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Climate change simulations predict altered biotic response in a thermally heterogeneous stream system.

Westhoff JT, Paukert CP - PLoS ONE (2014)

Bottom Line: Groundwater spring influence affected river water temperatures in both winter and summer, but springs that contributed less than 5% of the main stem discharge did not affect river temperatures beyond a few hundred meters downstream.By 2080, peak numbers of optimal growth temperature days for smallmouth bass are expected to shift to areas with more spring influence, largemouth bass are expected to experience more optimal growth days (21-317% increase) regardless of spring influence, and Ozark hellbenders may experience a reduction in the number of optimal growth days in areas with the highest spring influence.Our results provide a framework for assessing fine-scale (10 s m) thermal heterogeneity and predict shifts in thermal conditions at the watershed and reach scale.

View Article: PubMed Central - PubMed

Affiliation: Missouri Cooperative Fish and Wildlife Research Unit, Department of Fisheries and Wildlife Sciences, University of Missouri, Columbia, Missouri, United States of America.

ABSTRACT
Climate change is predicted to increase water temperatures in many lotic systems, but little is known about how changes in air temperature affect lotic systems heavily influenced by groundwater. Our objectives were to document spatial variation in temperature for spring-fed Ozark streams in Southern Missouri USA, create a spatially explicit model of mean daily water temperature, and use downscaled climate models to predict the number of days meeting suitable stream temperature for three aquatic species of concern to conservation and management. Longitudinal temperature transects and stationary temperature loggers were used in the Current and Jacks Fork Rivers during 2012 to determine spatial and temporal variability of water temperature. Groundwater spring influence affected river water temperatures in both winter and summer, but springs that contributed less than 5% of the main stem discharge did not affect river temperatures beyond a few hundred meters downstream. A multiple regression model using variables related to season, mean daily air temperature, and a spatial influence factor (metric to account for groundwater influence) was a strong predictor of mean daily water temperature (r2 = 0.98; RMSE = 0.82). Data from two downscaled climate simulations under the A2 emissions scenario were used to predict daily water temperatures for time steps of 1995, 2040, 2060, and 2080. By 2080, peak numbers of optimal growth temperature days for smallmouth bass are expected to shift to areas with more spring influence, largemouth bass are expected to experience more optimal growth days (21-317% increase) regardless of spring influence, and Ozark hellbenders may experience a reduction in the number of optimal growth days in areas with the highest spring influence. Our results provide a framework for assessing fine-scale (10 s m) thermal heterogeneity and predict shifts in thermal conditions at the watershed and reach scale.

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Location of the Ozark National Scenic Riverways (Jacks Fork and Current Rivers).Triangles indicate locations of stationary temperature loggers deployed for the entirety of 2012, with locations mentioned in the text noted by abbreviations (Tan Vat, TV; Cedar Grove, CG; Big Spring Downstream, BGD; Buck Hollow, BH; Rymers, RY; Bay Creek, BC, and Keatons, KE). Hollow circles surrounding a point indicate the locations of major springs referenced in the text (Welch Spring, WS; Pulltite Spring, PS; Blue Spring Current, BSC; Big Spring, BG; Blue Spring Jacks Fork, BSJ; and Alley Spring, AS).
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pone-0111438-g001: Location of the Ozark National Scenic Riverways (Jacks Fork and Current Rivers).Triangles indicate locations of stationary temperature loggers deployed for the entirety of 2012, with locations mentioned in the text noted by abbreviations (Tan Vat, TV; Cedar Grove, CG; Big Spring Downstream, BGD; Buck Hollow, BH; Rymers, RY; Bay Creek, BC, and Keatons, KE). Hollow circles surrounding a point indicate the locations of major springs referenced in the text (Welch Spring, WS; Pulltite Spring, PS; Blue Spring Current, BSC; Big Spring, BG; Blue Spring Jacks Fork, BSJ; and Alley Spring, AS).

Mentions: Our study occurred within the Ozark National Scenic Riverways (ONSR), which is a National Park Service Unit located in south-central Missouri, USA (37° N, 91° W) on the Ozark Plateau [47]. The park encompasses approximately 32,700 hectares, creating a narrow corridor along 215 km of the Current River and its largest tributary, the Jacks Fork River (Figure 1). The Current River is a southerly flowing stream which enters the ONSR as a 4th order [48] stream and reaches 6th order upon its exit, whereas the Jacks Fork River is an eastern flowing 5th order stream within the ONSR. Average (range) wetted channel width in the Current River was 47.6 m (17.5 – 127.3 m) and 26.3 m (12−49 m) in the Jacks Fork (J. Westhoff, unpublished data). The deepest pools in the Current and Jacks Fork Rivers rarely exceed 5 and 3 m, respectively (J. Westhoff, unpublished data). Substrate composition in the river channel was generally dominated by coarse chert gravel or large boulders associated with bluff pools or high gradient reaches [49]. The riparian zone was dominated by deciduous forest and was mostly intact along the entirety of the river contained with the ONSR. The overall catchment was primarily forested with 14% of the catchment in cleared land, only 2% of which is on areas with > 7° slopes [50].


