Macroscale hydrologic modeling of ecologically relevant flow metrics

Wenger, Seth J.; Luce, Charles H.; Hamlet, Alan F.; Isaak, Daniel J.; Neville, Helen M.

doi:10.1029/2009wr008839

Cited by 134 publications

(191 citation statements)

References 61 publications

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“…For example, as precipitation patterns and snow accumulation in mountain environments change, so will the magnitude and timing of stream runoff (12,31). The stream temperature scenario used here was founded on empirical support at more than 16,000 sites, but flow scenarios from hydrologic models are based on sparse monitoring networks of 10s to 100s of sites and predictions require extensive spatial extrapolations that may result in imprecise estimates of network extent and flow dynamics (41). The problem is most acute in headwater streams that are rarely instrumented and have small flow volumes, thereby translating to large relative prediction errors (42).…”

Section: Discussionmentioning

confidence: 99%

Slow climate velocities of mountain streams portend their role as refugia for cold-water biodiversity

Isaak

Young

Luce

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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203

236

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The imminent demise of montane species is a recurrent theme in the climate change literature, particularly for aquatic species that are constrained to networks and elevational rather than latitudinal retreat as temperatures increase. Predictions of widespread species losses, however, have yet to be fulfilled despite decades of climate change, suggesting that trends are much weaker than anticipated and may be too subtle for detection given the widespread use of sparse water temperature datasets or imprecise surrogates like elevation and air temperature. Through application of large water-temperature databases evaluated for sensitivity to historical air-temperature variability and computationally interpolated to provide high-resolution thermal habitat information for a 222,000-km network, we estimate a less dire thermal plight for cold-water species within mountains of the northwestern United States. Stream warming rates and climate velocities were both relatively low for 1968-2011 (average warming rate = 0.101°C/ decade; median velocity = 1.07 km/decade) when air temperatures warmed at 0.21°C/decade. Many cold-water vertebrate species occurred in a subset of the network characterized by low climate velocities, and three native species of conservation concern occurred in extremely cold, slow velocity environments (0.33-0.48 km/decade). Examination of aggressive warming scenarios indicated that although network climate velocities could increase, they remain low in headwaters because of strong local temperature gradients associated with topographic controls. Better information about changing hydrology and disturbance regimes is needed to complement these results, but rather than being climatic cul-de-sacs, many mountain streams appear poised to be redoubts for cold-water biodiversity this century.climate refugia | climate velocity | biodiversity | fish | network M ountain landscapes constitute 12% of the Earth's land surface (1) and have long served as sanctuaries for certain species by restricting human incursions and juxtaposing diverse environments (2). Mountains also host a suite of endemic species, many of which are perceived to be condemned to extinction as their habitats contract or disappear as a result of climate change-related temperature increases, environmental stochasticity, and nonnative species invasions (3-5). A substantial literature, to which we have contributed, has developed in previous decades suggesting a similar fate for cold-water fishes and other aquatic taxa in montane environments (6-8), but it rests largely on predictions about temperature increases and untested assumptions about the relationship between air temperature and water temperature. In particular, previous studies have failed to recognize that the highest and coldest streams are relatively insensitive to air temperature fluctuations (9, 10), and that the morphologies of many mountain ranges and their stream networks may mediate climate warming such that shifts in thermal habitat are small (2, 11).Dense stream networks drain moun...

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Section: Discussionmentioning

confidence: 99%

Slow climate velocities of mountain streams portend their role as refugia for cold-water biodiversity

Isaak

Young

Luce

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

203

236

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“…Winter was defined as December 1st through February 28th. Two candidate mean flow metrics were mean annual flow (mflow) and mean summer flow (sflow), with summer defined as the period between the decline of the spring flood and September 30th (38). All flow metrics were derived from the Variable Infiltration Capacity (VIC) model (39) coupled with simple routing (38) to produce daily hydrographs for stream segments in the 1:100 K National Hydrography Database (NHD) Plus dataset (http://www.horizon-systems.…”

Section: Methodsmentioning

confidence: 99%

Flow regime, temperature, and biotic interactions drive differential declines of trout species under climate change

Wenger

Isaak

Luce

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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519

