Archive for the View from the Ocean Category

Feb 17 2017

Scientists: Major Oxygen Loss to Oceans Linked to Warming Climate

— Posted with permission of SEAFOODNEWS.COM. Please do not republish without their permission. —

Copyright © 2017 Seafoodnews.com

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SEAFOODNEWS.COM [Washington Post] by By Chris Mooney – February 16, 2017

A large research synthesis, published in one of the world’s most influential scientific journals, has detected a decline in the amount of dissolved oxygen in oceans around the world — a long-predicted result of climate change that could have severe consequences for marine organisms if it continues.

The paper, published Wednesday in the journal Nature by oceanographer Sunke Schmidtko and two colleagues from the GEOMAR Helmholtz Centre for Ocean Research in Kiel, Germany, found a decline of more than 2 percent in ocean oxygen content worldwide between 1960 and 2010. The loss, however, showed up in some ocean basins more than others. The largest overall volume of oxygen was lost in the largest ocean — the Pacific — but as a percentage, the decline was sharpest in the Arctic Ocean, a region facing Earth’s most stark climate change.

The loss of ocean oxygen “has been assumed from models, and there have been lots of regional analysis that have shown local decline, but it has never been shown on the global scale, and never for the deep ocean,” said Schmidtko, who conducted the research with Lothar Stramma and Martin Visbeck, also of GEOMAR.

Ocean oxygen is vital to marine organisms, but also very delicate — unlike in the atmosphere, where gases mix together thoroughly, in the ocean that is far harder to accomplish, Schmidtko explained. Moreover, he added, just 1 percent of all the Earth’s available oxygen mixes into the ocean; the vast majority remains in the air.

Climate change models predict the oceans will lose oxygen because of several factors. Most obvious is simply that warmer water holds less dissolved gases, including oxygen. “It’s the same reason we keep our sparkling drinks pretty cold,” Schmidtko said.

But another factor is the growing stratification of ocean waters. Oxygen enters the ocean at its surface, from the atmosphere and from the photosynthetic activity of marine microorganisms. But as that upper layer warms up, the oxygen-rich waters are less likely to mix down into cooler layers of the ocean because the warm waters are less dense and do not sink as readily.

“When the upper ocean warms, less water gets down deep, and so therefore, the oxygen supply to the deep ocean is shut down or significantly reduced,” Schmidtko said.

The new study represents a synthesis of literally “millions” of separate ocean measurements over time, according to GEOMAR. The authors then used interpolation techniques for areas of the ocean where they lacked measurements.

The resulting study attributes less than 15 percent of the total oxygen loss to sheer warmer temperatures, which create less solubility. The rest was attributed to other factors, such as a lack of mixing.

Matthew Long, an oceanographer from the National Center for Atmospheric Research who has published on ocean oxygen loss, said he considers the new results “robust” and a “major advance in synthesizing observations to examine oxygen trends on a global scale.”

Long was not involved in the current work, but his research had previously demonstrated that ocean oxygen loss was expected to occur and that it should soon be possible to demonstrate that in the real world through measurements, despite the complexities involved in studying the global ocean and deducing trends about it.

That’s just what the new study has done.

“Natural variations have obscured our ability to definitively detect this signal in observations,” Long said in an email. “In this study, however, Schmidtko et al. synthesize all available observations to show a global-scale decline in oxygen that conforms to the patterns we expect from human-driven climate warming. They do not make a definitive attribution statement, but the data are consistent with and strongly suggestive of human-driven warming as a root cause of the oxygen decline.

“It is alarming to see this signal begin to emerge clearly in the observational data,” he added.

“Schmidtko and colleagues’ findings should ring yet more alarm bells about the consequences of global warming,” added Denis Gilbert, a researcher with the Maurice Lamontagne Institute at Fisheries and Oceans Canada in Quebec, in an accompanying commentary on the study also published in Nature.

Because oxygen in the global ocean is not evenly distributed, the 2 percent overall decline means there is a much larger decline in some areas of the ocean than others.

Moreover, the ocean already contains so-called oxygen minimum zones, generally found in the middle depths. The great fear is that their expansion upward, into habitats where fish and other organism thrive, will reduce the available habitat for marine organisms.

In shallower waters, meanwhile, the development of ocean “hypoxic” areas, or so-called “dead zones,” may also be influenced in part by declining oxygen content overall.

On top of all of that, declining ocean oxygen can also worsen global warming in a feedback loop. In or near low oxygen areas of the oceans, microorganisms tend to produce nitrous oxide, a greenhouse gas, Gilbert writes. Thus the new study “implies that production rates and efflux to the atmosphere of nitrous oxide … will probably have increased.”

The new study underscores once again that some of the most profound consequences of climate change are occurring in the oceans, rather than on land. In recent years, incursions of warm ocean water have caused large die-offs of coral reefs, and in some cases, kelp forests as well. Meanwhile, warmer oceans have also begun to destabilize glaciers in Greenland and Antarctica, and as they melt, these glaciers freshen the ocean waters and potentially change the nature of their circulation.

When it comes to ocean deoxygenation, as climate change continues, this trend should also increase — studies suggest a loss of up to 7 percent of the ocean’s oxygen by 2100. At the end of the current paper, the researchers are blunt about the consequences of a continuing loss of oceanic oxygen.

“Far-reaching implications for marine ecosystems and fisheries can be expected,” they write.


Copyright © 2016 Seafoodnews.com

 

Jan 12 2017

Ocean acidification to hit West Coast Dungeness crab fishery, new assessment shows

The acidification of the ocean expected as seawater absorbs increasing amounts of carbon dioxide from the atmosphere will reverberate through the West Coast’s marine food web, but not necessarily in the ways you might expect, new research shows.

Dungeness crabs, for example, will likely suffer as their food sources decline. Dungeness crab fisheries valued at about $220 million annually may face a strong downturn over the next 50 years, according to the research published Jan. 12 in the journal Global Change Biology. But pteropods and copepods, tiny marine organisms with shells that are vulnerable to acidification, will likely experience only a slight overall decline because they are prolific enough to offset much of the impact, the study found.

Dungeness crab.jkirkhart35/Flickr

Marine mammals and seabirds are less likely to be affected by ocean acidification, the study found.

