Temporal and Spatial Patterns of the Alga Cladophora conchopheria on the Shell of the Intertidal Gastropod Turbo coronatus coreensis

Shells of the intertidal gastropod Turbo coronatus coreensis at Tanabe Bay, central Japan, were fouled predominantly by the green alga Cladophora conchopheria, the latter being more abundant on these snails higher up the shoreline. The abundance of C. conchopheria on the shells of large snails (shell length> 10 mm) showed no significant seasonal changes, although the alga was recorded on small snails (shell length< 10 mm) from June to October and December but not in February or April. C. conchopheria was less abundant on T. coronatus coreensis shells inhabited by hermit crabs than on the shells of living snails. Increments of C. conchopheria coverage were not correlated with shell growth of individual snails. Under laboratory conditions, the coverage of C. conchopheria on snail shells decreased, and the rate of such not differing among early dead snails, later dead snails and shells inhabited by hermit crabs. The survival rates of T. coronatus coreensis in the laboratory was similar between snails fouled heavily or not at all by C. conchopheria.