Meeting Abstract
Ocean acidification (OA) and deoxygenation, both resulting from rising atmospheric CO2 levels, are lowering the pH and oxygen levels of global oceans. Assessing the impacts of OA and deoxygenation on harvested species is crucial for guiding resource management strategies to maintain healthy and sustainable populations. The Dungeness crab, Cancer magister, is an important species ecologically and economically for the US West Coast. Crabs transition through four life stages: zoea, megalopa, juvenile, and adult. Each stage differs distinctly in morphology and behavior, and thus differs in the pH and dissolved oxygen (DO) conditions they are exposed to. The first two stages exhibit diel vertical migration while the final two stages are benthic. We focused on the megalopa stage and their metabolic response to different pH and DO treatments. We exposed wild-caught megalopae to a low/high pH x low/high DO cross. We used closed-system respirometry at 12˚ C to assess the metabolic response (standard metabolic rate, SMR) to each of the four treatments. We predict that megalopae exposed to the low pH/high DO treatment will have higher metabolic rates than those exposed to the high pH/high DO treatment. We likewise predict that high pH and low DO will depress metabolism relative to exposure to high pH and high DO due to the megalopae conserving oxygen in a limiting environment. If results support our hypothesis, they would suggest that OA and hypoxia affects Dungeness crabs in sublethal ways.
