Some Factors Influencing the Diversity and Species Composition of Benthic Invertebrate Communities in Twenty Arctic and Subarctic Lakes

The factors influencing the density, diversity and species composition of benthic invertebrate communities in 20 lakes in the Canadian arctic and subarctic were determined during 1975, 1976 and 1977. Despite small differences in nutrient and phytoplankton levels among the lakes, there was a strong positive correlation between these parameters and the density and diversity of the communities. Other factors, including maximum summer water temperature, lake depth and surface area had little overall effect on the communities. The densities of 2 ultra‐oligotrophic chironomids (Heterotrissocladius oliveriandMicropsectracf.groenlandica) increased markedly in cold deep lakes. However the abundance of the majority of species, most notablyProcladius denticulatus, Tanytarsussp., andStictochironomussp., was not effected by temperature. Other species, (Pontoporeia affinis, Monodiamesa bathyphilaandDicrotendipes nervosus) were probably restricted in their northern distribution by temperature. Surface area usually had little effect on the densities of all common species.