Berger, H.M., Siedlecki, S.A., Matassa, C.M., Alin, S.R., Kaplan, I.C., Hodgson, E.E., Pilcher, D.J., Norton, E.L. and Newton, J.A., 2021. Seasonality and life history complexity determine vulnerability of Dungeness crab to multiple climate stressors. AGU Advances, 2(4), p.e2021AV000456.

The Northern California Current System (N-CCS) presently experiences effects from ocean acidification and hypoxia most strongly during the summer upwelling season. Conditions are expected to worsen under future climate change, threatening economically and culturally important marine resources of the region, including Dungeness crab (Metacarcinus magister). Here, we use Dungeness crab as a case study species with a complex life cycle for estimating vulnerability to future change in a seasonally dynamic habitat. Using regional ocean model projections for present and future (year 2100 under RCP 8.5) conditions, we quantified vulnerability (consequence x exposure) of benthic and pelagic life stages to low pH (<7.65), low dissolved oxygen (DO, <1.4 ml/l), and high temperature (>15°C) by overlaying model conditions with spatio-temporal species distribution maps and physical larval transport models. Our results show that vulnerability of the N-CCS Dungeness crab population to low pH, low DO, and high temperature will increase in the future, but the magnitudes of these effects depend on seasonality and life stage. Future vulnerability to low DO is projected to be greatest in the summer, while vulnerability to low pH is projected to emerge year-round. Vulnerability of the adult life stage, which is present year-round, may have the greatest impact on Dungeness population growth. Although vulnerability of larval stages, which are present mostly during the downwelling season, could act as a bottleneck, our larval transport modeling experiments indicate that physical transport and behavior may reduce the vulnerability of pelagic life stages to climate stressors. While our assessment provides information specific to Dungeness crab, it also provides an approach that can be adapted for other species with complex life cycles that live in seasonal habitats. Assessments like these can help guide management decisions and the design of multi-stressor experiments, which are needed to estimate the cumulative impacts of changing ocean conditions.

 Using regional ocean model projections for present and future (year 2100 under RCP 8.5) conditions, we quantified vulnerability (consequence x exposure) of benthic and pelagic life stages to low pH (<7.65), low dissolved oxygen (DO, <1.4 ml/l), and high temperature (>15°C) by overlaying model conditions with spatio-temporal species distribution maps and physical larval transport models. Our results show that vulnerability of the N-CCS Dungeness crab population to low pH, low DO, and high temperature will increase in the future, but the magnitudes of these effects depend on seasonality and life stage. Future vulnerability to low DO is projected to be greatest in the summer, while vulnerability to low pH is projected to emerge year-round. Vulnerability of the adult life stage, which is present year-round, may have the greatest impact on Dungeness population growth. Although vulnerability of larval stages, which are present mostly during the downwelling season, could act as a bottleneck, our larval transport modeling experiments indicate that physical transport and behavior may reduce the vulnerability of pelagic life stages to climate stressors. While our assessment provides information specific to Dungeness crab, it also provides an approach that can be adapted for other species with complex life cycles that live in seasonal habitats. Assessments like these can help guide management decisions and the design of multi-stressor experiments, wh

Berger, H.M., Siedlecki, S.A., Matassa, C.M., Alin, S.R., Kaplan, I.C., Hodgson, E.E., Pilcher, D.J., Norton, E.L. and Newton, J.A., 2021. Seasonality and life history complexity determine vulnerability of Dungeness crab to multiple climate stressors. AGU Advances, 2(4), p.e2021AV000456.