Environmental and algal community influences on benthic algal extracellular material in Lake Opeongo, Ontario

Abstract

Extracellular material can play a key role in benthic ecosystems, but most of our current knowledge about extracellular material comes from marine intertidal systems. Data from lakes are lacking. We worked in Lake Opeongo, a 5800-ha dystrophic lake on the Canadian Precambrian Shield, and investigated changes in extracellular material as a function of light intensity, sediment characteristics, and disturbance regime and algal biomass, community composition, and primary production, all factors important in marine intertidal studies. We used permutation-based path analysis to test alternative models. We found a negative effect of in situ primary production on loosely bound, colloidal extracellular material, indicating that extracellular material may be released under stressful conditions. The effect of algal community composition on colloidal extracellular material also was significant. Total extracellular material was affected only by time of year, indicating that tightly bound, capsular extracellular material is more refractory than colloidal extracellular material. We found no significant effects of environmental factors (light, nutrients, or wind-driven disturbance) on either colloidal or total extracellular material, despite their importance in marine intertidal systems.