A mechanistic understanding of ecological responses to land‐use change in headwater streams

Walker, Richard; Walters, Annika W.

doi:10.1002/ecs2.2907

Cited by 8 publications

(9 citation statements)

References 90 publications

(168 reference statements)

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“…Brown Trout; Salmo trutta), stream intermittency and algal food availability (Dauwalter & Rahel, ; Schultz, Bertrand, & Graeb, ). Thus, suckers may tolerate some degree of LUC, especially if it is associated with increased algal availability, as was the case in our study system (Walker and Walters, ). The positive relationship between sucker populations and increased ONGD could also be because suckers favour small, low‐gradient perennial streams (Dauwalter & Rahel, ) that correspond with where ONGD is situated (Entriken et al, ).…”

Section: Discussionsupporting

confidence: 52%

Anthropogenic land‐use change intensifies the effect of low flows on stream fishes

Walker

Girard

Alford

et al. 2019

Journal of Applied Ecology

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1. As ecosystems experience simultaneous disturbances, it is critical to understand how multiple stressors interact to affect ecological change. Land-use change and extreme flow events are two important stressors that could interact to affect fish populations.2. We evaluated the individual and interactive effects of discharge and land-use change associated with oil and natural gas development on populations of two stream fishes over a 7-year period. We used repeated-state (i.e. abundance trends) and rate (i.e. colonization and persistence) responses to advance our understanding of flow-ecology relationships in a multiple-stressor framework.3. Overall, fish abundance, colonization and persistence declined as discharge decreased. The effect of land-use change associated with oil and natural gas development differed between species, with the abundance of Mottled Sculpin declining and Mountain Sucker increasing as land-use change increased. We found both synergistic and antagonistic interactions between discharge and land-use change.Land-use change intensified the effect of low flows for Mottled Sculpin and lead to greater variability in responses to flow for Mountain Sucker. These differences between species' responses are likely due to differences in their physiological tolerances and behavioural adaptations to disturbance. Synthesis and applications.Our research provides empirical evidence for the complex interactions that can arise between discharge and anthropogenic land-use change. Management efforts to reduce inputs of sediments and chemical contaminants associated with land-use change (e.g. silt fences, vegetative buffers) and promote quality refuge habitats (i.e. in-stream habitat restoration) could help mitigate the negative effects of low-flow extremes on stream fishes. Further development of flow-ecology relationships in a multiple-stressor framework will help guide management of stream fishes, and provide a better understanding of the mechanisms underlying responses of different species. K E Y W O R D S colonization, multiple stressors, natural flow regime, oil and natural gas development, persistence, rate responses, repeated-state responses, stream fishes 150 | Journal of Applied Ecology WALKER Et AL. L a n d -u s e c h a n g e (% ) La nd -u se ch an ge (% ) Land-use change (%) Land-use change (%) Land-use change (%) Land-use change (%) Land-use change (%) Land-use change (%)

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Section: Discussionsupporting

confidence: 52%

Anthropogenic land‐use change intensifies the effect of low flows on stream fishes

Walker

Girard

Alford

et al. 2019

Journal of Applied Ecology

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“…Cl − , Na + , Ca 2+ , Mg 2+ and K + ; Kefford et al , 2002 , 2016 ; Griffith, 2014 ; Kaushal et al , 2018 ), requiring more research to evaluate the effects of non-chloride salts at different concentrations ( Cañedo-Argüelles et al , 2013 ; Iglesias, 2020 ). Sodium bicarbonate (NaHCO 3 − ) is a major constituent of ONGD produced waters and increased Na + and HCO 3 − ion concentrations have been associated with ONGD in several freshwater ecosystems ( Patz et al , 2004 ; Farag and Harper, 2014 ; Harper et al , 2014 ), including streams in this study ( Walker and Walters, 2019a ; Walters et al , 2019 ). Additionally, ONGD can alter water temperatures indirectly through decreased vegetative cover and increased solar radiation or directly via increased produced water discharge ( Davis et al , 2009 ).…”

Section: Introductionmentioning

confidence: 75%

“…However, stress associated with pH changes was likely minimal in our study, as pH remained between 7.9 and 8.7, which is within the range experienced by most freshwater organisms ( Fromm, 1980 ). Food stress was unlikely a stressor in the field ( Herring et al , 2011 ), as benthic macroinvertebrate prey biomass averaged 2966 mg m −2 across 40 sites in the study area in 2016 ( Walker and Walters, 2019a ). While food availability was not an issue, food intake could have influenced our laboratory results as many fish appeared to reduce food consumption in our experiments (although this was not explicitly measured).…”

