Periphyton community changes along a heavy metals gradient in a long narrow lake

Abstract

A lead-zinc-copper mine on Vancouver Island, British Columbia has been a source, since 1966, of heavy metal input into a long, narrow oligotrophic lake subject to little previous perturbation. Whilst nutrient levels have remained stable, zinc, copper and cadmium concentrations have risen throughout the lake and downstream waters, frequently exceeding the Environment Canada standard for freshwater life. The periphyton community throughout Buttle and Upper Campbell Lakes was dominated by Navicula cryptocephala. A minor dominant association consisted of Achnanthes microcephala, Synedra acus, and Synedra filiformis. Species diversity was low but increased with distance from the mine. Not only was diversity lowest near the mine, but diatoms known to be sensitive to heavy metals were rare or absent. The sensitive species become more abundant with distance from the mine.