JUVENILE BLUE CRAB ABUNDANCES IN NATURAL AND MAN-MADE TIDAL CHANNELS IN MANGROVE HABITAT, TAMPA BAY, FLORIDA (USA)

摘要

The blue crab (Callinectes sapidus M. J. Rathbun, 1896) is an ecologically and commercially important species common in the Gulf of Mexico and Western Atlantic Ocean (Virnstein, 1977; Hines et al, 1990; Guillory et al., 1998). The life cycle of the blue crab is considered to be classically estuarine-dependent with females mating within the estuary then migrating offshore to spawn. Larvae are transported back into estuarine habitats where they settle and grow to adult sizes (Tagatz, 1968). Studies of habitat utilization by juvenile blue crabs have focused largely on seagrass, saltmarsh, and unvegetated habitats. Previous studies indicate that seagrass and salt-marsh habitats are important to juvenile blue crabs: researchers report higher juvenile densities, decreased predation, and/or faster growth rates compared to unvegetated habitats (Orth and van Montfrans, 1987, 2002; Thomas et al., 1990; Williams et al., 1990; Perkins-Visser et al., 1996; Rozas and Minello, 1998; Rozas and Zimmerman, 2000). While the use of saltmarsh and seagrass by juvenile blue crabs is relatively well understood, knowledge of mangrove wetlands as habitat for blue crabs is limited. In Rookery Bay, Florida, blue crab densities were lowest in intertidal mangrove habitat, and higher in seagrass and open water (Sheridan, 1992). However, a study comparing mangrove and saltmarsh habitats in Caminada Bay, Louisiana found that blue crabs were more closely associated with mangrove habitat and suggested that this relationship was due to the greater structural complexity offered by mangroves (Caudill, 2005). However, juvenile densities were not reported in these two studies.