Influence of temperature and salinity on survival and growth of the pearl oyster larvae Pteria hirundo

Abstract

The most important factors affecting growth rates and survival of bivalve larvae are temperature and salinity. A species of pearl oyster, Pteria hirundo (Linnaeus, 1758), presents good potential for cultivation in southern Brazil. The aim was to evaluate different combinations of temperature (23, 26 and 29°C) and salinity (25, 30 and 35 psu) on survival and growth to optimize the production of larvae of this species in the laboratory, in order to implement the seed production. The experimental design was factorial randomized design with three replications. A total of 25,000 larvae per experimental unit (E.U.) has been placed in rectangular containers of polypropylene (10 L) with 5 L of water salinity in each study. They were kept in tanks with 250 L of water provided with heater and thermostat, regulated according to the experimental temperatures in a water bath system. In the lowest temperature tested (23°C), the survival was higher and growth of larvae was lower when compared to the higher temperatures used. This fact demonstrates that the lower temperature favors larval survival. This lower temperature combined with higher salinity (35 ups) gave the highest percentage with 31.2% survival. The larvae grew better at higher temperatures (26 and 29°C) and the salinity did not show statistical differences when independently tested. The best larval performance (growth x survival) occurred in the interaction of the lowest temperature (23°C) with higher salinity (35 psu) (P<0.05) and so, this combination is recommended for the larviculture of P. hirundo.