“What stands out is that some groups you’d expect to do poorly don’t necessarily do so badly – that’s probably the most important takeaway here,” saidKristin Marshall, lead author of the study who pursued the research as a postdoctoral researcher at the University of Washington and NOAA Fisheries’ Northwest Fisheries Science Center. “This is a testament in part to the system’s resilience to these projected impacts. That’s sort of the silver lining of what we found.”

While previous studies have examined the vulnerability of particular species to acidification in laboratories, this is among the first to model the effects across an entire ecosystem and estimate the impacts on commercial fisheries.

“The real challenge is to go from experiments on what happens to individual animals in the lab over a matter of weeks, to try to capture the effects on the whole population and understand how vulnerable it really is,” said Isaac Kaplan, a research scientist at NOAA Fisheries’ Northwest Fisheries Science Center in Seattle.

The research used sophisticated models of the California Current ecosystem off the Pacific Coast to assess the impacts of a projected 0.2 unit decline in the pH of seawater in the next 50 years, which equates to a 55 percent increase in acidity. The California Current is considered especially vulnerable to acidification because the upwelling of deep, nutrient-rich water low in pH already influences the West Coast through certain parts of the year.

The ocean absorbs about one-third of carbon dioxide released into the atmosphere from the burning of fossil fuels, which has led to a 0.1 unit drop in pH since the mid-1700s.

The research built on an earlier effort by NOAA scientists Shallin Busch and Paul McElhanythat quantified the sensitivity of various species to acidification, as originally reported in 393 separate papers. In a novel approach, Busch and McElhany weighed the evidence for each species based on its reported sensitivity in the laboratory, relevance to the California Current and agreement between studies.

This synthesis by Busch and McElhany identified 10 groups of species with highest vulnerability to acidification. Marshall and colleagues incorporated this into the ecosystem model to examine how acidification will play out in nature. The study particularly examined the effects on commercially important species including Dungeness crab; groundfish such as rockfish, sole and hake; and coastal pelagic fish such as sardines and anchovy over the period from 2013 to 2063.

graphic showing changes based on new study
The study modeled the potential risks of ocean acidification (under a future decrease in pH) on the West Coast marine food web and fisheries over 50 years, from 2013 to 2063. NOAA Fisheries

“This was basically a vulnerability assessment to sharpen our view of where the effects are likely to be the greatest and what we should be most concerned about in terms of how the system will respond,” said Tim Essington, a UW professor of aquatic and fishery sciences and a co-author of the research.

The study provides a foundation for further research into the most affected species, he said.

Although earlier studies have shown that Dungeness crab larvae is vulnerable to acidification, the assessment found that the species declined largely in response to declines in its prey – including bivalves such as clams and other bottom-dwelling invertebrate species.

Since Dungeness crab is one of the most valuable fisheries on the West Coast, its decline would have some of the most severe economic effects, according to the research. Groundfish such as petrale sole, Dover sole and deep-dwelling rockfish are also expected to decline due to acidification, according to the assessment. However, fisheries for those species are much less valuable so the economic impact would not be as large.

Coastal pelagic fish were only slightly affected.

“Dungeness crab is a bigger economic story than groundfish,” Kaplan said. “There are winners and losers, but the magnitude of the impact depends on how important the species is economically.”

The research was funded by the NOAA Ocean Acidification Program and the National Centers for Coastal Ocean Science. Marshall was supported by a National Research Council fellowship.

###

For more information, contact Marshall at kmarsh2@uw.edu and Kaplan atisaac.kaplan@noaa.gov 206-302-2446.

This piece was adapted from a Northwest Fisheries Science Center news release.

 

Jan 12 2017

Squid boats dot Malibu coast: Roughly 40,157 tons of squid caught this season

Squid boats are seen from Malibu’s Zuma Beach on a recent January evening. Suzanne Guldimann/22nd Century Media


Almost every night this winter, bright lights have appeared off the coast of Malibu.

It’s an eerie sight on a foggy evening, suggesting something unearthly or supernatural, but the only thing these ghostly lights portend is the presence of Doryteuthis opalescens, the common market squid.

It’s a good omen for California’s seafood industry. Market squid is one of California’s largest commercial fisheries, and tons of frozen California calamari are shipped all over the world each year. However, the species had almost entirely disappeared from Southern California waters last year. The absence of squid is being blamed on El Niño.

California Department of Fish and Wildlife environmental scientist Laura Ryley studies squid.

“Market squid was very limited in Southern California last year,” she told The Malibu Surfside News. 

Ryley explained that the squid are thought to react to the warmer water generated by El Niño, migrating further north in search of the right water temperature and conditions for spawning.

“The commercial fishery was landing squid in Eureka and off the coast of Oregon last year,” Ryley said.

She added that the management plan for the species implemented in 2005 provides an opportunity for scientists to gather data on the size, sex and abundance of the species. That data show that market squid generally have the ability to recover swiftly after an El Niño event.

“The patterns in the past show the squid are still able to reproduce and that they bounce back quickly,” she said.

While concerns are being raised over the potential impact of prolonged ocean warming on the species, the return of more normal temperature conditions in the Pacific this winter appears to have signaled the return of the squid. 

An abundance of cephalopods isn’t just an auspicious sign for the fishing industry. It may mean fewer problems for local sea lion and elephant seal populations, which have experienced mass stranding events blamed in part on the same warm water that impacted the squid and other key prey species like Pacific sardines and mackerel.

“I’ve heard that market squid isn’t the sea lion’s favorite, but they will eat it,” Ryley said. “It’s an important food for other species as well. Salmonids eat them. So do sea birds.”

The California Department of Fish and Wildlife’s management plan for the market squid fishery limits the seasonal catch to 118,000 tons per season. The season opens April 1 each year, and runs until the limit is met or until March 31, whichever comes first.

This season got off to a slow start but is accelerating. As of Dec. 30, 2016, the total landings of market squid were 40,157.6 tons.

That’s in sharp contrast to 2013, the last big year for squid, when the quota for the season was reached by early November, according to NOAA Fisheries data, but a major increase from 2014 and 2015, when the numbers plummeted in Southern California.

