Modelling effects of climate change on Michigan brown trout and rainbow trout: precipitation and groundwater as key predictors

Author(s):

Andrew K. Carlson, William W. Taylor, Dana M. Infante 

Journal or Book Title: Ecology of Freshwater Fish

Year Published: 2020

Abstract:

Understanding how changes in stream temperature affect survival and growth of coldwater fishes, including brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss), is important for conserving coldwater stream fisheries in a changing climate. However, some contemporary stream temperature models assume spatially uniform (i.e., unrealistic) air-stream temperature relationships or demand hydrometeorological predictors (e.g., solar radiation, convection) that are expensive and often impractical for fisheries managers to measure. As such, we produced a relatively cost-effective, management-relevant modeling approach for predicting effects of changes in air temperature, precipitation, and groundwater inputs on stream temperature and, consequently, the survival and growth of brown trout and rainbow trout in Michigan, USA. We found that precipitation- and groundwater-corrected stream temperature models (mean adjusted R2 = 0.77, range = 0.65-0.88) performed better than linear air-stream temperature models (mean adjusted R2 = 0.59, range = 0.21-0.80). Stream temperature was projected to increase by 0.07-3.88°C (1-22%) with simulated changes in air temperature, precipitation, and groundwater inputs. The greatest warming was predicted for surface runoff-dominated sites with limited groundwater-driven thermal buffering, where thermal habitat suitability for salmonid survival and growth declined 20-40%. However, groundwater-dominated sites may not be immune to temperature warming, especially if groundwater temperature increases or groundwater inputs decline in a changing climate. Our modeling approach provides a reliable, cost-effective method for predicting effects of climate change on brown trout and rainbow trout survival and growth, allowing for strategic management actions to increase the thermal resilience and sustainability of salmonid populations (e.g., groundwater conservation, riparian/watershed rehabilitation).

DOI: 10.1111/eff.12525

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