Benthic Macroinvertebrates of the St. Lawrence Great Lakes

The history of Great Lakes benthic research from 1870 to the present is briefly reviewed. An examination of the status of taxonomic work on benthic components, and a consideration of the zoogeographical history of the benthos leads to a discussion of bottom communities and macroinvertebrate production in the five major lakes.Profundal communities throughout the lakes are dominated by the glaciomarine relict amphipod Pontoporeia affinis and various species of Oligochaeta, Sphaeriidae, and Chironomidae. The specific composition of these components, and natural and recently imposed changes in their proportions within communities are examined. Population densities and standing stocks, and the proportion of oligochaetes in communities, all tend to increase in response to a natural gradient in productivity inferred from increasing concentrations of parameters such as organic matter and water hardness. Man's influence on water quality anywhere along this gradient compounds the effects of natural factors towards tubificid communities of predictable species composition: Limnodrilus hoffmeisteri, L. claparedeianus, L. cervix, L. maumeensis, Peloscolex multisetosus, and often Tubifex tubifex. The ameliorating influence of water depth is shown in Lake Erie where the change in community composition reflects improving profundal water quality from west to east — a reversed model of the Great Lakes system as a whole.