Acidification threatens wide swath of sea life

No one knows how — or when — ocean acidification will impact Puget Sound’s sea life. But scientists around the globe are finding corrosive water can alter marine systems in strange, subtle and sometimes worrisome ways.

DABOB BAY, Hood Canal — Inside the burbling tubs of the Taylor Shellfish hatchery here, oysters are incubating once again. But no one believes things are really back to normal.

Several years after oyster larvae around the Northwest began dying by the billions, hatcheries like this one are again ramping up production.

But that’s just because they’ve learned to avoid pumping in problem seawater.

Few know better than Northwest oyster growers that ecological upheaval is still rattling their industry — and that it may be a sign of greater marine-world shifts to come.

Pacific oysters in the wild on Washington’s coast haven’t reproduced in six seasons. Scientists suspect ocean-chemistry changes linked to the fossil-fuel emissions that cause global warming are helping kill these juvenile shellfish.

The oceans are becoming more acidic, and that corrosive water is finding its way into Puget Sound.

No one knows how it will impact the Sound’s sea life. But scientists in laboratories around the globe increasingly find corrosive water can alter marine systems in strange, subtle and sometimes worrisome ways.

Waters with a mildly lower pH can change the metabolism of squid, making them more lethargic. The increase in acidity can dramatically alter the shape of sea-urchin larvae. Corrosive waters have been shown to foul up the way some young fish sniff out prey — convincing them it’s safe to move directly toward predators. Some young brittle stars and barnacles start dying early in these waters, while larval tunicates, fist-size bloblike sea creatures, thrive and develop faster.

Acidification also can make marine waters noisier, which may have implications for killer whales and other animals that use sonar.

Researchers are scrambling to expand lab facilities in the San Juan Islands and at NOAA Fisheries in Montlake. They hope to predict the reactions of Northwest creatures — from algae and plankton to fish, clams, crab and bacteria.

“What I’m most worried about is the bottom of the food chain,” things such as plankton and other small sea creatures, said John Guinotte, a marine biogeographer with the Marine Conservation Biology Institute in Bellevue. “We’ve got some of the lowest pH levels found anywhere, but we don’t have any idea what the biological impacts are.”

The marine environment is complex and resilient. New impacts could appear in a few years — or decades. In the meantime, it’s hard to re-create a world in constant flux, with its shifting currents and warm- and cold-water cycles and acidity levels that shift with photosynthesis and marine-life respiration.

“You can’t really try to mimic evolution,” said Victoria Fabry, a professor of biological sciences at California State University, San Marcos. “In a sense, the world is in the middle of that experiment right now.”

But the oyster industry’s misfortune has given science a leg up.

Oysters’ fate up to wind?

In their early stages, young oysters look like mud.

In Dabob Bay, Taylor Shellfish hatchery technician Jason Brush pulled some 10 million microscopic larvae from a tank, strained the black goo and packaged them for sale.

The hatchery is having one of its best years, but people here attribute that to luck.

The facility grows oysters in seawater drawn off Dabob’s surface. But this year, south breezes have kept corrosive waters down deep, far below where Taylor slurps up its water.

“We basically think we’re being saved by the wind,” said chief hatchery scientist Benoit Eudeline.

The pH of the world’s oceans typically measures a slightly alkaline 8.1. But scientists long have predicted climate change would make waters more corrosive as carbon dioxide taken up by oceans dissolves.

But only in trying to understand why oyster-growing was falling apart did oceanographers figure out what made the West Coast unique: Waters down deep were acidifying more than anyone thought and were coming closer than anyone expected to shore, where most sea creatures live.

Deep, cold water typically carries more carbon dioxide than surface waters, but northwest winds regularly push those waters up along the coast in “upwelling” events. In some cases, that brings water to shore with a pH as low as 7.7, lower than anything scientists expected to see for decades.

“Nobody had thought about those upwelling events,” said NOAA oceanographer Richard Feely. “They didn’t predict any impacts along the coast until we observed them.”

Craig Welch, Seattle Times, 31 July 2010. Full article.


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