Adapting to a Changing Ocean

Netarts Bay. (Photo by iStock.com/skibreck, single seat license only.)

The Pacific Northwest may be among the most well equipped regions in the country to adapt to changing conditions.


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n 2007, Netarts Bay just west of Tillamook became the epicenter of a warning of seismic proportions to the West Coast seafood industry. In rearing tanks at the Whiskey Creek shellfish hatchery, nearly all oyster larvae died that summer and the next. Alarms went off in oyster farms up and down the coast.

Oyster farming may not match Dungeness crab or pink shrimp as a moneymaker, but in West Coast states, annual revenues typically exceed $80 million, and the industry employs more than 1,000 people. And Whiskey Creek is the main supplier for larvae or “seed” for oyster farmers from California to Alaska.

Mark Wiegardt operates a small oyster farm on the southern end of the bay and co-owns the hatchery with Sue Cudd, his wife. He remembers it like a bad dream. “We had three or four months when we had zero production. We’d never seen anything like it,” Wiegardt told Oregon Sea Grant’s Confluence magazine in 2013.

Alan Barton, manager at Whiskey Creek, discovered the cause of the die-off — acidified ocean waters. While the story of how he worked with Chris Langdon, George Waldbusser, Burke Hales, and other Oregon State University researchers to solve the problem has been told in news media outlets and magazines across the world, there is more to the story.

Adapting to the new normal

Today, larval oyster production has returned to near normal, thanks to a simple but innovative solution. Using a sensor-based system developed by Hales, Whiskey Creek monitors water piped in from the bay. The pH (a measure of acidity) is adjusted automatically by pumping sodium carbonate — aka washing soda or soda ash, available in bulk at the local feed store — into the rearing tanks. Some have called it the Tums solution.

Down the coast at the Hatfield Marine Science Center in Newport, scientists are finding signs that other commercially harvested marine animals — abalone, shrimp, cod, rock sole, Dungeness crab — may be affected by ocean acidification and its siblings — low dissolved oxygen (aka hypoxia) and toxin-producing plankton blooms. In research elsewhere, even salmon have shown behavioral changes in acidified water.

As CO2 rises in the atmosphere, there may be no long-term fix for the problem of ocean acidification. Globally, the oceans absorb about a quarter of annual CO2 emissions and are now 30% more acidic than they were in pre-industrial times. Scientists have also shown that in the last two decades, persistent summer winds along the West Coast have brought deep-ocean water — more acidic and lower in oxygen than surface waters — with increasing frequency onto the continental shelf.

Like sailors trying to stay ahead of a gathering storm, scientists and seafood businesses are racing to adapt to these trends. In 2016, Oregon State marine ecologist Francis Chan and a team of colleagues reported in the journal Nature that highly acidified waters were exposing fish and shellfish in estuaries and other near-shore waters to “some of the lowest, but also some of the most dynamic pH environments currently known for surface marine systems.”

It’s likely, say Chan and other scientists, that populations of organisms repeatedly exposed to these conditions are able to adapt. However, they add, environmental stress can also reach thresholds, beyond which organisms are less resilient or simply die. The canary in this mine may be Whiskey Creek’s oysters.

More creatures. More research.

Netarts is among those places that can lay claim to being the heart of Oregon’s shellfish industry. For thousands of years, the estuary supplied native people with oysters and clams. Middens, some six-feet thick, testify to the historical abundance of shellfish in addition to the bounty of crabs, fish, seals, and other animals in the bay.

When white settlers arrived in the 1860s, they began harvesting the native Olympia oyster for commercial purposes, even exporting them to San Francisco by ship and mule train. A shantytown called Oysterville emerged at the head of the bay. Within a few decades, Olympia populations had plummeted. In the 1920s, growers began replacing it with a larger, faster-growing variety, the Pacific oyster from Japan.

Today, Netarts hosts oyster farms, a state-managed shellfish preserve and Whiskey Creek, one of the country’s largest shellfish hatcheries, named for the bay’s major tributary. The region is also home to retirees, a state park, RV resorts and campgrounds. A narrow sand spit shelters popular clam digging and fishing spots from the open Pacific.

To understand how organisms in Netarts Bay and other estuaries will respond to increasing acidification, researchers expose shellfish, crustaceans, and finfish to waters with varying amounts of oxygen and with low, moderate and high CO2 concentrations. By doing this with animals at larval, juvenile and adult stages, scientists are discovering if, when and how seriously these commercially important species are affected by changing acidity.

Since sensitivity can vary at each stage, impacts may occur well before these animals become adults. In human terms, imagine a child deprived of essential vitamins. If the young survive, their function as adults may be impaired, but the damage can be traced back to earlier stages of life.

Hannah Gossner, a master’s student working with Chan, focused on Dungeness crab and red abalone. She found that in both species, respiration rates (a health indicator) decreased in response to increasing acidification and to low oxygen. However, crab appeared to be more strongly affected by hypoxia than by increasing acidity. Abalone, in contrast, showed sensitivity to both.

George Waldbusser, Oregon State marine ecologist, worked closely with Mark Wiegardt, Alan Barton and others at Whiskey Creek when oysters were dying there, and he has continued to explore the response of oyster larvae to acidified water. In 2013, he and master’s student Elizabeth Brunner showed that larvae fail to develop normally in water acidified at levels that currently upwell on the Oregon coast.

As they grow, larvae run a race against time. Although tiny, about the width of a human hair, they must develop shells and other organs that enable them to withstand environmental stresses. High acidity can prevent them from reaching that threshold.

