Biology subjects

Schuerings, C.

Publications and source records attributed to Schuerings, C..

3 recordsLinked to original sources

bioRxiv2024

Influence of salinity on the thermal tolerance of aquatic organisms

Aquatic organisms are challenged by changes in the external environment, such as temperature and salinity fluctuations. The response of an organism to temperature changes can be modified by salinity, thus pointing at the potential interaction of both variables. In the present study, we tested this assumption for freshwater, brackish, and marine organisms, including algae, macrophytes, heterotrophic protists, parasites, invertebrates, and fish. We reviewed the existing body of literature on potential interactions between temperature and salinity and performed a meta-analysis that compared the thermal tolerance (characterized by the temperature optima, lower and upper temperature limits, and thermal breadths). The final database includes 90 relevant publications (algae: 15; heterotrophic protists: 1; invertebrates: 43; and fish: 31). Relevant publications for microphytes and parasites were not available. Overall, our results show that decreasing salinity significantly increased the lower temperature limits and decreased the upper temperature limits irrespective of the organism groups. These findings mainly reflect the response to salinity changes in brackish and marine systems that dominate our database. Although the number of studies on freshwater species was limited, they showed negative, although statistically nonsignificant, effects of an increased salinity on the thermal tolerance of these species (i.e. increased lower limits and decreased upper limits). In addition, our meta-analysis shows nonsignificant differences in the responsiveness of thermal tolerance to salinity changes among different groups of organisms, but the sensitivity of thermal tolerance to salinity changes generally followed the order: algae > invertebrates > fish. Facing the impact of climate change, our findings point at adverse effects of salinity changes on the temperature tolerance of aquatic organisms. Further studies that investigate the thermal performance of freshwater species at various salinity gradients are required to broaden the evidence for interactions between salinity and temperature tolerance. This also applies to the influence of parasitic infections, which have been found to modulate the temperature tolerance of aquatic invertebrates and fish.

ecology↗

bioRxiv2024

Global-scale quantification of responses to anthropogenic stressors in six riverine organism groups

Rivers globally are impacted by numerous anthropogenic stressors, including water pollution, habitat degradation, and climate change, which collectively stress biodiversity and ecosystem functioning. This study systematically reviews and analyses published and unpublished data to understand how five aquatic organism groups (bacteria, algae, macrophytes, invertebrates, fish) respond to seven common stressors (salinization, oxygen depletion, fine sediment enrichment, temperature increase, flow modifications and nitrogen or phosphorus enrichment). Using an analytical framework that includes Generalized Linear Models (GLMs) and Robust Bayesian Meta Analysis (RoBMA), we extracted data from 143 relevant datasets out of 29,749 screened articles. Our results reveal a negative relationship between invertebrates and salinity, fine sediment enrichment, and temperature increase, while fish respond positively to increased oxygen levels and temperature. Bacteria and algae show variable responses, with algae positively associated with nitrogen. The findings highlight strong variability in stressor-response relations across organism groups and stressor types, and emphasize the need for more targeted studies on underrepresented groups like macrophytes and microorganisms. This analysis enhances the predictive understanding of stressor impacts on riverine biodiversity, informing future river ecosystem management and restoration efforts.

ecology↗

bioRxiv2024

Drivers of recovery and degradation of riverine benthic macroinvertebrate communities: A nationwide analysis of time series

In response to the global freshwater biodiversity crisis this study examines the drivers, influencing recovery and degradation in riverine benthic macroinvertebrate communities across Germany. Utilizing the Asymmetric Response Concept (ARC), which posits that species tolerances to stressors, dispersal capacity, and biotic interactions are critical drivers in aquatic ecosystem recovery, we analyzed a comprehensive dataset from 1568 sites, sampled between 2004 and 2022. Our findings indicate that abiotic stress consistently influences ecological status in both recovery and degradation phases. Interspecific competition shows a stronger positive relationship with ecological status improvements during recovery phases than during degradation, underscoring its importance in the recovery process. Additionally, land use intensity has a nuanced impact: catchments with higher proportions of cropland and urban areas are more likely to recover, while forested catchments are more prone to degradation. This study supports the ARC and highlights the complex interplay of biotic and abiotic variables in shaping ecological outcomes, underscoring the importance of integrated management approaches in freshwater conservation and restoration efforts.

ecology↗