Tolerance of increasing water salinity in the red swamp crayfish Procambarus clarkii (Girard, 1852)

The brackish habitat colonization by the red swamp crayfish Procambarus clarkii (Girard, 1852) has aroused lively interest among many biologists. Here, we focused on its salinity tolerance by carrying out laboratory experiments and histomorphological observations on its antennal glands. Adult crayfish of similar size were subject to increasing salinity levels up to 35 in a recirculating system. Only one male molted, and no specimens died during the experiment (only 3 females and 1 male). The antennal gland tissue organization (mainly regarding labyrinth and nephridial tubules) in the treated crayfish showed alterations if compared with the control specimens. We never found sexual differences in both laboratory experiments and histological observations. Our data highlighted the P. clarkii ability to survive in high salinity levels. This tolerance ought to be investigated in order to improve our understanding of mechanisms driving the coastal brackish area colonization by P. clarkii.