Biological production process and food environment for bivalves in tidal flat
2005
Ito, K.(Tohoku Univ., Sendai (Japan)) | Kaga, T. | Sasaki, K. | Omori, M.
A combination of ecological research, field experiments and laboratory experiments was carried out to analyze the biological production process and food environment for bivalves in a tidal flat around Sendai Bay. Both field experiments and stable isotope analysis indicated that the important nutritional resources for Ruditapes philippinarum and Nuttallia olivacea are benthic diatoms, with a lower contribution of detritus. Macoma contabulata and Corbicula japonica, inhabiting the same site with Nuttallia olivacea, are supplied with different resources that up to now have been unknown. The food requirement for Nuttallia olivacea is estimated to be about 1500 mg C m(-2) day(-1) at a high-density location in the tidal flat of the Natori River in spring. Conditions affecting food availability may be linked with physical environmental conditions, and clarification of the coupling mechanisms between the biological production process and physical conditions is important for the various microenvironments. Nuttallia olivacea showed marked differences in growth at each location. Most available conditions are considered to be moderate current velocity with shallow depth, low silt-clay content and high chlorophyll a in the sediment, and presence of a wide variety of diatom species with varied size compositions. We propose a fill-in sheet for evaluation of food environment and microenvironment for bivalves at different developmental stages.
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