Salinity tolerance of larvae of the mangrove red snapper (Lutjanus argentimaculatus) during ontogeny

Salinity tolerance and the effects of salinity on growth, condition factor and chloride cell (CC) densities were evaluated for Lutjanus argentimaculat us larvae during ontogeny. Tolerance of L. al argentimaculatus larvae to ab rupt changes of salinity from 32 ppt varied with age. Periods to 50% mortal ity (LT50) were significantly (P < 0.05) longer for 0-day-old larvae than f or 7-, 14- and 21-day-old larvae. Tolerance of abrupt salinity change incre ased remarkably, starting on day 28. Although abrupt transfer to test salin ities caused substantial mortalities, L. argentimaculatus larvae, regardles s of age (0-, 7-, 14-day-old), showed significantly longer LT50 when abrupt ly transferred to 8 and 16 ppt than for transfers to 24 and 40 ppt (P < 0.0 5). Growth of L. argentimaculatus larvae at 16, 24, 32 (control) and 40 ppt was not significantly different either at the end of the first rearing pha se (days 0-21) or second phase of rearing (days 22-50). Survival was signif icantly lowest at 40 ppt (4.3%) at the end of first phase of rearing (P < 0 .05). Then were no significant differences in survival rates at the end of the second phase of rearing; however, the condition factor (K) of larvae re ared at lower salinities was significantly higher than that of fish at 40 p ot (P < 0.05). Gill epithelia of 42- and 50-day-old larvae showed increasin g density of CC with increasing salinity. (C) 2000 Elsevier Science B.V. Al l rights reserved.