Category Archives: shellfish

Oyster die-offs – a new culprit?

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Oysters at Whiskey Creek hatchery

Oysters at Whiskey Creek hatchery

For years, research into West Coast oyster hatchery die-offs has pointed the finger at Vibrio tubiashii. Now Oregon State University researchers believe a different, but related, bacterium – V. coralliilyticus – may be the real culprit.

The findings were published in Applied and Environmental Microbiology, by researchers from OSU’s College of Veterinary Medicine, the U.S. Department of Agriculture, and Rutgers University. The research was supported by the USDA.

“These bacteria are very similar, they’re close cousins,” said Claudia Häse, an OSU associate professor and expert in microbial pathogenesis. “V. coralliilyticus was believed to primarily infect warm water corals and contributes to coral bleaching around the world. It shares some gene sequences with V. tubiashii, but when we finally were able to compare the entire genomes, it became apparent that most of what we’re dealing with in the Pacific Northwest is V. coralliilyticus.”

Scientists now say that V. coralliilyticus is not only far more widespread than previously believed, but that it can infect a variety of fish, shellfish and oysters, including rainbow trout and larval brine shrimp. And it appears to be the primary offender in bacterial attacks on Pacific Northwest oyster larvae.

Häse’s previous work with Chris Langdon of OSU’s Molluscan Broodstock Lab has been supported in part by Oregon Sea Grant, which has also worked with Northwest shellfish growers to help them rebound from oyster die-offs. By learning to counter the effects of increasingly acidic seawater, which prevents larval oysters from forming the shells they need to survive, many hatcheries have seen production return.

But while hatchery stocks are recovering, the scientists say bacterial infections remain a real problem for oysters – and other organisms – in the wild.

“Although we’ve largely addressed the problems the hatcheries face, these bacteria continue to pose threats to wild oysters,” Häse said. “And corals are still declining in many places, the Great Barrier Reef in Australia is dying at an alarming rate. Better diagnostics might help in all of these situations.”

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Bivalves on drugs: What goes in the water winds up in shellfish

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Bivalves like oysters assimilate environmental toxins into their body when filtering water.

Bivalves such as oysters assimilate environmental toxins into their body when filtering water.

What happens to an oyster on antidepressants? What about on caffeine? Or, what if you combine these contradictory drugs and then consume the oyster?

As odd as it sounds, this scenario is playing out along the Oregon coast where oysters and other bivalves—a staple food source for both humans and animals— are assimilating low levels of environmental contaminants into their body.  Portland State University researcher Elise Granek and colleagues are studying which chemicals are present, where, and what the effects may be up the food chain.

“The work in our lab is looking at how land based contaminants are affecting marine and coastal animals.” Granek said. “In the long term, what are the effects on humans?”

Bivalves—two-shelled animals such as clams, mussels and oysters—are integral to coastlines for food and structure. Not only do they serve as prime dining for many animals, but their colonies also provide shelter for small fish and invertebrates to hide. Bivalves filter water to feed, and thereby ingest a variety of chemicals from the water.

Granek and her team sampled native oysters at two sites along the Oregon coast to get an idea of what chemicals were present in their tissues. The results were stunning: ibuprofen, anti-inflammatory drugs, antihistamine and more. While each of these drugs was present in levels not considered harmful to humans, Granek is concerned about what the combined impact might be.

“These organisms don’t just have one compound. They have 2, 3, 4 types in them,” she explained. “So what happens when you have multiple of these compounds in one organism? How does that affect that organism or how does it affect predators that eat them, including us? We just don’t know.”

These contaminants likely seep into the water from outdated septic tanks or sewer overflows during storms and other high-water events.

Back in the lab, the team is conducting 90-day controlled experiments on each drug to get a better idea of the physiological effects on the bivalves. After they create a baseline for individual drugs—as early as spring—the lab will start combining different drugs to assess the effects.

“Most people who use pharmaceuticals or personal care products may not have any knowledge that what goes down the drain could harm aquatic and marine life,” said Joey Peters, a graduate student conducting the lab experiments. “I hope the results of this project elucidate one small piece of a growing problem.”

The next step is going back into the field to monitor which chemicals are present in other bivalves. From there, Granek wants to begin evaluating human impacts of eating these contaminated species. That information, she says, will help inform policy.

“My perspective has changed since I had a kid, and I think about all of the contaminants that she is exposed to in our world. Some things are harder to control and some things are easier to control. Food ought to be something that is easier to convince policy makers and managers to protect.”

