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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.

The invasion of the green crab Carcinus maenas in the northeastern U.S. and its competition with the native blue crab Callinectes sapidus and other native crustaceans has been well-documented and researched. Various reasons for the invader's success against native crabs have been examined (juvenile predation, food source flexibility, etc.), but another possibility is a difference in the learning ability of invasive versus native crab species. In this study, the learning ability of C. maenas and C. sapidus was tested by their increased speed in locating hidden food over successive days. The data suggest that C. maenas possesses a learning ability significantly greater than that of C. sapidus, which may partially contribute to its success.

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A field experiment was established in Bocas Del Tom, Panama to examine the relationship between sessile organisms living on mangrove prop roots and fish communities. Artificial mangrove roots (AMR) with different sets of artificial (AE) or real epibionts were established in five different locations in two separate years. Fish species in each plot were identified, counted, and their size estimated by visual census for 15 days in each replicate. In the artificial mangrove plots, the treatments with the most heterogeneous structure had significantly greater abundance of most families and species richness of fish in both years of the experiment. AMR plots with AEs attracted a more abundant and diverse fish assemblage than those with live epibionts, which had lower three-dimensional structure. All of the AMR plots had significantly greater fish abundance than comparable plots of sea grass alone. The location of the replicate also made a significant difference to fish abundance. The data indicate that prop-root epibionts can enhance fish abundance and diversity in mangroves,