In the Malibu area, autumn and winter are the peak time for commercial squid fishing. The shallow waters along the Malibu coast are usually a prime location for squid, which migrate to the shallow, sandy, near-shore area in the fall to spawn.

Special light boats equipped with high wattage bulbs attract the squid, which are caught using either seine or scoop nets. The lights are supposed to be shielded to reduce the impact on migratory birds and coastal residents, but compliance isn’t 100 percent yet.

The Monterey Bay Aquarium’s Seafood Watch program rates market squid as a “good alternative” for sustainability, but most of the California catch is frozen and shipped to Asia. 

“The American market prefers squid with a thicker mantle,” Ryley said. 

Market squid rarely grow to be more than 10 inches in length. They are short-lived; 9-10 months is usually the maximum life span, and they spawn just once, at the end of their lives.

Squid can only be caught on weekdays from the U.S.-Mexico border to the California-Oregon border. From noon Friday to noon Sunday the squid are given a “break.”

“The thinking behind that is to give them a time for uninterrupted spawning,” Ryley explained.

Squid fishing is permitted all along the Malibu coast, even within the boundaries of the Point Dume State Marine Conservation Area, located off the coast of Zuma and Lechuza beaches. Only Point Dume State Marine Reserve (Paradise Cove to Westward Beach) is off limits.

With more than half the season’s limit still swimming around in the Pacific, it’s a safe bet that the unearthly green and pink glow of the squid boats will continue to light up Malibu’s coast, drawing the curiosity of more than just squid.


Read the original post: http://www.malibusurfsidenews.com/

Jan 5 2017

Scientists: Global Ocean Circulation Could Be More Vulnerable to Shutdown Than We Thought

— Posted with permission of SEAFOODNEWS.COM. Please do not republish without their permission. —

Copyright © 2017 Seafoodnews.com

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SEAFOODNEWS.COM [The Washington Post] by Chelsea Harvey – January 5, 2017

Intense future climate change could have a far different impact on the world than current models predict, suggests a thought-provoking new study just out in the journal Science Advances. If atmospheric carbon dioxide concentrations were to double in the future, it finds, a major ocean current — one that helps regulate climate and weather patterns all over the world — could collapse. And that could paint a very different picture of the future than what we’ve assumed so far.

The Atlantic meridional overturning circulation, or AMOC, is often described as a large oceanic conveyor belt. It’s a system of water currents that transports warm water northward from the Atlantic toward the Arctic, contributing to the mild climate conditions found in places like Western Europe. In the Northern Atlantic, the northward flowing surface water eventually cools and sinks down toward the bottom of the ocean, and another current brings that cooler water back down south again. The whole process is part of a much larger system of overturning currents that circulates all over the world, from pole to pole.

But some scientists have begun to worry that the AMOC isn’t accurately represented in current climate models. They say that many models portray the current as being more stable than real-life observations suggest it actually is. Recent studies have suggested that the AMOC is weakening, although there’s some scientific debate about how much of this has been caused by human activities and how much by natural variations.

Nevertheless, the authors of the new study point out, many climate models assume a fairly stable AMOC — and that could be affecting the predictions they make for how the ocean will change under future climate change. And because overturning circulation patterns have such a significant effect on climate and weather all over the world, this could have big implications for all kinds of other climate-related projections as well.

“This is a very common and well-known issue in climate models,” said the new study’s lead author, Wei Liu, a postdoctoral associate at Yale University, who conducted the work while at the University of California at San Diego. “I wanted to see, if I use a corrected model, how this will affect the future climate change.”

Liu and colleagues from the UC-San Diego and the University of Wisconsin at Madison took a commonly used climate model and corrected for what they considered to be the AMOC stability bias. Then they ran an experiment to see how the correction would affect the model’s projections under future climate change. They instantaneously doubled the atmospheric carbon dioxide concentration from present-day levels in both the corrected and uncorrected models, and then they let both models run for hundreds of simulated years.

The differences were striking. In the uncorrected climate model, the AMOC weakens for a while, but eventually recovers. In the corrected model, however, the AMOC continues to weaken and after 300 years, it collapses altogether.

In a commentary also published today in RealClimate, Stefan Rahmstorf, an oceans physics expert at the Potsdam Institute for Climate Impact Research, explained how such a collapse could occur when the AMOC gets too weak.

“Freshwater continually flows into the northern Atlantic through precipitation, rivers and ice-melting,” he wrote. “But supply of salty waters from the south, through the Gulf Stream System, balances this. If however the current slows, there is less salt supply, and the surface ocean gets less salty.”

Because freshwater is less dense than salty water, this process can lead to a kind of stratification, in which the lighter freshwater gets stuck on the surface of the ocean and can’t sink to the bottom when it reaches the cooler north. When this happens, the overturning process that drives the current back down south again can’t occur.

“There is a critical point when this becomes an unstoppable vicious circle,” Rahmstorf wrote. “This is one of the classic tipping points in the climate system.”

The resulting climate consequences, compared to the uncorrected model, are also dramatic. Without the usual transport of warm water into the north, the corrected model predicts a marked cooling over the northern Atlantic, including in the United Kingdom, Iceland and northwestern Europe, as well as in the Arctic, where sea ice begins to expand.

Because the AMOC is part of a larger global conveyor system, which ferries warm and cold currents between the equator and both poles, the model predicts disruptions in other parts of the world as well. Without cold water moving back down south again, the corrected model indicates a stronger warming pattern south of the equator than what’s predicted by the uncorrected model, causing a polarization in precipitation patterns over the Americas — more rain for places like northeastern Brazil and less rain for Central America. The model also predicts a greater reduction in sea ice for the Antarctic.

All this doesn’t necessarily mean that everything we thought we knew about the future climate is wrong. For one thing, most modern climate projections focus on the next few decades or so, noted Thomas Haine, an expert on ocean circulation at Johns Hopkins University. And within 50 years or so, both the uncorrected and corrected models in the new study produce similar results. It is only after that, under extreme warming, that the current shifts.

Liu also cautioned that certain aspects of the experiment can’t exactly be considered realistic — for instance, instantaneously doubling the atmospheric carbon dioxide concentration. Current climate efforts are aimed at keeping us from ever getting to such a point — but even if we did, the process would happen gradually, not overnight. So the model’s outcome might have been different if the researchers had adopted a more realistic scenario.

