Pacific sardines likely to face another shuttered season
Pacific Sardines. NOAA photo.Environmental Impact Displacement in Fisheries & Food
Examples of environmental impact displacement
Environmental displacement in fisheries & food
Solutions to environmental displacement
- Think large-scale to consider all economic/biological/social relationships
- Enact both demand-side and supply-side policies
- International trade agreements and cooperation as a holistic approach to global conservation
Original post: https://sustainablefisheries-uw.org/environmental-impact-displacement/
Methane bubbling up from ocean floor provides a surprising food source for crabs, Oregon State University research shows
Oregon State University researchers have documented tanner crabs feeding at a methane seep site off British Columbia. Tanner crabs are also known as 'snow crabs' and sold as food. It is the first time a commercially harvested species has been known to feed at methane sites.The methane shouldn't cause any health concerns and, in fact, it may provide an alternative energy source for seafloor-dwelling marine species. [Oregon State University]
Climate change will result in less ocean-borne food falling into the deep sea, scientists say. But that likely won’t be a problem for tanner crabs, according to a recent discovery by Oregon State University researchers.The long-legged orange crabs — one of three species that crabbers harvest and sell as snow crabs — vigorously feed at methane seeps, where the gas bubbles up from the ocean floor.“The thinking used to be that the marine food web relied almost solely on phytoplankton dropping down through the water column and fertilizing the depths,” OSU Marine Ecologist Andrew Thurber said in a statement. “Now we know that this viewpoint isn’t complete and there may be many more facets to it.”Thurber co-authored a study that the journal Frontiers in Marine Science just published. The study details how scientists found tanner crabs in eating frenzies around a methane seep in the floor of the Pacific Ocean off British Columbia. It is one the first times that a commercially harvested seafood has been found to rely on methane seeps.Methane seeps appear to be serving up food to seafloor-dwelling species, such as tanner crabs. This would be a hedge against climate change because nearly all models predict less food will drop into the deep sea in coming years.“Tanner crabs likely are not the only species to get energy from methane seeps, which really haven’t been studied all that much,” Thurber said. “We used to think there were, maybe, five of them off the Pacific Northwest coast and now research is showing that there are at least 1,500 seep sites — and probably a lot more. ... They are all over the world, so the idea that they may provide an energy source is quite intriguing.”Researchers first noticed tanner crabs bunching up around methane seeps in 2012 off the British Columbia coast. The crabs sifted through sediment at the bubbling seeps. Mats of bacteria form around the seeps and the crabs munch on those.Underwater video shows methane building up below tanner crabs hanging out at seeps and eventually flipping them. The entertaining video drew researchers to wonder why the crabs were gathered around the seeps in the first place.OSU teamed up with scientists from the University of Victoria in Canada. The National Science Foundation in the U.S. provided support for the study.Off the Oregon Coast, Pacific sole and black cod have been seen near methane seeps. Like the crabs, the fish are harvested.But seafood lovers need not worry about what their food is eating. Researchers say methane seeps create nontoxic environments.Sarah Seabook, the lead author of the study and a Ph.D. candidate at OSU, said scientists examined the guts and tissues of tanner crabs to confirm they were feeding around methane seeps.″... We can apply these new techniques to other species and find out if the use of methane seeps as a food source is more widespread than just tanner crabs,” she said in a statement.
