An evaluation of the effects of a rapidly changing Miocene climate on the growth and stable isotopic ecology of the scallop chesapecten nefrens
LaPointe, Cullen Wittenmeyer
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We know little about how organisms respond to rapid climate change, especially within a latitudinally-restricted region. In this study, longevity and growth of scallops representing the warm Middle Miocene Climatic Optimum (MMCO) and cooler post-Miocene Climatic Transition (MCT) suggest that rapid global cooling did not significantly affect growth of Chesapecten nefrens within the Calvert Cliffs of Maryland. Oxygen stable isotopes of C. nefrens calcite indicate significantly lighter d18O of MMCO than MCT (difference in means: -0.21‰ with 95% CI: -0.31 to -0.11‰). Shell intervals with low d18O coincided with growth bands, indicating summer growth cessation in MMCO and MCT C. nefrens. Carbon stable isotopes did not exhibit seasonal cycles, although d13C suggests significantly lower mean primary productivity in the MMCO than MCT. Results suggest that annual growth combined with stable isotopic analysis of scallops provide excellent paleoenvironmental insight into a climatically complex middle Miocene.