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

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.”

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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)

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Original post: https://www.cbc.ca/news/canada/british-columbia/seal-hunt-b-c-1.4921610

Major Disease Outbreak Strikes California Sea Lions

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.”

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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.

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Original post: https://news-oceanacidification-icc.org/

Alterations to seabed raise fears for future

The ocean floor as we know it is dissolving rapidly as a result of human activity.

Normally the deep sea bottom is a chalky white. It’s composed, to a large extent, of the mineral calcite (CaCO3) formed from the skeletons and shells of many planktonic organisms and corals. The seafloor plays a crucial role in controlling the degree of ocean acidification. The dissolution of calcite neutralizes the acidity of the CO2, and in the process prevents seawater from becoming too acidic. But these days, at least in certain hotspots such as the Northern Atlantic and the southern Oceans, the ocean’s chalky bed is becoming more of a murky brown. As a result of human activities the level of CO2 in the water is so high, and the water is so acidic, that the calcite is simply being dissolved.

The McGill-led research team who published their results this week in a study in PNAS believe that what they are seeing today is only a foretaste of the way that the ocean floor will most likely be affected in future.

Long-lasting repercussions

“Because it takes decades or even centuries for CO2 to drop down to the bottom of the ocean, almost all the CO2 created through human activity is still at the surface. But in the future, it will invade the deep-ocean, spread above the ocean floor and cause even more calcite particles at the seafloor to dissolve,” says lead author Olivier Sulpis who is working on his PhD in McGill’s Dept. of Earth and Planetary Sciences. “The rate at which CO2 is currently being emitted into the atmosphere is exceptionally high in Earth’s history, faster than at any period since at least the extinction of the dinosaurs. And at a much faster rate than the natural mechanisms in the ocean can deal with, so it raises worries about the levels of ocean acidification in future.”

In future work, the researchers plan to look at how this deep ocean bed dissolution is likely to evolve over the coming centuries, under various potential future CO2 emission scenarios. They believe that it is critical for scientists and policy makers to develop accurate estimates of how marine ecosystems will be affected, over the long-term, by acidification caused by humans.

How the work was done

Because it is difficult and expensive to obtain measurements in the deep-sea, the researchers created a set of seafloor-like microenvironments in the laboratory, reproducing abyssal bottom currents, seawater temperature and chemistry as well as sediment compositions. These experiments helped them to understand what controls the dissolution of calcite in marine sediments and allowed them to quantify precisely its dissolution rate as a function of various environmental variables. By comparing pre-industrial and modern seafloor dissolution rates, they were able to extract the anthropogenic fraction of the total dissolution rates.

The speed estimates for ocean-bottom currents came from a high-resolution ocean model developed by University of Michigan physical oceanographer Brian Arbic and a former postdoctoral fellow in his laboratory, David Trossman, who is now a research associate at the University of Texas-Austin.

“When David and I developed these simulations, applications to the dissolution of geological material at the bottom of the oceans were far from our minds. It just goes to show you that scientific research can sometimes take unexpected detours and pay unexpected dividends,” said Arbic, an associate professor in the University of Michigan Department of Earth and Environmental Sciences.

Trossman adds: “Just as climate change isn’t just about polar bears, ocean acidification isn’t just about coral reefs. Our study shows that the effects of human activities have become evident all the way down to the seafloor in many regions, and the resulting increased acidification in these regions may impact our ability to understand Earth’s climate history.”

“This study shows that human activities are dissolving the geological record at the bottom of the ocean,” says Arbic. “This is important because the geological record provides evidence for natural and anthropogenic changes.”

McGill University (via SienceDaily), 29 October 2018. Article.

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Originally posted: https://news-oceanacidification-icc.org/

Coastal Pacific Oxygen Levels Now Plummet Once A Year

40-year crabber David Bailey says hypoxic water can show up like the flip of a switch, “If there are crabs in the pot, they’re dead. Straight up.” — Kristian Foden-Vencil/Oregon Public Broadcasting

 

Scientists say West Coast waters now have a hypoxia season, or dead-zone season, just like the wildfire season.

Hypoxia is a condition in which the ocean water close to the seafloor has such low levels of dissolved oxygen that the organisms living down there die.

Crabber David Bailey, who skippers the Morningstar II, is rattled by the news. He remembers a hypoxia event out of Newport, Oregon, about a decade ago. He says it shows up “like a flip of a switch.”

“It shows up like a flip of a switch,” he says.

“If there are crabs in the pot, they’re dead. Straight up,” Bailey says. And if you re-bait the pots, “when you go out the next time, they’re blanks, they’re absolutely empty. The crabs have left the area.”

A hypoxia event will kill everything that can’t swim away—animals like crabs, sea cucumbers and sea stars.

