Abstract
Mytilus coruscus community was sampled monthly throughout the year at an infralitoral reef in the Kurushima Strait. Annual mean biomass of the community amounted to 39.6kg wet wt m-2, of which 77 and 19% was the molluscs and the arthropods respectively. The biomass of M. coruscus population was 30.0kg wet wt m-2 and 1652g dry flesh wt m-2. The population was composed of three age groups, viz, age 0+, 1+ and 2+ groups, and a composite age group including age 3+ and above. Life span of the population is presumed to be roughly above 11+ years of age and probably reaches approximately 20years, considering the production of the respective age groups and longevity of the related species. Newly-attached plantigrades were observed almost throughout the year and they were most abundant in June and followed by July. Net production is estimated to be 48, 41, 25, 151 and 265g dry flesh wt m-2 yr-1 in age 0+, 1+, 2+, above 3+ and the total groups respectively. Ratio of production (P) to mean biomass (B) was calculated to be 6.00, 1.41, 0.83, 0.10 and 0.16 in age 0+, 1+, 2+, above 3+ and the whole groups respectively.
