too late in the season, there can be less plankton available to them, shrinking their chance of survival. She calls it a “mismatch” between when the fish spawn and when seasonal plankton blooms.Knowing just how vulnerable our fisheries are to potential climate change is on the radar of NOAA Fisheries. The agency has put together a Fish Stock Climate Vulnerability Assessment report expected to be released in early 2016. And like many things associated with climate change, there will be winners and losers.Jon Hare is the oceanography branch chief for NOAA Fisheries’ Northeast Fisheries Science Center and a lead researcher on the agency’s assessment. He says they looked at 82 fish and invertebrate species in the Northeast. About half of the species, including Atlantic cod, were determined to be negatively impacted by climate change in the Northeast U.S. Approximately 20 percent of the species are likely to be positively impacted — like the Atlantic croaker. The remainder species were considered neutral.Similar assessments are underway in the California Current and the Bering Sea, and eventually in all of the nation’s large marine ecosystems.“This is where the idea of ecosystem-based management comes in. It’s not only fishing that is impacting these resources,” says Hare. “We need to take a more holistic view of these resources and include that in our management.”Britten says the fact that productivity of a fishery can change should be an eye-opener for fisheries management.“It’s no longer just pull back on fishing and watch the stock rebound. It’s also a question of monitoring and understanding the ability of stocks to rebound, and that’s what we demonstrated in this study. The rebound potential is affected as well,” says Britten.
Original story: www.npr.org/ Copyright 2015 NPR.
Could market squid become a new Southeast fishery?
Southeast Alaska marine scientists got a rare peek this year into the hatching of a certain species of squid.“I’ve never seen it. In fact, I’ve never seen squid in Southeast and I’ve been here since 1976,” said Gordon Garcia. He works at the National Oceanic and Atmospheric Administration’s Ted Stevens Marine Research Institute in Auke Bay.Market squid eggs were found this past summer in a salmon capture device at the NOAAs Little Port Walter field station. That’s located on the eastern shore of the southern tip of Baranof Island.The squid are native to Southeast and are commercially harvested in California. But Garcia said this is the first time evidence of market squid spawning has been found at the research station, which has been there since the 1920s.
NOAA’s Gordon Garcia shows one of the tanks that is being used to hatch and culture market squid in the wet lab at Ted Stevens Marine Research Institute. (Photo by Matt Miller/KTOO)
“The squid actually spawned in the capture device and our staff there grabbed some of them,” Garcia said. The live squid died quickly, so he settled for eggs and began experimenting in July. I visited him in September.Garcia is a facilities manager at the institute, but he studied marine zoology in college and spent 30 years at the Alaska Department of Fish and Game. He’s curious to know if the squid can be cultured.In the tanks where the squid eggs are kept, Garcia points out what he calls “squidleys,” also known as hatchlings.“We see this mass of squid hatching and they’re all attracted to the light,” Garcia said as we watched the squidleys dart around and swim.
Garcia calls this photo “Squidnado” because of the tornado-like formation of market squid hatchlings that swam toward the light. (Photo courtesy Gordon Garcia/NOAA)
The eggs are housed in what looks like a puffy, translucent white sea anemone. About 30 to 40 eggs are in each finger.Garcia took an early photo of the first hatchlings that resembled an underwater tornado. He dubbed it “Squidnado” as an homage to recent cheesy sci-fi movies that mix weather phenomenon and marine life.The experiment is conducted in eight tanks. One of the tanks has water piped in from Auke Bay, which stays around 49 degrees Fahrenheit. In another tank, the water is warmed to 61 degrees.The eggs in the warmer tank hatched first but then died after about a week. Eggs in the cooler tank began to hatch about four weeks later.Garcia said market squid typically live about a year and grow to 8 to 10 inches long.“You could get those little calamari rings out of them. Yeah, dice them up,” he said, laughing.At one point, there were clouds of squidleys in the lab’s tanks, Garcia said. As many as 7,000 hatched between late summer and early fall.“They’re just popping out as we’re talking. You can see that cloud is getting denser and denser. If I were to go shake these egg masses, I’d probably triple the number of critters that you see there,” Garcia said.“I’m not sure what I’m going to do with them all. I hate to see them die, but that’s nature, of course. We’ll take the strongest and see if we can’t make them grow.”
