The Mullineaux Lab
Larval Dispersal in Coastal Bivalve Populations
Juvenile Mya arenaria
Larvae of the soft-shell clam Mya arenaria spend several weeks in the plankton, giving them the potential to disperse tens or even hundreds of kilometers away from their natal populations. We are studying larval exchange among coastal populations of Mya in order to understand how it is influenced by coastal hydrodynamic processes and how population dynamics at one site might affect recruitment and dynamics at another. Direct tracking of larvae is difficult, so we are using naturally occurring elements as dispersal tags. This approach is promising because elements such as Pb, Mg, Sr and Ba vary in concentration along the New England coastline, and create a location-specific elemental signature in the water of many bays. This signature gets incorporated into the shells of larval bivalves as they develop. Individuals retain this shell after they settle, and laser ablation ICPMS can be used to analyze its elemental composition. That analysis tells us whether a clam recruited back into its natal population or into a remote one. This study has direct applications to shellfish management because we are developing a way to identify source and sink populations, and predict the effects of one population on another in a given hydrodynamic setting. Several aspects of the project are part of a student's thesis research. Our efforts are part of a broader mutidisciplinary project funded by the National Science Foundation.