Induction of larval metamorphosis in the sea cucumber Stichopus japonicus by periphitic diatoms

The mass production of juvenile seeds of the sea cucumber, Stichapus japonicus has recently developed by the Sea Farming Center of Saga Prefecture. Methods for the culture of periphicic diatoms have been improved. There are three important steps in propagating the diatoms. The first step is the enrichment, with the addition of the nutrient salts, under controlled light intensity. The second step is washing with high pressure seawater and reversal of the plates. The last step is elimination of copepods, which feed on diatoms, using a pesticide. Small periphitic diatoms such as Navicula, Amphora, Achnanthes, and Nitzschia are easily cultured at a density of more than one million cells cm(-2), and these diatoms are able to induce larval metamorphosis and serve as a food source for juvenile sea cucumbers.