Metamorphosis in summer flounder: effects of acclimation to low sind high salinities

The aim of these studies was to provide larviculturists with information ab out the effect of low and high salinities on the survival, growth, and deve lopment of summer flounder (Paralichthys dentatus) with the goal of enhanci ng commercial success of land-based flounder culture. Larvae were transferr ed after first feeding and prior to the onset of metamorphosis and monitore d for 3 to 7 weeks. In experiments 1 and 2, larvae were raised in 2-1 bowls containing seawater altered to salinities of 14, 30, or 38 ppt at starting densities of 3 premetamorphic and 6 prometamorphic larvae/l, respectively. Survival and development were not affected, nor was growth in experiment 1 . Growth was affected in experiment 2, and larvae in 14 ppt had greater tot al lengths than larvae in 38 ppt. In experiments 3 and 4, larvae were raise d in 38-1 tanks at starting densities 4 and 3 prometamorphic larvae/l, resp ectively, containing water with salinities of 8, 30, or 38 ppt or in salini ties of 8 and 30 ppt. Again, survival was not significantly affected by sal inity. In experiment 3, 8 ppt resulted in better growth and more advanced d evelopment; however, no differences were found in experiment 4. Overall, 38 ppt may tend to result in adverse effects. Larval summer flounder are not adversely affected by low salinity (8 or 14 ppt) and were observed in some cases to grow and develop better in environments more closely approximating their internal environment. (C) 1999 Elsevier Science B.V. All rights rese rved.