Large-scale cultivation of Haliclona simulans sponge larvae on soft substrates and the enhancing effect of Chlorella

Abstract

Sustainable sponge cultivation depends on advanced larval cultivation techniques. This study investigates the cultivation of Haliclona simulans larvae on soft substrates, aiming to develop a scalable and easily manipulated method. Initial screening of 40 materials identified linen, 80-mesh nylon, 80-mesh polyethylene mesh, and black silk as optimal settlement materials. 14-day survival test confirmed 80-mesh nylon as the optimal soft substrate. Subsequent large-scale cultivation on nylon sheet involved approximately 160,000 H. simulans larvae. These larvae experienced indoor incubation followed by in-situ sea cultivation. Indoor cultivation resulted in a 65.26 ± 13.32 % settlement rate, and groups supplemented with microalgae achieved a 63.71 ± 23.98 % survival rate over 30 days. The optimal indoor-to-in-situ transition window was determined to be 28 days, with one individual achieving a 130-fold volume increase within 14 days post-transfer. During in-situ cultivation, larvae showed higher survival rates when oriented sideward or downward. However, environmental stress, sedimentation, and predation highlighted the need for optimizing the indoor-sea transfer process. This study presents initial insights into larval cultivation on soft substrates, offering valuable information for the sustainable, large-scale cultivation of H. simulans larvae and potentially other sponge species.