Behavior of Blue Crabs in a Contaminated Environment

Participants: Judith S. Weis, Rutgers University

Status: Ongoing, ends fall 2008


Blue crabs (Callinectes sapidus) are important both commercially and ecologically. They are important members of estuarine and salt marsh food webs, being predators, scavengers, and juveniles are also prey to larger organisms. Studies have shown that an animal’s behavior is a sensitive response to contaminants, and that effects on an organism’s behavior can have consequences at the population and community level. Large blue crabs are also cannibalistic on smaller members of their species. We have been comparing behaviors of crabs from Hackensack (HM) and less polluted sites at Tuckerton (TK), and have found that HM juveniles are more aggressive than those from TK, and are also less likely to be preyed upon by adults, perhaps because of their aggressive responses. This study will investigate the prey capture ability of adult blue crabs from HM vs. TK using a variety of prey.


Define the factors responsible for the difference in HK and TK blue crab behavior by transplanting and monitoring blue crabs in both the “other” site and their native site. There will be a Field Study, Salinity Study, and Contaminated Food Study.


Monitor blue crab behavior by the following methods: transplanting 20 blue crabs to the “other” site for six weeks; twenty blue crabs kept in their own site as controls; 20 kept in the lab aquarium in their native salinity; 20 kept in the lab at the “other” salinity level; 20 blue crabs fed their native killifish; and 20 fed killifish from the “other” site. After a six week period, all blue crabs will be brought to the lab for individual prey capture ability.


Field Studies: transplanting 20 blue crabs from their own site to the “other” site, 20 caged in their own site as controls for six weeks
Salinity Study: 20 blue crabs maintained in the lab aquarium at the typical salinity level as their own site, 20 maintained at the “other” site salinity level for six weeks
Contaminated Food: 20 blue crabs maintained in the lab and fed killifish from their own site, 20 fed killifish from the “other” site for six weeks
All blue crabs taken to lab aquarium after the six week period for prey capture ability and behavior monitoring
Diet Study: stomachs will be dissected for diet


Reports illustrating the above findings will help indicate behavioral responses and the ecological health of an important species in the Hackensack River.