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Register-Guard: Changing ocean chemistry threatens marine life

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The Whiskey Creek Shellfish Hatchery on the state’s north coast watched oyster larvae die en masse for three years in a row in the mid-2000s — depriving oyster farms along the entire West Coast of seed oysters.

Florence crabber Al Pazar saw baby octopuses, an inch or two long, climb up his crab lines to escape the sea waters in the 2005 season. When he pulled up his pots, the crab were dead.

Eugene fisherman Ryan Rogers, who drags in great piles of salmon on an Alaska purse seiner, has instead brought up nets full of jellyfish in recent years.

“Sometimes we’ll catch 4,000 or 5,000 pounds of jellyfish. They spray all around. We get stung,” he said. “It makes it difficult to bring your net in. You have to let it go and lose the salmon that are in your net.”

Scientists — including many at Oregon State University — are beginning to define the cause of these events. They call it ocean acidification and hypoxia.

Wind, currents and ocean chemistry conspire to create pools of corrosive waters that can be lethal to key commercial species in Northwest waters — and favorable to some nuisance species, such as jellyfish. …

The Eugene Register-Guard examines what OSU scientists – some of them working with Oregon Sea Grant funding – are learning about the causes and consequences of ocean acidification.

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South coast native oysters may survive acidification threat

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Oyster baskets at Whiskey Creek Shellfish HatcheryCOOS BAY – While some West coast oyster stocks are threatened by rising ocean acidity, native oysters on Oregon’s south coast seem to be doing well.

Netarts Bay’s Whiskey Creek Shellfish Hatchery — which produces much of the oyster seed used by commercial farms in the region —has experienced a decline in production that Oregon State University researchers traced directly to ocean acidification.

But biologist Steve Rumrill, director of the Oregon Department of Fish and Wildlife shellfish monitoring program at the South Slough National Estuarine Research Reserve, suspects that the shallow parts of Coos Bay “may be able to act as a sort of buffer,” protecting native Olympia oysters in that area from the shell-destroying effects of ocean acidification.

Another clue could lie in the oysters’ breeding habits, according to George Waldbusser, an OSU biologist who studies oyster reproduction and survival.

“Olympias are brooders,” Waldbusser said, referring to the species’ trait of carrying eggs in an internal chamber for several weeks after fertilization, whereas the Pacific oysters bred in Netarts Bay broadcast their fertilized eggs into the open water, where they are directly exposed to chemical changes at an earlier point in their life cycles, when they may be more vulnerable.

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OSU secures critical funding to continue ocean acidification research

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Oregon State University will receive funds that will help the West Coast’s shellfish industry in its fight against ocean acidification, thanks largely to the efforts of Oregon state Senator Betsy Johnson (D-Scappoose). Receipt of these funds will give a critical boost to Oregon State University’s and the shellfish industry’s efforts to reduce the negative impacts of ocean acidification on shellfish production.

House Bill 5008 allocated $250,000 to Oregon State University. A portion of the funds will be used to continue OSU’s efforts to improve the resilience of oyster to ocean acidification through its selective breeding program at the Hatfield Marine Science Center in Newport. The remaining funds will be dedicated to OSU’s collaboration with industry leaders at the Whiskey Creek Shellfish Hatchery (see “The Whiskey Creek Shellfish Acid Tests” in the current issue of Confluence) on Netarts Bay as they continue to identify better ways to manage the negative effects of ocean acidification on shellfish larvae.

You can read the rest of this story here.

Summer issue of Confluence magazine now online

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The summer 2013 issue of Oregon Sea Grant’s magazine, Confluence, is now online at http://seagrant.oregonstate.edu/confluenceconfluence-2-1-cover

Articles in this issue, which focuses on aquaculture in Oregon, include “The Whiskey Creek Shellfish Acid Tests,” “Priced out of our own seafood,” and “The traveling ornamental defender.”

Millions of dead krill found on Oregon beaches

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Bill Peterson, an oceanographer with the NOAA Northwest Fisheries Science Center in Newport, Ore., says millions of dead North Pacific krill have washed ashore recently between Newport and Eureka, Calif. He says it’s the largest die-off he can recall in recent history.Krill

North Pacific krill primarily live on the eastern side of the Pacific, between southern California and southern Alaska. They’re typically found along the continental shelf, Peterson says. The shrimp-like crustaceans are an important source of food for salmon and other species of fish, birds and marine mammals.

