Collaborative Research: Estuarine Crab Transport: Linking Post-Settlement Dispersal, Bio-Physical Mechanisms and Hydrodynamic Corridors

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Secondary pelagic dispersal of juvenile benthic organisms following initial larval settlement may strongly influence local and regional population dynamics, yet secondary dispersal is rarely considered in recruitment studies. While the relative importance of post-settlement blue crab dispersal in determining recruitment patterns in Pamlico Sound, NC, is presently recognized, the factors initiating movement by early juvenile blue crabs away from settlement habitats, the mechanisms mediating across-sound transport, and the population-level consequences of redistribution to alternative habitats, have not yet been explored. This project will address these issues through an interdisciplinary study that incorporates: (1) small-scale field measurements in seagrass beds along the sound-side of the Outer Banks to identify the factors cueing initial movement from settlement habitats, (2) laboratory experiments to test the behavioral mechanisms that drive pelagic emigration, and (3) sound-wide hydrographic surveys to characterize Pamlico Sound circulation coupled with synoptic measurements of the spatiotemporal distribution of postlarval and juvenile blue crabs. The project will be conducted during 2002-2003 to take advantage of concurrent postlarval and juvenile sampling supported by another NSF award. This project will contribute to the understanding of how pelagic dispersal occurs in estuaries that are not dominated by tidal motions, but by irregular or persistent wind-induced motions. Generalizations of recruitment dynamics from past work on systems with strong tidal signals (e.g., Chesapeake and Delaware Bays) may not accurately characterize patterns of estuarine recruitment in predominantly large, wind-driven systems such as Pamlico Sound.