Environmental controls on shell growth rates and δ18O of the shallow-marine bivalve mollusk Phacosoma japonicum in Japan

摘要: Microgrowth patterns and the oxygen isotope composition of juvenile, shallow-marine bivalve mollusk shells Phacosomajaponicum (Reeve) in Japan were analyzed cross-calibrated with environmental parameters. Mark-and-recovery experiments indicate that a pair two microgrowth lines increments is produced every lunar day. This finding makes it possible to assign exact calendar dates each portion shell. Average daily growth rates decrease by 61% from age three 55% four. The length growing season rate are mainly controlled temperature: shell ceases below 14.2°C (age two) 16.8°C four) most rapid between 24.6°C 27.2°C. Based on local temperature cycles, longest Seto Inland Sea, central Honshu (from May November) shortest at Hakodate Bay, North June October). annual profiles reflect cycle varying amounts freshwater added seawater precipitation. negative δ18O values –3.15‰ occur during rainy season, i.e. monsoon typhoon seasons. Growth only slightly affected salinity changes. Strongly reduced second half year Sea lesser extent Tokyo Bay explained nutrient deprivation. Our study provides basis for use P. japonicum high-resolution ecological studies reconstructions.