Juvenile Dungeness Crabs Reared in High CO2 Have Higher Base Metabolic Rates

Ocean acidification (OA) is an caused by increasing anthropogenic CO₂ absorbed by the ocean which produces chemical changes leading to decreasing pH. This drop in pH levels will likely cause shifts in abundance or distribution of species that are of vital ecological and economical importance. In the Pacific Northwest, the Dungeness crab, Cancer magister, is a commercially important species. Under short-term exposures to low pH, Dungeness crab zoea have shown lower survival and slower developmental rates (Miller et. al, 2016). This study examined how CO₂ concentration treatments affected the respiration rate of juvenile Dungeness crabs. It was hypothesized that long term exposure to low pH will affect the crabs’ metabolic activity. In this study, we used respirometry, which measured oxygen consumption in a closed jar, to examine the metabolic sensitive of C. magister to high and low CO₂ treatments. The juveniles used in this study were exposed to two CO₂ treatments (ambient and high CO₂₎ for 300 days. In preparation for the respirometry trials, crabs were starved 24 hours prior and weighed the morning of their trial. Preliminary analysis shows a significant effect of high CO₂ treatment in increasing respiration rate. Separate analyses indicate that CO₂ treatments affected the size of the crabs in this study, suggesting complicated trade-offs in maintaining metabolic rate in a high CO₂ environment and energetic resource allocation.