Nematodes in the periphyton of lakes: Variations in diversity, species composition, age structure and sex ratio

Schroeder F, Peters L, Traunspurger W. Nematodes in the periphyton of lakes: Variations in diversity, species composition, age structure and sex ratio. International Review of Hydrobiology. 2013;98(6):322-333.Temporal fluctuations in the diversity, sex ratio, age, and species composition of free-living nematodes inhabiting the periphyton of stony hard-substrates were determined in three Swedish lakes differing in trophic state. Over a two-year sampling period, different temporal patterns were observed. In the oligotrophic lake, nematode diversity showed moderate fluctuations and peaked in early summer. Diversity in meso- and eutrophic lakes showed the opposite pattern. Species composition changed along seasons, enabling to identify typical early and late season assemblages. This succession was linked to different reproduction periods of dominant species. The age structure and sex ratio of periphytic nematode communities varied both temporally and between lakes according to species traits. As an example, the male/female ratio increased with increasing lake trophic state. This trend reflects the decrease of partenogenetically reproducing species with increasing lake trophic state, and may be further considered as an indicator of lake trophic state