Growth and survival of blacklip pearl oyster larvae fed different densities of microalgae

This paper reports on an experiment to determine growth and survival of blacklip pearl oyster, Pinctada margaritifera (L.), larvae fed a 1:1 mixture of Isochrysis aff. galbana clone T-ISO and Pavlova salina at six different densities (1, 2, 5, 10, 20 and 30 × 10³ cells ml⁻¹. Larval growth and survival were assessed every four days over a 20–day period. Exponential and logistic regression models were fitted to the growth and survival responses, respectively. Overall growth of larvae fed ≥5 × 10³ cells ml⁻¹ was significantly greater (p > 0.01) than growth of larvae reared at other algal densities. The optimal food ration for maximum larval growth was 20 × 10³ cells ml⁻¹, which resulted in larvae with antero-posterior shell length of 230 μm after 20 days. These larvae were significantly larger (p > 0.05) than those in all other treatments at the end of the experiment. Survival of larvae fed 0, 1 and 2 × 10³ cells ml⁻¹ was significantly lower than that of larvae in all other treatments at the end of 15 days (p > 0.01). Maximal survival (8%) over the 20 day period was shown by larvae fed 10 × 10³ cells ml⁻¹, while lower survival was shown by larvae fed 2 × 10³ cells ml⁻¹ (2%) and 1 × 10³ cells ml⁻¹ (0%)