Diet of the juvenile blue crab, Callinectes sapidus, in shallow-water nurseries in response to large-scale variations in benthic communities

Muddy shallow-water coves in Chesapeake Bay have abundant infaunal food resources and serve as nursery grounds for juvenile blue crabs, Callinectes sapidus.  For this study, I sought to uncover the relationships that exist between the diet of very small (7 to 40 mm CW) juvenile blue crabs and the benthic infauna that serve as food resources in shallow, unvegetated nursery coves as part of an effort to understand where small aquaculture-raised juvenile crabs should be placed in a vital effort to restore the blue crab populations in Chesapeake Bay.  This was accomplished by comparing benthic infaunal samples to the gut contents of wild juvenile blue crabs taken from six shallow coves along two rivers, the York and the Rappahannock, both subestuaries of lower Chesapeake Bay, Virginia, USA.  Benthic communities differed depending on river and location, with abundant clams in both upriver regions, abundant polychaetes in lower salinity areas, and insect larvae in one site that had extremely low salinity (3.4 ppt).  The juvenile crabs, like adults, appear to be opportunistic feeders, with gut contents containing the remains of clams, amphipods, polychaetes, small crustaceans, vegetation, and detritus.  There is a significant positive relationship between polychaetes in the benthic samples and in the guts (p = 0.002), suggesting that juvenile crabs target polychaetes.  Other relationships between the benthos and crab gut contents were not significant but may become more apparent with further study.  Portions of this study are in progress and will be completed by April 2007.