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Contributed Talk

Session: : Fisheries Management And Models 2

COS 304-3 - Creating mechanistic, multiple stressor climate vulnerability assessments for U.S. West Coast shellfish

Thursday, August 10, 2023
4:00 PM – 4:15 PM PDT
Location: E141
Abstract: Shellfish are commercially, recreationally, and culturally important to many people living on the U.S. West Coast. Further, shellfish are vulnerable to multiple stressors associated with climate disruption, such as hypoxia, warming, and ocean acidification. Assessments of climate vulnerability that account for these multiple stressors are sparse for shellfish, in part because several relevant oceanographic variables are poorly resolved across space. Here, we leverage an oceanographic synthesis dataset and physiological meta-analysis to fill this gap. This synthesis dataset incorporates 70+ datasets that include high-quality measurements of temperature, dissolved oxygen, and/or pH in nearshore environments across the contiguous US West Coast. From this dataset, we predict exposure to low pH, hypoxia, and high temperatures at three depths from southern California through Washington using data from 2010-2022. The physiological meta-analysis provides us with taxa-specific log response ratios for shellfish to low pH and hypoxia, and we created similar log response ratios for temperature stress based on species’ thermal performance curves. Using these exposures and sensitivities, we summed vulnerability to each individual stressor (i.e. hypoxia, low pH, and high temperatures) together to calculate a climate vulnerability index for Dungeness crabs (Metacarcinus magister), purple urchins (Strongylocentrotus purpuratus), red urchins (Mesocentrotus franciscanus), red abalone (Haliotis rufescens), and krill (Euphausia pacifica) across the study domain.

From these assessments, we find substantial differences in vulnerability by species, latitude, depth, and distance offshore. For instance, while southern California is often the most stressful thermal environment for the shellfish examined here, northern Oregon, southern Washington, and the San Francisco area often have the highest exposure to low pH and hypoxia. Across depths temperature stress often drives spatial climate vulnerability for shellfish in the shallowest depth bin (0-10m), whereas in the deepest depth bin (50-200m), vulnerability corresponds most to low pH and hypoxia. These results also illustrate species-specific differences in what drives climate vulnerability. For example, red abalone vulnerability was driven primarily by temperature stress, whereas purple urchin vulnerability was driven both by temperature and pH levels. Finally, this study is useful in identifying future areas of research, such as highlighting data gaps in pH and dissolved oxygen across the coast and elucidating the role of organismal adaptive capacity in shellfish climate vulnerability. These assessments represent a much needed synthesis of current scientific knowledge about spatial variability in shellfish climate vulnerability that can inform a wide range of natural resource management efforts, including species restoration, fisheries management, and aquaculture-sector climate adaptation.