Some relationships between stream benthos and substrate heterogeneity

Abstract

Baskets filled with stones, to give four different degrees of heterogeneity, were placed in a stream and made available for colonization by benthic invertebrates. No difference resulted in the total numbers and weights of animals colonizing; 26% of the species, however, showed clear substrate preferences, 35% showed slight preferences, and 39% showed none. The last group made up most of the benthic invertebrate biomass. A high quantity of detritus accumulated in each substrate, and this may account for the similar densities of detritivores collected on all four substrates.