Banks, J. Shannon Point Marine Center REU,
SETTLEMENT BEHAVIOR OF DUNGENESS CRAB (CANCER MAGISTER) MAGALOPAE WHEN EXPOSED TO CHEMICAL AND VISUAL CUES FROM THE SHORE CRAB, HEMIGRAPSUS
Artificial habitat is often created to augment populations of commercially valuable species. The complex structure of the habitat serves to provide refuge from predation. In Grays Harbor, WA, this concept is being applied by establishing intertidal oyster shell plots for Dungeness megalopae settlement. Previous monitoring of these plots revealed a negative relationship between Hemigrapsus populations and Dungeness crab juveniles within the shell plots. The present study investigated the relationship between the presence of Hemigrapsus and the settling behavior of Dungeness magalopae. The study also explores the predation interactions between Hemigrapsus and Dungeness crab instars. Dungeness crab megalopae avoid the vicinity of Hemigrapsus, whose presence is detected chemically, not visually. Results support the hypothesis that Dungeness magalopae are avoiding the presence of Hemigrapsus when selecting areas to settle. Hemigrapsus predation upon Dungeness crab, with carapace width ~8cm, begins to occur when the shore crab is approximately 1.5 times the size of the Dungeness. Percentage mortality of Dungeness instars by predation increases as the size ratio (Dungeness crab: Hemigrapsus) increases.
Day: Wednesday, Feb. 3
Location: Sweeney Center