A study done on Juneau's glaciers shows that the hulking blocks of ice produce high-quality food for the organisms that live in downstream rivers and the ocean.
The information will help scientists better understand marine food chains as glaciers continue to shrink, said researcher Eran Hood, a University of Alaska Southeast associate professor who led the study.
The report is published in today's issue of Nature, a weekly international journal of science.
The basic purpose of the research was to determine how water chemistry is different in rivers fed by glaciers compared to those that aren't.
The scientists found that glacial waters supply more carbon to marine micro-organisms. In some cases, the carbon being metabolized was thousands of years old. Larger organisms feed on the microbes, and on up the food chain.
While the finding means that runoff from glaciers could contribute to healthy marine life, it does not say glacial retreat spells doom for the ecosystems, Hood said.
"This study helps us understand the role glaciers play, but it doesn't definitely prove if it's better that they're there or not there," he said.
Hood teaches environmental science and geography at UAS.
Samples were collected in 2008 on 11 coastal watersheds in the Gulf of Alaska, including five on the Juneau road system. They were tested at the U.S. Forest Service Forestry Sciences Laboratory in Juneau.
The research documents an interesting paradox, said Rick Edwards, a co-author on the study and a scientist at the Pacific Northwest Research Station of the U.S. Forest Service.
Scientists expect that organic matter becomes less biologically active over time, yet waters tested in this study were nearly 4,000 years old. A high percentage - 23 to 66 percent - was metabolized by marine microbes and incorporated into the food chain, Edwards said.
The article, "Glaciers as a source of ancient and labile organic matter to the marine environment," was authored by Hood, Edwards and University of Alaska Fairbanks Ph.D. student Jason Fellman; Robert G.M. Spencer and Peter J. Hernes of the Department of Land, Air and Water Resources at the University of California Davis; David D'Amore of the Pacific Northwest Research Station of the U.S. Forest Service in Juneau; and Durelle Scott of Virginia Tech.
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