“We can now say that Oregon has a hypoxia season much like the wildfire season,” says Francis Chan, co-chair of the California Hypoxia Science Task Force.

“Every summer we live on the knife’s edge and during many years we cross the threshold into danger – including the past two years,” Chan says. “When oxygen levels get low enough, many marine organisms who are place-bound, or cannot move away rapidly enough, die of oxygen starvation.”

The hypoxia season hits Oregon, Washington and California waters in the summer and can last from a few of days to a couple of months. Some years it only affects a few square miles of ocean; other years it’s thousands of square miles.

Video taken by the Oregon Department of Fish and Wildlife in 2006 showed dead marine life littering the sea floor.

“These reefs that used to be full of rockfish, they were all gone and a lot of the marine life: the sea stars, the sea cucumbers. They were dead,” says Chan.

The question now is: Why is this happening?

“One of the more fundamental reasons is that the ocean is warmer now and warmer water holds less oxygen,” says Chan. “And then the second part is that a warmer surface ocean, it acts as an insulating blanket.”

So that blanket stops colder low-oxygen water from rising up and mixing with oxygen in the surf.

Scientists say climate change is behind this. The ocean has been absorbing nearly all the rising heat from greenhouse gas emissions, and it’s projected to grow even warmer in coming decades.

Other factors may be contributing too. Oregon State University oceanographer and co-chair of the Oregon Coordinating Council on Ocean Acidification and Hypoxia Jack Barth, thinks higher temperatures are also slowing ocean currents. If we could see under the waves, he says, there’d be a lot more concern.

Oregon State University oceanographer Jack Barth deploys a glider that will spend weeks at sea collecting data on everything from dissolved oxygen levels to temperature. “When we used to think about hypoxia in the ocean, we think about little areas. But now what we’re looking at is…out in the ocean, there’s low oxygen…all along the coast,” he says.

Original post: https://www.npr.org/

Sardines

The little things

Consider the sardine. The small fish sits at the base of the ocean’s food web. Cold currents welling up in the Pacific and Atlantic oceans nurture schools of billions of the creatures, their populations waxing and waning in decades-long global cycles. Entire industries and ecosystems have been built upon the little swimmers.

Not that they get much credit. Sardines are ground up into animal meal, rendered into oil or bait, and stuffed unceremoniously into cans for mass consumption.

But their star is on the rise. Trendy, delicious, and aesthetically irresistible, sardines have begun to garner public adoration once again. In Portugal, the city-wide celebration of Santo António, Lisbon’s patron saint, wouldn’t be complete without a fresh sardine, grilled on a street corner with a splash of lemon. In fact, Portugal has elevated the sardine to the pinnacle of its culinary culture, prizing them equally at home or on a white tablecloth. And finally, the rest of the world is catching on.

But just as they’re ready to swim back into our lives again, the fish may be leaving for cooler waters. Climate change is threatening the species’ ancestral homes. Let’s dive in.

Sardine populations have been rising and falling for thousands of years. An average cycle is approximately 55-60 years. But combination of overfishing in some regions and natural cycles means catches have been falling since the 1990s.

 

Wait, what’s a sardine again?

Sardines are not just one, but at least 21 species of cold-water loving fish. Silds, sprats, herring and pilchards are all classified as sardines, depending on whether one is fishing in the Mediterranean, North Sea, Pacific or elsewhere.

Sardines live fast, but they don’t die young. The oldest can live for 15 years, reaching 90% of their adult length (about 27 cm) within a year. They swim with their mouths open, gorging on tiny phytoplankton and zooplankton in the water column. Within a few years, females can spawn 400,000 to 1 million eggs annually (to match their fecundity, hens would need to lay almost 5,000 eggs.)

That’s good news, because sardines are the all-you-can-eat buffet of the sea. They are the key forage species for predators including fish, squid, marine mammals, and seabirds. Not to mention humans: Fishery experts estimate every major sardine fishery in the world is already fully exploited.

Reuters/Lucy Nicholson

 

The fish that filled a thousand factories

The ancient Greeks and Romans loved sardines, and the first modern sardine factory opened in Setúbal, Portugal in 1880. The country is the fish’s greatest champion on the continent, and celebrates St. Anthony’s Day (June 13th) by grilling fresh sardines on every street corner.

Sardines are typically washed, cleaned, and steamed before being packed in oil or water. Styles vary. Olive oil is preferred in Portugal, Spain, and Morocco. Soybean oil is common in the US, herring oil in Norway, while some prefer water, mustard or tomato sauce. Sardine scales are suctioned off to make cosmetics, lacquers, and artificial pearls.

