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Climate refugia for salmon in a changing world
Ebersole, Joe. Climate refugia for salmon in a changing world. American Geophysical Union, San Francisco, CA, December 14 - 18, 2015.
The recognition and protection of climate refugia has been proposed as a potential adaptation strategy that may be useful for protecting biodiversity under a changing climate. Climate refugia are areas that are buffered from climate change effects relative to other areas so as to favor greater persistence of valued social, physical, and ecological resources. In the past, refugia allowed species to persist through prior periods of climate change, even as surrounding regions became unsuitable. Might refugia allow species to persist in the future? And if so, how can we best identify, protect and manage these features? In this presentation, we provide an overview of the conceptual basis for climate refugia for salmon, and illustrate key uncertainties in the responses of salmonids and their habitats to altered temperature and streamflow regimes currently not well addressed by physical or ecological models. We conclude that these uncertainties need not delay anticipatory planning, but rather highlight the need for identification and communication of actions with high probabilities of success, and targeted research within an adaptive management framework.
Climate change threatens to create fundamental shifts in in the distributions and abundances of endothermic organisms such as cold-water salmon and trout species (salmonids). Recently published projected declines in salmonid distributions under future climates range from modest to severe, depending on modeling approaches, assumptions, and spatial context of analyses. Given these projected losses, increased emphasis on management for ecosystem resilience to help buffer cold-water fish populations and their habitats against climate change is emerging. Using terms such as “climate-proofing”, “climate-ready”, and “climate refugia”, such efforts stake a claim for an adaptive, anticipatory planning response to the climate change threat. To be effective, such approaches will need to address critical uncertainties in both the physical basis for projected landscape changes in water temperature and streamflow, as well as the biological responses of organisms. Recent efforts define future potential climate refugia based on projected streamflows, air temperatures, and associated water temperature changes. These efforts reflect the relatively strong conceptual foundation for linkages between regional climate change and local hydrological responses and thermal dynamics. Yet important questions remain. Drawing on case studies throughout the Pacific Northwest, we illustrate some key uncertainties in the responses of salmonids and their habitats to altered hydro-climatic regimes currently not well addressed by physical or ecological models. Key uncertainties include biotic interactions, organismal adaptive capacity, local climate decoupling due to groundwater-surface water interactions, the influence of human engineering responses, and synergies between climatic and other stressors. These uncertainties need not delay anticipatory planning, but rather highlight the need for identification and communication of actions with high probabilities of success, and targeted research within an adaptive management framework.