Predation risk increases in estuarine bivalves stressed by low salinity.

UNLABELLED

Salinity drops in estuaries after heavy rains are expected to increase in frequency and intensity over the next decades, with physiological and ecological consequences for the inhabitant organisms. It was investigated whether low salinity stress increases predation risk on three relevant commercial bivalves in Europe. In laboratory, juveniles of , and the introduced were subjected to low salinities (5, 10 and control 35) during two consecutive days and, afterwards, exposed to one of two common predators in the shellfish beds: the shore crab and the gastropod a non-indigenous species present in some Galician shellfish beds Two types of choice experiment were done: one offering each predator one prey species previously exposed to one of the three salinities, and the other offering each predator the three prey species at the same time, previously exposed to one of the three salinities. Consumption of both predators and predatory behaviour of (handling time, rejections, consumption rate) were measured. Predation rates and foraging behaviour differed, with being more generalist than . Still, both predators consumed significantly more stressed (salinity 5 and 10) than non-stressed prey. The overall consumption of the native species and was greater than that of , likely due to their vulnerability to low salinity and physical traits (e.g., thinner shell, valve gape). Increasing precipitations can alter salinity gradients in shellfish beds, and thus affect the population dynamics of harvested bivalves via predator-prey interactions.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s00227-021-03942-8.