Original post: https://www.registerguard.com/news/20190225/methane-bubbling-up-from-ocean-floor-provides-surprising-food-source-for-crabs-oregon-state-university-research-shows
Understanding Ocean Acidification Impacts to California’s Living Marine Resources – Ocean Science Trust
Helping the State visualize what’s at stake as oceans acidify
Now Available: http://www.oceansciencetrust.org/wp-content/uploads/2019/01/OST-OA-Impacts-Infographic-Final.pdf
OVERVIEW: UNDERSTANDING OA RISKS TO CALIFORNIA’S LIVING MARINE RESOURCES
VISUALIZING IMPACTS OF OA TO LIVING MARINE RESOURCES IN CALIFORNIA
WORKSHOP: DEFINING OCEAN ACIDIFICATION HOTSPOTS IN CALIFORNIA
- Help identify research and data gaps to understanding OA impacts to California’s fishery resources
- Inform species selection for a modeling exercise to identify species vulnerability thresholds
- Provide the groundwork for a quantitative OA or climate vulnerability assessment for California or the West Coast
Originally posted: http://www.oceansciencetrust.org/
Global warming today mirrors conditions leading to Earth’s largest extinction event, UW study says
A melting iceberg floats along a fjord leading away from the edge of the Greenland ice sheet near Nuuk, Greenland, in 2011. By this century’s end, if emissions continue at their current pace, humans will have warmed the ocean about 20 percent as much as during the Permian extinction event, newly published research says. (Brennan Linsley / The Associated Press)
If humans continue to pump greenhouse gases at our current rate, “we have no reason to think it wouldn’t cause a similar type of extinction," said Curtis Deutsch, a UW professor and author of the research.
More than two-thirds of life on earth died off some 252 million years ago, in the largest mass extinction event in Earth’s history.Researchers have long suspected that volcanic eruptions triggered “the Great Dying,” as the end of the Permian geologic period is sometimes called, but exactly how so many creatures died has been something of a mystery.Now scientists at the University of Washington and Stanford believe their models reveal how so many animals were killed, and they see frightening parallels in the path our planet is on today.Models of the effects of volcanic greenhouse-gas releases showed the earth warming dramatically and oxygen disappearing from its oceans, leaving many marine animals unable to breathe, according to a study published Thursday in the peer-reviewed journal Science. By the time temperatures peaked, about 80 percent of the oceans’ oxygen, on average, had been depleted. Most marine animals went extinct.The researchers tested the model’s results against fossil-record patterns from the time of the extinction and found they correlated closely. Although other factors, like ocean acidification, might have contributed some to the Permian extinction, warming and oxygen loss account for the pattern of the dying, according to the research.By this century’s end, if emissions continue at their current pace, humans will have warmed the ocean about 20 percent as much as during the extinction event, the researchers say. By 2300, that figure could be as high as 50 percent.“The ultimate, driving change that led to the mass extinction is the same driving change that humans are doing today, which is injecting greenhouse gases into the atmosphere,” said Justin Penn, a UW doctoral student in oceanography and the study’s lead author.Curtis Deutsch, a UW associate professor of oceanography and an author of the research, said if society continues to pump greenhouse gases at our current rate, “we have no reason to think it wouldn’t cause a similar type of extinction.”
Massive eruptions
The earth 252 million years ago was a much different place. The continents as we know them today were still mostly one landmass, named Pangea, which looks like a chunky letter “C” on a map.The climate, however, resembled Earth’s now, and researchers believe animals would have adapted many traits, like metabolism, that were similar to creatures today. Nearly every part of the Permian Ocean, before the extinction, was filled with sea life.“Less than 1 percent of the Permian Ocean was a dead zone — quite similar to today’s ocean,” Deutsch said.The series of volcanic events in Siberia that many scientists believe set off the mass extinction “makes super volcanoes look like the head of a pin,” said Seth Burgess, a geologist and volcanologist with the United States Geological Survey.“We’re talking about enough lava erupted onto the surface and intruded into the crust to cover the area of the United States that if you looked at the U.S. from above was maybe a kilometer deep in lava,” he said.
Burgess, who has researched the Siberian Traps volcanic events but did not work on the new Science paper, said scientists believe magma rising from the earth released some extinction-causing greenhouse gases.In addition, sills of magma still inside the earth heated massive deposits of coal, peat and carbonate minerals, among others, which vented even more carbon and methane into the atmosphere.“That’s how you drive the Permian mass extinction, by intruding massive volumes of magma into a basin rich in carbon-bearing sediments,” he said.The UW and Stanford research “takes the next step in figuring out why things died at the end of the Permian,” Burgess said. “It couples what we think was happening in the climate with the fossil record, and it does it elegantly.”
