1Graduate school of Bioresources, Mie University, Tsu, Mie 514-8507, 2International Coastal Research Center, Ocean Research Institute, The University of Tokyo, Otsuchi, Iwate 028-1102, Japan
To establish a method to estimate habitat salinity of Corbicula species, we examined the strontium (Sr) to calcium (Ca) ratios of C. japonica collected from lakes with different salinity and that of a freshwater species C. leana with an electron probe micro analyzer (EPMA). Sr/Ca ratios in the shell of C. japonica from Lake Ogawara, Aomori Pref. (salinity: 0.2-1.7 psu), Lake Shinji, Shimane Pref. (3.3-15.2 psu), Lake Jinzai, Shimane Pref. (7.5-32 psu), Ibi River, Gifu and fresh water species C. leana from Hatahoko River, Iki Island, Fukuoka Pref. C. japonica collected from high salinity lakes showed high shell Sr/Ca ratios: 8.06±0.30 from Lake Jinzai and 6.84±0.21 from Lake Shinji, respectively. On the contrary, C. japonica from low salinity Lake Ogawara and Ibi River showed low Sr/Ca ratios: 3.68±0.18 and 1.33±0.14, respectively. The fresh water species C. leana also showed low Sr/Ca ratio (1.65±0.11). Thus, habitat salinity of Corbicula species can be roughly estimated by Sr/Ca analysis using EPMA, and such information may be useful in the determination of place of origin.