Change of Population Density of Strombus luhuanus in the Acropora tumida Coral Community Area of Suruga Bay, Japan

概要

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Population density of the strawberry conch Strombus luhuanus was surveyed at the area of Acropora tumida community in Suruga Bay, Japan. The shell feature of this population, estimated from the ratio of the shell width to length, was slender evidently as compared with that of the southern populations in Kagoshima and Okinawa. The population density at 2005 increased rapidly after 1999 and became to of about 1,000 individuals per 100 m2. The conch tended to prefer a dead coral ground rather than a sand ground, and aggregate with a decrease in water temperature so as to form high dense colonies. Strombus luhuanus indicated remarkable avoidance behavior for Acropora polyps but no reaction to dead corals. The quantity of periphytic algae on dead corals was significantly higher than that on sands. Shell length composition of the dead conchs was occupied mainly with adults over 40 mm. The shells without sessile organisms, being shortly after the death, were hardly broken, but about 60% of those with sessile organisms suffered for damage. The factors in the rapid increase of the population size were discussed with relation to the biological characteristics of the conch inhabiting the northernmost area of the distribution.
日本水産増殖学会の論文