Comparative Physiological Ecology of Centrarchids in Hyposaline Environments

Empirical evidence and data from this study suggests that there are intrafamilial differences in salinity tolerance that apparently change longitudinally along salinity gradients. Lepomis punctatus and Micropterus punctulatus require a significantly longer time to acclimate to increased salinity than L. microlophus, which apparently acclimates within 1 h. Both increased salinity (0–8 ppt) and the time (1–72 h) exposed to a particular salinity impact osmotic and hematocrit regulation. Observed intrafamilial differences in osmotic and hematocrit regulation underlay the distribution and relative abundance of centrarchids and could explain their seasonal use o low salinity marshes. Furthermore, the > 12-h acclimation times of L. punctatus and M. punctulatus suggest that these two species may never become fully acclimated to a salinity during a diurnal tidal cycle.