Multiscale Thermal Refugia and Stream Habitat Associations of Chinook Salmon in Northeastern Oregon

Abstract

We quantified distribution and behavior of adult spring chinook salmon (Oncorhynchus tshawytscha) related to patterns of stream temperature and physical habitat at channel-unit, reach-, and section-level spatial scales in a wilderness stream and a disturbed stream in the John Day River basin in northeastern Oregon. We investigated the effectiveness of thermal remote sensing for analyzing spatial patterns of stream temperature and assessed habitat selection by spring chinook salmon, evaluating whether thermal refugia might be responsible for the persistence of these stocks in rivers where water temperatures frequently exceed their upper tolerance levels (25ЊC) during spawning migration. By presenting stream temperature and the ecology of chinook salmon in a historical context, we could evaluate how changes in riverine habitat and thermal spatial structure, which can be caused by landuse practices, may influence distributional patterns of chinook salmon. Thermal remote sensing provided spatially continuous maps of stream temperature for reaches used by chinook salmon in the upper subbasins of the Middle Fork and North Fork John Day River. Electivity analysis and logistic regression were used to test for associations between the longitudinal distribution of salmon and cool-water areas and stream habitat characteristics. Chinook salmon were distributed nonuniformly in reaches throughout each stream. Salmon distribution and cool water temperature patterns were most strongly related at reach-level spatial scales in the warm stream, the Middle Fork (maximum likelihood ratio: P Ͻ 0.01), and most weakly related in the cold stream, the North Fork (P Ͼ 0.30). Pools were preferred by adult chinook salmon in both subbasins (Bonferroni confidence interval: P Յ 0.05); however, riffles were used proportionately more frequently in the North Fork than in the Middle Fork. Our observations of thermal refugia and their use by chinook salmon at multiple spatial scales reveal that, although heterogeneity in the longitudinal stream temperature profile may be viewed as an ecological warning sign, thermal patchiness in streams also should be recognized for its biological potential to provide habitat for species existing at the margin of their environmental tolerances.

Synthesis of thermal tolerances of the common freshwater fish species in large Western Europe rivers

“…On a scale of several days, we must not underestimate the influence of cumulative exposure to temperatures close to the maximum tolerated temperatures; -on a local scale (a few meters to a few hundred meters), there are temperature contrasts in streams and fish are able to seek out thermal refuges in tributaries, secondary channel, or cooler groundwater upwelling (Torgersen et al, 2001). Salmonids use these contrasts very effectively (Torgersen et al, 1999); the behavior of other families is less well documented; a radiotracking study conducted by Cooke et al (2004) on small-mouth black bass (Micropterus dolomieu) showed that this species actively avoids the warmest zones around industrial releases and that once having "experienced" them, they never return.…”

“…certain mollusks in the Saône River, France, Mouthon and Daufresne, 2006), while others, on the contrary, will expand their area of distribution (Hickling et al, 2006). To fully understand the changes observed or to anticipate the future state of species distribution, it is essential to know their thermal preferenda; interpretation of temperature should, however, be nuanced given that certain behaviors (Davey et al, 2006; aptitude to dispersion, ability to find thermal shelters, Torgersen et al, 1999) and certain phenotypic aptitudes (plasticity in the period of development, Schaefer and Ryan, 2006) enable some species to survive critical thermal episodes.…”

A geomorphic assessment to inform strategic stream restoration planning in the Middle Fork John Day Watershed, Oregon, USA

“…The MFJD River has been the focus of multiple previous geomorphic investigations (e.g. Butcher, Crown, Brannan, Kishida, & Hubler, 2010;Dietrich, 2014Dietrich, , 2016McDowell, 2001;Reclamation, 2008;Torgersen, Price, Li, & McIntosh, 1999). Kasprak et al (2016) used the MFJD to compare and contrast different reach typing (stream channel classification) frameworks (including river styles).…”

“…The MFJD has been the subject of stream temperature thermal fish habitat studies (e.g. Feldhaus, Heppell, Hiram, & Mesa, 2010;McNyset, Volk, & Jordan, 2015;Torgersen et al, 1999), continuous fish surveys and habitat assessments (e.g. Blanchard, 2015), site-scale bioenergetic ecohydraulic modeling (Wall, Bouwes, Wheaton, Saunders, & Bennett, 2015), and salmonid life cycle modeling (McHugh et al, in press).…”

Spatial and temporal stream temperature prediction: Modeling nonstationary temporal covariance structures

“…Specifically, stream temperature plays a significant role in the metabolic rates and life history traits of aquatic organisms in addition to affecting nutrient cycling and productivity [Poole and Berman, 2001;Torgersen et al, 2001]. Fluctuations in stream temperatures as well as thermal heterogeneity stimulate behavioral and physiological changes in aquatic organisms, directly influencing survival, reproductive success, and altering ranges of suitable habitat [Torgersen et al, 1999;Poole and Berman, 2001]. Because of its importance as a determinant of water quality, there is a continuing need to find better methods of monitoring and modeling stream temperatures.…”