http://www.oregonlive.com/news/oregonian/index.ssf?/base/news/1151733444141130.xml&coll=7
Cycle of life in ocean spinning into extremes
- Models suggest climate change is causing
strange disruptions among organisms off the coast
July 02, 2006
MICHAEL MILSTEIN
The ocean is behaving strangely along the west
coast in the latest of a string of unusual years,
with scientists reporting crashing bird populations
off California for the second consecutive year and
hiccups in the nutrients that feed marine life off
Oregon.
It has researchers wondering more openly whether
global warming is driving unpredictable shifts with
repercussions for familiar species such as seabirds
and salmon.
"The evidence is accumulating that climate
change is likely disrupting the atmospheric and
oceanic processes that drive our ocean system," said
Jane Lubchenco, a professor of marine biology at
Oregon State University.
Although the ocean's behavior is always
changing, "we're seeing more variability in some new
and bizarre ways," she said.
Usually summer along the west coast brings a
shift in wind patterns where breezes begin blowing
from the north. The winds push water offshore,
making way for cold water rich in nutrients to well
up, conveyor-like, from the deep ocean.
The nutrients carried by the upwelling of deep
water are an essential ingredient in the rich marine
life along the Oregon Coast. They nurture tiny
plants known as phytoplankton, which in turn feed a
chain of sea life including salmon and other fish,
whales and seabirds.
Upwelling usually shows up first along
California by April, said Frank Schwing, director of
the Environmental Research Division of the federal
Southwest Fisheries Science Center in Pacific Grove,
Calif. But it has not happened this year.
"There's just not enough feeding the food
chain," he said.
Many seabirds that usually nest in great numbers
on the Farallon Islands near San Francisco abandoned
their nests, probably because they could not find
enough food, said Jesse Irwin, a biologist at
Farallon National Wildlife Refuge.
It's not as grim in Oregon. Winds began bringing
nutrients up from the deep ocean about the end of
April, said Bill Peterson, an oceanographer at the
Northwest Fisheries Science Center in Newport.
But the winds died out for two to three weeks in
late May, interrupting the flow, he said. That has
set back phytoplankton growth, which remains below
normal.
So far, though, it's not as bad in Oregon as it
was last year.
Upwelling came roughly two months late last year
to most of the west coast, especially Oregon,
leaving waters starved of nutrients, plankton scarce
and many other species starving. Seabirds washed up
dead on beaches in record numbers with nothing in
their stomachs and some salmon nearly disappeared
from coastal waters.
But when the upwelling finally arrived last
year, it did so with a vengeance.
Plankton multiplied so rapidly it died off and
sucked oxygen from the water as it decayed, creating
an eerie "dead zone" off the coast that further
stressed sea life, Lubchenco said.
"We went from no upwelling to very intense
upwelling," she said.
Similar dead zones appeared in 2002 and 2004.
The striking shifts match what climate models
suggest will happen as greenhouse gases accumulate
in the atmosphere, causing global warming,
researchers said. For instance, some models suggest
that coastal upwelling will begin later each year,
Schwing said.
"Certainly there's consistency there that's
intriguing," he said.
Research also suggests warming will lead to the
kind of unpredictable and extreme swings in
conditions the Oregon coast has seen in the last few
years, Lubchenco said.
"We're just seeing much greater variability in
ways that have consequences at least for some
important species," she said. "We have to build into
our management of the ecosystem the expectation it's
going to be more variable. We need to expect some
surprises."
Biologists at national wildlife refuges along
the Oregon coast do not have the staff to track the
nesting success of birds, so they're not yet sure
how Oregon populations have done this year, said Roy
Lowe, manager of the refuges.
Few starved seabirds have washed up on beaches
so far. But last year they did not begin turning up
in large numbers until July.
He said Oregon bird populations need a few
productive years to help recover from declines they
suffered last year.
Michael Milstein: 503-294-7689; michaelmilstein@news.oregonian.com
|