Market squid hatchling is photographed under extreme magnification. (Photo courtesy Gordon Garcia/NOAA)
Garcia spent three months experimenting with the size of the tank, the kind of gravel at the bottom, water flow and food sources. The tricky part was getting the squid to eat.He tried salmon meal, rehydrated freeze-dried rotifers or a form of zooplankton and brine shrimp. Some of the cold water squid doubled in size after feeding on the brine shrimp, but the shrimp themselves did not thrive very well in the cold water.Sadly, despite Garcia’s attempts to keep the squidleys alive, the experiment only lasted about three months. The last one died Oct. 6.
Watch the video on the original post: http://www.ktoo.org/
El Nino pushes California calamari landings down
A stand-up paddler strokes past squid boats anchored off of the Santa Cruz Municipal Wharf. (Shmuel Thaler -- Santa Cruz Sentinel)
SANTA CRUZ >> After several years of bounty, California’s commercial landings of market squid — the species better known to hungry diners as calamari — are down by about two-thirds compared to this time last year.The squid are responding to this year’s El Nino conditions, scientists say, but whether their numbers are declining or they’re simply eluding fishermen is unknown, according to California Department of Fish and Wildlife environmental scientist Laura Ryley.Commercial fishermen brought in about 114,000 tons of market squid last year, generating more than $72 million. That was about 30 percent of California’s commercial fishing income for the year, according to the California Department of Fish and Game. Fishermen landed about 107,000 tons by the end of October last year, compared to only about 34,000 tons by the end of October this year.“When we look for squid during or shortly after El Nino events, we find less of them,” said Louis Zeidberg, a professor at Cal State Monterey Bay.El Nino conditions are caused by higher than average surface water temperatures in the Pacific Ocean, according to the National Oceanic and Atmospheric Administration. Those higher temperatures may be altering the briny buffet of krill and other small crustaceans that market squid eat, Zeidberg said.“The simplest conclusion is that what these guys like to eat gets scarcer during El Nino years, and what is there is crappier,” Zeidberg said. “They’re most likely starving to death.”Fishermen typically catch market squid when they congregate in shallow, near-shore areas to spawn. Some squid may be seeking out cooler, deeper water and evading fishermen in the process, said Ryley.“We’ve had anecdotal reports from fisherman that they’ve gone deeper,” Ryley said. “They’re deeper than their fishing gear can reach.”But if market squid deposit their eggs in water that’s too cold, the eggs might take longer than the typical two-week period to develop, said Stanford University biology professor William Gilly.“Just because the eggs are out of danger doesn’t mean they’re not in another kind of stress,” Gilly said. If eggs take more time to develop, hatchlings may emerge during the wrong season, and the next generation’s life cycle may be thrown out of whack.Another theory is that market squid move off shore, Ryley said, or they may not be as successful at spawning during El Nino years. There may be a combination of factors at play, Zeidberg said, with some squid starving and the survivors swimming to deeper water.The decline in market squid landings this year did not catch fishermen by surprise, said Diane Pleschner-Steele, executive director of the California Wetfish Producers Association.“They know when El Nino comes they’re not going to see squid,” Pleschner-Steele said. “We’re resilient, as long as the regulators allow enough flexibility for us to go from one fishery to another.”
