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.