Posts Tagged ocean acidification

May 30 2018

Consequences of spatially variable ocean acidification in the California Current: Lower pH drives strongest declines in benthic species in southern regions while greatest economic impacts occur in northern regions

 

Emma E. Hodgsona, Isaac C. Kaplanb, Kristin N. Marshallc, Jerry Leonardc, Timothy E. Essingtona, D. Shallin Buschd, Elizabeth A. Fultone, f, Chris J. Harveyb, Albert Hermanng, h, Paul McElhanyb

  • a School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA 98195-5020, USA
  • b Conservation Biology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, NOAA, 2725 Montlake Blvd E, Seattle WA 98112, USA
  • c Fishery Resource Analysis and Monitoring Division, Northwest Fisheries Science Center, National Marine Fisheries Service, NOAA, 2725 Montlake Blvd E, Seattle WA 98112, USA
  • d Ocean Acidification Program, Office of Oceanic and Atmospheric Research and Northwest Fisheries Science Center, National Marine Fisheries Service, NOAA, 2725 Montlake Blvd E, Seattle WA 98112, USA
  • e CSIRO Oceans and Atmosphere, GPO Box 1538, Hobart, Tasmania 7001, Australia
  • f Centre for Marine Socioecology, University of Tasmania, 20 Castray Esplanade, Hobart, Tasmania 7004, Australia
  • g NOAA Pacific Marine Environmental Laboratory, 7600 Sand Point Way NE, Seattle WA 98115, USA
  • h Joint Institute for the Study of the Atmosphere and Ocean, University of Washington, 3737 Brooklyn Ave NE, Seattle, WA 98105, USA

Abstract

Marine ecosystems are experiencing rapid changes driven by anthropogenic stressors which, in turn, are affecting human communities. One such stressor is ocean acidification, a result of increasing carbon emissions. Most research on biological impacts of ocean acidification has focused on the responses of an individual species or life stage. Yet, understanding how changes scale from species to ecosystems, and the services they provide, is critical to managing fisheries and setting research priorities. Here we use an ecosystem model, which is forced by oceanographic projections and also coupled to an economic input-output model, to quantify biological responses to ocean acidification in six coastal regions from Vancouver Island, Canada to Baja California, Mexico and economic responses at 17 ports on the US west coast. This model is intended to explore one possible future of how ocean acidification may influence this coastline. Outputs show that declines in species biomass tend to be larger in the southern region of the model, but the largest economic impacts on revenue, income and employment occur from northern California to northern Washington State. The economic consequences are primarily driven by declines in Dungeness crab from loss of prey. Given the substantive revenue generated by the fishing industry on the west coast, the model suggests that long-term planning for communities, researchers and managers in the northern region of the California Current would benefit from tracking Dungeness crab productivity and potential declines related to pH.

 

Access to full article can be found here: https://www.sciencedirect.com/science/article/pii/S0304380018301856

Oct 7 2017

Coastal Researchers, Fishermen Worried About More Frequent Low Oxygen Zones

Olympic Coast National Marine Sanctuary research team members, Kathy Hough and LTJG Alisha Friel, recover sensors deployed seasonally off the coast of Washington from the research vessel Tatoosh in July 2017. — S. Maenner / NOAA

 

Scientists in Oregon and Washington are noticing a disruptive ocean phenomenon is becoming more frequent and extreme. It involves a suffocating ribbon of low oxygen seawater over our continental shelf.

The technical term is hypoxia, sometimes called “dead zones,” It’s an unwelcome variation on normal upwelling of cold, nutrient rich water from the deep ocean. When the dissolved oxygen drops too low, it drives away fish and can suffocate bottom dwellers such as crabs and sea worms who can’t scurry away fast enough.

It seemed to marine ecologist Francis Chan like this is happening most every summer lately. So the Oregon State University researcher looked back as far as coastal oxygen readings go—to about 1950—to see if it’s always been this way.

