A Preliminary Assessment of Microalgal Diets for Echinopluteus Larvae Culture of the Sea Urchin Sphaerechinus granularis (Lamarck, 1816) (Echinoidea: Toxopneustidae)

Abstract

Sea urchins play an important role in coastal marine ecosystems and are an economically valuable resource for their gonads (roe or uni). Increased demand by Asian and European countries caused overfishing of wild stocks resulting in a sharp decline of sea urchin populations. The increased efforts in developing cost-effective protocols are focused on larval development up to pre- and post-metamorphosis stages, as they are one of the main difficulties of echinoculture. This is a preliminary study to evaluate the influence of microalgal varying diet rationing on larval development, growth, and survivorship at pre-metamorphosis of Sphaerechinus granularis echinopluteus (30 days post-fertilization). Three microalgae diets based on Dunaliella tertiolecta and Rhodomonas marina and the combination of both species were tested. Each diet used three ration treatments: low ration (500–3000 cells⋅ml−1); medium ration (1000–6000 cells⋅ml−1); and high ration (4000–24,000 cells⋅ml−1), which were cell-density adjusted to larval development. Assays used three triplicated treatments in 8 L cylindrical–conical glass incubators. Results showed that the survival of S. granularis echinopluteus was positively influenced by diets of lower cellular densities and a combined microalgae diet. Adoption of this type of diet regime is expected to improve larval production and provide the groundwork for future research on S. granularis in aquaculture.