Age and Growth of Glossocardia obesa, a "Large" Bivalve in a Submarine Cave Within a Coral Reef, as Revealed by Oxygen Isotope Analysis

作者：Kitamura Akihisa^*; Tada Keigo; Sakai Saburo; Yamamoto Nagisa; Ubukata Takao; Miyaji Tsuzumi; Kase Tomoki

来源：Veliger, 2011, 51(2): 59-65.

Dark submarine caves are unique habitats from which most coastal species are excluded because of darkness, marked oligotrophy, and reduced water circulation. Many bivalves have been found in caves of tropical West Pacific coral reefs, but nearly all reported species are very small in adult shell size, generally < 5 mm in length. Glossocardia obesa (Reeve, 1843) is an exceptionally large bivalve in the cave fauna and grows to 80 mm in adult shell length. Since live specimens of G. obesa are apparently very uncommon, there has been no study on its life-history traits. We performed an oxygen isotope analysis of a G. obesa (72 mm in shell length) collected alive in a submarine cave at Okinawa Islands, Japan. The delta O-18 record is divided into early- and late-growth phases. There is no systematic change in delta O-18 value in the early-growth phase, whereas the delta O-18 record for the late-growth phase contains six cycles. Comparing ihe delta O-18-derived temperatures from G. obesa with water-temperature records and delta O-18 value of seawater in the cave shows that the delta O-18 cycles of G. obesa reflect seasonal variation in water temperature. This result demonstrate; that the oxygen isotope analysis can usefully be employed to estimate growth and age in this species.

• 出版日期2011-5-26