ECOLOGY OF LARVAE OF CHIRONOMUS TENTANS (DIPTERA: CHIRONOMIDAE) IN SALINE LAKES IN CENTRAL BRITISH COLUMBIA

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Abstract
The occurrence and abundance of larvae of Chironomus tentans Fabricius in saline lakes in central British Columbia were studied with respect to: (1) physico-chemical properties of the lakes, (2) physical composition of the bottom muds, (3) food availability, and (4) co-occurrence with other species of chironomids. The study was done to determine the ranges of environmental conditions to which the larvae are adapted and to identify specific environmental factors which might be of particular significance to natural selection. Abundance was significantly correlated with the amount of food available; the numbers of individuals of other Chironomus present; the percentage of mud particles in the 0.59–0.83 mm range; pH; conductivity; and the concentrations of potassium, magnesium, chloride, sulfate, and dissolved oxygen. In general, occurrence was affected by the same factors which affect abundance. Additionally, larvae did not occur when hydrogen sulfide was greater than 0.3 p.p.m. The ecological data are particularly relevant since they provide a basis for studying the evolutionary significance of ecological adaptation in C. tentans.