The effects of light intensity on epipelic algae and associated fauna.

Abstract

Our research examined the effect of light intensity on this benthic FPOM community. The primary goal of this study was to examine the benthic FPOM community and describe the assemblage of algae, diatoms, and meiofauna found there. Effects of light on this community wass assessed by surveying these habitats in different regions of a stream with different light levels and by experimentally manipulating light in artificial streams. The research was begun with several predictions; first, at higher irradiances production of epipelic algae and diatoms will increase. Second, this increase in primary productivity may in turn generate greater densities of meiofaunal grazers, larger grazers, and a shift in the community structure of meiofauna. Third, the alga assemblages may shift from one dominated by the more shade tolerant diatoms in the lowest light treatments to a chlorophyte dominated assemblage in the highest light treatment. Finally, this shift in the alga assemblage should be accompanied by a corresponding shift in the associated fauna. Chlorophytes often support their own community of diatoms and organisms.