Behavioral Responses of Postlarval Penaeid Shrimp to Galveston Bay Olfactants

A laminar-flow choice chamber was developed to measure the orientative responses of postlarval penaeid shrimp to olfactants. Animals were provided with a free choice between two water types separated by a steep concentration gradient. In preliminary experiments, both postlarval brown shrimp Penaeus aztecus and white shrimp P. setiferus were significantly attracted to water from a West Galveston Bay saltmarsh. Subsequent experiments with brown shrimp indicated that this estuarine water lost its attractiveness over winter, which suggests that the attractant(s) is biogenic in origin. Experiments were unable to identify conclusively the attractants associated with the primary saltmarsh nursery habitats. Postlarval brown shrimp did not demonstrate significant attraction to the odor of smooth cordgrass Spartina alterniflora or Spartina detritus. Responses to epiphytic algae from S. alterniflora were equivocal but suggested that these epiphytes may produce an attractant. Significant avoidance of the odor of amphipods Gammarus mucronatus was observed in two of three experiments. A rinse from conspecific postlarvae was significantly avoided in a single experiment.