BERNATIS, JL; MCGAW, IJ; University of Nevada, Las Vegas; University of Nevada, Las Vegas: Feeding and Digestion in the Dungeness Crab, Cancer magister, in Hypoxic Conditions

Decapod crustaceans encounter hypoxia periodically in their natural environment. Such conditions may limit their distribution and foraging ability. In Barkley Sound, British Columbia,the inshore environments inhabited by the Dungeness crab, Cancer magister, ranged in dissolved oxygen concentrations from 22.9KPa at the water surface to 9.4KPa just above the sediment. While the mud/water interface dropped as low as 0.8KPa. During hypoxic exposure, crabs reduced food intake and tended to cease feeding below 5.2KPa. In a dissolved oxygen gradient(19.8KPa – 10.4KPa) starved crabs were active, moving around the tank among the varying oxygen levels. However, postprandial (3-6h) crabs spent the majority of time in higher oxygen and spent very little time in the lowest oxygen levels. The specific dynamic effect of food ingestion caused a change in the physiological state of the animal. Postprandial crabs exhibited a behavioral response that allowed optimal oxygen uptake for digestive processes. Thus, the nutritional state of an animal may be important in regulating both behavior and distribution in their natural environment.