Ocean warming harms wildlife
SCIENTISTS UNSURE WHAT CAUSED CHANGE
By Glennda Chui
Unusually warm conditions off the West Coast this year are hammering wildlife, and scientists don't know why -- or what it bodes for the future.
Tens of thousands of seabirds failed to breed this spring. While sea lions still bark and bicker at Santa Cruz wharf, they've all but vanished from the waters of Monterey Bay. So have krill, small crustaceans that are food for seabirds and whales. Meanwhile, toxic algae that cause ``red tides'' are thriving.
None of this would be unusual in a strong El Niño year, which sends a pulse of warm water from the tropical Pacific to the coast of the Americas. But last winter's El Niño was weak and already has dissipated.
``This is clearly a bad one, and the evidence is coming from the marine life, dead seabirds and warm-water creatures on the inshore,'' said Nathan Mantua, a climate scientist at the University of Washington.
``I don't have any good ideas about why this is happening,'' he said. ``There's no pattern I can draw out of this that really makes sense to me.''
At the Farallon Islands, the largest seabird colony in the continental United States with about 250,000 birds from a dozen species, biologists say the impact has been unprecedented in the 35 years they've been monitoring.
Cassin's auklet, a small burrowing bird that feeds on krill, produced almost no young this year, with many birds abandoning their nests, said marine biologist Russell Bradley of the Point Reyes Bird Observatory.
Other bird species there were at least two to three weeks late in breeding, Bradley said. Now, he said, ``they're pressed up against a wall in terms of getting finished'' before summer ends.
While most of these birds are long-lived and can make up their loss if conditions are better next year, he said, ``There's concern that the frequency of these events may be increasing.''
The pigeon guillemot, a small, swallow-like seabird, failed to nest this spring in the cliffs around Santa Cruz. Bird breeding also plummeted at Año Nuevo Island off the San Mateo County coast.
``For all those fish and birds and mammals that depend upon springtime, it's over. It's done,'' said William Peterson, an oceanographer with the Northwest Fisheries Science Center in Newport, Ore. ``They're not going to lay eggs now. It's too late.''
One factor behind all this havoc seems clear enough: Strong winds that normally blow in off the ocean failed to arrive this spring. Without them, a critical process that brings cold, nutrient-rich water to the surface could not get going.
This upwelling should have been in full force by May, nourishing a food chain that links microscopic plants and animals with fish, seabirds, sea lions, whales and fishermen.
Without it, seabirds and whales had less krill to eat. Market squid -- the calamari on restaurant menus -- were scant. Sea lions were forced to travel farther out to sea in search of fish.
Volunteers who patrol central California beaches found an unusually high number of dead seabirds from January through May, most with clear signs of starvation.
All along the coast, from California's Point Conception to Alaska and the Aleutian Islands, the surface waters in May were up to 3.6 degrees warmer than normal, according to the National Oceanic and Atmospheric Administration.
Although the winds have now kicked in and some upwelling has started, it's been sporadic and weak, according to biologists and oceanographers who monitor conditions off the coast.
It's not clear whether these anomalies are related to global climate change, part of a natural climate cycle or both.
Researchers estimate that the Earth has warmed by about a degree since the late 1800s, and that gases released by human activity will raise temperatures in California by at least 4 to 6 degrees by the end of the century.
The warming has penetrated into the top few hundred yards of the world's oceans, according to a report this month in the journal Science.
Given those changes, it's not surprising to see impacts on wildlife, said John McGowan, a biological oceanographer at Scripps Institution of Oceanography in La Jolla.
Studies over the past 50 years along the California coast show that as the top layer of the water warms, it becomes more difficult to mix and stir the ocean and bring cold, nutritious water to the surface, he said.
``That has, I think, all kinds of unpredictable consequences, except it's all bad and we don't know how bad,'' he said. ``It's changing things in unexpected ways. It's a huge, large-scale thing, ocean-wide, and biologists are not used to doing ecology on scales of that size.''
But there are also natural forces at work. One natural cycle warms and cools the waters off California roughly every 20 years. It flipped to a warmer state in 1977 and then to a cooler and more productive one in 1998. In 2002, far earlier than expected, it again shifted to a warm phase, and has been stuck there since.
``Every year we're faced with this puzzle of trying to determine what are the causes'' of a given weather pattern, said Mantua. ``Most of the time there are multiple causes that lead you to where you are.''
In Monterey Bay, scientists have been going out in ships once a month to monitor wildlife along seven imaginary lines that extend 10 to 13 miles from shore.
Last week they saw almost no California sea lions, which should be plentiful this time of year. From studies of adult male sea lions that were tagged last winter, it appears that the animals are swimming farther out to sea in search of fish, said Michael Weise, a graduate student in marine biology at the University of California-Santa Cruz.
He said there are now about 1,000 to 1,500 sea lions at Año Nuevo Island -- compared with 5,000 to 6,000 in a typical July -- as well as more reports of dead sea lions there.
On the other hand, last week's survey did spot three blue whales and 12 humpback whales in the bay -- ``about what we'd expect in July,'' said Donald Croll, a marine biologist at UCSC. It was a relief, he said, since no whales were seen in June. But it was also a puzzle, since the krill on which they feed are down sharply in number.
``It's kind of scary,'' said David Gardner, a biologist with Pt. Reyes Bird Observatory who monitors seabirds at Año Nuevo.
``Then again,'' he said, ``the ecosystem is very dynamic. Hopefully this is an unusual year, and they'll come back strong next year. But we cannot tell.''
Contact Glennda Chui at [email protected] or (408) 920-5453.
This is the Second of Two, here is the first:
From the Chronicle, July 12, 2005 Front Page, above the fold:
Add to that the FOLLOWING:
The Arctic is hitting 98 degrees!