Many estuarine crustaceans have planktonic larvae that develop in coastal/shelf areas and then return to estuaries as postlarvae. This study is designed to test the hypothesis that estuarine crustaceans use chemical and physical cues (1) for up-estuary transport, settlement, and metamorphosis of postlarvae (megalopae) and (2) for retention and juveniles (J1-J3 instars) in specific habitats. Using the blue crab, Callinectes sapidus, as a representative species, stimulatory and inhibitory chemical cues will first be tested in a chemical choice tube to determine effective concentration ranges for behavioral responses that are potentially involved in habitat location. Further laboratory experiments with a paddle wheel flume will study settlement site location behavior and settlement in the presence of realistic flow conditions, chemical cues and structure. Finally, the effects of stimulatory and inhibitory cues on metamorphosis will be determined. This information will permit a better understanding of the conditions necessary for successful completion of the postlarval and early juvenile phases of the life cycle of some estuarine crustaceans and the development of an integrative descriptive model of the behavioral responses to environmental stimuli during the transition from a planktonic phase (postlarval) to a mostly benthic existence as a juvenile in a nursery habitat.
