Optimizing Growth and Rearing Techniques for Larvae and Juveniles of the Sea Cucumber Holothuria arguinensis

Abstract

The ever-growing demand for sea cucumbers is a threat to these echinoderms and their habitats; however, a way to relieve stock pressure lies in meeting demand through aquaculture. As such, this study aimed to improve the growth and survival percentage of Holothuria arguinensis during larval development, settlement and juvenile growth. Three diets of microalgae (Diet RbPt = Rhodomonas baltica + Phaeodactylum tricornutum; Diet RbSm = Rhodomonas baltica + Skeletonema marinoi; Diet RbCc = Rhodomonas baltica + Chaetoceros calcitrans) were administered daily to the larval phase. Additionally, three substrates were supplied (pvc rolls, wavy pvc plaques and tile) at three different depths in order to determine the most favourable for settlement. Lastly, the potential benefits on growth and survival from introducing macroalgae (Sacchoriza polyschides) in the juvenile diet were assessed over a period of 6 months. Despite larvae under diet RbPt having presented a larger mean width, H. arguinensis fed with Diet RbCc presented a higher settlement survival at the end of the trial. No preferences were noted among the tested substrates, regardless of diet. Lastly, juveniles with added S. polyschides in their diet showed increased growth in mean weight and length when compared to individuals that were not fed with this seaweed.

Aquaculture of emerging species in North-Eastern Atlantic and Mediterranean Sea: a systematic review on sea cucumber farming and potential development

“…However, the mixture of microalgae promoted higher larval survival rates than treatments with single algae (Domıńguez-Godino and Gonzaĺez-Wangüemert, 2019b). In terms of nutritional content, diets rich in lipids resulted more suitable for larval development since the lipids assimilated from the food during the first larval stages are stored in specific cells, called hyaline spheres, and become important energy resources for the subsequent non-feeding larval phases (Ramofafia et al, 2003;Sousa et al, 2023). Larval development was also influenced by the feeding regime with overfeeding conditions promoting morphological malformations, while underfeeding regime resulted in high mortality rates (Rakaj et al, 2018;Schagerström et al, 2022).…”