“The ocean starting in 2000 really looked different from the ocean we had between the 1950s and 1990s,” Chan said.

Chan said climate change could affect oxygen levels via disrupted circulation and ocean warming. 
 A September storm flushed away this year’s low oxygen zone by churning Northwest coastal waters. But Chan described the severity of the low oxygen readings recorded this summer as among the worst ever observed locally.

“It’s very much a patchy ribbon,” he said from his post in Newport, Oregon. Marine surveys and fixed instruments recorded notably low oxygen values from south of Yachats up past Newport.

Ten oceanographic moorings deployed by the Olympic Coast National Marine Sanctuary also found very low (hypoxic) oxygen values between Cape Elizabeth and Cape Flattery, Washington, this summer.

“This is not a happy year for organisms out on the coast,” said Jenny Waddell, the marine sanctuary’s research coordinator.

Waddell added that at least one sensor dipped into anoxic conditions, “where there’s literally no oxygen.”

“We had indications of a relatively persistent hypoxia event along the Quinault Reservation coastline,” wrote marine scientist Joe Schumacker of the Quinault Department of Fisheries in an email Friday. “Dead fish and shellfish at various locations and times beginning near the end of July and extending through most of August.”

More frequent and severe near-shore hypoxia concerns fishermen and crabbers. Commercial harvesters face reduced catches and economic losses when crabs suffocate and fish and prawns flee the oxygen-starved waters.

One of the tip-offs to OSU researchers of the onset of low oxygen conditions this summer was when Oregon Department of Fish and Wildlife biologists monitoring crab populations noticed crabs dying from lack of oxygen in a research trap. Other observers noted crabs leaving the ocean to seek more oxygenated waters in coastal estuaries and bays.

Earlier this year, researchers and fishery advocates found a receptive ear at the Oregon Legislature when they presented their concerns about silent changes in the ocean. Legislators approved the creation of a new council to be co-chaired by the state Fish and Wildlife director and an OSU leader.

The council is tasked with recommending and coordinating a long-term strategy to address hypoxia as well as ocean acidification.


Originally published: http://nwnewsnetwork.org/

Oct 4 2017

What scientists are learning about the impact of an acidifying ocean

The effects of ocean acidification on marine life have only become widely recognized in the past decade. Now researchers are rapidly expanding the scope of investigations into what falling pH means for ocean ecosystems.

The ocean is becoming increasingly acidic as climate change accelerates and scientists are ramping up investigations into the impact on marine life and ecosystems. In just a few years, the young field of ocean acidification research has expanded rapidly – progressing from short-term experiments on single species to complex, long-term studies that encompass interactions across interdependent species.

“Like any discipline, it takes it time to mature, and now we’re seeing that maturing process,” said Shallin Busch, who studies ocean acidification at the National Oceanic and Atmospheric Administration’s (NOAA) Northwest Fisheries Science Center in Seattle.

As the ocean absorbs carbon dioxide from the burning of fossil fuels, the pH of seawater falls. The resulting increase in acidity hinders the ability of coral, crabs, oysters, clams and other marine animals to form shells and skeletons made of calcium carbonate. While the greenhouse gas effect from pumping carbon dioxide into the atmosphere has been known for decades, it wasn’t until the mid-2000s that the impacts of ocean acidification became widely recognized. In fact, there is no mention of acidification in the first three reports from the United Nations Intergovernmental Panel on Climate Change, issued in 1990, 1995 and 2001. Ocean acidification did receive a brief mention in the 2007 report summarizing the then-current state of climate science, and finally was discussed at length in the latest edition released in 2014.

But about halfway through that brief dozen years of acidification research, a shift started taking place.

“The early studies were just a first step and often quite simple,” said Busch of ocean acidification research. “But you can’t jump into the deep end before you learn how to swim.”

That started to change about five or six years ago, according to Philip Munday, who researches acidification effects on coral reefs at Australia’s James Cook University. “The first studies were often single species tested against ocean acidification conditions, often quite extreme conditions over short periods of time,” he said. “Now people are working on co-occurring stresses in longer-term experiments.”

