PARENT SESSION
Oral Session #61: Aquatic Ecology: Fish - Communities and interactions. Presiding: J. Chick.
Thursday, August 9, 2001. 8:00 AM to 11:45 AM. Hall of Ideas F.
Dynamics of the Lake Michigan food web, 1970-2000.
MADENJIAN, CHARLES1, FAHNENSTIEL, GARY2, JOHENGEN, THOMAS3, NALEPA, THOMAS2, VANDERPLOEG, HENRY2, FLEISCHER, GUY 1, SCHNEEBERGER, PHILIP4, BENJAMIN, DARREN5, SMITH, EMILY6, BENCE, JAMES6, RUTHERFORD, EDWARD 3, LAVIS, DENNIS7, ROBERTSON, DALE 1, JUDE, DAVID3, EBENER, MARK8, 1 2 3 4 5 6 7 8
ABSTRACT- We document changes in the Lake Michigan food web between 1970 and 2000 and attempt to identify the factors responsible for these ecosystem changes. Dramatic recoveries of lake whitefish (Coregonus clupeaformis) and burbot (Lota lota) populations, as well as the spectacular buildup of salmonine populations, were attributable to sea lamprey (Petromyzon marinus) control. Based on our analyses, salmonines were primarily responsible for the substantial reduction in alewife (Alosa pseudoharengus) population size during the 1970s and early 1980s. In turn, control of the alewife population probably contributed toward recoveries of deepwater sculpin (Myoxocephalus thompsoni), yellow perch (Perca flavescens), and burbot populations during the late 1970s and 1980s. Decrease in the abundance of all three dominant benthic macroinvertebrate groups, including Diporeia, oligochaetes, and sphaeriids, during the 1980s in the nearshore (> 50 m deep) waters of Lake Michigan was believed to be due to a decrease in primary production linked to a decline in phosphorus loadings between 1980 and 1987.
KEY WORDS: Lake Michigan, food web, anthropogenic stressors, dynamics