Effect of food strategy and stocking density on larval performance of captively reared Mytilus galloprovincialis

Abstract

Food availability is a crucial factor influencing the behavioral responses, development and physiology of bivalve’s larvae. In this study, we investigated the effects of two feeding strategies (Fv: number of microalgae cells per volume and Fb: number of microalgae cells per biomass) on Mytilus galloprovincialis larvae reared at three different stocking densities (D5: 5 larvae/ml, D15: 15 larvae/ml and D30: 30 larvae/ml). The results showed that larvae fed per volume (Fv) exhibited the highest survival rates across all tested densities (59%, 53% and 39% for D5, D15and D30 respectively), compared to larvae fed per biomass (Fb) (40%, 39% and 32% for, D15, D30 and D5 respectively). Conversely, feeding per biomass led to a significant increase in cumulative shell length gain (D5: 211.4 µm; D15: 214.99 µm and D30: 208.11µm) compared to feeding per volume (D5: 201.12 µm; D15: 166.23 µm and D30:130.09 µm). Statistical analysis revealed that food availability significantly influenced survival only at low larvae density (D5: F=20.13; P<0.01). However, it significantly affected cumulative gain only at high stocking densities D15 (F=148.96; P<0.001) and D30 (F=318.74; P<0.001). These findings emphasize the importance of feeding strategy and stocking density as crucial factors in regulating larval performance during captivity rearing.