The effects of diet, temperature and salinity on survival of larvae of the fluted Giant clam, Tridacna squamosa

Abstract

Giant clams have been cultured for decades, yet few formal studies have examined their reproduction and early life history. Here we present two experiments that provide baseline information on the effects of micro-algal feeding, temperature and salinity on fertilization success and development of the fluted giant clam, Tridacna squamosa. The effect of different micro-algae feeds, i.e. Tetraselmis suecica (CS-187), Chaetoceros mulleri (CS-176), and yeast, on veliger survival was tested. A mixed-algal diet of 1:1 v/v T. suecica + C. mulleri + yeast resulted in approximately double larval survival by 24 h but no significant differences were identified between the uni-algal and mixed-algal diets at 48 h. Temperature and salinity were examined using a 2x2 design; with temperatures of ∼22.5°C and ∼29.5°C, and salinities of27%o and 30%o. At ∼29.5°C fertilization success was significantly greater than at ∼22.5°C, but higher temperatures were detrimental to the development of trochophores. There were no significant differences in either embryo or trochophore numbers for the salinities tested. The results indicate that both micro-algal diet and temperature can affect T. squamosa larval initiation and development; knowledge that can be used to improve their mariculture.