Streams in an uninhabited watershed have predictably different thermal sensitivities to variable summer air temperatures

作者：Culler Lauren E^*; Wood Zachary T; Diaz Jimena; Fey Samuel B; Timmins Dianne; Ayres Matthew P

来源：Freshwater Biology, 2018, 63(7): 676-686.

DOI：10.1111/fwb.13105

• climate change
• streams
• temperature models
• thermal change
• thermal heterogeneity

Warming temperatures from climate change are altering the distributions and abundances of many species. Aquatic organisms, however, may be buffered from the immediate impacts of air temperature change due to the thermal inertia of water. The extent of this buffering in freshwater ecosystems will determine the fate and possible management strategies for many ecologically and economically important species. Using 11years of air and stream temperature data collected from an uninhabited New Hampshire watershed, we investigated the relationship between air and water temperature change throughout the summer months. Maximum daily stream temperatures during the summer months are known to influence the distribution and phenology of aquatic organisms. As such, we built a predictive model of maximum daily stream temperature as a function of air temperature change, discharge and stream order. Diurnal changes in stream temperatures and changes in stream temperature through the summer consistently lagged changes in air temperature, and deviations in daily air temperatures from seasonally predicted means were a strong driver of water temperatures. A mean increase in residual air temperature over the past 5days of 1.0 degrees C corresponded to a 0.5-0.8 degrees C increase in maximum daily stream temperature. Smaller, headwater streams were colder and less sensitive to changes in air temperature. Although stream temperatures did not increase as much as air temperatures, our results suggest that even small increases in water temperatures will extend the duration of physiologically stressful conditions for biota in this watershed. Thus, preserving thermal heterogeneity and unrestricted access to thermal refuges may be key for species' persistence. We encourage continued use of monitoring data to document within-stream and within-watershed thermal heterogeneity and to generate stream temperature models. These tools will be key for developing management strategies to mitigate the impacts of climate change on streams and their biota.

• 出版日期2018-7