That includes studying how acidification could change how organisms across a community or ecosystem interact – in other words, how the impacts on one species affect those it eats, competes with or that eat it. It also means looking at how impacts could change over time, due to species migrating or adapting, either in the short term or across a number of generations and how such effects may vary within the same species or even with the same population.

Nine examples of this new generation of acidification research are included in the latest issue of the journal Biology Letters. One study, for example, found that the ability to adapt to pH changes differed in members of the same species of sea urchins based on location. Another discovered that a predatory cone snail was more active in waters with elevated carbon dioxide levels but was less successful at capturing prey, reducing predation on a conch species. Another highlights that an individual organism’s sex can affect its response to acidification.

Munday, who edited the series of papers, said one of the major takeaways is that researchers are increasingly studying the potential for species to adapt to ocean acidification and finding those adaptations can be quite complex.

He pointed to a study on oysters. Previous work had shown that oysters whose parents were exposed to acidification conditions do better in those conditions than those whose parents weren’t. But in a new study, researchers found that when they exposed the offspring to additional stressors – such as hotter water temperatures and higher salinity – those adaptive advantages decreased.

All the studies call for including often-overlooked factors such as sex, location or changes in predation rate in future studies. Otherwise, researchers warn, impacts will be increasingly difficult to predict as the ocean continues to acidify.

“It’s far too early to make any sort of generalities,” Munday said.

The latest paper from NOAA’s Busch also cautions against generalities. By building a database of species in Puget Sound and their sensitivity to changes in dissolved calcium carbonate, she found that summarizing species’ sensitivity by class or order rather than the specific family can result in overestimating their sensitivity.

She compared it to similarities between people in the same immediate family versus people who are distant cousins. “There would be a lot more variation among those people because they’re not super closely related,” she said. “But when people started summarizing data really early in the field, there wasn’t much data to pull from. So it was done at a class level.

“Now that we have many more studies and information to pull from, how we draw summaries of species response should be nuanced,” she added.

Acidification research is likely to get only more nuanced in the years ahead. From the broad initial projections of average, ocean-wide surface acidity, for instance, researchers have started to pinpoint local pH projections, local impacts and local adaptations.

“We know the ocean is changing in a number of ways,” said Busch. “So just studying one of those factors without looking at the other changes in what’s going on in the ocean is not going to yield useful results.”

Matthew O. Berger, NewsDeeply, 2 October 2017. Article.


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

Apr 23 2017

Canary in the kelp forest

The one-two punch of warming waters and ocean acidification is predisposing some marine animals to dissolving quickly under conditions already occurring off the Northern California coast, according to a study from the University of California, Davis.

In the study, published in the journal Proceedings of the Royal Society B: Biological Sciences, researchers at the UC Davis Bodega Marine Laboratory raised bryozoans, also known as “moss animals,” in seawater tanks and exposed them to various levels of water temperature, food and acidity.

The scientists found that when grown in warmer waters and then exposed to acidity, the bryozoans quickly began to dissolve. Large portions of their skeletons disappeared in as little as two months.

“We thought there would be some thinning or reduced mass,” said lead author Dan Swezey, a recent Ph.D. graduate in professor Eric Sanford’s lab at the UC Davis Bodega Marine Laboratory. “But whole features just dissolved practically before our eyes.”

SKELETONS KEY

Bryozoans are colonial animals, superficially similar to, but not related, to corals. They are abundant in California kelp forests and are calcareous, meaning they build their honeycomb-shaped skeletons from calcium carbonate.

The scientists found that when raised under warming conditions, bryozoans altered their chemical composition by building higher levels of magnesium into their skeletons, particularly if they were also eating less food. When exposed to acidic conditions already observed off coastal California, these changes predisposed the animals to dissolve.

The researchers consider bryozoans a canary in the coal mine for other marine animals that build calcareous skeletons containing magnesium. These include sea stars, sea urchins, calcifying algae and tube-building worms.