Read the original post: http://www.santacruzsentinel.com/
Crab Fishermen Train as First Responders for Entangled Whales
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Copyright © 2015 Seafoodnews.com
But this October, around 100 fishermen from three ports near San Francisco took time away from their preparations to learn a new set of skills — how to identify, report, and monitor humpback (Megaptera novaeangliae), and gray whales (Eschrichtius robustus) trapped by fishing gear. The training is part of a larger collaboration between the fishermen, regulators, and conservancy groups to better understand how and where whales are likely to become entangled and what can be done to minimize the harm done to these animals. It’s an attempt by environmental advocates and those who make a living from the ocean to strike a balance that preserves the industry while protecting the world’s largest mammals.“No one wants to tangle a whale,” crab fisherman Geoff Bettencourt told Mongabay.But evidence shows that whales regularly get caught by fishing gear or marine debris. According to a detailed study of humpback fluke photographs taken in feeding and mating grounds in the Pacific Ocean, between 20 and 60 percent of the whales’ tails showed scarring patterns that indicated a past entanglement. And crab gear was involved in nearly half of the west coast whale entanglements reported during the past decade, according to National Oceanic and Atmospheric Administration (NOAA) Fisheries.Bettencourt is a fourth-generation fisherman out of the port of Half Moon Bay, a small town 30 miles south of San Francisco. In his more than 30 years on the ocean, neither he nor any of the other fishermen he knows have seen an entangled whale. But he has seen them in recent TV news stories and knew his industry had to respond. “If the whales are on an upswing, that’s a great thing. We just need to manage the fishing around that,” he said.This year’s unusually warm ocean waters have brought whales in large numbers to the California coast, as well as a record number of sightings of whales trapped in or dragging fishing gear. So far, 46 entangled whales have been reported, four times the annual average for the entire continental west coast recorded by NOAA Fisheries between 2000 and 2012.Unlike whale–boat collisions, which often result in a speedy death for the whale, entanglement can be a drawn-out process. Ropes from crab or lobster pots or fishing nets can catch on the whale’s flippers, flukes, or dorsal fin (for humpbacks) or become enmeshed in the baleen plates in its mouth. Dragging the gear can sap the animal’s strength and leave deep cuts in its skin. Large whales entangled in extensive gear have been spotted repeatedly over the course of weeks or months before disappearing and presumably dying. On the U.S. east coast, entanglement is the leading cause of death for large whales.“One of the biggest problems facing large whale conservation and welfare is whale entanglement,” Michael Moore, a Woods Hole Oceanographic Institution veterinary scientist who has studied whales since 1978, told Mongabay.The possibility of training the Dungeness crab fishermen to be first responders was suggested by Tom Dempsey, a senior fisheries project director for The Nature Conservancy (TNC), at an August informational meeting for crab fishermen hosted in Oakland by the California Department of Fish and Wildlife, the California Ocean Protection Council, and NOAA Fisheries. In 2013, prior to joining TNC, Demspey helped the Cape Cod Commercial Fishermen’s Alliance organize the training of 60 fishermen by the National Marine Mammal Entanglement Response Program.The nationwide network is made up of primarily volunteers ranging from those who have attended an introductory session to learn how to document and report injured whales — level 1 — up to those with extensive hands-on training to maneuver a craft close enough to a whale and to be able to cut through the lines — levels 4 and 5. Dempsey likens the level-1 training the lobster fishermen received to a basic CPR course: they may never use it, but if they do encounter an entangled whale, they’ll know who to contact and to do it right away.“In the past, we’d get notification [from fishermen spotting an entangled whale] after they had come in at the end of the day, we can’t do anything about that,” Pieter Folkens, a level-4 responder for California’s whale disentanglement program, the California Stranding Network, told Mongabay.Folkens was invited to discuss the network and its goals at a follow-up meeting for crab fishermen in September. He remembered the meeting starting off with the fishermen expressing a lot of acrimony toward NOAA Fisheries. But as he explained that his organization wasn’t out to vilify the crab-fishing industry and that in fact it wanted the fishermen’s help to reduce entangled whale deaths, the atmosphere began to change. “By the end of the day, they were buying us beers and asking us questions,” he said.This enthusiasm resulted in the October session held in Half Moon Bay and live-streamed to ports in San Francisco and Bodega Bay, 60 miles north of the city. Justin Viezbicke, the coordinator for the California Stranding Network and a level-4 responder, presented an overview of his organization and ways that the crab fishermen could help.