The impact of turbidity on foraging and risk taking in the invasive Nile tilapia (Oreochromis niloticus) and a threatened native cichlid (Oreochromis amphimelas)

摘要: Anthropogenic activity can increase water turbidity, changing fish behaviour by reducing visibility. The spread of invasive species is also facilitated human activity, further increasing the pressure on native species. In two experiments, we measured foraging efficiency, risk perception and inter-individual consistency risk-taking (personality variation in boldness) an species, Nile tilapia (Oreochromis niloticus), a threatened tilapia, Manyara amphimelas), clear turbid water. experiment one, O. niloticus was faster to initiate feeding, encountered more food items consumed than amphimelas. latency start decreased Turbidity did not affect amphimelas but number they highest at intermediate turbidity. There however no significant effect turbidity either total consumed. contrast this context, with refuge available, taking similar both responded similarly reduced Evidence personality weak, being observed only when first leaving shelter Overall, differences were greater context important context. sensitive during foraging, likely have competitive advantage situations, especially degraded habitats. Under human-induced environmental change, are often exposed multiple stressors. Here, tested responses cichlid which throughout tropics, indigenous Tanzania. We found that beneficial niloticus, contrast, without present, displayed increased little evidence between individuals Our results suggest tolerant habitats may outcompete less well-adapted for food.