THE EARLY DEVELOPMENT OF A BOTTOM FAUNA IN A NEW POWER RESERVOIR IN THE ROCKY MOUNTAINS OF ALBERTA

Abstract

The Barrier reservoir, Alberta, was examined periodically from May, 1947, shortly after water impoundment began, until June 1949. The reservoir is fundamentally oligotrophic; rapid replacement of water, periodic fluctuation of the water level, and a marked annual deposition of sediment contribute to this condition. The bottom fauna, consisting chiefly of immature Chironomidae, was much influenced by these factors during the period of the investigation. A Pentapedilum–Chironomus–Tanytarsus succession is interpreted as indicating a change from original eutrophic conditions on the bottom to oligotrophic, as the rich leaf litter of the original bottom was lost under sediments.