Aquatic invertebrates and wastewater effluents: behavioral responses and ecological implications : examining habitat preferences in aquatic invertebrates in northern Sweden

Sammanfattning

This study investigated the influence of wastewater discharges on the behavior and habitat choices of aquatic invertebrates in northern Sweden, including dragonfly larvae (Odonata), caddisfly larvae (Trichoptera), and crayfish (Decapoda). Furthermore, the potential role of ecological traps, where organisms may preferentially inhabit polluted habitats, potentially compromising their survival was explored. Four hypotheses were evaluated to assess whether and how these species react to wastewater effluent cues. For this, behavioral choice trials were conducted, where the tested animal could freely move between two water zones, a zone with clean tap water and a wastewater effluent zone. The analysis focusing on habitat preferences showed diverse preferences among the tested species. While caddisfly larvae and dragonfly larvae displayed fluctuating preferences across trials, crayfish did not exhibit distinct preferences across trials. However, not all behavioral analyses produced significant results. Exploration behaviors, measured by zone transitions, highlighted significant differences among species. The invertebrates’ lack of a clear preference in this study is concerning. It implies that they might not be able to identify some hazards in their environment, leading them to persist in polluted waters for feeding and reproduction. This research enhances the understanding of how aquatic ecosystems function amid emerging pollutants.