Animals couldn’t breathe
It took a supercomputer more than six months to simulate all the changes the volcanic eruptions are suspected of causing during the Permian period. The computer models go into remarkable detail — simulating things like clouds, ocean currents and marine plant life — in describing what temperatures and conditions were like on Earth.The researchers knew that surface temperatures rose about 10 degrees Celsius in the tropics because of previous scientific analysis of the fossilized teeth of eel-like creatures called conodonts.To run their model, researchers pumped volcanic greenhouse gases into their simulation to match temperature conditions at the end of the Permian period.As temperatures climbed toward the 10-degree mark, the model’s oceans became depleted of oxygen, a trend scientists are evaluating in today’s oceans, too.To measure how rising temperatures and less oxygen would affect animal species of the Permian period, the researchers used 61 modern creatures — crustaceans, fish, shellfish, corals and sharks. The researchers believe these animals would have similar temperature and oxygen sensitivities to Permian species because the animals adapted to live in similar climates.Warming’s effects were twofold on the creatures, the researchers found. In warmer waters, animals need more oxygen to perform bodily functions. But warm waters can’t contain as much dissolved oxygen, which means less was available to them.In other words, as animals’ bodies demanded more oxygen, the ocean’s supply dropped.In their model, the researchers were able to quantify the loss of habitat as species faced increasingly challenging ocean conditions. Surface-temperature rise and oxygen loss were more substantial in areas farther from the equator. Extinction rates also increased at higher latitudes.Animals in the tropics were already accustomed to warmer temperatures and lower oxygen levels before the volcanic eruptions shifted the climate, according to the research. As the world warmed, they could move along with their habitat.Marine creatures that favored cold waters and high oxygen levels fared worse: They had nowhere to go.“The high latitudes where it’s cold and oxygen is high — if you’re an organism that needs those kind of conditions to survive, those conditions completely disappear from Earth,” Deutsch said.In modern oceans, warming and oxygen loss have also been more pronounced near the poles, researchers said, drawing another analogue between the shift in climate some 252 million years ago and what’s happening today.“The study tells us what’s at the end of the road if we let climate [change] keep going. The further we go, the more species we’re likely to lose,” Deutsch said. “That’s frightening. The loss of species is irreversible.”
Original post: https://www.seattletimes.com/Evan Bush: 206-464-2253 or ebush@seattletimes.com; on Twitter: @EvanBush.
'Get the balance back': Amid seal and sea lion boom, group calls for hunt on B.C. coast
Quickest way to reverse declining salmon stocks is to introduce a harvest: Pacific Balance Pinnipeds Society
Greg Rasmussen · CBC News · Posted: Dec 01, 2018 1:00 AM PT
For the first time in decades, a small-scale seal hunt is taking place on Canada's West Coast — all in the hopes that it leads to the establishment of a commercial industry to help control booming seal and sea lion populations and protect the region's fish stocks.In early November, a group called the Pacific Balance Pinnipeds Society (PBPS) started using First Nations hunting rights as part of a plan to harvest 30 seals. The society plans to test the meat and blubber to see if it's fit for human consumption and other uses."We can look at opening up harvesting and starting a new industry," said Tom Sewid, the society's director and a commercial fisherman. "Since the [West Coast] seal cull ended in the 1970s, the population has exploded."Sewid, who is a member of the Kwakwaka'wakw First Nation, points out that Indigenous people have hunted the animals for thousands of years. Recent decades with little or no hunting have been an anomaly, he said, pointing to research that shows seal numbers are even higher now than in the 1800s.
