A Preliminary Assessment of Benthic Algal Communities and Physical Habitat at Several Locations within the Minnesota River Watershed

Abstract

Stream ecosystems are influenced by environmental factors that occur at a variety of scales (Minshall 1988). Biological monitoring within the Minnesota River Assessment project has focused on comparisons of large watersheds in relation to fish and invertebrate communities. The primary objectives of the present study were to make a preliminary evaluation of benthic algal communities that exist among several representative streams in the Minnesota watershed and to attempt to identify limiting features to their abundance and productivity. Algal communities play an important role within stream systems due to their importance to invertebrates and fish as food, as moderators of ambient nutrient concentrations, and as indicators of stream condition. Stream periphyton communities can be limited by a variety of factors including light (Mclntire et al. 1964, Hill and Knight 1988), nutrients (Patrick 1966, Pringle and Bowers 1984), and turbidity (Munn et al. 1989). One effective means of examining algal growth and productivity has been through the use of nutrient diffusing substrates (Pringle and Bowers 1984, Lowe et al. 1986). This technique along with measurements of physical and chemical parameters and examination of natural community composition was used to survey algae in mainstem and tributary sites.