USGS - Science for a changing world

Are Melting Glaciers Disturbing Alaska’s Ecosystems?

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Mountains towering above the mouth of the Copper River from the coastal Gulf of Alaska.

As warming temperatures cause glaciers to melt, the flow of freshwater in the Gulf of Alaska changes and impacts are felt across coastal ecosystems. Increased water flow can flush higher levels of iron and nitrate into coastal waters, and these compounds can radically alter the production of phytoplankton and zooplankton (tiny, free floating organisms), which serve as food for seabirds and fish such as salmon. Glacier runoff is of particular concern in the Copper River, which is the Gulf’s largest freshwater source and a major salmon production area.

How will accelerated glacial melting over the next 50 years as a result of climate change affect the unique Gulf of Alaska and Copper River coastal ecosystems? USGS scientists are studying these processes and impacts.

Planktic Foraminifera collected from a sediment-trap moored in the northern Gulf of Mexico, magnified 255x.

An extensive field campaign in 2010 included three oceanographic cruises studying the Copper River plume and adjacent regions off of the coast, six monthly river-sampling trips, and stream flow monitoring of several rivers. Modeling of these systems is also underway, including a predictive ecosystem model of the Gulf of Alaska. In addition, a glacier component is being added to an existing and widely-used water model. Model results will be an important resource for resource managers, as will mapping of current glacial areas using high resolution satellite imagery. These results will help scientists and resource managers assess the potential impacts that future changes in glaciers may have on the environment.

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Contact: John Crusius                                    (206) 543-6978