Section: Discussionmentioning

confidence: 99%

“…The time between in situ measurements and fish sampling never exceeded 4 hours and no major changes in temperature, precipitation or flows that occurred during sampling to affect in situ measurements. In situ measurements were monitored multiple times (8–20) in the summer of 2016 and 2017 and are reflective of differences in water quality among sample streams during stable baseflow conditions ( Walker and Walters, 2019a ; Walters et al , 2019 ). We used in situ temperature and salinity as predictors in all field analyses because they were most representative of baseline conditions experienced by fish.…”

Section: Methodsmentioning

confidence: 99%

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Warmer temperatures interact with salinity to weaken physiological facilitation to stress in freshwater fishes

Walker

Smith

Hudson

et al. 2020

Conservation Physiology

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Management of stressors requires an understanding of how multiple stressors interact, how different species respond to those interactions and the underlying mechanisms driving observed patterns in species’ responses. Salinization and rising temperatures are two pertinent stressors predicted to intensify in freshwater ecosystems, posing concern for how susceptible organisms achieve and maintain homeostasis (i.e. allostasis). Here, glucocorticoid hormones (e.g. cortisol), responsible for mobilizing energy (e.g. glucose) to relevant physiological processes for the duration of stressors, are liable to vary in response to the duration and severity of salinization and temperature rises. With field and laboratory studies, we evaluated how both salinity and temperature influence basal and stress-reactive cortisol and glucose levels in age 1+ mottled sculpin (Cottus bairdii), mountain sucker (Catostomus platyrhynchus) and Colorado River cutthroat trout (Oncorhynchus clarki pleuriticus). We found that temperature generally had the greatest effect on cortisol and glucose concentrations and the effect of salinity was often temperature dependent. We also found that when individuals were chronically exposed to higher salinities, baseline concentrations of cortisol and glucose usually declined as salinity increased. Reductions in baseline concentrations facilitated stronger stress reactivity for cortisol and glucose when exposed to additional stressors, which weakened as temperatures increased. Controlled temperatures near the species’ thermal maxima became the overriding factor regulating fish physiology, resulting in inhibitory responses. With projected increases in freshwater salinization and temperatures, efforts to reduce the negative effects of increasing temperatures (i.e. increased refuge habitats and riparian cover) could moderate the inhibitory effects of temperature-dependent effects of salinization for freshwater fishes.

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“…Human land‐uses have altered the relationship between diversity and ecosystem functions (biomass production) through direct and diversity‐mediated indirect pathways (Barnes et al, 2014, 2017). Direct effects involve changes in environmental conditions, such as reductions in riparian vegetation, stream depths, and dissolved oxygen, all of which can decrease biomass production (Walker & Walters, 2019). Indirect effects are more difficult to predict and may manifest via effects on taxonomic and functional diversities and across multiple assemblages (Barnes et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Human land‐uses homogenize stream assemblages and reduce animal biomass production

Moi

Barrios

Tesitore

et al. 2023

Journal of Animal Ecology

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Human land‐use change is a major threat to natural ecosystems worldwide. Nonetheless, the effects of human land‐uses on the structure of plant and animal assemblages and their functional characteristics need to be better understood. Furthermore, the pathways by which human land uses affect ecosystem functions, such as biomass production, still need to be clarified. We compiled a unique dataset of fish, arthropod and macrophyte assemblages from 61 stream ecosystems in two Neotropical biomes: Amazonian rainforest and Uruguayan grasslands. We then tested how the cover of agriculture, pasture, urbanization and afforestation affected the taxonomic richness and functional diversity of those three species assemblages, and the consequences of these effects for animal biomass production. Single trait categories and functional diversity were evaluated, combining recruitment and life‐history, resource and habitat‐use, and body size. The effects of intensive human land‐uses on taxonomic and functional diversities were as strong as other drivers known to affect biodiversity, such as local climate and environmental factors. In both biomes, the taxonomic richness and functional diversity of animal and macrophyte assemblages decreased with increasing cover of agriculture, pasture, and urbanization. Human land‐uses were associated with functional homogenization of both animal and macrophyte assemblages. Human land‐uses reduced animal biomass through direct and indirect pathways mediated by declines in taxonomic and functional diversities. Our findings indicate that converting natural ecosystems to supply human demands results in species loss and trait homogenization across multiple biotic assemblages, ultimately reducing animal biomass production in streams.

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A mechanistic understanding of ecological responses to land‐use change in headwater streams

Cited by 8 publications

References 90 publications

Anthropogenic land‐use change intensifies the effect of low flows on stream fishes

Anthropogenic land‐use change intensifies the effect of low flows on stream fishes

Warmer temperatures interact with salinity to weaken physiological facilitation to stress in freshwater fishes

Human land‐uses homogenize stream assemblages and reduce animal biomass production

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