Fundamental Studies on Control of Marine Fouling Organisms by Sea Urchin

Abstract

Grazing activity of sea urchins, Strongylocentrotus nudus and St. intermedius, which were fed marine fouling organisms, was obserbed. Mussel, Mytilus edulis galloprovincialis, and barnacles, Balanus tintinnabulum, B. rostratus and B. trigonus, were eaten by sea urchins. A linear relation was found between the maximum diameter of the mouth of sea urchins (d mm) and the the maximum shell length of the mussels (l mm). The mussels were eaten completely in the case of l≤d. The maximum number of mussels eaten was 15/day/sea urchin. The mussels were eaten partially in the case of d 1.75d. Averege number of barnacles scraped was 3.3/day/sea urchin. B. tintinnabulum of thin shell was eaten better than B. trigonus and B. rostratus of thick shell. When a sea urchin was introduced into the netting cage of cultured scallop, Patinopecten yessoensis, the sea urchin fed on encrusting bryozoans and compound ascidians as well as slime fouled on the shell surface of the scallop. Thus, the grazing activity of the sea urchins is applicable to controlling fouling organisms on cultured scallop.