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Pacific Coast Ecosystems Return to Normal

August 17, 2005

SAN FRANCISCO — The northerly winds that sustain the Pacific Coast’s marine ecosystems have returned, but their arrival came too late for fish and birds that couldn’t survive the unseasonably warm waters.

Coastal ecosystems rely on winds blowing south to push warmer surface waters away from shore and bring up colder water from the ocean bottom. That upwelling of nutrient-rich water feeds massive blooms of plankton – the tiny plant-like organisms that form the basis of the marine food web.

The winds usually start blowing in March or April, but when they didn’t arrive this spring, researchers saw the effects up and down the coast – higher ocean temperatures near the shore, very little plankton, a drop in groundfish catches and a spike in dead seabirds on beaches.

The winds finally returned in mid-July and generated the long-delayed upwelling and a dramatic increase in plankton populations, according to researchers who recently returned from ocean-monitoring trips.

“We’re not sure why the winds didn’t come (in the spring), but the situation has remarkably changed, and the ecosystems seem to be getting back to normal,” said William Cochlan, a marine ecologist at San Francisco State University, who spent most of July monitoring algae off the coast of Washington and British Columbia.

Earlier this summer, bird researchers along the coast reported a sharp increase in deaths of seabirds such as common murres, Brandt’s cormorants and Cassin’s auklets. Marine biologists reported unusually low counts of juvenile salmon and rockfish.

William Peterson, an oceanographer with the National Oceanic and Atmospheric Administration in Newport, Ore., said ocean conditions have normalized off the coasts of California and Oregon, but it’s too late for many species.

Peterson and other scientists hope the coastal waters stay cold through the fall and carry over until next spring. They warn that the biological effects of this year’s oceanic disruption could be felt for months, or years.

Some researchers suspect that global warming – the rise in temperatures blamed on emissions of greenhouse gases such as carbon dioxide – may have played a role in delaying the winds, but a connection is difficult to prove because atmospheric systems are so complex. Peterson wants to bring together scientists from different fields to discuss what happened.

“There’s no doubt that the planet’s warming, but who knows how it’s going to affect the coastal systems,” Peterson said. “It certainly was an odd year. If we could figure out what might have caused it, then maybe we could predict it in the future.”




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