A weekly series by UPI examining the potential effects of global climate change.
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BOULDER, Colo., Aug. 9 (UPI) From deep ocean to high mountain, the fickle finger of global warming is pointing the way to extinction for some species -- or, at least, to changing the composition of populations.
At the ocean bottom, there has been a surprising link between global warming and animal communities there.
Meanwhile, on the mountaintops, the hardy, slope-dwelling American pika may be the first mammal that succumbs to the vagaries of a changing climate.
Henry Ruhl and Kenneth Smith, marine scientists at the Scripps Institution of Oceanography in La Jolla, Calif., wrote in a paper published in the July 30 issue of the journal Science that animals living in the very deep ocean have been affected by the climate change at the surface.
Ruhl and Smith studied mobile sea cucumbers, brittlestars and other marine creatures that live about 4 kilometers (2.5 miles) deep in the northeastern Pacific. Although ocean layers may not mix for hundreds of years, the scientist found there is a time lag of only 40 to 60 days between particulate carbon flux -- that is, the animals' food supply -- and the upper ocean processes affected by climate and weather.
"Photographic abundance estimates of epibenthic megafauna (large animals in the upper ocean) from 1989 to 2002 show that two taxa decreased in abundance after 1998 by two to three orders of magnitude," the authors wrote, "whereas several other species increased in abundance by one to two orders of magnitude." These changes correlated to climate fluctuations induced by the El Niño/La Niña cycles of the Pacific.
The mechanism by which these changes occur appears to be the variability of the amount and quality of the food supply that sinks to the deep ocean from the surface layers. As the weather above the ocean changes, the composition and amount of food sinking to the bottom changes, inducing alterations in the deep water species composition.
"Abyssal time-series studies of mobile epibenthic megafauna have provided evidence of major megafaunal community changes that are correlated to modern climate variation, as well as to food supply," the authors conclude.
In other words, there is a direct link between climate change and deep ocean animal populations.
It might be surprising that animals so far removed from surface weather can be so directly affected by it, but there is ample evidence emerging that it is happening.
Science News magazine reported recently that work in the Northeast Atlantic Porcupine Abyssal Plain, conducted by the Southampton Oceanography Center in England, confirms the essential findings. In that area, a boom in another sea cucumber's population has coincided with a change in the composition of the surface food supply.
"The compelling thing is that we're finding that climate change impacts all the wildlife we look at," Lara Hansen, chief scientist on climate change at the World Wildlife Fund, told United Press International. "It is hard to find species in which we don't see an impact from climate change."
Research by the WWF also indicates that global warming has contributed to the local extinction of populations of American pika in Great Basin -- the eastern Sierra Nevada and western Rocky Mountains -- during the second half of the 20th century.
Pikas, a smaller relative of rabbits and hares, live in fairly inhospitable conditions, on the talus slopes of mountains near and above timberline. In the western United States, hikers in these remote areas are accustomed to the high-pitched, "Meee! Meee!" that a startled pika will emit before retreating into its rocky burrow.
Conditions for pikas are tough at the best of times. It eats the green plants that grow at high elevations, and spends the short summer season gathering food and storing it for winter like a farmer gathers hay. The pika does not hibernate, but remains active, living on this supply all winter.
"An observer of pikas once noted a fascinating sequence of events, when a weasel, attempting to capture an American pika, was chasing it among the rocks," said a release from the National Wildlife Federation. "When the pika began to tire, another pika emerged and ran between the weasel and the first pika. The weasel then pursued the newcomer until the larger animal tired and withdrew to find easier prey."
Because of its highly specialized lifestyle, pikas are vulnerable to a warming climate. Between 1994 and 1999, WWF surveyed 25 sites where pikas previously had been recorded. They found only 18 of the sites still had pika populations, so 28 percent of the local populations had been eliminated, even though there was no change in the habitat.
"Pikas had apparently vanished from the other seven locations in at most 55-86 years," the WWF release said.
"They are less tolerant of warm temperatures," Hansen told UPI. "This species has a pretty low threshold of how much change it can take."
Populations are disappearing, and climate change is the most likely culprit.
"Anywhere we look, we see the fingerprint of climate change," she added.
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Dan Whipple covers the environment for UPI Science News. E-mail [email protected]
