Tidal transport of postlarval bivalves in a flood dominated estuary

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Despite a growing recognition of the role of recruitment in structuring benthic communities, post-larval dispersal remains a critical gap in our understanding of the processes determining patterns of distribution and abundance in soft bottom communities. There have been many observations of post-larval dispersal, but far fewer measurements of rates or distances of dispersal and their relationship to physical and biological factors. In particular, we know very little about the scales over which post-larval dispersal occurs. Knowledge of the distances post-larvae disperse is crucial in understanding the ecological consequences of this dispersal, including its interaction with other processes. The overall objective of this study is to examine the scale and magnitude of post-larval transport of a bivalve, the soft shell clam Mya arenaria, in a small flood-dominated estuary. In a laboratory flume experiment and field experiments, the investigators will make measurements of near bottom current speeds and examine the relationship between physical factors (flow speed, tidal state and range, sediment type) and rates and distances of post-larval transport. At the end of the study, they will examine the consequences of post-larval transport for patterns of distribution and abundance by combining the physical and biological data to drive a numerical model of post-larval transport. The research will substantially advance our understanding of the role of post-larval dispersal in bivalve recruitment. The study will be one of the first to make direct field measurements of the scale of post-larval dispersal using mark-recapture techniques. Quantifying the scale and magnitude of post-larval transport under observed physical conditions will be applicable to future studies of other species and other systems. The proposed research will have an educational impact by providing undergraduate students with the opportunity to conduct independent research as part of an interdisciplinary study.