Survival, osmoregulation and oxygen consumption of YOY coastal largemouth bass, Micropterus salmoides (Lacepede) exposed to saline media

The effect of salinity on survival, osmoregulation and oxygen consumption was determined on coastal young-of-the-year (YOY) largemouth bass Micropterus salmoides by exposing them to saline media of 0, 4, 8, 12, and 16 parts per thousand. The data indicated a decrease in survival with longer exposure time and increased salinity. There were no significant differences in plasma osmolality with increased salinity from 0 to 8 parts per thousand but osmolality was significantly greater at 12 parts per thousand than 0 parts per thousand and osmolality from 16 parts per thousand was greater than all other salinity treatments. No significant differences in hematocrits were detected between 0 and 12 parts per thousand, but hematocrits in the 16 parts per thousand treatment were significantly reduced compared to all other treatments. YOY M. salmoides are good osmoregulators up to 8 parts per thousand but increased salinity caused measurable osmoregulatory dysfunction. Oxygen consumption rate increased significantly as salinity increased, suggesting that adaptation of this species to hypersaline media is in part accompanied by increased energy expenditure.