Haine also suggested that the correction in the new study may have actually been a bit too strong, compared to actual observations — in other words, the modeled AMOC is “probably more unstable than the real system,” he said.

Rahmstorf also pointed out this issue in his commentary — but he added that the climate model used also did not account for an influx of meltwater from Greenland under future climate change, an event that recent research suggests could substantially speed the AMOC’s weakening.

“With unmitigated emissions . . . the Gulf Stream System weakens on average by 37 percent by the year 2300 without Greenland melt,” he notes. “With Greenland meltwater this doubles to 74 percent. And a few months ago, a study with a high-resolution ocean model appeared, suggesting that the meltwater from Greenland is likely to weaken the AMOC considerably within a few decades.”

The fact that current models don’t take this melting into account is further support for the idea that scientists have been underestimating the risk of a future AMOC collapse, he suggested.

According to Liu, the new study serves to make a point about the dramatic effects that can occur when corrections are made in climate models, as well as the AMOC’s major role in the global climate. By tweaking a climate model to make it more consistent with real-life observations, very different outcomes may be observed, Liu noted.

“I would say that it is reasonably well-accepted that a current generation of climate models [is] missing the essential physics in representing the AMOC,” said Haine. And he added that the new study “points to the need to fix these biases in the climate models.”


Peggy Parker, Science and Sustainability Editor
SeafoodNews.com 1-781-861-1441
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Reporter’s Email: peggyparker@seafood.com

Copyright © 2017 Seafoodnews.com

Download/Watch: NASA ThermohalineConveyor.mp4 | 81MB

Dec 1 2016

Millions of Sardines Cloud San Diego Coast

A large sardine shoal showed up off the coast of California.


View original article/video: http://abcnews.go.com/

Dec 1 2016

NOAA research links human-caused CO2 emissions to dissolving sea snail shells off U.S. West Coast

November 22, 2016 – For the first time, NOAA and partner scientists have connected the concentration of human-caused carbon dioxide in waters off the U.S. Pacific coast to the dissolving of shells of microscopic marine sea snails called pteropods.

Commercially valuable fish such as salmon, sablefish and rock sole make the pteropod a major part of their diet.

“This is the first time we’ve been able to tease out the percentage of human-caused carbon dioxide from natural carbon dioxide along a large portion of the West Coast and link it directly to pteropod shell dissolution,” said Richard Feely, a NOAA senior scientist who led the research appearing in Estuarine, Coastal and Shelf Science. “Our research shows that humans are increasing the acidification of U.S. West Coast coastal waters, making it more difficult for marine species to build strong shells.”

The global ocean has soaked up one-third of human-caused CO2 emissions since the start of the Industrial Era. While this reduces the amount of this greenhouse gas in the atmosphere, it comes at a cost to the ocean. CO2 absorbed by seawater increases its acidity, reducing carbonate ions, which are building blocks used by shellfish to grow their shells.

fairweather (NOAA)

The pteropod, a sea snail the size of the head of a pin, is found in the Pacific Ocean. It has been the focus of research in recent years because its shell is affected by how much CO2 is in seawater and it may be an indicator of ocean acidification affecting the larger marine ecosystem.

A key piece of the new research was determining how much human CO2  emissions have added to naturally occurring CO2 in seawater off the U.S. West Coast. Using several decades of measurements from the Pacific Ocean taken through the U.S. Global Ocean Carbon and Repeat Hydrography Programoffsite link and new data from four NOAA West Coast research cruises conducted between 2007 and 2013, the research team developed a method to estimate additional CO2 from human-caused emissions since the start of the Industrial Era as compared to CO2 from natural sources.

The analysis shows that concentrations of human-caused CO2 are greatest in shallow waters where the atmosphere gives up large amounts of its CO2 to the sea. The researchers also estimated that CO2 concentrations from fossil fuel emissions make up as much as 60 percent of the CO2 that enriches most West Coast nearshore surface waters. But the concentrations dropped as they measured deeper. It drops to 21 percent in deeper waters of 328 feet or 100 meters, and falls even lower to about 18 percent in waters below 656 feet or 200 meters. Concentrations vary depending on location and seasons as well.

Once researchers created a detailed map of the human-generated CO2 concentrations, they  looked at how pteropod shells fared in areas with varying seawater CO2 concentrations. They found more than 50 percent of pteropod shells collected from coastal waters with the high CO2 concentrations were severely dissolved. An estimated 10 to 35 percent of pteropods taken from offshore waters showed shell damage when examined under a scanning electron microscope.

“We estimate that since pre-industrial times, pteropod shell dissolution has increased 20 to 25 percent on average in waters along the U.S. West Coast,” said Nina Bednaršek of the University of Washington. Earlier research by Bednaršek and others has shown that shell dissolution affects pteropod swimming ability and may hamper their ability to protect themselves from predators.

“This new research suggests we need a better understanding of how changes in pteropods may be affecting other species in the food chain, especially commercially valuable species such as salmon, sablefish, and rock sole that feed on pteropods,” Bednaršek added.

Media Contact:

Monica Allen, 301-734-1123

Nov 9 2016

Sea Snails on Acid

Twice a day the rocky Pacific coast traps seawater in pools as the tide rolls in and out. Compared to the ocean, the puddles are so small and innocuous that it seems nothing momentous could possibly be happening there, but there is. It turns out tiny black turban snails may be getting a buzz from the changing levels of acidity caused by ocean acidification. The scientists at Bodega Marine Lab looked closely at sea stars and snails to find out.

The underside of the purple sea star is covered in tiny delicate suction cups that make one wonder how it moves fast enough to be a voracious hunter, but it is. It’s the bully on the playground, a merciless predator. It can pry open mussel shells, turn its stomach inside out and wrap it around large prey, and digest its meal before even swallowing. It’s no wonder that when black turban snails sense the purple star’s arrival, they all flee to safety, crawling quickly up the side of a tide pool until the enemy leaves the water. Quickly for snails, that is.

