Higher survival but smaller size of juvenile Dungeness crab (Metacarcinus magister) in high CO2
2022
McElhany, Paul | Busch, Danielle Shallin | Lawrence, Amanda | Maher, Michael | Perez, Danielle | Reinhardt, Emma M. | Rovinski, Kate | Tully, Erin M.
Dungeness crab (Metacarcinus magister) are the most valuable fishery on the U.S. West Coast and both larval and adult Dungeness crabs are important components of regional food webs. Previous experiments have shown decreased survival and a slower development rate for Dungeness crab zoea reared in water with high CO₂, indicating a susceptibility to ocean acidification. In this study we reared late-stage megalopae and juvenile Dungeness crabs in both ambient and high CO₂ conditions for over 300 days. Counter to expectations, crabs reared in high CO₂ had a higher survival rate than those reared in ambient conditions and crabs in high CO₂ transitioned more quickly in one of the stages (J5 to J6). However, crabs reared in high CO₂ were generally smaller and had a higher resting metabolic rate than crabs in ambient CO₂. We hypothesized that two separate mechanisms were in effect, with one process driving survival and a second process driving size and respiration rate. We further hypothesized that increased mortality in ambient CO₂ could be caused by a CO₂-sensitive microbial pathogen, but that size and respiration differences were caused by the direct effects of CO₂ on the crabs themselves. Overall, the zoea stages seem more sensitive to CO₂ than the megalopae and juvenile stages.
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