LIFE HISTORY PATTERNS AND CONSERVATION PALEOBIOLOGY OF MARINE BIVALVES FROM WARM VS COLD CLIMATES

Bivalve shellfishing contributes over $1,000,000 annually to the US marine fisheries industry, yet the impact of climate and environmental change on shellfisheries remain unclear. The northern and southern hard clams (Mercenaria mercenaria and M. campechiensis, respectively) are economically and ecologically important bivalves harvested along the eastern seaboard. In part because of their economic importance, growth patterns (sclerochronology) in modern Mercenaria have been long studied throughout their biogeographic range. Few studies document the impact of climate and environmental change on their growth. We examine how these economically important species may respond to future projected seawater warming by using a conservation paleobiology approach. We use sclerochronology to assess changes in life history during warm vs. cold climate conditions (mid-Pliocene and early Pleistocene, respectively) recorded in fossil Mercenaria from the US Atlantic and Gulf Coastal Plains along a latitudinal gradient compared with modern populations. The differences in lifespan and growth rates between these populations will be assessed using the von Bertalanffy growth equation. We hypothesize that fossil Mercenaria from the early Pleistocene (cold climate) will have longer lifespans and slower growth rates compared with mid-Pliocene and modern Mercenaria (warm climates). To date, our results show that an early Pleistocene population from North Carolina (Waccamaw Fm) have slower growth rates and longer lifespans relative to modern populations from similar latitudes. Analysis of modern and fossil populations from Virginia, North Carolina, and Florida are underway and will be presented in the context of these results.