Black turban snail, upper right, with its nemesis the purple sea star in the foreground. Credit: Gabriel Ng

 

Snails have always been good at running away from their primary predator – the purple sea star – until now. Brittany Jellison, a graduate student at University of California Davis, has found in a recent study that the snail’s dramatic response might be slowing down because of ocean acidification. Jellison modified tide pools to mimic ocean acidification conditions. Then she observed the snail’s response by measuring the path they took to safety. What she found when watching the snail was a trippy set of behaviors.

“Elevated carbon dioxide is a foreign substance in seawater, and snails are taking that foreign substance into their body, so yes, they in essence are on drugs,” said Brian Gaylord, a professor at UC Davis Bodega Marine Lab, where Jellison discovered that under ocean acidification conditions, snails didn’t immediately flee the pool to safety.

Ocean acidification occurs when the ocean absorbs excess carbon dioxide from the atmosphere.  While most scientists studying the phenomenon are trying to understand how it effects a single species in a lab, Jellison’s work explores how ocean acidification effects multiple species interactions.

Brittany Jellison collecting black turban snails for lab studies. Credit: Gabriel Ng

 

“I think what’s really important here is that she is moving beyond thinking about an individual species, and instead thinking about how the direct effects on individuals scale up when they are in nature and interacting with other species. That is the important part of it,” said Kristy Kroeker, Assistant Professor at the Department of Ecology and Evolutionary Biology at University of California Santa Cruz.

Professor Philip Munday of James Cook University agrees. He studies how ocean acidification effects reef fish and their ability to adapt to a changing environment.

“Ecosystems are a whole combination of interactive species,” said Munday. “If we want to understand how ocean acidification is going to impact marine ecosystems we need to understand how it will impact with the really critical ecological interactions, such as predatory-prey interactions. That’s one of the really exciting things about Jellison’s work.”

Tide pools on the Pacific coast have natural fluctuations in acidity, and the black turban snail and other animals that live there have adapted to that. Jellison wondered if the snails would be tolerant to ocean acidification conditions as well, or if they would reach their tipping point, and no longer able to tolerate the changes.

To find out, Jellison made model tide pools in aquariums. So that the snails would feel most at home, she simulated the conditions of natural tide pools, with one exception. Jellison changed the levels of acidification in some of the pools to mimic the levels that are expected for rock pools under ocean acidification by the year 2100. Having some tide pools with normal conditions and some with future acidic conditions allowed her to compare the behavior of sober snails with snails on acid.

With the arena built, let the show begin. Clutching her camera, Jellison carefully lowered black turban snails into the tank. One by one the snails reacted to a chemical cue produced by the predator sea star. Jellison took photos every two minutes for a half hour, then analyzed them for the distance the snails traveled, where they moved, and most importantly, if they left the water and escaped to safety. In total, Jellison did two 5-day trials, created 32 aquariums, tested 32 snails, and took photos every two minutes for 28 minutes per snail.

Under normal conditions, the snails will run away and exit the water, a flight response that keeps them safe. Jellison found that in water with higher acidity the snails started to run away, but instead of moving to dry ground, they seemed to get confused, haphazardly meandering around the pool.

Ocean acidification’s ability to change the interactions between predators and prey can have far reaching consequences. Jellison and her team aren’t yet sure exactly why the snails act confused. They think it’s related to changes in the brain as the animal tries to maintain balanced brain chemistry, which is something they would like to understand further.

“I really love research and I especially love working with marine animals,” said Jellison, “but when I think about what my work is saying about the future it can be a little bit hard to take in. Most of the things we are finding is that the world is going to look very different form what we see today.”

In the meantime, Jellison continues this research out in the field, in a creative study that has her waking up at all hours to hike to the tide pools and observe snails – all to understand the cascading effects of ocean acidification on the ecosystem. “I have a lot of hope that we will move forward as a society and try to come up with solutions and actually make changes. It is having hope that is important,” said Jellison.

Ocean acidification may cross national boundaries, and reach all corners of the earth, but a glimpse into a puddle of seawater reveals an elaborate community, a tiny snail, and a big message.


Read the original post: https://blogs.scientificamerican.com/guest-blog/sea-snails-on-acid/

Nov 1 2016

‘The Blob’ Is Back: What Warm Ocean Mass Means for Weather, Wildlife

This illustration of temperature in the northeast Pacific shows the status of the “Blob,” a warm-water phenomenon, as of September 2016.

The blob is back.

Since 2014, a mass of unusually warm water has hovered and swelled in the Pacific Ocean off the West Coast of North America, playing havoc with marine wildlife, water quality and the regional weather.

Earlier this year, weather and oceanography experts thought it was waning. But no: The Blob came back, and it is again in position off the coast, threatening to smother normal coastal weather and ecosystem behavior.

The Blob isn’t exactly to blame for California’s drought, though it certainly aggravated the problem. But it is to blame for seriously disrupting the ocean food chain and for creating conditions that fed unprecedented algal blooms in the coastal Pacific.

With the Blob back in play again, what does it mean for the winter ahead? To find out, Water Deeply spoke with Nicholas Bond, a research meteorologist at the University of Washington in Seattle and Washington’s state climatologist. In June 2014, Bond named this persistent weather phenomenon, and later wrote the first scientific paper characterizing it.

Water Deeply: What exactly is the Blob?

Washington’s state climatologist Nicholas Bond named the warm ocean mass now commonly known as “the Blob.”

Washington’s state climatologist Nicholas Bond named the warm ocean mass now commonly known as “the Blob.” (Nicholas Bond)

 

Nicholas Bond: It’s a large mass of water in the northeast Pacific Ocean that’s considerably warmer than usual. It doesn’t have any real sharply defined boundaries, but it’s an area that, at times, has stretched from Baja California up to the Bering Sea. At other times, it’s kinda shrunk back down. It’s been at least 1,000 miles (1,600km) across and, recently, quite deep.

Typically, it’s been something like2.7–3.6F (1.5–2C) warmer than normal. But there have been places where it’s been as much as 9F (5C) warmer. It’s waxed and waned, but it’s been that way since early 2014. The warmer-than-normal water extends down to something like 300m (1,000ft) below the surface. So that’s a huge volume of considerably warmer-than-normal water.

Water Deeply: Is it still out there?