Out go the nets, in come the sea lions
What's become an ongoing battle between humans and sea lions played out on a recent nighttime fishing expedition, when Sewid and a crew of commercial fishermen set out in a 24-metre seine boat to fish for herring off the coast of Parksville, B.C.The crew's goal was to catch about 100 tonnes of herring, which rise to the surface to feed after dark. But the faint barking of sea lions was soon heard over the thrum of the boat's diesel engine."All them sea lions out there are all happy — [they're] all yelling, 'Yahoo, it's dinner time!'" Sewid said.Once the crew spotted the herring, they let out hundreds of metres of net, while a smaller boat helped to circle it around the huge mass of fish. The crew then closed the bottom of the net, capturing the herring. Watch sea lions pillage fishermen's nets:
But the catch also provided some uninvited visitors with a captive dinner: Dozens of sea lions jumped over the floats holding up the net and started to gorge."These guys, it's just a buffet for them," said Sewid, as the bodies of the sea lions glistened in the boat's floodlights. "Just like pigs at a trough."Sewid said the sea lions have learned there's an easy meal to be had whenever they see or hear the fishing boats."They're not afraid of us. They've habituated themselves to seeing that humans and fishing equates easy access to food, which is not right," he said. "The animal kingdom is not supposed to be like that."
Restarting a banned hunt
The hunting of seals and sea lions — which are collectively known as pinnipeds — has been banned on the West Coast for more than 40 years. It's one reason their numbers have exploded along the entire Pacific coastline of North America.According to one study, the harbour seal population in the Salish Sea is estimated at 80,000 today, up from 8,600 in 1975. The study also says seals and sea lions now eat six times as many chinook salmon as are caught in the region's commercial and sports fisheries combined.That adds up to millions of tonnes of commercially valuable fish.Sewid's group is proposing to cull current populations of harbour seals and sea lions by half, which would see thousands of the animals killed each year.
Tom Sewid is leading the effort to secure what he calls a sustainable harvest of seals and sea lions along the B.C. coast. (Greg Rasmussen/CBC)
The society's small-scale "test" harvest is taking place between B.C.'s southern Gulf Islands and as far north as Campbell River, on Vancouver Island. It's being carried out under the provisions of the Aboriginal Fisheries Strategy, which gives some First Nations harvesting and management rights for food and ceremonial purposes.Testing the meat to see if it's safe for human consumption is a first step in a plan to eventually gain permission for what the PBPS envisions as a sustainable, humane commercial hunt, which would largely be carried out by coastal First Nations."All the meat that's in there, you're looking at the high-end restaurants [that would sell it]," Sewid said. "The hides can also be used."Seal blubber is particularly valuable, he said, because it can be rendered down into an oil that's in demand because of its high Omega-3 fatty acid content. Watch fishing crew struggle to free sea lions entangled in their nets:
One of the biggest hurdles facing the group is convincing the federal Department of Fisheries and Oceans to open a commercial hunt on the West Coast.The seal hunt that takes place in the Atlantic and Arctic is controversial, and has long been subject to protests and fierce opposition from animal rights groups. The group expects a West Coast harvest to also face fierce confrontations.Canadian Inuit have been waging a counter-campaign, highlighting the importance of the animal and the longstanding tradition of their hunt.Most Canadian seal products are also banned in Europe and a handful of other countries, but the society says demand is strong in Asia.
Supporters and opponents
The PBPS does have a growing list of supporters, including 110 First Nations groups, a number of commercial fishing organizations, and some sectors of B.C.'s economically important sport fishing sector.However, one key player, the Sport Fishing Institute of B.C., opposes a large commercial hunt, fearing it would generate public outrage and might not achieve the goal of enhancing fish stocks.The institute's director, Martin Paish, says the group sees some value in targeting some seals and other fish predators at specific times of year in a number of key river systems; he believes a limited hunt would help protect salmon stocks and boost the billion-dollar-a-year B.C. sport fishing industry."Our goal is to use predator control in a careful manner to improve chinook [salmon] production where it is needed," said Paish.
Carl Walters is a fish biologist and UBC professor who supports cutting B.C.'s population of seals and sea lions by half. (Nic Amaya/CBC)
Fisheries scientist Carl Walters, a professor emeritus with UBC, believes culling the regions sea lions and seals could dramatically boost salmon stocks. He points to numerous studies showing how pinniped populations have been increasing, while salmon numbers have been plummeting."They're killing a really high percentage of the small salmon shortly after they go into the ocean, about half of the coho smolts and a third of the chinooks," he said.Advocates of a hunt are also pitching it as a way to help B.C.'s endangered southern resident killer whales, which feed mainly on salmon."The thing that would benefit southern resident killer whales is to see improved survival of small chinook salmon — and I think the only way we can achieve that is by reducing seal numbers," Walters said.
