title: Environmentally-controlled, density-dependent secondary dispersal in a local estuarine crab population.
abstract: The mechanisms driving the pelagic secondary dispersal of aquatic organisms following initial settlement to benthic habitats are poorly characterized. We examined the physical environmental (wind, diel cycle, tidal phase) and biological (ontogenetic, density-dependent) factors that contribute to the secondary dispersal of a benthic marine invertebrate, the blue crab (Callinectes sapidus) in Pamlico Sound, NC, USA. Field studies conducted in relatively large (0.05 km2) seagrass beds determined that secondary dispersal is primarily undertaken by the earliest juvenile blue crab instar stages (J1 crabs). These crabs emigrated pelagically from seagrass settlement habitats using nighttime flood tides during average wind conditions (speed approximately 5 m s-1). Moreover, the secondary dispersal of J1 crabs was density-dependent and regulated by intra-cohort (J1) crab density in seagrass. Our results suggest that dispersal occurs rapidly following settlement, and promotes blue crab metapopulation persistence by redistributing juveniles from high-density settlement habitats to areas characterized by low postlarval supply. Collectively, these data indicate that blue crab secondary dispersal is an active process under behavioral control and can alter initial distribution patterns established during settlement. This study highlights the necessity of considering secondary dispersal in ecological studies to improve our understanding of population dynamics of benthic organisms.
authors.affiliation: Center for Marine Sciences and Technology, Department of Marine, Earth and Atmospheric Sciences, North Carolina State University, 303 College Circle, Morehead City, NC 28557, USA. nbreyns@unity.ncsu.edu
authors.forename: Nathalie B
authors.initials: NB
authors.lastname: Reyns
authors.forename: David B
authors.initials: DB
authors.lastname: Eggleston
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D049628:Body Size; D003386:Brachyura / Q000502:physiology*; D003710:Demography; D004777:Environment; D009657:North Carolina; D011156:Population Density; D011157:Population Dynamics; D013037:Spatial Behavior / Q000502:physiology*; D014872:Water Movements; D014919:Wind