The authors do not know why the bryozoans added more magnesium to their skeletons under warmer temperatures. But they conclude that marine organisms with skeletons made of high-magnesium calcite may be especially susceptible to ocean acidification because this form of calcium carbonate dissolves more easily than others.

Bryozoans grow in connected colonies. During the experiments, the animals shut down parts of themselves when undergoing the stress of ocean acidification, redirecting their energy to new growth. This was somewhat like closing down units of a condominium complex while building new ones at the same time. But the moss animals could not outpace the dissolution.

“They were trying to grow but were dissolving at the same time,” Swezey said.

CALCIFIED ANIMALS INCREASINGLY VULNERABLE

The authors said the study underlines the increasing vulnerability of calcified animals to ocean acidification, which occurs as the ocean absorbs more atmospheric carbon emitted through the burning of fossil fuels.

During the spring and summer months, deep ocean water rich in carbon dioxide periodically wells up along the California coast when surface waters are pushed offshore by strong winds. These upwelling events also push nutrients to the surface to help support kelp forests and productive fisheries. However, this deep water tends to be more acidic.

Climate modeling shows that the trends of warming ocean temperatures, stronger winds and increasingly strong upwelling events are expected to continue in the coming years as carbon dioxide concentrations in the atmosphere increase. This indicates that acidic conditions will likely become more common, rather than episodic.

MARINE LIFE FACES MANY CHANGES AT ONCE

“Marine life is increasingly faced with many changes at once,” said co-author Sanford, a professor in the UC Davis Department of Evolution and Ecology. “For bryozoans, their response to warmer temperature makes them unexpectedly vulnerable to ocean acidification. The question now is whether other marine species might respond in a similar way.”

###

The study’s other co-authors include Jessica Bean, Aaron Ninokawa, Tessa Hill, and Brian Gaylord from UC Davis. Bean is also affiliated with UC Berkeley.

The study was supported by grants from the National Science Foundation and the University of California Multicampus Research Programs and Initiatives. Swezey was also supported by a NSF Graduate Research Fellowship.

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.


Originally posted: https://www.eurekalert.org/pub_releases/2017-04/uoc–cit041717.php

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.

 

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/

Jun 29 2016

Ocean Acidification Affects Predator-Prey Response Acidic Waters Dull Snails’ Ability to Escape from Predatory Sea Stars

starfish

Black turban snails escape predation by sea stars by crawling out of tide pools. Experiments at UC Davis’ Bodega Marine Laboratory show that the snails lose this escape response as waters become more acidic, a consequence of climate change. Photo: Brittany Jellison

Ocean Acidification Affects Predator-Prey Response | UC Davis

 

Quick Summary

  • Sea snails in more acidic sea water did not show escape response
  • Atmospheric carbon dioxide affects ocean chemistry, may impact ocean life
  • Changes in tide pools now foreshadow future changes in the open ocean

Ocean acidification makes it harder for sea snails to escape from their sea star predators, according to a study from the University of California, Davis.

The findings, published in the journal Proceedings of The Royal Society B, suggest that by disturbing predator-prey interactions, ocean acidification could spur cascading consequences for food web systems in shoreline ecosystems.

For instance, black turban snails graze on algae. If more snails are eaten by predators, algae densities could increase.

“Ocean acidification can affect individual marine organisms along the Pacific coast, by changing the chemistry of the seawater,” said lead author Brittany Jellison, a Ph.D. student studying marine ecology at the UC Davis Bodega Marine Laboratory.

“But it can also alter how species interact, such as by impairing the ability of prey to avoid predators,” she said.

Sea star and snail interactions under ocean acidification

Jellison and colleagues from the UC Davis Bodega Marine Laboratory collected ochre sea stars and black turban snails — two common species along the Pacific coastline — from tide pools on the Bodega Marine Reserve. In lab tanks, they explored interactions between the sea stars and snails under 16 different levels of seawater pH, or acidity, ranging from present levels to those expected for rocky intertidal pools by the year 2100.