Peter Ross, from the Coastal Ocean Research Institute, says there would be little benefit to salmon from a seal and sea lion cull. (Nic Amaya/CBC)
Others disagree, including Peter Ross, the vice-president of research and executive director of the Coastal Ocean Research Institute."Killing of seals and sea lions is not going to have any positive impact for any salmon populations in coastal British Columbia," he said.While a few localized populations of salmon might benefit from a cull, Ross said climate change, habitat destruction and overfishing are all bigger factors in the overall decline of stocks.Other subspecies of orcas, however, feed mainly on seals, so a hunt would reduce their access to prey.Back on the boat, Sewid concedes a hunt would be controversial — but he firmly believes it's necessary."All the indicators are there," he said. "It's time to get the balance back."
The fishing crew from the Western Investor are shown harvesting herring in November. But they say they are being hampered by dozens of sea lions in their nets almost every night. (Nic Amaya/CBC)
Original post: https://www.cbc.ca/news/canada/british-columbia/seal-hunt-b-c-1.4921610
Major Disease Outbreak Strikes California Sea Lions
Leptospirosis afflicts sea lions on a semi-regular cycle, but warming waters and migrating fish could make the marine mammals more susceptible
Princepajaro, a male California sea lion, swims in a pool during treatment for leptospirosis at The Marine Mammal Center in Sausalito, CA. When a leptospirosis outbreak occurs, the Center’s scientists study the disease to learn more about what causes an outbreak and how we can improve treatment for infected animals. (Bill Hunnewell / The Marine Mammal Center)
Shawn Johnson knew it was coming.“Last fall, we saw a few cases,” he said. “And that was a warning signal, so we were prepared—well, we weren’t prepared for this level of an outbreak.”Over the past month, Johnson, director of veterinary science at the Marine Mammal Center, just north of San Francisco, and his team have been getting an average of five sick California sea lions a day. The animals have leptospirosis, a bacterial infection that affects their kidneys, causing fatigue, abdominal pain and, more often than not, death.As of October 16, Johnson’s team had seen 220 sea lions with the disease, which made it the center’s second largest outbreak. Since then, the center reported 29 more sea lions have been rescued and 10 of those died due to leptospirosis. More than a dozen animals are still awaiting diagnosis. The number of cases has started to slow, but if historical trends hold up, Johnson expects this outbreak to eventually surpass 2004’s record of 304 cases of sea lion leptospirosis.
The Marine Mammal Center in Sausalito, CA, is responding to an outbreak of a potentially fatal bacterial infection called leptospirosis in California sea lions. The pictured sea lion, Glazer, is seen curled up with his flippers folded tightly over his abdomen prior to his rescue by trained Center responders in Monterey. The posture exhibited is known as “lepto pose,” and is often an indication the sea lion is suffering the effects of the disease. (The Marine Mammal Center)
All told, about 70 percent of the sea lions the team tried to save have died.Leptospirosis outbreaks among sea lions occur at fairly regular intervals, but changing ocean conditions—warmer waters and relocating fish—are affecting how the disease strikes populations along the Pacific Coast. The threats aren’t new, but they’re threatening in slightly new ways. Changes in marine conditions appear to be affecting the population’s resiliency to this disease and others. While researchers scramble to save sick sea lions today, they are also studying what this year’s outbreak can tell us about how sea lions will fare down the line.The good news is that sea lions are fairly mobile and resilient animals. And until recently, their populations were booming. The National Oceanic and Atmospheric Administration announced in January that California sea lions had reached carrying capacity—the number of individuals their environment can sustainably support—in 2008.Since then, though, their numbers have fluctuated. A “blob” of unusually warm and long-lasting water moved in along the West Coast from 2013 to 2015, causing widespread algal blooms that spread a neurotoxin called domoic acid throughout the marine food chain. Sea lions with elevated levels of the toxin suffered brain damage, resulting in strokes and an impaired ability to navigate, ultimately killing most of the afflicted individuals.The warm water also sent fish and smaller marine life out to search for cooler environments, meaning the sea lions had to travel farther to find food. The combination of more distant hunting and impaired navigation led to record numbers of stranded pups—many taken in by the Marine Mammal Center—as well as a dip in the sea lion population during those years.
