Effects of microalgae diets and stocking density on larval growth, survival and metamorphosis of dwarf surfclam, Mulinia lateralis

Abstract

The dwarf surfclam Mulinia lateralis is widely considered a model species in bivalves because of its small size and short generation. An efficient culture system is necessary to continuously obtain enough high quality larvae for genetic research. In the present study, the impacts of microalgae diets and stocking density on larval growth, survival and metamorphosis were investigated to optimize the culture system for M. lateralis. Six of seven tested microalgae were ingested by 2 to 10-day-old larvae, including Isochrysis galbana (IG), Chlorella pyrenoidesa (CP), Nitzschia closterium (NC), Platymonas helgolandica (PH), Chaetoceros muelleri (CM) and Pyramimonas delicatula (PD). The exception was Dunaliella salina (DS), which was not ingested by larvae during the experimental period. This results indicated the larvae could ingest microalgae with larger size as larvae develop. The time needed for digestion gradually decreased as the larvae develop. According to the growth, survival and metamorphosis of larvae after feeding with different microalgae diets, the optimal diets were a single diet of IG for D-shaped larvae, mixed diets of IG + PH at a 1:1 ratio by cell density for umbo larvae and IG + NC + PH at a 1:1:1 ratio by cell density for pediveliger larvae. The better microalgae concentration was 2.4–3.6 × 103 cells mL−1 for D-shaped larvae, 6.0–12 × 103 cells mL−1 for umbo larvae, and 30–40 × 103 cells mL−1 for pediveliger larvae. In addition, the better density of D-shaped larvae was ≤9 larvae mL−1, the density of umbo larvae was ≤7 larvae mL−1, and the density of pediveliger larvae was ≤5 larvae mL−1. In conclusion, ingestion and digestion of microalgae, microalgae combination, microalgae concentration and stocking density significantly affected growth, survival, and metamorphosis of M. lateralis larvae. The optimized conditions will be of great significance for establishing a standard culture system for M. lateralis.