Abteilung Aquatische Ökologie

Indirect ecological interactions—where one species influences another via changes to a third species or the environment—are ubiquitous in natural communities but are rarely linked directly to rapid evolutionary change. Using large outdoor mesocosms, we show that terrestrial aphid herbivory on macrophytes (duckweed) cascades through species interaction networks to alter phytoplankton abundance and water chemistry, driving rapid adaptive evolution of the planktonic crustacean Daphnia magna. The aphid-herbivory-mediated changes in the aquatic community then benefited the aphids by enhancing their performance on duckweed. Our findings provide direct evidence that indirect ecological interactions in near-natural communities can drive rapid evolutionary changes and mediate ecoevolutionary interactions between seemingly independent organisms.

Environmental changes linked to urbanization influence wildlife health and may increase zoonotic risks. In this study, we examined the impact of urban stressors on the cellular immunity of two bat species, Nyctalus noctula and Eptesicus serotinus, along an urban-natural gradient in Eastern Ukraine. Using white blood cell (WBC) profiles as immunity markers, we found that N. noctula from urban and suburban habitats had significantly higher WBC counts, as well as lymphocyte and neutrophil proportions, compared to individuals from natural areas. Meanwhile, E. serotinus, a species more adapted to urban environments, exhibited lower neutrophil levels and a trend toward reduced neutrophil-to-lymphocyte ratios. These findings suggest species-specific immune responses to urban stressors, with potential implications for wildlife conservation and disease dynamics. Further research is needed to understand long-term physiological adaptations in urban-dwelling bats.

Freshwater ecosystems support a disproportionate share of global biodiversity. Freshwater macroinvertebrates are frequently used as bioindicators to assess the ecological status of streams and rivers. However, ongoing climate change is altering the compositions of these communities, highlighting the need for tools to detect climate-related shifts. We propose and evaluate an ecological index based on the SPEcies At Risk (SPEAR) approach to quantify the proportion of species that are sensitive to higher temperatures within Ephemeroptera, Plecoptera and Trichoptera communities. We calculated this index using six different data sources for thermal preferences: experimentally measured thermal tolerances, the mean temperature from global occurrence records (GBIF), preferred temperatures obtained from multivariate species distribution models (SDM), the central temperature tendency derived from Swiss monitoring data according to the KLIWA approach, and two different sources of expert knowledge from a curated trait database. For all sources, we designated the species comprising the lower 50th percentile of thermal preference values as sensitive and the upper half as insensitive to warmer temperatures. To evaluate the performance of the six versions of this SPEAR_temperature on a geographic scale, we leveraged data from two Swiss wide monitoring programs including samples from 570 sites for the period 2010–2022 and from 183 sites for 2018–2023. While all six versions recapitulated a declining proportion of sensitive species with increasing water temperature, the relation was strongest when using the KLIWA-based thermal preference classification. On average across all sites, we observed a significant decline of the SPEAR_temperature index over the 2010–2022 period, independent of the source for the classification. This is consistent with a signal of warming-related community turnover, or ‘thermophilisation’. These results indicate that the index is suitable to document temperature-associated variation in EPT communities over both time and space. The attempt to derive a similar SPEAR_temperature index for fish was not successful.