Although seagrass in the lower segments of estuaries provides good nursery habitat for blue crabs, the role of alternative inshore habitats for early blue crab recruitment is not well-known. Using suction sampling, we examined the recruitment dynamics of early blue crabs (Callinectes spp.) over a 10-wk study period at 7 sites representing potential nursery habitats, including 2 marsh edge sites, 2 subtidal unvegetated sites adjacent to salt marsh, 2 subtidal unvegetated sites adjacent to developed marsh, and 1 upestuary subtidal vegetated site. Abundances of small (<6.0 mm CW) and large (≥6.0 mm) juvenile crabs varied over the study period, mainly reflecting two monthly pulses of small crabs coinciding with the new moon phase. Early crabs were significantly more abundant from structured habitats than from subtidal unvegetated habitat; although small crabs were moderately abundant at subtidal unvegetated sites situated lower in the estuary. Large crabs were not abundant from subtidal unvegetated sites; whereas large crabs were abundant from sites with structured habitat. Subtidal unvegetated sites were characterized by crab size-distributions with single modes representing postsettlement crabs and with few large crabs; whereas structured habitats contained relatively more large crabs. However, crab size-distributions varied among structured habitats. Spatio-temporal variation in the early recruitment dynamics of blue crabs reflected temporal changes, such as lunar periodicity; landscape effects, such as proximity to currents; and habitat effects.
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Vol. 24 • No. 1