Distribution and abundance of phytoplankton in 153 lakes, rivers, and pools in the Northwest Territories

Abstract

A survey of phytoplankton in lakes, rivers, and temporary pools in the Northwest Territories was conducted during 1975, 1976, and 1977. Dinobryon bavaricum was the most abundant and widespread species, occurring in almost all collections. It was followed in order of decreasing importance by D. cylindricum, D. sociale, and D. divergens. The predominant diatoms were Cyclotella glomerata and C. ocellata. Both species reached greatest abundance in lakes and rivers in the high arctic and were completely absent from temporary pools. Although Asterionella formosa, Diatoma tenue var. elongatum, and Melosira islandica were common in Great Slave Lake and other southern lakes, they were either rare or absent north of latitude 65°. The Chlorophyta, particularly Ankistrodesmus falcatus and Scenedesmus spp., occurred in almost all collections but always in low numbers. Planktonic Cyanophyta (primarily Oscillatoria limnetica) were normally rare.