The scientists found that lower pH levels, which indicate higher acidity, did not slow the snails’ movements or reduce their ability to sense the predatory sea stars. However, the more acidic waters did impair the snails’ escape response.

Tipping point

Usually, when a black turban snail senses an ochre sea star, it quickly crawls up and out of the tide pool to avoid it, as sea stars rarely leave the water to eat. But when pH levels fell to 7.1 or below, the snails failed to fully implement their escape response. Neither did the snails recover their escape response when the water’s acidity fluctuated between normal and more acidic levels.

The pH levels that spur these behavioral changes already occur in tide pools and are expected to become more frequent in coming decades.

More research is needed to understand why the snails show a degraded escape response, or if they may adapt to more acidic ocean conditions in the future.

More CO2, more ocean acidification

One-third of carbon dioxide emitted by humans enters the oceans, making seawater more acidic, the study noted.

Rocky tide pools may operate as an indicator for future ocean conditions. They experience pH levels that are predicted for the open ocean later. Models project a 0.3-0.4 drop in the global average of ocean pH by 2100.

“Dozens of West Coast species display escape responses to sea stars,” said senior author Brian Gaylord, a professor of evolution and ecology at the UC Davis Bodega Marine Laboratory and Jellison’s faculty adviser. “We don’t yet know the extent to which ocean acidification could alter these additional predator-prey interactions, but there is clear potential for broader disruption of links within shoreline food webs.”

The study’s co-authors, all affiliated with the UC Davis Bodega Marine Laboratory, include graduate student Aaron Ninokawa, Professor Tessa Hill of the Department of Earth and Planetary Sciences and Coastal Marine Science Institute, and professors Eric Sanford and Brian Gaylord of the Department of Evolution and Ecology.

The study was funded by grants from the National Science Foundation, California Sea Grant and UC Davis Bodega Marine Laboratory.

Media contact(s)

Andy Fell, News and Media Relations, UC Davis, 530-752-4533, ahfell@ucdavis.edu

Brian Gaylord, Bodega Marine Laboratory, 707-875-1940, bpgaylord@ucdavis.edu

Brittany Jellison, Evolution and Ecology, 805-338-6610, bmjellison@ucdavis.edu

Apr 25 2016

Ocean souring on climate change

climate

“This upwelling is both a blessing and a curse,” Chan said. “The upwelling injects nutrients that make our ocean so productive. That’s why Steinbeck wrote ‘Cannery Row.’ We live in a very special ocean. But the curse is that this upwelling creates low oxygen and low pH. So we’re much closer to any tipping points that could push us past a threshold.”

Although the causes and effects of ocean acidification and low oxygen are global, the panel found hopeful news about the potential to deal with it locally.

Seagrass beds and kelp forests are more productive than tropical forests, capturing more carbon than other systems on the planet. By restoring marine vegetation, scientists hope to raise pH and oxygen levels in key areas.

Curbing marine pollution can also improve ocean chemistry, scientists said. Runoff from farms and lawns, such as nitrogen and phosphorus, feed algal blooms that dump carbon and deplete oxygen from local waters. Cutting back on those pollutants can “put off a potential evil hour when carbon dioxide are so high” that they cause irreparable damage to marine life, Dickson said.

Efforts to battle ocean acidification and low oxygen on the West Coast will be test cases for dealing with the problem elsewhere, scientists said

“The West Coast will be a harbinger for the types of ocean acidification impacts that will be widely felt across coastal North America in the coming decades,” the report states.

Despite the gloomy news, Chan said he’s hopeful that a solution is at hand, noting that bills pending in the California Legislature — Assembly Bill 2139 and Senate Bill 1363 — would study ocean acidity and promote eelgrass restoration.

“I’m leaving with an optimistic note, which I tend not to as a scientist, but I think the people who make decisions get it, and are ready to do something,” he said.


