Metapopulation dynamics of the softshell clam, Mya arenaria

Carly A. Strasser, Ph.D., 2008
Lauren Mullineaux, Advisor

I explored metapopulation dynamics and population connectivity, with a focus on the softshell clam, Mya arenaria. I first worked towards developing a method for using elemental signatures retained in the larval shell as a tag of natal habitat. Using a laboratory experiment, I showed that current instrumentation is not able to measure the first larval shell. In concert with developing this method, I reared larval M. arenaria in the laboratory under controlled conditions to understand the factors that may influence elemental signatures in shell. My results show that growth rate and age have significant effects on juvenile shell composition, and that temperature and salinity affect larval and juvenile shell composition in variable ways depending on the element evaluated. Next, I examined the regional patterns of M. arenaria diversity using the mitochondrial gene, cytochrome oxidase I. I found minimal variability across all populations sampled, suggesting a recent population expansion. Finally, I employed theoretical approaches to understand patch dynamics in a two-patch metapopulation when one patch is of high quality and the other low quality. I found that the spatial distribution of individuals within the metapopulation affect whether growth rate is most elastic to parameters in good or bad patches.