Contamination may induce behavioural plasticity in the habitat selection by shrimps: A cost-benefits balance involving contamination, shelter and predation

Abstract

When shrimps select a habitat, the presence of elements like predators, shelter and contamination might determine if an area is preferred or avoided. We hypothesised that when shrimps are exposed to a situation in which they have to select whether to avoid contamination, seek shelter or protect themselves against predators, they will avoid the situation that supposes a higher cost for their survival (cost-benefits balance). The current study aimed to assess the plasticity of the selection behaviour of the freshwater shrimp Atyaephyra desmarestii between moving to a clean and unprotected area (no shelter and with a risk of predation), thus avoiding exposure to contamination, or moving to a contaminated and protected area (with shelters), thereby avoiding potential predators. Shrimps were experimentally exposed in a free-choice system simulating a heterogeneous environment with a contaminant (copper), shelter and a predator signal (kairomones of Salmo trutta). The shrimps avoided the copper by moving towards a less contaminated area, both in the absence or presence of shelter. When confronted with a choice between a cleaner zone with no shelter and a contaminated zone with shelter, the shrimps preferred being in the cleanest area. However, when the uncontaminated area contained a predator signal, the shrimps balanced the risk of predation and exposure to contamination by selecting a moderately contaminated area relatively further away from the predator signals. In summary, contamination might favour a plasticity of the habitat selection behaviour of shrimps, modifying the cost-benefits balance of such a selection.