Temperature‐Related Changes in Habitat Quality and Use by Bonneville Cutthroat Trout in Regulated and Unregulated River Segments

Hillyard, Ryan W.; Keeley, Ernest R.

doi:10.1080/00028487.2012.717517

Cited by 19 publications

(28 citation statements)

References 50 publications

(76 reference statements)

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“…). Low densities of individuals may persist near warm boundaries if cold microrefugia are available (Hillyard and Keeley ), but refugia will become increasingly isolated in future years as the surrounding matrix of warmer waters continues to grow. Range contractions may also be exacerbated by upstream dispersal of predator species with warmer thermal preferences, as is occurring in some northwestern rivers with the expansion of Smallmouth Bass Micropterus dolomieu populations (Lawrence et al.…”

Section: Discussionmentioning

confidence: 99%

Global Warming of Salmon and Trout Rivers in the Northwestern U.S.: Road to Ruin or Path Through Purgatory?

et al. 2018

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Large rivers constitute small portions of drainage networks but provide important migratory habitats and fisheries for salmon and trout when and where temperatures are sufficiently cold. Management and conservation of coldwater fishes in the current era of rapid climate change require knowing how riverine thermal environments are evolving and the potential for detrimental biological impacts. Robust estimates of warming rates, however, are lacking due to limited long‐term temperature monitoring, so we compiled the best available multidecadal records and estimated trends at 391 sites in the 56,500‐km river network of the northwestern USA. Warming trends were prevalent during summer and early fall months in recent 20‐ and 40‐year periods (0.18–0.35°C per decade during 1996–2015 and 0.14–0.27°C per decade during 1976–2015), paralleled air temperature trends, and were mediated by discharge trends at regional and local levels. To illustrate the biological consequences of warming later in this century, trend estimates were used to inform selection of river temperature scenarios and assess changes in thermal exposure of adult Sockeye Salmon Oncorhynchus nerka migrating to four population areas as well as thermal habitat shifts for resident Brown Trout Salmo trutta and Rainbow Trout O. mykiss populations throughout the region. Future warming of 1–3°C would increase Sockeye Salmon exposure by 5–16% (3–143 degree‐days) and reduce thermally suitable riverine trout habitats by 8–31% while causing their upstream shift. Effects of those changes on population persistence and fisheries are likely to be context dependent, and strategic habitat restoration or adaptation strategies could ameliorate some biological impairments, but effectiveness will be tempered by the size of rivers, high costs, and pervasiveness of thermal effects. Most salmon and trout rivers will continue to provide suitable habitats for the foreseeable future, but it also appears inevitable that some river reaches will gradually become too warm to provide traditional habitats.

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Section: Discussionmentioning

confidence: 99%

Global Warming of Salmon and Trout Rivers in the Northwestern U.S.: Road to Ruin or Path Through Purgatory?

et al. 2018

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“…We could not test the role of different habitat features, in particular that of thermal refugia. However, the diversity, abundance and connectivity of these habitat features are often reduced in agricultural streams due to water abstraction, riparian deforestation, channelization and deposited fine sediment (Allan, ; Hillyard & Keeley, ; Lange et al., ; Schinegger et al., ), thereby constraining behavioural responses.…”

Section: Discussionmentioning

confidence: 99%

Biotic interactions modify multiple‐stressor effects on juvenile brown trout in an experimental stream food web

Bruder

Salis

Jones

et al. 2017

Global Change Biology

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Agricultural land use results in multiple stressors affecting stream ecosystems. Flow reduction due to water abstraction, elevated levels of nutrients and chemical contaminants are common agricultural stressors worldwide. Concurrently, stream ecosystems are also increasingly affected by climate change. Interactions among multiple co-occurring stressors result in biological responses that cannot be predicted from single-stressor effects (i.e. synergisms and antagonisms). At the ecosystem level, multiple-stressor effects can be further modified by biotic interactions (e.g. trophic interactions). We conducted a field experiment using 128 flow-through stream mesocosms to examine the individual and combined effects of water abstraction, nutrient enrichment and elevated levels of the nitrification inhibitor dicyandiamide (DCD) on survival, condition and gut content of juvenile brown trout and on benthic abundance of their invertebrate prey. Flow velocity reduction decreased fish survival (-12% compared to controls) and condition (-8% compared to initial condition), whereas effects of nutrient and DCD additions and interactions among these stressors were not significant. Negative effects of flow velocity reduction on fish survival and condition were consistent with effects on fish gut content (-25% compared to controls) and abundance of dominant invertebrate prey (-30% compared to controls), suggesting a negative metabolic balance driving fish mortality and condition decline, which was confirmed by structural equation modelling. Fish mortality under reduced flow velocity increased as maximal daily water temperatures approached the upper limit of their tolerance range, reflecting synergistic interactions between these stressors. Our study highlights the importance of indirect stressor effects such as those transferred through trophic interactions, which need to be considered when assessing and managing fish populations and stream food webs in multiple-stressor situations. However, in real streams, compensatory mechanisms and behavioural responses, as well as seasonal and spatial variation, may alter the intensity of stressor effects and the sensitivity of trout populations.

