A Brief Survey of the Profundal Benthic Fauna of Lakes in Manitoba

Abstract

The profundal benthic fauna of nine lakes lying along the margin of the Precambrian Shield in the Province of Manitoba was investigated during August 1963, and is described with particular attention to the midges (Diptera: Chironomidae).Comparison with a Scottish lake, similarly situated with respect to Precambrian rocks, showed no close agreement in the distribution of species of Chironomidae. This can be credited to differences in the Palaeozoic rocks adjoining the Precambrian.Chironomus tentans and C. decorus were most numerous and most frequent at water depths up to 15 m whereas C. anthracinus and Chironomus sp. A were generally in water over 20 m.In Falcon, Reed, and Morton lakes, C. anthracinus tended to be more successful where sediments contained appreciable amounts of allochthonous debris and to give way to Chironomus sp. A where sediments were autochthonous.