California sea lion Yakshack is one of 220 patients at The Marine Mammal Center in Sausalito, CA, that has been rescued so far this year impacted by a bacterial disease known as leptospirosis. The Center has been at the forefront of research on leptospirosis in marine mammals and has published a number of scientific papers on the disease dating back to 1985. (Bill Hunnewell / The Marine Mammal Center)
But the warm water conditions also led, ironically, to a decline in cases of leptospirosis during that time. Over the past decade, scientists have determined that the disease, which spreads via a parasite, is endemic to the population. Some animals carry the disease and don’t get sick, but they do excrete the parasites in their urine, which is how it spreads to other individuals. When sea lions haul out on a pier or beach, they freely roll around in each other’s pee.When the blob of warm water appeared, sea lions had to swim farther to find food and had less time to haul out and be social, Johnson says, meaning less time sitting around in each other’s pee and parasites—and fewer cases of leptospirosis. But the lack of the disease a few years ago led to consequences today. Sea lions that get leptospirosis and survive develop antibodies that fend off the parasite in the future, says Katie Prager, a veterinarian researcher at UCLA’s Lloyd-Smith Laboratory who collaborates with the Marine Mammal Center. These antibodies, however, cannot be inherited by offspring.“It’s not something that can be passed on,” Prager says. “Antibodies are something that the pup has to develop on its own.”The warm waters meant fewer sick sea lions, but it left the population very vulnerable. Now the disease is back with a vengeance.“A lot of the animals are now naive to that bacteria and their immune systems haven’t been exposed to that,” says Alissa Deming, a veterinarian researcher at Dauphin Island Sea Lab in Alabama who previously studied sea lion diseases at the Marine Mammal Research Center. “There is a group of animals that haven’t seen this before.”The risk, according to the researchers, is that continued domoic acid outbreaks could result in a vicious cycle—fewer cases of leptospirosis produce unexposed populations, and then major outbreaks flare up like we are seeing this year.“This is a great example of how environmental change has so much impact on a wild species—all the way from where they eat, where they migrate and how their diseases change over time, just based on a few degrees’ increase,” Johnson says.
California sea lion Herbie lays on his pen floor during treatment for leptospirosis at The Marine Mammal Center in Sausalito, CA. Veterinarians can usually identify leptospirosis in a patient even before laboratory tests confirm a diagnosis because of the infection's distinctive symptoms in California sea lions, which include drinking water and folding the flippers over the abdomen. (Bill Hunnewell / The Marine Mammal Center)
The first documented case of a marine mammal suffering from the domoic acid toxin was in 1998, and the events are now increasing in frequency—so much so that the spread of domoic acid has become a yearly sign of the changing seasons around San Francisco Bay. “The days are getting shorter, pumpkin spice lattes are here and once again, it’s time for that other Bay Area rite of fall: worrying about the levels of toxins in local Dungeness crabs,” begins a recent San Francisco Chronicle article on the influence of the toxin on the start of crabbing season.Sea lions don’t wait for permission from the Department of Public Health before they start eating crabs, though.To exacerbate the issue even more, an El Nino event is predicted over the coming months, meaning warmer ocean waters off the West Coast and possibly more algal blooms and toxins. Already, Southern California waters—where researchers have found some of the highest concentrations of diatoms that produce domoic acid—have had record high temperatures this year.NOAA has even deemed the recent warm-water years a “climate change stress test” for West Coast oceans. The agency said the conditions “may offer previews of anthropogenic climate change impacts projected for the latter part of the 21st century.”If this has been a test, sea lions might not have passed, says Robert DeLong, a scientist with NOAA’s Alaska Fisheries Science Center. DeLong has been studying California sea lions for decades at their breeding grounds, Channel Islands off Santa Barbara. He says the species should be pretty resilient in the face of climate change, but the rate of warming waters is proving a major challenge.