Climate change simulations predict altered biotic response in a thermally heterogeneous stream system.

Westhoff JT, Paukert CP - PLoS ONE (2014)

Location of the Ozark National Scenic Riverways (Jacks Fork and Current Rivers).Triangles indicate locations of stationary temperature loggers deployed for the entirety of 2012, with locations mentioned in the text noted by abbreviations (Tan Vat, TV; Cedar Grove, CG; Big Spring Downstream, BGD; Buck Hollow, BH; Rymers, RY; Bay Creek, BC, and Keatons, KE). Hollow circles surrounding a point indicate the locations of major springs referenced in the text (Welch Spring, WS; Pulltite Spring, PS; Blue Spring Current, BSC; Big Spring, BG; Blue Spring Jacks Fork, BSJ; and Alley Spring, AS).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4214750&req=5

pone-0111438-g001: Location of the Ozark National Scenic Riverways (Jacks Fork and Current Rivers).Triangles indicate locations of stationary temperature loggers deployed for the entirety of 2012, with locations mentioned in the text noted by abbreviations (Tan Vat, TV; Cedar Grove, CG; Big Spring Downstream, BGD; Buck Hollow, BH; Rymers, RY; Bay Creek, BC, and Keatons, KE). Hollow circles surrounding a point indicate the locations of major springs referenced in the text (Welch Spring, WS; Pulltite Spring, PS; Blue Spring Current, BSC; Big Spring, BG; Blue Spring Jacks Fork, BSJ; and Alley Spring, AS).
Mentions: Our study occurred within the Ozark National Scenic Riverways (ONSR), which is a National Park Service Unit located in south-central Missouri, USA (37° N, 91° W) on the Ozark Plateau [47]. The park encompasses approximately 32,700 hectares, creating a narrow corridor along 215 km of the Current River and its largest tributary, the Jacks Fork River (Figure 1). The Current River is a southerly flowing stream which enters the ONSR as a 4th order [48] stream and reaches 6th order upon its exit, whereas the Jacks Fork River is an eastern flowing 5th order stream within the ONSR. Average (range) wetted channel width in the Current River was 47.6 m (17.5 – 127.3 m) and 26.3 m (12−49 m) in the Jacks Fork (J. Westhoff, unpublished data). The deepest pools in the Current and Jacks Fork Rivers rarely exceed 5 and 3 m, respectively (J. Westhoff, unpublished data). Substrate composition in the river channel was generally dominated by coarse chert gravel or large boulders associated with bluff pools or high gradient reaches [49]. The riparian zone was dominated by deciduous forest and was mostly intact along the entirety of the river contained with the ONSR. The overall catchment was primarily forested with 14% of the catchment in cleared land, only 2% of which is on areas with > 7° slopes [50].

Bottom Line: Groundwater spring influence affected river water temperatures in both winter and summer, but springs that contributed less than 5% of the main stem discharge did not affect river temperatures beyond a few hundred meters downstream.By 2080, peak numbers of optimal growth temperature days for smallmouth bass are expected to shift to areas with more spring influence, largemouth bass are expected to experience more optimal growth days (21-317% increase) regardless of spring influence, and Ozark hellbenders may experience a reduction in the number of optimal growth days in areas with the highest spring influence.Our results provide a framework for assessing fine-scale (10 s m) thermal heterogeneity and predict shifts in thermal conditions at the watershed and reach scale.

View Article: PubMed Central - PubMed

Affiliation: Missouri Cooperative Fish and Wildlife Research Unit, Department of Fisheries and Wildlife Sciences, University of Missouri, Columbia, Missouri, United States of America.

ABSTRACT
Climate change is predicted to increase water temperatures in many lotic systems, but little is known about how changes in air temperature affect lotic systems heavily influenced by groundwater. Our objectives were to document spatial variation in temperature for spring-fed Ozark streams in Southern Missouri USA, create a spatially explicit model of mean daily water temperature, and use downscaled climate models to predict the number of days meeting suitable stream temperature for three aquatic species of concern to conservation and management. Longitudinal temperature transects and stationary temperature loggers were used in the Current and Jacks Fork Rivers during 2012 to determine spatial and temporal variability of water temperature. Groundwater spring influence affected river water temperatures in both winter and summer, but springs that contributed less than 5% of the main stem discharge did not affect river temperatures beyond a few hundred meters downstream. A multiple regression model using variables related to season, mean daily air temperature, and a spatial influence factor (metric to account for groundwater influence) was a strong predictor of mean daily water temperature (r2 = 0.98; RMSE = 0.82). Data from two downscaled climate simulations under the A2 emissions scenario were used to predict daily water temperatures for time steps of 1995, 2040, 2060, and 2080. By 2080, peak numbers of optimal growth temperature days for smallmouth bass are expected to shift to areas with more spring influence, largemouth bass are expected to experience more optimal growth days (21-317% increase) regardless of spring influence, and Ozark hellbenders may experience a reduction in the number of optimal growth days in areas with the highest spring influence. Our results provide a framework for assessing fine-scale (10 s m) thermal heterogeneity and predict shifts in thermal conditions at the watershed and reach scale.

Show MeSH
Related in: MedlinePlus