Melting glaciers feed marine life with ancient carbon

Washington, December 31 (ANI): A new study has determined that glaciers that naturally melt each summer along the Gulf of Alaska flush out huge amounts of ancient carbon, made up mostly of dead microbes, which feeds Alaska's marine animals.

According to a report in National Geographic News, those microbes had feasted on ancient carbon from boggy forests, which lined the Alaska coast between 2,500 to 7,000 years ago and were later trapped under glaciers.

Once released via glacial melt, the dead microbes provide a tasty treat for living microbes, which are at the base of the marine food web, according to researchers.

Previous studies had shown that carbon from living forests eventually makes its way into fish through the water cycle, so "fish are made out of the forest," said study leader Eran Hood, an environmental scientist at the University of Alaska Southeast in Juneau.

The new study reveals that "the same kind of thing-the fish are probably made out of carbon from glaciers," Hood said. "This is a surprising thing we didn't know before," he added.

Glacial melt may even have a hand in maintaining Gulf of Alaska fisheries, some of the most productive in the country, he added.

For their research, Hood and colleagues analyzed organic matter in runoff from 11 coastal watersheds in 2008, during the annual peak of glacial melting.

The team sampled streams running through watersheds with different amounts of glacial coverage.

Watersheds with no glaciers at all would be expected to contain less meltwater, while those dominated by ice would be filled with glacial runoff.

What they found is that streams fed by glacial melt had a surprising amount of easily digestible, or "bioavailable," carbon.

In addition, the more glacially rich the water, the older the carbon-up to 4,000 years old.

The new study goes against a long-held belief that older carbon is less palatable to simple organisms, according to Hood.

"But in our case the older it was, the more the microbes wanted to eat it," he said.

That's mainly because glacial carbon is made of dead microbes that have been essentially preserved in ice.

The dead microbes contain more easily digestible nitrogen and not much lignin, a plant compound that's tough for microbes to break down.

Overall, the contribution of glaciers to the productivity of rivers and oceans is "greatly underappreciated," according to the researchers. (ANI)