The Effect of Metabolites from the Brown Alga Saccharina cichorioides (Miyabe) on the Feeding Habits, Fertilization, and Embryonic Development of the Sea Urchin Strongylocentrotus intermedius A. Agassiz, 1863

— The substances contained in the aqueous–ethanol and aqueous extracts from freshly collected and destroyed brown algae Saccharina cichorioides in their second vegetation season and from excrement of the sea urchins Strongylocentrotus intermedius that had been fed these algae specimens were studied for effects on the digestive enzyme 1,3-β-D-glucanase, sperm, egg cells, and developing embryos of the sea urchin . The yield, composition, and structure of substances from fresh and destroyed S. cichorioides and from sea urchin excrement were analyzed. Sea urchins assimilated mannitol, proteins, and almost completely laminarans from destroyed thalli of S. cichorioides . The detection of activators of sea urchin 1,3-β-D-glucanase in the aqueous–ethanol extracts of destroyed algae and inhibitors of fertilization processes in the extracts of fresh algae is consistent with field observations. The biochemical study has shown that the digestion and reproduction processes in S. intermedius are controlled by metabolites of S. cichorioides to a significant extent.