Joe Tyburczy, a researcher with the California Sea Grant Extension office and a former Oregon Sea Grant Knauss Fellow, says the culprit could be hypoxia. Indeed, oceanographic cruises along the northern California coast found lower oxygen levels than usually seen in Pacific Northwest waters. “If it is hypoxia, there’s a possibility of implications for other species like crab,” Tyburczy says.

Another possibility, Peterson says, is that the shrimp were victims of unfriendly weather conditions during their mating cycle, and were driven to shore by high winds.

For the moment, Peterson and Tyburczy are asking that the public keep them informed of any more dead krill sightings. Peterson can be reached at 541-867-0201; Tyburczy at 707-443-8369.

 

Oyster shells help restore chemical balance to acid waters

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Healthy young oyster spatThe shells of oysters – a commercially important shellfish whose reproduction and growth is threatened by climate-linked ocean acidification – may help counteract the effects of increased local acidity levels, according to a new study of New England’s Chesapeake Bay by a team of researchers led by Oregon State University’s George Waldbusser.

The study, published in the journal Ecology and reported this week in the New York Times , concludes that the buildup of old shells in undisturbed oyster beds – along with the oysters’ waste – can help restore alkalinity to waters that might otherwise be too acid for the shellfish to survive.

Like ocean waters around the world, the Chesapeake has become more and more acidic as a result of rising levels of carbon dioxide in the atmosphere. Now, by studying oyster populations in relation to acidity levels,Waldbusser’s team has concluded that oysters — particularly their shells — can play a significant role in reducing that acidity.

“Oyster shells are made out of calcium carbonate, so they’re sort of like an antacid pill,” said Waldbusser, an assistant professor of earth, ocean and atmospheric sciences at OSU and an author of the study. “In an undisturbed oyster reef, healthy oysters are generating a lot of biodeposits,” a genteel term for excrement, “which helps generate CO2 to help break down those shells, which helps to regenerate the alkalinity back into the environment.”

Ocean acidification is of great concern to commercial oyster growers. Additional  research by Waldbusser and colleague Burke Hales, conducted at an Oregon oyster hatchery, has shown that increasing acidity near commercial shellfish operations inhibits the larval oysters from developing shells and growing at a pace that makes oyster farming economically viable.

Waldbusser is also working on a Sea Grant-funded project to develop Web-based tools that would allow oyster growers and resource managers to better understand how acidification affects larval oysters so they can more effectively adapt, mitigate and adjust their operations to increase oyster survival and growth.

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New online booklet explores export capacity of live shellfish in Oregon

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The booklet Development of Live Shellfish Export Capacity in Oregon is available as a free download from Oregon Sea Grant.

There are many opportunities for seafood exporters to earn substantial profit in Asian markets. The trade in live shellfish exports to China could be especially lucrative. In many respects, Oregon’s shellfish industry is well positioned to meet this demand. However, due to certain impediments, interested parties remain largely unable to establish effective means of competing in the Chinese marketplace.

At the request of Oregon Sea Grant, a project was undertaken to provide stakeholders with recommendations for the continuing development of live shellfish export capacity in Oregon. The project was carried out by two investigators in three parts under the direction of Dr. Tim Miller-Morgan, Oregon Sea Grant Extension veterinarian at Oregon State University. Investigations consisted of reviews of literature on current live shellfish shipping practices, research of the prevailing export procedures and the economic and regulatory environments, and visits to sites of special interest and interviews with representative stakeholders.

Findings from this joint investigation formed the basis of this report.

Washington state declares war on ocean acidification

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Washington state, the leading US producer of farmed shellfish, this week launched a 42-step plan to reduce ocean acidification. The initiative — detailed in a report by a governor-appointed panel of scientists, policy-makers and shellfish industry representatives — marks the first US state-funded effort to tackle ocean acidification, a growing problem for both the region and the globe.

The state governor Christine Gregoire,  says she will allocate $3.3 million to back the panel’s priority recommendations.

“Washington is clearly in the lead with respect to ocean acidification,” says Jane Lubchenco, administrator of the US National Oceanic and Atmospheric Administration (NOAA).

As growing carbon dioxide gas emissions have dissolved into the world’s oceans, the average acidity of the waters has increased by 30% since 1750. Washington, which produces farmed oysters, clams and mussels, is particularly vulnerable to acidification, for two reasons: seasonal, wind-driven upwelling events bring low-pH waters from the deep ocean towards the shore, and land-based nutrient runoff from farming fuels algal growth, which also lowers pH.

Read the full story in Nature.

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