The effect of salinity and temperature on intracellular osmoregulation and muscle free amino acids in Fundulus diaphanus

Abstract

1. 1. Fundulus diaphanus tolerates both freshwater and 30‰ sea water at 15°C. At 0.5°C only freshwater was tolerated well, and only 50% of the sample population survived in 30‰ sea water after 2 weeks. 2. 2. At 15°C tissue inorganic ions and free amino acids increased with an increase in ambient salinity. In freshwater adapted fish, tissue K + increased while free amino acids decreased with a decrease in water temperature. 3. 3. The primary amino acids involved with salinity change were alanine, glycine, serine, proline, and aspartic acid. Taurine did not change with salinity and apparently does not function in intracellular osmoregulation.