“We want to build out the capacity to respond to these events,” he told Mongabay, adding “we need to have as many people lined up as we can because [entanglements] happen at the most inopportune times.” He noted that the fishermen present at the training would increase his volunteer base by over 10 percent.The most useful help the fishermen can offer, Viezbicke told the crowd, is to report to his group an injured whale when they sight it and, if possible, to stay with the animal until another boat can arrive. “Once we lose the whale, it’s a needle in a really large haystack,” Viezbicke said.Also important is to assess the situation, explained Viezbicke: identify the whale, note its condition, what gear is attached, and how. Because fishermen are familiar with the gear, they are well equipped to report this. And the information is valuable beyond saving the whale. “The biggest part of our program right now is documentation and learning about what’s going on out there,” he said.Figuring out what circumstances lead to crab gear entangling whales is a principal goal of a working group set up this spring by California’s Dungeness Crab Task Force, the government-mandated body that reviews and makes recommendations on the management of the state’s Dungeness crab fisheries. The working group is composed of fishermen and representatives from three government regulatory groups and four conservation organizations.Based on evidence from the U.S. east coast that whales can avoid lobster-pot lines better when they are vertical and taut in the water than when they are running horizontally or slack, the California working group will study how weighted or floating crab-pot lines behave in the water under different conditions. They plan to test the strength of these lines to find out how easily a whale can break free from them or a whale rescuer’s knife can cut them.They also want to collect data on the distribution and density of pots, as well as their proximity to whales. To help with this, the coast guard will perform helicopter flyovers during the first weekend of the Dungeness crab season. “We can see right here right now where the pots are, and where the whales are,” Jim Anderson, a crab fisherman and member of both the task force and working group, told Mongabay.Other fishing ports have requested first responder training sessions, which the working group hopes to organize later in the season. For now, a best practices guide to help Dungeness crab fishermen avoid entangling whales and report distressed whales is available on the California Ocean Protection Council’s website.Fishermen like Bettencourt believe this collaborative approach is the best chance for the whales, and his industry, to thrive. “The newer generation fishermen realize that the only survivability is in that new way of thinking. It has to be sustainable, it has to be right, it has to have the science to protect it,” he said.The Dungeness crab season was scheduled to open this year on November 15, but the Department of Fish and Wildlife delayed it indefinitely due to a toxic algal bloom. Andersen told Mongabay that the working group’s ideas will be implemented when the season begins.
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Ocean activists, fishers and scientists differ on heavy anchovy declines
Longtime bait fisherman, Mike Spears near the net aboard the In-Seine off the shores of Marina del Rey.
A new, beautifully produced but troubling public service announcement from Oceana features “Glee” television actress and singer Jenna Ushkowitz diving with sea lions off Santa Barbara.Fishing, she says, decimated Southern California’s historically booming stocks of Pacific sardine and Northern anchovy, a major food source for top ocean predators. Those stocks have dropped dramatically in the past decade, prompting reduced fishing quotas as starved sea lion pups and California brown pelican chicks die in record numbers.“Sea lions rely on forage fish for survival. But years of overfishing have put this important food source in jeopardy,” Ushkowitz narrates while underwater footage shows her swimming through kelp. “Join Oceana and help protect forage fish in the Pacific. ... We need to stop this and replenish.”The West Coast’s leading fishery scientists, however, disagree. They believe the fish are most likely enduring natural population fluctuations and are on the cusp of making a big comeback.Oceana, a nonprofit advocacy organization favored by celebrities such as Leonardo DiCaprio, insists that fishing is the primary problem. The group lobbied aggressively to close the West Coast anchovy fishery, delivering nearly 40,000 letters from concerned citizens nationwide to the Pacific Fishery Management Council, a 14-member body that sets fishing policy for California, Oregon and Washington, before its meeting last week.