Sampling approaches for the assessment of shoreline development based on littoral macroinvertebrates: the case of Lake Werbellin, Germany

Human induced shoreline alterations are a common feature of lake ecosystems worldwide. This study investigates the efficiency of different sampling strategies for the monitoring of lakes, including anthropogenically caused shoreline alterations such as erosion control structures or recreational beaches, by comparing littoral macroinvertebrate diversity and community structures of unmodified with soft (recreational beaches) and hard (retaining walls, ripraps) altered shorelines in a central European lake. Littoral macroinvertebrates were sampled at three different shoreline types at Lake Werbellin, Germany using habitat-specific and composite sampling. We tested the efficiency of a single composite sample as an adequate and cost-efficient alternative to labour intensive stratified habitat specific sampling of macroinvertebrates for routine lake monitoring. Both sampling schemes provided similar taxon richness estimates for all shoreline types. Variability in macroinvertebrate community structures within composite replicate samples did not differ significantly from that within habitat-specific replicate samples, with single habitats, however, supporting distinct macroinvertebrate communities. Our results show that composite samples, when collected proportionally to habitat availability at respective sampling sites, effectively represent littoral macroinvertebrate diversity and community structures at modified and unmodified shorelines. We conclude that composite macroinvertebrate samples can be considered as a useful, time-and cost-efficient tool for lake monitoring, but it has yet to be tested whether this method is applicable to other lake types and ecoregions.