Evolution of life-history strategy and paleoclimate changes from an geochemical record of a cave-dwelling marine micro-bivalve.

在日本冲绳附近的一个海底洞穴中，发现了一种长、高均小于3.5 mm的穴居微型双壳类-家岛卡氏壳。标记放流和再捕获调查结果表明，该物种具有全年持续生长的潜力。如果这种解释是正确的，那么壳可能需要1年以上才能达到1毫米的高度，4年才能达到3毫米;因此，C。据估计，iejimensis至少有4年。为了评估该物种作为定量古海洋学代表的用途，我们分析了60个活体C的δ 18 O值。从海底洞穴采集的标本。结果表明，大部分个体的δ 18 O值与年平均温度和海水δ 18 O值一致。这些结果，当应用于化石壳δ 18 O记录从洞穴，表明，最近的变暖可能是例外，在过去的7000年的古温度记录，其中包括中世纪温暖期和中全新世气候最佳的背景下来看。

Cave-dwelling micro-bivalve Carditella iejimensis,which is less than 3.5 mm in height and length, inhabits the sediment surfacein a submarine cave off the Okinawa Islands, Japan. The result of mark-release and recapture surveys indicates that the species is potentially able to undergo year-round continuous growth. If this interpretation is correct, the shell probably requires more than 1 year to reach 1 mm in height, and 4 years to reach 3 mm; consequently, the lifespan for C. iejimensis is estimated to be at least 4 years. To evaluate the use of this species as a quantitative paleoceanographic proxy, we analyzed the δ18O values of 60 living C. iejimensisspecimens collected from the submarine cave. Results show that most individuals preserve δ18O values corresponding to the mean annual temperature and δ18O of seawater. These results, when applied to fossil shell δ18O records from the cave, indicate that the recent warming is likely exceptional, when viewed in the context of the past 7000 years paleotemperature record, which includes the Medieval Warm Period and the Middle Holocene Climatic Optimum.