Working with Waldbusser at Whiskey Creek, Ph.D. student Iria Giménez Calvo exposed batches of oyster larvae to varying levels of acidity and tracked their growth responses. She produced a computer model, the ocean acidification stress index for shellfish, or OASIS. In the journal Elementa, she reported that the model can help shellfish growers predict how their operations will be affected by acidification.

It also turns out that native sea grass (Zostera marina) may assist oysters in resisting the effects of acidity. In trials with Whiskey Creek oysters in Netarts Bay, Waldbusser and his students found that the best growth occurred in beds of Zostera. That may be, he said, because when these sea grasses are actively growing, they reduce CO2 in the water to pre-industrial levels. Such effects, he says, were seen for shorter periods of time with a non-native sea grass species.

With support from Oregon Sea Grant, Waldbusser has also been studying how Oregon pink shrimp respond to acidification. Graduate students working in his lab in Corvallis have found that shrimp grow more slowly when exposed to water with acid levels that occur now on the Oregon coast. Waldbusser is repeating those experiments. Shrimp, he stresses, is often Oregon’s second largest commercial fishery, bringing in as much as $30 million in annual landed value.

In addition, finfish species have received attention from researchers. Tom Hurst of the Alaska Fisheries Science Center in Newport has been studying three commercially important fish species — walleye pollock, Pacific cod, and northern rock sole. He found that pollock are resilient in the face of higher acidity, while cod and sole may be more vulnerable at early life stages.

At the University of Washington, scientists reported last winter that acidification reduced the ability of coho salmon to detect smells that they would typically avoid. By changing the way salmon avoid predators or detect prey, they added, higher acidity could have far-reaching consequences for salmon populations and marine ecosystems.

More trouble is brewing near the base of the marine wood web. Researchers at the NOAA Pacific Marine Environmental Lab in Seattle have found evidence that acidified waters are weakening the shells of a type of plankton known as a pteropod — a significant food for salmon, herring, and other fish. Their findings show how acidification impacts can amplify through the food chain.

A more resilient future

Compared to aquaculture operations like Whiskey Creek, wild fisheries are in a more precarious position, says Caren Braby, Marine Resource Program manager with the Oregon Department of Fisheries and Wildlife. “With oysters, you can control exposure of the animals to the environment in the hatchery. There are culture practices. With wild stocks like Dungeness crab, there is no such ‘spigot’ that you can turn on and off. They are exposed to whatever nature throws at them.”

Oregon’s Dungeness crab regulations provide an example of what it takes to manage a wild fishery in the face of changing ocean conditions. During the crab season, the Marine Resource Program monitors razor clams from selected locations every two weeks for biotoxins produced by harmful algal blooms. When toxins are found, crabs are then sampled — both the viscera and the white meat — to determine if they are safe to eat.

The process requires fishermen to bring crabs to regulators for testing. “That’s one of the best examples of wild fishery impacts and management response, maybe globally,” says Braby.

The future of both wild and farmed species may lie in understanding their genetics. At the Hatfield Marine Science Center, Chris Langdon, professor in the College of Agricultural Sciences at Oregon State, has been breeding oysters since 1996. Among the primary goals of the Molluscan Broodstock Program are rapid growth and resistance to disease — and now resilience in the face of acidification.

Chris Langdon with a mesh bag of oysters

Working in Langdon’s lab, Evan Durland, a graduate student, showed that oysters can be domesticated to better perform under hatchery conditions and, as a consequence, are more adapted to acidified conditions that are similar to what currently upwells during the summer along the Oregon coast.

Durland also found that acidification had its greatest impacts at the larval stage. His experiments showed that exposure to acidified conditions affected hundreds of genes. Among them are genes responsible for membranes critical to calcium transport, which is vital in building shells. Nevertheless, Durland’s work also suggests that the initial adverse effects are reversible as larvae develop.

Using such results to breed a more resilient oyster will take time. “It’s unlikely that there are a handful of genetic markers that can be easily used to identify stocks tolerant of ocean acidification,” says Langdon. “Selecting stocks based on hundreds of markers is very difficult.”

Nevertheless, there may be a silver lining. In research funded by the National Science Foundation, Langdon, Waldbusser and a team of researchers found that the native Olympia oyster — the species harvested nearly to extinction in Netarts and other locations in the late 1800s — is much more resistant to acidification than is the Pacific oyster. Rather than reproducing by broadcasting eggs and sperm into the water, as Pacific oysters do, Olympia oysters internally fertilize and brood their young for 10 to 12 days before releasing them. “This is good news for the long-term viability of populations of native Olympia oysters,” says Langdon.

The Pacific Northwest may be among the most well-equipped regions in the country to respond to changing conditions, adds Waldbusser. “The hazard from acidification may be high in the Northwest, but when you look at indicators of adaptation potential, it turns out we have a high capacity to adapt.”

With funding from NOAA, Waldbusser is working with Oregon State colleagues David Wrathall and David Kling to evaluate the social and economic vulnerability of the West Coast shellfish industry. “The natural science is important, but the economy and social structure are a big part of the story,” Waldbusser says.

Perpetual Innovation

For oyster growers and other parts of the seafood industry, climate change and acidification raise the ante for research. The solution developed in 2007 at Whiskey Creek may not be adequate in the future. As nature deals a deck of unpredictable impacts, scientists and their allies face ongoing challenges to understand environmental changes and to help producers respond.

Staying in front of the science necessary to adapt can seem like an uphill race in sand. But that is where the seafood industry’s future resides — with relentless focus and perpetual innovation.

That invisible hard work is constant. It is critical. And, it is happening every day.


By Nick Houtman

 

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