Habitat selection and copper toxicity in the freshwater amphidromous shrimp <i>Caridina multidentata</i> Stimpson, 1860 (Decapoda: Caridea: Atyidae)

Abstract Amphidromous atyid shrimps, like Caridina multidentata Stimpson, 1860, play a crucial role in freshwater ecosystems. Despite their ecological significance, our understanding of the factors influencing their distribution, abundance, and behaviour remains limited. We aim to fill this knowledge gap by investigating the sensory ecology of C. multidentata, focusing on the role of biotic and abiotic factors in microhabitat selection and response to environmental stressors such as pollution. Olfactory choice tests indicated that the shrimp did not respond to chemical cues from conspecifics or heterospecific species, but displayed a preference for environments with current flow and avoided light. They did not demonstrate a preference for a “refuge” combination of conditions, suggesting that they did not perceive a threat in the experimental setting and were able to distribute themselves according to their preferred conditions of darkness or current. Acute toxicity tests established a median lethal concentration (LC50) of copper at 1.15 mg l–1. Pre-exposure to sublethal copper concentrations impaired the ability of shrimp to detect food odours, suggesting potential impacts on habitat selection and survival. Future research should investigate the long-term effects of pollutants on the behaviour and survival of shrimp, and explore the role of environmental cues such as river chemical waterscape.