Bond: Yeah. There was sort of a reinvigoration this past summer. The temperatures were moderating early in 2016, and then, at least in a large area south of Alaska and off the coast of the Pacific Northwest, it really warmed up again this past summer.

Water Deeply: What causes it?

Bond: A lot of it, almost all of it, is due to just the unusual weather patterns that have been occurring over the northeast Pacific during the past few years. They haven’t been the same patterns, but what really got it started was when a ridge of higher-than-normal sea-level pressure set up during the winter of 2013–14 over the northeast Pacific.

That was a very persistent and strong ridge of higher-than-normal pressure that kind of blocked the usual parade of storms across the Pacific. That meant less heat was drawn out of the ocean into the atmosphere than usual. It meant there was less cold water (from the deeper ocean) mixing near the surface part of the ocean. And also the unusual winds meant the upper-level currents in the ocean were a little bit different from usual.

Water Deeply: Is it unprecedented?

Bond: Yeah, certainly. In terms of the magnitude of anomalies in a lot of locations, we haven’t seen anything quite like this. I did a fairly careful study using the data that’s available, going back decades. There have been other periods with considerably warmer-than-normal ocean temperatures in the region. But they were never of the kind of geographic extent and magnitude we’ve seen with this recent event.

Emaciated juvenile sea lions undergoing rehabilitation at the Marine Mammal Center in California. Their plight is thought to have been triggered by the unusually warm water conditions that persist in the coastal Pacific Ocean, upsetting the usual food web upon which sea lions and other wildlife depend.

Emaciated juvenile sea lions undergoing rehabilitation at the Marine Mammal Center in California. Their plight is thought to have been triggered by the unusually warm water conditions that persist in the coastal Pacific Ocean, upsetting the usual food web upon which sea lions and other wildlife depend. (NOAA Fisheries)

Water Deeply: What caused that persistent high pressure?

Bond: It became known as the “ridiculously resilient ridge.” There’s been a number of independent studies that have basically shown that much warmer than normal waters in the far western tropical Pacific, in the vicinity of New Guinea – and thunderstorms that those warm waters helped spawn – had this kind of ripple effect on the atmospheric-circulation weather patterns over much of the globe.

It set up this series of very large-scale high- and low-pressure centers, with the ridge over the coast of western North America, and then a trough of lower pressure over the northeastern part of North America.

Water Deeply: How did the Blob affect the drought in California?

Bond: That same ridge of high pressure basically blocked the storms. There was just a real lack of those regular storms. The warm water didn’t cause the unusual weather patterns. But those unusual weather patterns that brought the warm water also were a large cause of the drought in California.

It turned out that was the same case in the Pacific Northwest. Not quite the same extent, but we were looking at very low snowpack in mid-February 2014. Then there was enough of a shift that we actually had a pretty wet period there at the end of winter and got enough rain and snow to kind of tide us through the summer of 2014. But there weren’t enough (storms), and those didn’t extend far enough south for California to get relief.

But it gets kind of complicated. Once that warm water formed out there in a big way, it does tend to warm the air that’s passing over it. Once that water was warmed, it did help warm the air coming off the ocean. This was especially the case in the winter of 2014–15. It led to warmer air temperatures and higher snow levels. The freezing level was 1,000–2,000ft (300–600m) higher than usual in the mountains. So that certainly ended up being a real problem. We count on that snowpack coming out of winter to get us through the summer. But it fell as rain rather than snow during that 2014–15 winter.

Water Deeply: Is there a climate change connection here?

Bond: This is sometimes called a marine heat wave, and it’s a short-term kind of event. There is some evidence that long-term trends are favoring the patterns we’ve had over the past few years. But that’s a very small effect.

So it’s not due to global warming. But it does provide some hint, at least, of what it’s going to be like in future decades, in particular, with some of the impacts we’ve seen in the marine ecosystem. What we’ve had the past few years is something that is liable to be more the rule rather than the exception toward the middle of the century. So maybe this is kind of a little preview or something. So we’re trying to learn from it.

Water Deeply: How has the Blob affected ocean life?

Bond: The impacts were quite a few and widespread. At the bottom of the food chain, we saw a higher preponderance at the plankton level of subtropical species versus ones that are more adapted to cooler water.

That had repercussions all the way up the food chain – everything from the kind of suitable prey for salmon that was present and whether they were getting the food they need, to some real problems with fur seals and sea lions in California in particular. In the Gulf of Alaska we had what National Oceanic and Atmospheric Administration has called a marine mammalmortality event last year. Seabirds are another one: There were some species with some very large mortalities, with lots more dead seabirdswashing up on the beaches.

One of the more alarming things is the harmful algal blooms. That was sort of way out there in terms of how far along the coast it stretched, how long it lasted, how high the toxin levels got. That was something that was really scary.

Water Deeply: How long will the Blob be with us?

Bond: That’s kind of the $64,000 question. We thought this whole event was winding down earlier this year, and then we’ve seen it rear its ugly head again in some locations.

Water Deeply: How will this affect our weather this coming winter?

Bond: The more prominent temperature anomalies are a little north of California. It’s all going to depend on the weather patterns. There are kind of borderline La Niña conditions now, which doesn’t tend to imply too much one way or another for Northern California. In the past, it probably has meant somewhat less precipitation than normal for Southern California. But we see a lot of exceptions there.

It’s kind of an admission of defeat, but it’s basically a crapshoot in terms of how much rain you get.

I think in terms of temperature, it’s not liable to be quite as warm as the past two winters, so that’s good, at least for the winter-sports folks. What falls in the mountains should be snow at the higher elevations. I think Northern California is liable to do OK. Southern California? Wow, that’s a tough one.


Read the original post: https://ww2.kqed.org/

Oct 30 2016

Seafood’s new normal

hogisland

Hog Island Oyster Co. employee Wilber Mejia pushes a bag of farmed oysters onto a boat during harvesting on Oct. 12. The bags are taken back to the company’s Marshall headquarters, where the bivalves are prepared for sale.

