New research by the U.S. Geological Survey finds that prey fish and phytoplankton – microscopic organisms that feed other animals – are seriously declining in the Great Lakes.
One of the surprising reasons for the decline seems to be reductions in the phosphorus entering the lakes since the 1972 Great Lakes Water Quality Agreement was signed. Invasive species, such as zebra mussels and quagga mussels, also were identified in the research as a possible cause for a decline of phosphorus and the impact on fish and phytoplankton.
Read a USGS news release describing the research. Download the research paper, published in December in the journal BioScience.