Influences of desiccation, submergence, and salinity change on survival of Ligia cinerascens (Crustacea, Isopoda): high potential implication for inland migration and colonization

The terrestrialization success of aquatic organisms requires physiological adaptations, of which water loss restraint, respiratory, and osmoregulatory systems are notably critical. Isopods of the genus Ligia (Oniscidea) have a particular significance for understanding the evolutionary transition of crustaceans from marine to terrestrial/freshwater environments. The main aim of this study was to analyze whether Ligia cinerascens as a supralittoral species has the potential for inland migration and colonization based on its performance of survival under desiccation, submergence, and salinity change. The change of body weight and survival time in desiccation experiments was measured and calculated for the loss of body water and water-specific rate of water loss. The survival of individuals submerged in the seawater (33 ppt) and different salinities of water (0, 10, 30, 50, 70, 90 ppt) was recorded. Salinity acclimation experiments were then conducted with or without food provision. The larger individuals exhibited stronger desiccation tolerance but poorer ability against submergence. Ligia cinerascens could survive the lower water salinity (0, 10, 30 ppt), especially when adequate food was provided. This work suggests the high potential of inland migration and colonization in L. cinerascens based on its strong desiccation tolerance and freshwater adaptation.