California’s coastal ecosystem — and the fisheries that depend on it — are in the grip of a huge disruption

In the shallow waters off Elk, in Mendocino County, a crew from the California Department of Fish and Wildlife dived recently to survey the area’s urchin and abalone populations. Instead of slipping beneath a canopy of leafy bull kelp, which normally darkens the ocean floor like a forest, they found a barren landscape like something out of “The Lorax.”

A single large abalone scaled a bare kelp stalk, hunting a scrap to eat, while urchins clustered atop stark gray stone that is normally striped in colorful seaweed.

“When the urchins are starving and are desperate, they will the leave the reef as bare rock,” said Cynthia Catton, an environmental scientist with Fish and Wildlife. Warm seawater has prevented the growth of kelp, the invertebrates’ main food source, so the urchins aren’t developing normally; the spiky shells of many are nearly empty. As a result, North Coast sea urchin divers have brought in only one-tenth of their normal haul this year.

The plight of urchins, abalones and the kelp forest is just one example of an extensive ongoing disruption of California’s coastal ecosystem — and the fisheries that depend on it — after several years of unusually warm ocean conditions and drought. Earlier this month, The Chronicle reported that scientists have discovered evidence in San Francisco Bay and its estuary of what is being called the planet’s sixth mass extinction, affecting species including chinook salmon and delta smelt.

Baby salmon are dying by the millions in drought-warmed rivers while en route to the ocean. Young oysters are being deformed or killed by ocean acidification. The Pacific sardine population has crashed, and both sardines and squid are migrating to unusual new places. And Dungeness crab was devastated last year by an unprecedented toxic algal bloom that delayed the opening of its season for four months.

The collapses are taking a financial toll on the state’s seafood industry. A report from the National Oceanic and Atmospheric Administration released Wednesday showed the California fishing harvest decreased in value by $109 million between 2014 and 2015, or by 43 percent.

The impact has already been felt in Bay Area homes. This summer, chinook salmon sold for more than $35 per pound in some markets, about 50 percent higher than in previous years. The absence of Dungeness crab during the 2015 holidays jarred many locals, though the Bay Area’s favorite crustacean is still slated to return to tables on Nov. 15, when the 2016 commercial season is scheduled to begin.

More disturbing are signs that the recent changes to the Pacific Ocean could represent the new normal.

Six distressed seafood species in Northern California
Here is a look at how six Pacific fisheries have been affected by recent unusual weather patterns and what we can expect in the future.
Chinook Salmon
The issues:
Drought and warm river conditions impede reproduction and salmon’s ability to make the journey from river to ocean and back again. Some runs of salmon face extinction.
Commercial season:
May through September and part of October

The five-year drought has had a dramatic impact on this already challenged population of native fish. Salmon caught by local fishers outside of the Golden Gate are part of the Sacramento-San Joaquin River Delta system, which has four different seasonal spawning runs. The salmon that reach our markets are the fall and late-fall run, migrating from July to December and mid-October to December.

Most native salmon’s original spawning grounds have been disrupted by dams in the river system, so they are dependent on two factors: how much it rains and/or the amount of water that state officials decide to release into the river during drought. When the river water was too warm in 2014 and 2015, 95 percent of winter-run baby and juvenile salmon died.

Salmon take several years to mature, which means that during the last few salmon seasons the fish were born under traumatic conditions. The 2016 season, which just ended, was also hampered by the late crab season, which kept gear and crabbers out in the water later.

The Bay Institute, along with Natural Resources Defense Council and other organizations, has been working since 1998 to reconnect part of the San Joaquin River to San Francisco Bay that had been disconnected since the 1950s. When the restoration is complete, it could restore the runs of 30,000 spring and fall-run salmon every year.

Loss of salmon habitat in the Central Valley
Historic salmon spawning grounds in the Central Valley have been cut off by dams and other impassable barriers, making it difficult for adult salmon to lay eggs and for the babies to make their way to the ocean.

“Weather and climate are two very closely related things that are difficult to tease apart. What is short-term variable weather versus long-term climate change?” said Toby Garfield, director of the Environmental Research Division at San Diego’s National Oceanic and Atmospheric Administration Southwest Fisheries Science Lab. “Almost any scientist you talk to would say, ‘Yes, the climate is changing, and we’re seeing a lot of variability.’”

But, Garfield added, “Most agencies are working very hard to understand what these changes are.”

Not hard to understand is the financial hit the state’s fisheries have taken. Last year’s Dungeness crab season, normally one of the most lucrative fisheries in the state, brought in $37 million, far less than the average $68 million over the previous five years. The chinook salmon harvest dropped by two-thirds between 2013 and 2015, cutting fishers’ earnings to $8 million from $22.7 million. Many in the industry think this year’s numbers will be worse.

John Eiserich closes up the boat he has docked at Pier 45 in San Francisco after his last chinook salmon trip of the season on Oct. 7.

The causes of these dramatic changes are complex and loosely interrelated. The combination of a strong El Niño weather pattern, which warmed ocean waters last year, and a persistent patch of warm water near Alaska, colloquially known as the Warm Blob, caused toxic algal blooms to spike and fish to migrate erratically.

The Blob — Garfield prefers “North Pacific Marine Heat Wave” — is in a zone of atmospheric high pressure that diverts the winter storms that normally help cool down the ocean. While it first appeared in 2014 and is not influencing California coastal water temperatures the way it did last year, it’s still an unusual phenomenon that can be self-perpetuating. The Blob’s staying power and the gradual rise of global ocean temperatures fuel concerns that there could be an eventual repeat of last year’s crab disaster.

“Temperature really impacts the growth of many of these species. They’ve evolved in a very specific temperature range and suddenly that’s getting out of whack,” said Garfield. “It’s really impacting their growth and development in ways that we’re just beginning to understand.”

Sardines and squid, two hallmarks of local seafood, usually spawn off of California, but as warm water pushed them north last year, both sardines and squid laid eggs near Oregon and even Alaska. In 2015, almost 3 million pounds of squid were harvested off Oregon, which hadn’t seen a big catch since the 1980s. Meanwhile, California’s squid harvest, normally the largest in the country and worth $73 million, dropped by 64 percent between 2014 and 2015.

John Blanchard • jblanchard@sfchronicle.com

Pacific sardines are in even greater decline. The population, which naturally fluctuates a great deal, is estimated at one-tenth of what it was in 2007, when the fishery was worth $8.2 million. Because of the decline, that fishery has been closed for the past two years, though the recent warm ocean temperatures have had an impact, too.

