Phytofaun of Eleven Macrophyte Beds of Differing Trophic Status, Depth, and Composition

Abstract

Macrophyte beds in 11 lakes of differing trophic conditions were sampled intensively to examine the influence of macrophyte abundance and composition, epiphyton biomass, phytoplankton concentration, and water depth on the abundance of phytophilous invertebrates. Numerical abundance and biomass of phytofaunal taxa were only weakly correlated. Phytofauna biomass ranged from 17 to 270 mg dry mass∙g macrophyte dry mass−1(1–29 g dry mass∙m−2) among the macrophyte beds. Multiple regression analysis showed that total phytofaunal biomass was positively correlated with the biomass of the three primary producers in the littoral zone: macrophytes, epiphyton, and phytoplankton. Phytofauna biomasses in deeper macrophyte beds or near the water surface were lower than those found in shallower water or near the sediment surface. Correlations of phytofauna biomass with macrophytes, epiphyton, and depth varied somewhat among phytofaunal taxa. The phytofauna biomass was often dominated by chironomid larvae, but gastropods, water mites, and oligochaetes were also important components of the phytofauna biomass. Small crustaceans such as cladocerans and copepods frequently were numerically dominant but usually composed only a small fraction of the biomass. Preference of various invertebrate taxonomic groups for particular species of aquatic macrophyte was slight.