TitleBehavioral ecology and population genetics of two populations of blue crab, Callinectes sapidus (Rathbun), in New Jersey
NameReichmuth, Jessica M. (author), Weis, Judith (chair), Holzapfel, Claus (internal member), Morrison, Douglas (internal member), Jivoff, Paul (outside member), Rutgers University, Graduate School - Newark,
DescriptionBlue crabs are important estuarine organisms, both ecologically and economically. Due to historical differences of human impact between contaminated Hackensack Meadowlands (HM) and cleaner Tuckerton (TK), adult prey capture, juvenile predator avoidance, adult/juvenile aggression, metal accumulation/depuration and population genetics were investigated.
HM adults had reduced prey capture on active prey compared to TK crabs, suggesting HM crabs may have reduced coordination. Stomach analysis revealed HM crabs’ stomachs contained ~60% algae/plant and detritus/sediment, and lower crab and fish weights than TK crabs. TK crabs were caged in HM or fed HM food for 8 weeks; their prey capture declined significantly indicating environmental factors were responsible for the behavioral differences.
Crabs were then analyzed for metals in muscle and hepatopancreas. HM crabs were fed clean food or transplanted to TK; TK crabs were fed contaminated food or transplanted to HM. Significant tissue differences were found for Cu, Hg, Pb and Zn. HM crabs did not show a significant decrease in Hg after switching environment or diet, but showed a significant decrease in Cu, Pb and Zn in hepatopancreas after switching. TK crabs showed a significant increase of Hg in muscle and Cr and Zn in hepatopancreas after switching environment or food.
In the lab, HM juveniles attacked threatening stimuli significantly more and TK juveniles fled or gave a mixed response significantly more. HM juveniles were significantly better at avoiding a crab predator when substrate was present. Follow-up experiments were conducted without substrate to determine if aggression was important. Aggressive juveniles were no more successful than non-aggressive ones at avoiding a predator. Adults were placed in a large tank with a crab pot; significantly fewer HM adults entered the pot. The first HM crab to enter generally prevented others from entering or attacked those that did, suggesting aggression may be causing low pot counts.
Microsatellites were analyzed using four markers. Genotypic differences were not found among the three years which indicates these populations are not genetically distinct. Yearly differences were not found. These results indicate genetics can be ruled out. The ‘switch’ experiments results indicate the environment is causing the behavioral differences.
NoteIncludes bibliographical references (p. 108-121)
Noteby Jessica M. Reichmuth
CollectionGraduate School - Newark Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.