Effect of stocking density and food ration on growth and survival of veliger and pediveliger larvae of the taquilla clam Mulinia edulis reared in the laboratory

In order to evaluate the effect of stocking density on growth and survival, veliger larvae of Mulinia edulis were reared at densities of 10 and 20 larvae ml^-1 fed with a mix of 25,000 cells ml^-1day^-1 of Isochrysis aff. galbana (T-ISO) and Nannochloropsis oculata in 5 L buckets. In ration experiments, larvae were fed with of 25,000 and 50,000 cells ml^-1 day^-1. By the end of the stocking experiment, significant differences were found in survival but not in larval growth rate. The ration experiment showed no differences in the growth nor in the survival of the larvae. To establish the effect of stocking density on settlement of pediveliger larvae, these were reared in a down-welling system at densities of 5, 10, 20 and 40 larvae cm^-2. To determine an adequate food ration during settlement, pediveliger larvae were provided with 25,000, 50,000 and 100,000 cells ml^-1day^-1 of T-ISO; a fourth treatment with a progressive increase of cells (25,000 to 100,000 cells ml^-1day^-1) was used. Lower density treatments showed greater sizes and survival. Postlarvae fed with a ration of 100,000 cells ml^-1day^-1 had the greatest valve length (1728 ± 293 mm). The progressive treatment had the best survival (65%) at age 50 days from D larvae. To improve the productivity of larval culture for a massive seed production an initial stocking density of 10 larvae ml^-1 and a microalgae ration of 25,000 cells ml^-1day^-1 were recomended. For settlement stage we recommend a stocking density between 5 to 10 pediveliger cm^-2 and the increasing food ration.