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

Mar 20 2016

Ocean acidification takes a toll on California’s tide pools at nighttime

A new study, based on the most extensive set of measurements ever made in tide pools, suggests that ocean acidification will increasingly put many marine organisms at risk by exacerbating normal changes in ocean chemistry that occur overnight. Conducted along California’s rocky coastline, the study shows that the most vulnerable organisms are likely to be those with calcium carbonate shells or skeletons.

Ocean acidification is occurring as the oceans absorb increasing amounts of carbon dioxide from the atmosphere, where carbon dioxide concentrations are steadily rising due to emissions from the burning of fossil fuels. Absorption of carbon dioxide changes seawater chemistry, pushing it toward the lower, acidic end of the pH scale, although it remains slightly alkaline. A small decrease in pH affects the chemical equilibrium of ocean water, reducing the availability of carbonate ions needed by a wide range of organisms to build and maintain structures of calcium carbonate, such as the shells of mussels and oysters.

Kristy Kroeker, assistant professor of ecology and evolutionary biology at UC Santa Cruz, is a coauthor of the new study, published March 18 in Scientific Reports. “There is a lot of concern about how ocean acidification is going to affect marine species in the future, but most of our understanding comes from laboratory studies where a single organism is exposed to acidified seawater under very controlled conditions for a short period of time,” Kroeker explained. “In reality, every organism is embedded in a complex community that experiences dynamic environmental conditions that will gradually change over time.”

researchers-400.jpg
 
Researchers studied changes in tide pools near the Bodega Marine Laboratory. (Photos by Ken Caldeira/Carnegie)

tide-pool-400.jpg

An extensive set of measurements recorded daily swings in the chemistry of seawater in tide pools.

Calcifying organisms

In the new study, researchers closely monitored conditions in tide pools along California’s rocky coast, which are isolated from the open ocean during low tides. During the daytime, photosynthesis—the mechanism by which plants use the sun’s energy to convert carbon dioxide and water into sugar, giving off oxygen in the process—takes up carbon dioxide from the seawater and acts to reverse ocean acidification’s effects. At night, however, photosynthesis stops, while the respiration of plants and animals takes up oxygen and releases carbon dioxide. This adds carbon dioxide to the seawater and exacerbates the effects of ocean acidification, increasing the risk to calcifying organisms.

“Tide pools are home to lots of different species that regularly experience daily swings in chemistry,” Kroeker said. “Tide pools can experience particularly corrosive seawater during nighttime low tides, when all of the animals are ‘exhaling’ carbon dioxide into the water that has been cut off from the ocean.”

The research team, led by scientists at the Carnegie Institution of Science, used these natural nighttime spikes in corrosive conditions to examine how entire communities of marine species respond to natural acidification. Observing a variety of California’s natural rocky tide pools near the Bodega Marine Laboratory, they found that the rate of shell and skeletal growth was not greatly affected by seawater chemistry in the daytime. However, during low tide at night, water in the tide pools became corrosive to calcium carbonate shells and skeletons. The study found evidence that the rate at which these shells and skeletons dissolved during these nighttime periods was greatly affected by seawater chemistry.

“Unless carbon dioxide emissions are rapidly curtailed, we expect ocean acidification to continue to lower the pH of seawater,” said lead author Lester Kwiatkowski of the Carnegie Institution of Science. “This work highlights that even in today’s temperate coastal oceans, calcifying species, such as mussels and coralline algae, can dissolve during the night due to the more acidic conditions caused by community respiration.”

These results highlight the vulnerability of marine species in even the most dynamic conditions to the global process of ocean acidification, Kroeker said.

According to coauther Ken Caldeira of the Carnegie Institution, “If what we see happening along California’s coast today is indicative of what will continue in the coming decades, by the year 2050 there will likely be twice as much nighttime dissolution as there is today. Nobody really knows how our coastal ecosystems will respond to these corrosive waters, but it certainly won’t be well.”