“We are greatly concerned that management of the commercial forage fisheries off California, Oregon and Washington is leaving ocean wildlife without enough fish to eat,” said Oceana’s form letter to the council, signed by thousands of citizens. “Approximately three times as many sea lions washed ashore in 2015 compared to 2013. Similarly, California brown pelicans have been abandoning their nests due to lack of forage fish.”Oceana helped to close the Pacific sardine fishery earlier than usual this year by stoking public concern about declining stocks of the important food source. They hoped to do the same for Northern anchovies, but the council decided to allow anchovy fishing to continue this season until the current, relatively low quota of 25,000 metric tons is reached.Sardine fishing will not resume until researchers complete another assessment of their population numbers, though fishers report seeing tons of them in the water.Corbin Hanson, a fisherman who supplies Tri Marine Fish Co. on Terminal Island with catch from his family-run fishing boat, the Eileen, said anchovies and sardines are plentiful.“Anchovies are still here in large volumes,” Hanson said. “I was just driving through them (Thursday) night. To say there are no anchovies in this water is absurd. It comes from such an obtuse perspective on our ecosystem.“The anchovy population ebbs and flows a lot and, as fishermen, we know that it’s going to come back. The volatility in the anchovy stocks is present with or without commercial fishing.“I don’t find it comforting that organizations (like Oceana) can make knee-jerk decisions about our coastal ecosystem when they’re not even on the water. The research they’re using to formulate their opinion isn’t even recent.”Researchers agree environmental changes, not fishers, caused the population crash. New evidence points to a record-breaking boom in young anchovies and sardines farther north this year in Central and Northern California, and on the Oregon border, according to the National Oceanic and Atmospheric Administration’s Southwest Fisheries Science Center. Researchers say that they appear to have eluded study because the fish changed their spawning times and locations with the sustained warmer ocean temperatures.But the intense public scrutiny prompted fishery managers last week to re-evaluate how they count the fish in an effort to find out whether overfishing is truly a problem. They will hold a spring workshop to determine the best, most accurate way to estimate their numbers. They’re hoping to strengthen partnerships with Canadian and Mexican fishery managers to best estimate how many fish are out there. These fish are difficult to track because they often don’t travel in schools, and they move quickly with changing environmental conditions, researchers say.Historically, they’ve relied on landing data, and the acoustic-trawl method of using echo-sounding and sonar beams to develop underwater maps of fish densities. They also collect egg samples to determine how many fish are likely to be born in a season, and take aerial and ship surveys.“The fish move north, south, onshore, offshore, up and down in the water column. They’re here one day and gone the next. And they’re subject to big population swings, so it’s hard to get a true picture of the biomass at any time,” said Kerry Griffin, a staff officer for the council.“There are weird things going on in the ocean right now, with the ‘warm blob,’ El Niño, ocean acidification and toxic algae up and down the coast,” Griffin said. “We are gradually incorporating ecosystem-based management into our fishery-management plans.“And paying more attention to environmental and oceanic patterns is the first step to getting a better understanding of relationships between species and the environment.”
Read the original post: http://www.dailybreeze.com/
Bay Area Dungeness crab fishermen stoic despite financial hardship
PRINCETON-BY-THE-SEA -- This was supposed to be the winter Braeden Breton finally realized his dream of running his own crab fishing boat. After putting down $7,500 in April toward a commercial permit, he was counting on earning enough money as a deckhand this fall to pay off the rest and begin setting his own traps after the new year.Now the indefinite postponement of the commercial Dungeness crab season has thrown that plan into disarray. Like hundreds of other fishermen in the Bay Area, Breton finds himself scrambling to pay the bills.Breton, of El Granada, and a partner must make monthly payments on the $20,000 they still owe for the permit. He may head north this month in the hope of finding work on a boat in Oregon, where the Dungeness crab season is tentatively slated to open Dec. 1 on the northern half of the coast.