Today the industry is almost gone from the US. The value of sardines consumed once routinely exceeded that of Maine lobsters in the 1960s. But by 2005, per capita sardine consumption had fallen to 0.1 pounds per year in the US (compared to 16 pounds for all seafood and 220 pounds of meat), and has yet to recover. California’s famed canneries, immortalized in John Steinbeck’s Cannery Row, declined from about 51 in 1948 to just one in 1968—today there are zero. Maine’s last cannery closed in 2010.

Reuters/Nacho Doce

How do I eat them?

Sardines were once considered finer than lobster. Oscar Wilde’s son even opened a sardine tasting club in 1930s London. The finest specimens ended up in European pantries next to foie gras and caviar.

Demand for protein during WWII transformed them into lunchbox food for workers and soldiers in the US, takng the shine off the species’ reputation. Human consumption has been declining ever since.

But all is not lost. A cadre of “sardinistas” around the world are resurrecting the culinary glory days of the sardine. (They happen to be great for you: full of protein, essential fats, and amino acids, vitamins, and minerals.)

The classic preparation is to grill up fresh sardines rubbed with olive oil, garlic, and parsley and splash on a bit of red wine vinegar and lemon juice. There’s also sardelosalata, a version of a classic caviar, and no shortage of inventive things to do with the canned ones.

Staying out of hot water

Sardines may not be sticking around. Stocks have recently plummeted by almost 80% off the coast of Portugal and Spain, grounding their fleets for months (a 15-year ban is being contemplated). The US just shut down the west coast sardine fishery for the fourth straight year after a 97% collapse in sardine populations since 2006.

The reason? Natural cycles in the oceans, for the most part. But now global warming is set to take over. As soon as ocean temperatures rise above sardines’ preferred 10 to 15°C, they leave, says Francisco Chavez, a biological oceanographer at the Monterey Bay Aquarium Research Institute.

For now, natural cycles are the primary factory in sardines’ boom and bust cycles. “It’s not going to be that way in the future,” Chavez says. “In maybe 20 years, climate change will be the dominant player.” When that happens, sardines will head to the poles, leaving their traditional fishing grounds, and the countries that rely on them, high and dry.

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Wait, So How Much of the Ocean Is Actually Fished?

September 10, 2018 — The following is excerpted from an article published today by The Atlantic. More information about this paper is available at Sustainable Fisheries UW. 

How much of the world’s oceans are affected by fishing? In February, a team of scientists led by David Kroodsma from the Global Fishing Watch published a paper that put the figure at 55 percent—an area four times larger than that covered by land-based agriculture. The paper was widely covered, with several outlets leading with the eye-popping stat that “half the world’s oceans [are] now fished industrially.”

Ricardo Amoroso from the University of Washington had also been trying to track global fishing activity and when he saw the headlines, he felt that the 55 percent figure was wildly off. He and his colleagues re-analyzed the data that the Global Fishing Watch had made freely available. And in their own paper, published two weeks ago, they claim that industrial fishing occurs over just 4 percent of the ocean.

How could two groups have produced such wildly different answers using the same set of data? At its core, this is a simple academic disagreement about scale. But it’s also a more subtle debate that hinges on how we think about the act of fishing, and how to measure humanity’s influence on the planet. “I think this discussion really shows how little we know about the world’s oceans and why making data publicly available is so important for stimulating research,” says Kroodsma.

As ships traverse the oceans, many of them continuously transmit their position, speed, and identity to satellites. This automatic identification system was originally developed to prevent collisions, but by training Google’s machine-learning tools on the data, the Global Fishing Watch (GFW)—a nonprofit founded by Oceana, SkyTruth, and Google—can identify different kinds of fishing vessels, and work out where they’re dropping their lines and nets.

They quantified that activity by dividing the oceans into a huge grid of around 160,000 squares. Each of these squares had sides that span half a degree of latitude, and an area of around 3,100 square kilometers. And in 2016, around 55 percent of them included some kind of fishing activity. “You’re dividing the ocean into 160,000 cells, and you’re seeing fishing activity in half of them,” says Kroodsma. “One reason this resonated with people is that however you slice it, that’s impressive.”

Actually, it’s misleading, says Ricardo Amoroso from the University of Washington. He and his colleagues had spent years trying to measure the impact of trawlers and based on their early results, the GFW’s estimates smelled fishy. The problem is that they divided the ocean into such large squares that if a single boat drops a net in an area the size of Rhode Island, that area would count as “fished” in a given year.

Fortunately, the GFW made all their data freely available, so Amoroso’s team could analyze it at finer resolutions. When they divided the ocean into smaller squares that are 0.1 degrees of latitude wide and take up around 123 square kilometers, they found that fishing activity occurs in just 27 percent of them. And when they used even smaller squares that are 0.01 degrees wide and 1.23 square kilometers in area—the size of a city block—just 4 percent of the ocean is “fished.”

Read the full story at The Atlantic

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