Interannual variation of bivalve populations on temperate tidal flats

Abstract

Studies were undertaken on long-term fluctuations of densities of different life stages (planktonic larvae, new settlers, and small and large bivalves) of three bivalve species (Ruditapes philippinarum, Musculista senhousia, Nuttallia olivacea) common on tidal flats, based on samples collected for 7 years from 1990 to 1996 in the Shitomo and Ano Rivers along the west coast of Ise Bay, central Japan. Seasonal and interannual variations in densities of different life stages for the three species were remarkable. In general, seasonal variations in densities of planktonic larvae corresponded to those of the benthic populations for each species, while interannual variations in densities of the larvae did not correspond to those of the benthic populations. However, 'great' peaks of densities of the larvae sometimes contributed to establish the benthic populations of each species.