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“…This minimizes the potential role of prey density in the between‐river movement differences observed in the present study. For salmonids species, Hillyard and Keeley () found that the total distance (m) moved per week by Bonneville cutthroat trout ( Oncorhynchus clarki utah ) during the summer in a regulated river (average of 701 m; sedentary) was 11‐fold smaller than in an unregulated river (average of 7964 m; mobile); a movement pattern also observed in the Mississagi and Aubinadong rivers. Hillyard and Keeley () attributed the difference in mobility to small, infrequent, and widely distributed hospitable patches of cold water during warm summer months in the regulated river.…”

Section: Discussionmentioning

confidence: 99%

“…For salmonids species, Hillyard and Keeley () found that the total distance (m) moved per week by Bonneville cutthroat trout ( Oncorhynchus clarki utah ) during the summer in a regulated river (average of 701 m; sedentary) was 11‐fold smaller than in an unregulated river (average of 7964 m; mobile); a movement pattern also observed in the Mississagi and Aubinadong rivers. Hillyard and Keeley () attributed the difference in mobility to small, infrequent, and widely distributed hospitable patches of cold water during warm summer months in the regulated river. Water temperatures exceeded the upper thermal limit of the Bonneville cutthroat trout (24.2 °C; Johnstone and Rahel, ) in the study by Hillyard and Keeley ().…”

Section: Discussionmentioning

confidence: 99%

“…Short-term (i.e. minutes to hours) flow changes in rivers lead to dynamic environmental conditions that have long been known to modify fish habitats (Valentin et al, 1996;Scruton et al, 2003;Hillyard and Keeley, 2012). Fish have been hypothesized to cope with these short-term flow changes by moving rapidly from an original habitat to a relocated habitat of a presumed similar suitability, thereby increasing their travel rate as flow fluctuates (Taylor et al, 2014a).…”

Section: Introductionmentioning

confidence: 99%

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Differences in movements of northern pike inhabiting rivers with contrasting flow regimes

et al. 2016

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Little is known about the effect of short‐term flow changes on the movement of northern pike (Esox lucius L.). We conducted a comparative study in two rivers with different flow regimes (i.e. one regulated and one unregulated) to evaluate the extent to which adult northern pike movement is influenced by short‐term river flow conditions. Data on northern pike hourly movement were collected in northeastern Ontario on 40 individuals in the Mississagi River, a river subjected to extreme daily flow variations associated with hydro‐electric operations (i.e. hydropeaking), and the Aubinadong River, an unregulated river. Using manual tracking by radio‐telemetry, we found that northern pike moved at a higher rate in the river subjected to short‐term changes in river flow than in the unregulated river. Results also show that the relationship between movement of northern pike and flow can vary among rivers. In the Mississagi River, flow had a significant positive effect on northern pike activity, while the effect of flow in the Aubinadong River depended on water temperature. Moreover, fish in the Mississagi River utilized a restricted river section and travelled more laterally in comparison to fish inhabiting the Aubinadong River, where longer upstream‐downstream movements were more common. The present study contributes to our understanding of the effects of short‐term changes in flow on fish movement. This constitutes the first step towards assessing the effect of flow on fish habitat use, and eventually developing flow management strategies to mitigate impacts on fish. Copyright © 2016 John Wiley & Sons, Ltd.

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Temperature‐Related Changes in Habitat Quality and Use by Bonneville Cutthroat Trout in Regulated and Unregulated River Segments

Cited by 19 publications

References 50 publications

Global Warming of Salmon and Trout Rivers in the Northwestern U.S.: Road to Ruin or Path Through Purgatory?

Global Warming of Salmon and Trout Rivers in the Northwestern U.S.: Road to Ruin or Path Through Purgatory?

Biotic interactions modify multiple‐stressor effects on juvenile brown trout in an experimental stream food web

Differences in movements of northern pike inhabiting rivers with contrasting flow regimes

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