The study was a collaborative effort by the Carnegie Institution for Science, UC Davis, and UC Santa Cruz. This work was funded by the Carnegie Institution for Science, UC Multi-campus Research Initiatives and Programs, and the National Science Foundation.


Read the original post: http://news.ucsc.edu/

Jan 12 2016

Dual Impact of Ocean Acidification and Low-Oxygen on West Coast Foretells Future for World Oceans

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SEAFOODNEWS.COM [UW Today] By Michelle Ma – January 12, 2016

The Pacific Ocean along the West Coast serves as a model for how other areas of the ocean could respond in coming decades as the climate warms and emission of greenhouse gases like carbon dioxide increases. This region — the coastal ocean stretching from British Columbia to Mexico — provides an early warning signal of what to expect as ocean acidification continues and as low-oxygen zones expand.

Now, a panel of scientists from California, Oregon and Washington has examined the dual impacts of ocean acidification and low-oxygen conditions, or hypoxia, on the physiology of fish and invertebrates. The study, published in the January edition of the journal BioScience, takes an in-depth look at how the effects of these stressors can impact organisms such as shellfish and their larvae, as well as organisms that have received less attention so far, including commercially valuable fish and squid.

The results show that ocean acidification and hypoxia combine with other factors, such as rising ocean temperatures, to create serious challenges for marine life. These multiple-stressor effects will likely only increase as ocean conditions worldwide begin resembling those off the West Coast, which naturally expose marine life to stronger low-oxygen and acidification stressors than most other regions of the seas.

“Our research recognizes that these climate change stressors will co-occur, essentially piling on top of one another,” said co-author Terrie Klinger, professor and director of the University of Washington’s School of Marine and Environmental Affairs.

“We know that along the West Coast temperature and acidity are increasing, and at the same time, hypoxia is spreading. Many organisms will be challenged to tolerate these simultaneous stressors, even though they might be able to tolerate individual stressors when they occur on their own.”

Oceans around the world are increasing in acidity as they absorb about a quarter of the carbon dioxide released into the atmosphere each year. This changes the chemistry of the seawater and causes physiological stress to organisms, especially those with calcium carbonate shells or skeletons, such as oysters, mussels and corals.

Hypoxia, on the other hand, is a condition in which ocean waters have very low oxygen levels. At the extreme, hypoxia can result in “dead zones” where mass die-offs of fish and shellfish occur. The waters along the West Coast sometimes experience both ocean acidification and hypoxia simultaneously.

“Along this coast, we have relatively intensified conditions of ocean acidification compared with other places. And at the same time we have hypoxic events that can further stress marine organisms,” Klinger said. “Conditions observed along our coast now are forecast for the global ocean decades in the future. Along the West Coast, it’s as if the future is here now.”

Klinger is co-director of the Washington Ocean Acidification Center based at the UW and served on the West Coast Ocean Acidification and Hypoxia Science Panel, which was convened two years ago to promote coast-wide collaboration and cooperation on science and policy related to these issues.

For this paper, the authors examined dozens of scientific publications that reported physiological responses among marine animals exposed to lower oxygen levels, elevated acidity and other stressors. The studies revealed how physiological changes in marine organisms can lead to changes in animal behavior, biogeography and ecosystem structure, all of which can contribute to broader-scale effects on the marine environment.

The tri-state panel has completed this phase of its work and will wrap things up in the coming months. Among the products already published or planned are a number of scientific publications — including this synthesis piece — as well as resources for policymakers and the general public describing ocean research priorities, monitoring needs and management strategies to sustain marine ecosystems in the face of ocean acidification and hypoxia.

The group’s other papers and findings related to ocean acidification and hypoxia will soon be available on its website.

Co-authors of this paper include George Somero, Jody Beers and Steve Litvin at Stanford University’s Hopkins Marine Station; Francis Chan of Oregon State University; and Tessa Hill of the University of California, Davis.

The research was funded by the California Ocean Protection Council, the California Ocean Science Trust, the Institute for Natural Resources at Oregon State University and the National Science Foundation.


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