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RESEARCH PRODUCT

Comparison of sampling methods and habitat types for detecting impacts on lake littoral macroinvertebrate assemblages along a gradient of human disturbance

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We explored environmental variables structuring littoral macroinvertebrate communities in a large lake basin along a gradient of nutrient enrichment. Furthermore, we evaluated sensitivity and cost-effi ciency of different sampling schemes (i.e. combinations of three habitat types and a number of standard sampling methods) to detect changes in macroinvertebrate communities along this anthropogenic disturbance gradient. Partial canonical ordination analysis showed that habitat characteristics accounted for a major part (56 % uniquely) of the explained variation in the species composition of invertebrate communities. When different mesohabitats were examined separately, assemblage variation of stony bottoms was most strongly associated with human-induced changes in water chemistry (51 % of the explained variation). In sandy and vegetated habitats, shore morphometry and habitat characteristics were more infl uential factors. The most time-consuming phases of sample processing were sorting and identifi cation, whilst the time-costs of fi eld sampling were relatively low. The duration of sample treatment was positively correlated with the numbers of individuals counted and taxa identifi ed. Additionally, processing time was associated with habitat type, samples from stony bottoms being the least laborious. Kick-net sampling on stony shores was the most cost-effi cient sampling scheme with low costs and highest sensitivity to detect anthropogenic impacts.