Managing climate refugia for freshwater fishes under an expanding human footprint
Ebersole, J., R. Quiñones, S. Clements, AND B. Letcher. Managing climate refugia for freshwater fishes under an expanding human footprint. FRONTIERS IN ECOLOGY AND THE ENVIRONMENT. Ecological Society of America, Ithaca, NY, 18(5):271-280, (2020). https://doi.org/10.1002/fee.2206
Many rivers and streams supporting cold-water fish such as salmon and trout in United States are currently listed as impaired under the Clean Water Act as a result of high summer water temperatures. Adverse effects of warm waters include impacts to cold-water fish populations that may already be stressed by habitat alteration, disease, predation, and competition with other species. Much effort is being expended to improve conditions for species like salmon and trout, with increasing emphasis on preparing for future climate change. One climate change adaptation strategy that is gaining increased attention is identification and management of climate refugia – defined as watersheds that are buffered from regional climate effects such that they are likely to continue to maintain viable populations of cold-water fishes in the face of warming that may be occuring elsewhere. In this review, we provide examples from the Northeastern US and Pacific Northwest of state and regional efforts to implement and manage potential climate refugia for cold-water fishes.
Within the context of climate adaptation planning, the concept of climate refugia has emerged as a potential framework for addressing future threats to cold-water fish populations. Our aim is to evaluate recent cold-water refugia management efforts within the context of human water demand and regulation, resource consumption, and landscape modification. From these case studies, we illustrate tools, principles and guidelines that can be broadly applied. While many early efforts at identifying climate refugia focused on water temperature, significant gains in evaluating other factors and processes regulating cold-water refugia (e.g. stream flow and groundwater withdrawal) are allowing refined mapping and assessment of ecological value. Significant challenges remain for incorporating climate refugia into water quality standards, evaluating trade-offs among policy options, and planning for uncertainty. But with a procedurally-transparent and conceptually-sound framework to build upon, recent efforts illustrate a promising path forward.