The overall situation is dire, so many scientists and fishers are taking aggressive steps to deal with the changes.

Hog Island Oyster Co. in Tomales Bay has been plagued by ocean acidification, caused as carbon is absorbed by the ocean — a result of climate change. This has limited the supply of seed stock the company needs to grow oysters.

“To us what’s scary is not just the change in ocean chemistry, it’s the rate of change,” said co-owner John Finger.

Because the problem will only worsen as more carbon is absorbed, Hog Island is building a hatchery to produce its own seed and breed oysters that Finger hopes can better withstand acidification.

“Unless you have your head in the sand, you realize this is going to get drastically worse,” said Finger. “We need to have more seed production in various places because we don’t know what the patterns are for this.”

The Golden Gate Salmon Association has been trucking baby salmon to the ocean rather than risk the fish dying on the perilous trip from their birthplace in the Sacramento River down to San Francisco Bay. A new study from the Bay Institute concluded that so little water is flowing through the bay and its estuary — because of diversions for urban and Central Valley farm use — that some salmon and other native species are facing extinction. By some estimates, 80 percent of California’s native freshwater fish species could be gone by 2100.

Salmon fishers and crabbers, meanwhile, are trying to adjust to the new seascape. Some are chartering their boats for recreational fishing while they wait for things to improve.

Somewhat ironically, with more squid moving north from its normal Southern California environs lately, Northern California has had some banner squid years. Earlier this month, Larry Collins of the San Francisco Community Fishing Association at Pier 45 had to show up at midnight several times to receive ton after ton of squid caught near the Farallon Islands or off Ocean Beach.

“There’s just miles of squid out there,” he said at the time.

Kelp loss in Northern California
Based on aerial photos taken at different sites on the North Coast, these images show a dramatic decrease in kelp forests, which sustain red urchin, abalone and thousands of other species. While 2008 was a good kelp year, the images from 2014 show effects of the Warm Blob, warm water conditions that caused a severe reduction in kelp.
Graphic artist: John Blanchard • jblanchard@sfchronicle.com
Developer: Emma O’Neill • eoneill@sfchronicle.com@emmaruthoneill
Source: California Department of Fish and Wildlife

The California coast is part of what is normally one of the most productive fisheries in the world. Winds that run southward down the West Coast push surface water offshore, allowing deeper, nutrient-rich water to come up and feed seaweed and phytoplankton. That sets the food chain in motion for zooplankton, including krill, which in turn nourish an incredibly diverse ecosystem of marine mammals and larger fish like the chinook.

“Our salmon have some of the highest omega-3 content and best flavor of any salmon in the world,” said John McManus of the Golden Gate Salmon Association. “There’s a section of the population that recognizes that and is willing to pay for real, honest-to-god king salmon.”

In an opinion page article in The Chronicle in August, Alice Waters of Chez Panisse and Patricia Unterman of Hayes Street Grill argued for better protection of chinook salmon and rebuilding of its runs, citing its importance in the region’s culture.

“Every year, the return of salmon is eagerly anticipated by California fishermen, restaurants and the public,” they wrote.

Catton, the Fish and Wildlife scientist, is concerned both about the sustainability of local marine species like salmon and urchin, and the entire state fishery. Urchin divers usually augment their income with crabbing and salmon fishing, but as those are no longer lucrative, many divers are working construction instead, she said.

“Many of them have weathered a lot of these good times and bad times,” she said. “They say it’s a cycle. Kelp comes and kelp goes.”

What’s different this time, she said, is the kelp forests have never been quite this bare.


Sep 14 2016

‘Son of Blob’ springs to life in the Pacific

Satellite monitoring on Sept. 10 found a huge area of much warmer than normal surface temperatures in the Northeast Pacific Ocean.

NOAA GRAPHIC – Satellite monitoring on Sept. 10 found a huge area of much warmer than normal surface temperatures in the Northeast Pacific Ocean.

 

LONG BEACH — The Blob, a news-making patch of unusually warm ocean surface water from late-2013 through autumn 2015, was reborn this month.

The ocean warmed quickly. As recently as July, “The northeast Pacific off our coast was slightly above normal, but nothing exceptional,” University of Washington meteorologist Cliff Mass noted Sunday on his popular blog.

By Sept. 10, some limited areas of the nearby Pacific were 5.4 to 7.2 degrees F above normal, Mass noted, while satellite monitoring shows an enormous zone of overall warmth extending west from the coasts of Washington and Oregon, north to Alaska.

News about the birth of this “Son of Blob” comes just as climate experts have officially declared this will not be a La Niña winter. The flip side of more-famous El Niño conditions that influenced the winter of 2015-16, La Niña is a pattern of unusually cold surface waters in the equatorial Pacific Ocean. It tends to result in wetter and cooler winter conditions here in the Pacific Northwest.

On Sept. 22, the National Oceanic and Atmospheric Administration will issue its new 30- and 90-day long-range forecasts, and will try to determine how the Son of Blob will influence our weather in a winter with neutral El Niño/La Niña conditions. The short-term forecast for this week is for warm and generally pleasant late-summer weather on the coast, but critical fire weather conditions for parts of the interior.

 

The original Blob

 

A result of a persistent zone of high atmospheric pressure in our part of the Pacific, the original Blob created “highly unusual weather,” according to Washington State Climatologist Nick Bond.

Ocean conditions made their way onto dry land in the form of drought and record temperatures — “2015 was by far the warmest year we’ve had in the Cascades” and “Oct. 1, 2014 through September 2015 [was a time of] record warmth in much of the Northwest,” Bond said at the 2016 Pacific County Marine Science Conference in Long Beach on May 21. Widespread forest fires and possibly the largest documented seabird mortality event in world history were linked to the 2013-15 Blob.

Mass said Sunday that experimental modeling he conducted found a modest 1 to 2 degrees F increase in land temperatures from the Blob. But even that amount of additional warmth can have a noticeable impact on snowpack and other terrestrial conditions in the Pacific Northwest.


Read the original post: http://www.chinookobserver.com/