Volunteers from The Marine Mammal Center in Sausalito, CA, release California sea lions Bogo (left), Brielle (center), and Biggie (right) back to the wild near Bodega Bay. All three sea lions were treated for leptospirosis at the Center’s Sausalito hospital. Many different animal species, including humans and dogs, can become infected with Leptospira through contact with contaminated urine, water or soil. The Center has a number of safety protocols in place to prevent transmission to veterinarians and volunteers working with sea lion patients. (Bill Hunnewell / The Marine Mammal Center)
The center of the West Coast sea lion population is around Baja California, so the species has adapted to warmer water than is currently being seen farther north up the coast. “They have that capability to live in warmer water,” DeLong says. And unlike, say, coral reefs, sea lions are very mobile, able to swim long distances to find suitable habitats.But while males can chase food far up north, during the breeding season females are tied to a small radius around the rookery. If there is less food available there because fish have moved to cooler waters, it could present a major problem for sea lion mothers and their pups.“So if this is what climate change looks like, and this period is an adequate proxy, if that’s really the case, then sea lions may not do as well as we would think,” DeLong says.There are still signs of hope. Sea lions are increasingly moving north to new breeding grounds off the San Francisco Bay, for instance. The limiting factor is time.“If the environmental changes are slow enough to adapt, they’ll be able to move and will probably move farther up the coast,” Johnson said. “If changes are slow enough, I could see them being able to adapt.”
Original post: https://www.smithsonianmag.com/
Quantifying sensitivity and adaptive capacity of shellfish in the Northern California Current Ecosystem to increasing prevalence of ocean acidification and hypoxia
The severity of carbonate chemistry changes from ocean acidification is predicted to increase greatly in the coming decades, with serious consequences for marine species- especially those reliant on calcium carbonate for structure and function (Fabry et al. 2008). The Northern California Current Ecosystem off the coast of US West Coast experiences seasonal variations in upwelling and downwelling patterns creating natural episodes of hypoxia and calcite/aragonite undersaturation, exacerbating global trends of increasing ocean acidification and hypoxia (OAH) (Chan et al. 2008) (Gruber et al. 2012). The goal of these experiments was to identify thresholds of tolerance and attempt to quantify a point at which variance in responses to stress collapses. This study focuses on two species: Cancer magister (Dungeness crab) and Haliotis rufescens (red abalone). These species were selected for this study based on their economic and ecological value, as well as their taxonomic differences. Respirometry was used as a proxy for metabolic activity at four different scenarios mimicking preindustrial, upwelling, contemporary upwelling, and distant future conditions by manipulating dissolved oxygen and inorganic carbon (DIC) concentrations. Both species showed a decrease in mean respiration rate as OAH stressors increase, including an effect in contemporary upwelling conditions. These results suggest that current exposure to ocean acidification (OA) and hypoxia do not confer resilience to these stressors for either taxa. In teasing apart the effects of OAH as multiple stressors, it was found that Dungeness crab response was more strongly driven by concentration of dissolved oxygen, while red abalone data suggested a strong interactive effect between OA and hypoxia. Not only did these two different taxa exhibit different responses to a multiple stressors, but the fact that the Dungeness crab were secondarily impacted by acidification could suggest that current management concerns may need to be focus more strongly on deoxygenation.Gossner H. M., 2018. Quantifying sensitivity and adaptive capacity of shellfish in the northern California current ecosystem to increasing prevalence of ocean acidification and hypoxia. MSc thesis, Oregon State University, 104 p. Thesis.
Original post: https://news-oceanacidification-icc.org/