BERNATIS, JL; MCGAW, IJ; University of Nevada, Las Vegas: Dungeness crabs use behavior to minimize the physiological costs of feeding and digestion in hypoxia

The Dungeness crab, Cancer magister, inhabits areas that are frequently subject to periods of hypoxia. These crabs use a variety of physiological mechanisms to survive in these hypoxic conditions. However, this shift in metabolic priority may then reduce energy available for other activities, such as foraging. In Barkley Sound, British Columbia, the inshore habitats of C. magister ranged in dissolved oxygen from 20kPa to less than 1.0kPa just above the sediment/water interface. In the lab, starved crabs would enter hypoxic waters to obtain and consume food, but exited the area of hypoxia and settled in higher oxygen regimes for digestion. In a high (21.5kPa – 10.5kPa) and low (10.5kPa – 3.0kPa) dissolved oxygen gradient, starved crabs showed no preference for a specific oxygen regime and were more active than postprandial crabs which preferred higher oxygen levels (>10.0kPa). Consistent with this, crabs released into the field and tracked with telemetry tags exhibited similar behavior. Starved crabs ventured into areas of hypoxic waters and remained mobile, while postprandial crabs settled in areas of higher oxygen. This suggests, C. magister, uses behavioral responses that minimize the use of costly physiological mechanisms and maximize foraging and digestive processes.