INVESTIGATING THE EFFECT OF CLIMATE CHANGE ON METABOLISM AND LIFESPAN: DOES CLIMATE STATE IMPACT THE LIFESPAN OF THE BIVALVE ASTARTE?

The metabolic theory of ecology states that temperature has a large effect on metabolism and is the primary control on the lifespan of an organism. Astarte shells exhibit changes in shell size and biogeographic range through geologic time. Modern and fossil populations exhibit decreasing shell size toward the equator. Pliocene Astarte from the US Mid Atlantic and Gulf Coastal Plains (MACP and GCP, respectively) are larger in size and have a wider biogeographic distribution compared with Astarte shells since the early Pleistocene extinction. These Pliocene deposits represent warm-temperate conditions. Our study tests the hypothesis that larger Pliocene A. concentrica from the Yorktown Formation in North Carolina have shorter lifespans than smaller modern populations of A. borealis from the cold-temperate zone in the Baltic and White Seas. Maximum lifespan of modern individuals from the Baltic and White Seas are 34 years (20-34 years; mean 26±4.2; n=30) and 47 (25-47 years; mean 32±5.6; n=11), respectively. Preliminary data suggest the Pliocene shells from North Carolina are shorter lived (maximum=21; 9-21 years; mean 14±3.9; n=6) and that lifespan varies spatially and relative to temperature. Additional shell counts will confirm this trend. Future work will use the von Bertalanffy growth equation and standard growth index to compare growth rate among populations.