Read the original post: http://www.mercurynews.com/
NOAA Finds Arctic Ocean, Northern Pacific and Antarctic Waters Acidifying Fastest
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Copyright © 2015 Seafoodnews.com
SEAFOODNEWS.COM [Alaska Dispatch] By Yereth Rosen - November 13, 2015 -The Arctic Ocean and the northern Pacific Ocean, along with Antarctic waters, are acidifying faster than the rest of the world’s marine waters, a new National Oceanic and Atmospheric Administration-led study finds.The study, which analyzed measurements from thousands of monitoring stations across the globe, found these bodies acidified faster as carbon dioxide absorbed from the atmosphere combines with natural sources of carbon swept into them by marine currents and held fast by low temperatures.Ocean acidification is the chemical transformation seawater undergoes as it absorbs and stores more carbon. The increasingly acidic water more easily dissolves the calcium carbonate from which many marine species make their shells -- affecting not only commercially important shellfish, such as oysters and clams, but also smaller creatures, such as tiny pteropods, upon which marine food webs depend. That could upend entire ecosystems, harming other important species, including salmon.The new study, published online in the journal Global Biogeochemical Cycles, uses data from 11,431 sampling stations to evaluate aragonite saturation levels in oceans worldwide -- the degree to which aragonite, a form of calcium carbonate that sea creatures use to build shells, is held in the water.When water is saturated, it holds the maximum amount of dissolved aragonite. When it is supersaturated, it holds excess suspended aragonite. All the world’s oceans, measured down to a depth of 50 meters, are supersaturated with aragonite, according to measurements from the Global Ocean Data Analysis Project used in the study.Still, those measurements and other large-scale programs monitoring ocean conditions, show that aragonite saturation levels have slipped globally, a troubling sign, the study’s lead author said.“A decline in the saturation state of carbonate minerals, especially aragonite, is a good indicator of a rise in ocean acidification,” Li-Qing Jiang, an oceanographer at NOAA’s Cooperative Institute for Climate and Satellites at the University of Maryland, said in a statement issued by the agency.The study found that at depths shallower than 100 meters, aragonite saturation levels declined by an average rate of 0.4 percent a year from the decade spanning 1989 to 1998 to the decade after then, spanning the years 1998 to 2010.Low levels of aragonite saturation were pronounced in the North Pacific Ocean at latitudes above 50 degrees north, according to the study. At depths of 200 meters and below, all the sections measured in that part of the Pacific showed undersaturated states for aragonite, the study said. Aragonite undersaturation, a condition normally found in the very deep parts of the world’s oceans, can be a troubling sign when it occurs in shallower waters, scientists say.The Arctic Ocean also showed lowered aragonite saturation states, though not as low as those at corresponding depths of the North Pacific. Less data was available from the Arctic Ocean, researchers noted.In contrast, the Atlantic Ocean was found to have aragonite-supersaturated waters down to much deeper levels, thanks to a lower level of lingering carbon from decaying organisms, according to the study.“The deepest saturation horizon and youngest water are found in the North Atlantic. The shallowest saturation horizon and oldest deep waters are found in the North Pacific. This is because older water has had more time for CO2 accumulation from organic matter remineralization,” the study said.In the polar regions, even the surface waters -- though supersaturated with aragonite -- held far less of the mineral than did waters in more temperate latitudes, the study found.The Arctic, Antarctic and North Pacific are vulnerable to acidification in part because of their cold waters, which hold in carbon dioxide, the study said. Those regions, along with some other marine areas in the world, such as a region off the coast of Africa, are more vulnerable because the pattern of ever-moving ocean currents brings in carbon-dioxide-rich waters from elsewhere in the world and causes that older water to rise up to shallower levels closer to the surface, the study said.That's especially the case in the fish-rich North Pacific, site of major Alaska-based commercial seafood catches, which has the distinction of being at the very end of the Global Thermohaline Circulation, the pattern sometimes called the "ocean conveyor belt," Jiang said in an email.
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