Biological Consequences of Environmental Change in the Bivalve, Astarte: Relationships Between Lifespan, Growth Rate, and Cold vs. Warm Climate States

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What are the biological consequences of environmental change? The goal of this research is to determine the impact of regional climate and geographic range size on the shell growth rate and lifespan of a common clam species from modern and fossil populations found along the southeastern US coastal plains and Mid-North Atlantic. The populations included in the study will provide an understanding of how environmental change will affect the lifespan of bivalves that live in regions with different annual temperature ranges. Outcomes will advance our knowledge of the effects of environmental change on organisms that live in sensitive coastal habitats. Our methods and results will have a significant educational benefit, especially for students from underrepresented groups (e.g., first-generation college students interested in STEM fields), and will be used by high school and undergraduate students by stimulating innovation using STEM educational mechanisms. Through the UNC-BEST (Baccalaureate Education in Science & Teaching) program, we will award future high-school earth science teachers the opportunity to perform scientific research that will generate authentic laboratory curricula for K-12 science courses. We will help teachers from Pender County Schools (which serves low income and disadvantaged households) to improve instruction by integrating writing with scientific discovery through the "Writing in Science and Science in Writing" program (a collaborative program with UNCW).Astarte shells are uniquely suited to investigate links between environmental change and biological consequences (e.g., changes in lifespan and metabolic rate) because of their change in size and biogeographic distribution through time. We will focus on the abundant populations of Astarte in Plio-Pleistocene deposits along the US Mid-Atlantic and Gulf Coastal Plains and modern populations in the North Atlantic. The main objectives are to: 1) establish the seasonal timing of annual growth checks in different biogeographic populations of modern and fossil Astarte using isotope sclerochronology; 2) establish the relationship between biogeographic zone to growth rate and lifespan; and 3) establish the relationship of climate state to growth rate and lifespan. Objectives 2 and 3 employ the von Bertalanffy growth equation and its derivative (standard growth index; SGI) to compare shell growth of a population between modern and fossil, across biogeographic zones, and between cold vs. warm climates. Our null hypotheses will be tested using a mixed model ANOVA and PCA tests. These tests will determine the principal components controlling variability among Astarte populations. This study provides a greater understanding of how biogeographic distribution and differences in seasonal temperature range may influence bivalve growth and longevity and how changing conditions may affect future populations.