Populations living in contaminated environments may exhibit behavioral changes that can alter predator-prey interactions. Blue crabs from the contaminated Hackensack Meadowlands (HM) had reduced ability to capture juvenile blue crabs and adult mummichogs (both active prey) compared with crabs from a reference site (Tuckerton (TK)). However, they consumed equivalent amounts of ribbed mussels and fiddler crabs, which are less active prey. Crabs may have reduced coordination rather than appetite or motivation. The lab data are supported by stomach analysis of field-caught crabs. HM crab stomachs contained ∼60% algae, plant material, detritus, and sediment and much lower weights of crab, fish, and other live food than TK crabs. However, the relative absence of bivalves in their diet may reflect reduced amounts available. When TK crabs were caged in HM or fed food from HM in the lab for 8 weeks, their prey capture ability declined significantly, and mercury in their muscle tissue increased significantly, indicating that environmental factors were responsible for the behavioral differences. When HM crabs were caged in TK or fed fish from TK in the lab for 8 weeks, their prey capture ability improved significantly. Mercury levels were variable and did not show a significant decrease.

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Recent literature has suggested aggression may be context dependent. The purpose of this investigation was to examine aggressive and predator avoidance behaviors in juvenile blue crabs of two populations. Furthermore, we wanted to determine whether aggression persisted into the adult stages. Juvenile blue crabs collected from an impacted estuary, the Hackensack Meadowlands (HM), were found to attack a threatening stimulus significantly more often (70%) than conspecifics from a less impacted estuary (Tuckerton-TK). TK juveniles responded significantly more often with a flight (*35%) or mixed response (*30%). Additionally, HM juveniles were significantly more successful than TK juveniles at avoiding an adult blue crab predator when sandy substrate was present in laboratory experiments. However, the video clarity made it impossible to determine which interactions were allowing survival. To determine if ''aggression'' exhibited by the HM juveniles was the reason for their enhanced survival, follow-up predator avoidance experiments were conducted without substrate and videotaped. The results of these experiments suggest that aggression per se is not the reason since aggressive juveniles were no more successful than non-aggressive individuals. The aggressive behavior exhibited by HM juveniles continues into the adult stages. This behavior may be important to recognize when estimating population size as well as local fishery efforts.

As rivers flow toward the coast, freshwater mixes with saltwater in estuaries. The mixing here creates a wide range of environments for many organisms. The Satilla River Estuary has been cut eight times, which has altered the salinity gradients that are a result of natural tidal flow. Altered salinity gradients pose a threat to migratory fish species because they are no longer able to pick up on directional cues that these gradients provide, ultimately affecting species richness in the estuary. The purpose of this study is to determine if Noyes Cut has affected salinity gradients at five collection sites in Umbrella and Dover Creeks. Experimental gill nets were set one hour before max flood tide and soaked for two hours. All fish were identified to species with total and fork lengths measured to the nearest centimeter. Noyes Cut and Parsons Creek had the most species richness while River Marsh Landing and Todd Creek experienced the lowest diversity. We believe these large salinity fluctuations are due to a sediment deposit that blocks water flow as a result of Noyes Cut. When Noyes Cut is closed, we expect fish to redistribute into Umbrella and Dover Creeks as a result of restored salinity gradients.