The macrobenthic community was in terms of biomass and density dominated by the following taxa: oligochaetes Stylaria lacustris (L.), Limnodrilus hoffmeisteri Claparede, and species of the genus Nais; the hirudineans Erpobdella octoculata (L.) and Glossiphonia complanata (L.); the amphipods Gmelinoides fasciatus (Stebbing) and Pontogammarus robustoides (Sars); the ephemeropterans Caenis spp.
There were no significant differences in biomass between benthic taxa (chironomids, trichopterans, amphipods, hirudineans, oligochaetes, gastropods, bivalves, ephemeropterans, and others) at the studied distances (one-way ANOVA, df = 6, MS = 1.8; F = 3.14; p < 0.001, post hoc comparisons, ns).
The stressed habitats consisting of drifting algae in the Neva estuary were colonized by eurybiotic taxa (chironomids, oligochaetes, hirudineans), locally adapted populations of stenobiotic species of trichopterans and ephemeropterans, typical of the studied habitat, as well as some recently introduced species of amphipods (Gmelinoides fasciatus, Pontogammarus robustoides).
