Meeting Abstract

S7.1  Thursday, Jan. 6  Diet preferences and bottom-up control of blue crabs in Chesapeake Bay SEITZ, R.D.*; KNICK, K.E.; WESTPHAL, M.; Virginia Institute of Marine Science, The College of William and Mary; Virginia Institute of Marine Science, The College of William and Mary; University of Alaska Fairbanks, School of Fisheries and Ocean Sciences seitz@vims.edu

Shallow coves in Chesapeake Bay have abundant food resources and serve as nursery grounds for juvenile blue crabs. In this study, we examined relationships between the diet of very small (7 to 40 mm CW) juvenile blue crabs and benthic infauna in shallow, unvegetated nursery coves. We compared infauna in benthic samples with gut-contents of juvenile blue crabs from six shallow coves in two subestuaries (York and Rappahannock Rivers) in Chesapeake Bay, Virginia, USA. Benthic communities differed depending on river and location, with abundant clams in upriver regions and abundant polychaetes in downriver regions. Juvenile crabs, like adults, appeared to be opportunistic feeders, with gut contents including clams, amphipods, polychaetes, small crustaceans, vegetation, and detritus. There was a positive relationship between polychaetes in the benthic samples and in crab guts, suggesting that juvenile crabs target polychaetes in the benthos. Crab densities also corresponded with polychaete benthic densities, thus, there may be bottom-up control of crab distributions. In comparison to larger juvenile crabs, small juveniles prefer polychaetes and crustaceans, with ontogenetic shifts towards more bivalves and conspecifics.