Slow climate velocities of mountain streams portend their role as refugia for cold-water biodiversity

• DOI: 10.1073/pnas.1522429113
• Publication Date: 2016-04-05T03:51:28Z
• Authors: Daniel J. Isaak; Michael K. Young; Charles H. Luce; Steven W. Hostetler; Seth J. Wenger; Erin E. Peterson; Jay M. Ver Hoef; Matthew C. Groce; Dona L. Horan; David E. Nagel
• Keywords: Cold climate

The imminent demise of montane species is a recurrent theme in the climate change literature, particularly for aquatic that are constrained to networks and elevational rather than latitudinal retreat as temperatures increase. Predictions widespread losses, however, have yet be fulfilled despite decades change, suggesting trends much weaker anticipated may too subtle detection given use sparse water temperature datasets or imprecise surrogates like elevation air temperature. Through application large water-temperature databases evaluated sensitivity historical air-temperature variability computationally interpolated provide high-resolution thermal habitat information 222,000-km network, we estimate less dire plight cold-water within mountains northwestern United States. Stream warming rates velocities were both relatively low 1968-2011 (average rate = 0.101 °C/decade; median velocity 1.07 km/decade) when warmed at 0.21 °C/decade. Many vertebrate occurred subset network characterized by velocities, three native conservation concern extremely cold, slow environments (0.33-0.48 km/decade). Examination aggressive scenarios indicated although could increase, they remain headwaters because strong local gradients associated with topographic controls. Better about changing hydrology disturbance regimes needed complement these results, but being climatic cul-de-sacs, many mountain streams appear poised redoubts biodiversity this century.