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Broad-scale studies of climate change effects on freshwater species have focused mainly on temperature, ignoring critical drivers such as flow regime and biotic interactions. We use downscaled outputs from general circulation models coupled with a hydrologic model to forecast the effects of altered flows and increased temperatures on four interacting species of trout across the interior western United States (1.01 million km 2 ), based on empirical statistical models built from fish surveys at 9,890 sites. Projections under the 2080s A1B emissions scenario forecast a mean 47% decline in total suitable habitat for all trout, a group of fishes of major socioeconomic and ecological significance. We project that native cutthroat trout Oncorhynchus clarkii, already excluded from much of its potential range by nonnative species, will lose a further 58% of habitat due to an increase in temperatures beyond the species' physiological optima and continued negative biotic interactions. Habitat for nonnative brook trout Salvelinus fontinalis and brown trout Salmo trutta is predicted to decline by 77% and 48%, respectively, driven by increases in temperature and winter flood frequency caused by warmer, rainier winters. Habitat for rainbow trout, Oncorhynchus mykiss, is projected to decline the least (35%) because negative temperature effects are partly offset by flow regime shifts that benefit the species. These results illustrate how drivers other than temperature influence species response to climate change. Despite some uncertainty, large declines in trout habitat are likely, but our findings point to opportunities for strategic targeting of mitigation efforts to appropriate stressors and locations.global change | hydrology | invasive species | niche model | distribution modeling N early all broad-scale analyses of climate effects on freshwater species have focused on temperature shifts, to the exclusion of other climate-driven drivers. Although temperature is a critical determinant of metabolic and physical processes (1), important ecosystem effects on streams and rivers may also be mediated by flow regime and biotic interactions. Flow regime has been described as a "master variable" (2) that controls or influences many aspects of the physical aquatic environment, as well as the timing of reproduction and migration of many organisms (3). Biotic interactions are increasingly recognized as important components of climate-species relationships (4, 5), but are rarely included in projections of species distributions under future climates, with some notable exceptions (6). Competitive interactions in particular are not commonly modeled (but see ref. 7), despite interest in invasive-native species interaction under climate change (8). It is likely that all three factors-temperature, flow regime, and biotic interactions-will play important roles in future aquatic species distributional shifts (8-11).Trout serve as excellent model organisms for examining how these mechanisms could alter population dynamics and species distributio...

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“…If one 328 monitoring goal is to develop accurate prediction maps showing spatial variation in one or more 329 thermal metrics (e.g., Isaak et al, 2017b), sites may also need to be more densely sampled than the 330 above considerations otherwise suggest. Spatial autocorrelation in temperature metric values is 331 minimal beyond network distances of 10-100 km (Isaak et al, 2010), so similar sensor spacing is 332 required to generate the most accurate maps. Given the extent of most river networks, that would 333 often translate to a large number of sites but most of these could be monitored for short periods 334 while temporal dynamics were represented by a subset of long-term sites since temporal covariance 335 among sites would be strong.…”

Section: Implications For Monitoring and Bioassessments 314mentioning

confidence: 99%

Principle components of thermal regimes in mountain river networks

Isaak¹,

Luce²,

Chandler³

et al. 2018

Preprint

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Abstract. Description of thermal regimes in flowing waters is key to understanding physical 6 processes, enhancing predictive abilities, and improving bioassessments. Spatially and temporally 7 sparse datasets, especially in logistically challenging mountain environments, have limited studies 8 on thermal regimes but inexpensive sensors coupled with crowd-sourced data collection efforts 9 provide efficient means of developing large datasets for robust analyses. Here, thermal regimes are 10 assessed using annual monitoring records spanning a five-year period (2011)(2012)(2013)(2014)(2015) at 226 sites 11 across several contiguous montane river networks in the northwestern U.S. Regimes were 12 summarized with 28 metrics and principle components analysis (PCA) was used to determine those 13 metrics which best explained thermal variation on a reduced set of orthogonal axes. Four principle 14 components (PC) accounted for 93.4% of the variation in the temperature metrics, with the first PC 15 (49% of variance) associated with metrics that represented magnitude and variability and the second 16 PC (29% of variance) associated with metrics representing the length and intensity of the winter 17 season. Another variant of PCA, T-mode analysis, was applied to daily temperature values and 18 revealed two distinct phases of spatial variance-a homogeneous phase during winter when daily 19 temperatures at all sites were < 3 °C and a heterogeneous phase throughout the year's remainder 20 when variation among sites was more pronounced. Phase transitions occurred in March and 21November, and coincided with the abatement and onset of subzero air temperatures across the study 22 area. S-mode PCA was conducted on the same matrix of daily temperature values after transposition 23 and indicated that two PCs accounted for 98% of the temporal variation among sites. The first S-24 mode PC was responsible for 96.7% of that variance and correlated with air temperature variation (r 25 = 0.92) whereas the second PC accounted for 1.3% of residual variance and was correlated with 26 discharge (r = 0.84). Thermal regimes in these mountain river networks were relatively simple and 27 responded coherently to external forcing factors, so sparse monitoring arrays and small sets of 28 summary metrics may be adequate for many aspects of their description. PCA provides a 29 computationally efficient means of extracting key information elements from large temperature 30 datasets and could be applied broadly to facilitate comparisons among more diverse stream types 31 and develop classification schemes for thermal regimes. 32 33

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Macroscale hydrologic modeling of ecologically relevant flow metrics

Cited by 134 publications

References 61 publications

Slow climate velocities of mountain streams portend their role as refugia for cold-water biodiversity

Slow climate velocities of mountain streams portend their role as refugia for cold-water biodiversity

Flow regime, temperature, and biotic interactions drive differential declines of trout species under climate change

Principle components of thermal regimes in mountain river networks

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