Glacial nitrogen
Melting glaciers in the American West are releasing chemicals that cause ecosystem changes in alpine lakes, including large quantities of nitrogen that reduce biodiversity, according to an international research team led by University of Maine paleoecologist Jasmine Saros.
The study, funded by a $509,000 grant from the National Science Foundation, determined that glaciers in alpine watersheds are the largest geomorphic and biogeographic influences of nitrate concentrations in high-elevation lake ecosystems.
Nitrogen is a key limiting nutrient in alpine lakes that can dramatically affect ecosystem productivity and species diversity.
The researchers from UMaine, Miami University, the U.S. Geological Survey, University of Nebraska – Lincoln and the University of Alberta studied the ecosystems of 26 high-elevation lakes in the northern and central U.S. Rocky Mountains, where atmospheric nitrogen deposition is low and where alpine glaciers have receded substantially in the 20th century.
Those lakes fed by melting glaciers and snow had up to 100 times higher nitrate concentrations and lower algal biomass than those fed solely by snowpack. In those lakes affected by glacial melt, sediment diatoms were less diverse than at any other time in the past century.
