The overall goal of this study was to quantify factors influencing post-settlement,
planktonic dispersal of early juvenile blue crabs within seagrass habitats. Field mark–
recapture experiments quantified the proportion of crabs that dispersed planktonically, as
well as the effects of crab size (first–second benthic instars: J1–J2 vs. third–fifth benthic
instars: J3–J5) and day versus night on rates of planktonic dispersion. A subsequent
laboratory flume study examined whether or not planktonic dispersal was an active
behavioral response or a passive response to increasing flow speed, and assessed the role
of water flow, crab density and size, and day versus night on the proportion of early
juvenile crabs that dispersed planktonically. The results from these experiments
demonstrated that: (1) planktonic dispersal can account for up to 18% to the overall loss
of juvenile crabs from an initial seagrass patch; (2) planktonic dispersal is an active
behavioral response; and (3) crab size and current speed are key determinants of
planktonic dispersal.