Salinity tolerance of the invasive red swamp crayfish Procambarus clarkii (Girard, 1852)

Introduction of alien species leading to unfavorable economic impacts and ecosystem collapse is a well-known threat. The aim was to define if high salinity may be a limiting factor for the survival and spread of the invasive crayfish Procambarus clarkii. Both sexes were exposed to increasing salt concentrations reaching 35.3% after 65 days to simulate the natural transition from freshwater into seawater. Higher mortality was recorded for salinitytreated females than for males. Condition indexes gave evidence of minor adverse effects, whereas altered values of oxidative stress biomarkers suggested a perturbation of redox state induced by the exposure conditions. The female survivors showed a strengthening of levels of oxidative stress biomarkers. A moderate oxidative pressure was recorded for gills in both sexes. Nevertheless, the non-indigenous red swamp crayfish has shown great resistance and adaptability to these simulated adverse environmental conditions. Survival of P. clarkii at high salinity may suggest that both sexes can be able to invade estuarine brackish water and lagoons initially exploited as ecological corridors, causing ecological imbalances in transitional ecosystems and in seawater. Moreover, this alien invasive species could be able to descend rivers up to the sea and vice versa to colonize new environments.