The organic matter of the gulf's watersheds is "remarkably" biologically active and is likely to decrease as glacial ice melts and the biomass is not replenished, said Rick Edwards, an aquatic ecologist with the Pacific Northwest Station in Juneau, Alaska.
The organic matter supports life to the highest level of the marine food chain, Edwards and his team wrote in a recent issue of the journal Nature.
Some of the organic matter discharged from the watersheds is almost 4,000 years old, yet more than 66 percent of it is rapidly metabolized by marine microbes into living biomass to support the food chain, said Eran Hood, a researcher from the University of Alaska Southeast.
"We don't currently have much information about how runoff from glaciers may be contributing to productivity in downstream marine ecosystems," Hood said. "This is a particularly critical question given the rate at which glaciers along the Gulf of Alaska are thinning and receding."