Influence of spatial complexity on the density and diversity of periphytic rotifers, microcrustaceans and testate amoebae

Abstract

Species richness, diversity and density in periphytic communities generally increase with substratum complexity. Aquatic macrophytes are often a main component of habitat complexity in lentic ecosystems, and the texture of aquatic macrophytes may alter the structure of periphytion. Here, we tested the hypothesis that even a subtle increase in complexity promotes an increase in species richness and density of periphytic organisms by means of a paired experiment with artificial plants. Artificial leaves were constructed simulating leaves of submerged aquatic macrophytes with veins (0.01 cm tall) and without veins (with the same foliar area). Nineteen pairs of artificial leaves, with two levels of complexity (with or without veins), were submerged during three weeks in Samambaia Lake, a small (ca. 4 ha) pond localized in Central Brazil. Species richness and density were significantly higher in the more complex leaves for rotifers and small bodied organisms (< 100 μm). Species composition as determined by ordination was not altered by complexity. The results suggest that even subtle differences in complexity of aquatic macrophytes (i.e. more complex venation) can influence the diversity of periphytic communities.