Effect of the ascidian Styela clava on the growth of small holothurians of the species Apostichopus japonicus.

We studied the effect of the common ascidianStyela clavaon the growth of small holothurians of the speciesApostichopus japonicus(Selenka, 1867). In a traditional aquaculture system, the oxygen consumption rates, ammonia excretion rates, and ingestion rates of smallA. japonicuswere reduced significantly, which suggested that this group was stressed by the presence of largeA. japonicus, and that this stress grew stronger with time. Oxygen consumption rates, ammonia excretion rates, and ingestion rates of smallA. japonicusin an integrated aquaculture (IA) system withS. clava,microalgae, andA. japonicuswere higher than those observed in the traditional culture system. Metabolic and digestive enzymes were more active in smallA. japonicusin the IA system than in those in the traditional aquaculture system. These results suggest that the IA model did not affect the growth of largeA. japonicas, but produced a marked positive impact on the growth of small individuals. [ABSTRACT FROM AUTHOR]