Response of Periphyton to Nutrient Enrichment in Lake Chelan, WA

Abstract

ABSTRACT Enhanced growth of periphyton (primarily attached algae) is an early indicator of nutrient enrichment in lakes. Periphyton abundance, composition, and spatial distribution were examined in ultra-oligotrophic Lake Chelan, Washington to characterize relationships to nutrient inputs. The wide range in the nutrient content of tributaries discharging to Lake Chelan provided a unique opportunity to evaluate nearshore periphyton development in relation to nutrient concentration while minimizing the interference of other potentially controlling factors (e.g., light, temperature, substrate, wave energy). Periphyton samples were quantitatively collected during summer 1987 from rocks located in nearshore areas at discrete distances from five tributaries. The distribution of tributary waters was assessed using specific conductance as a tracer. Compared to stations distant from the nutrient-rich tributaries, high periphyton biomass (50–216 mg chlorophyll a/m2) with a greater proportion of filamentous algae was generally found at stations influenced by the tributary plumes.