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At least 1,549 records · Page 86Linked to original sources
USGS2007

Using a coupled eco-hydrodynamic model to predict habitat for target species following dam removal

A habitat suitability index (HSI) model was developed for a water quality sensitive fish (Greater Redhorse) and macroinvertebrate (Plecoptera) species to determine the restoration success of the St. John Dam removal for the Sandusky River (Ohio). An ArcGIS?? model was created for pre- and post-dam removal scenarios. Inputs to the HSI model consist of substrate distributions from river surveys, and water level and velocity time series, outputs from a hydrodynamic model. The ArcGIS?? model predicted habitat suitability indices at 45 river cross-sections in the hydrodynamic model. The model was programmed to produce polygon layers, using graphical user interfaces that were displayed in the ArcGIS?? environment. The results of the model clearly show an increase of habitat suitability from pre- to post-dam removal periods and in the former reservoir. The change in suitability of the model is attributed mostly to the change in depth in the river following the dam removal for both the fish and invertebrate species. The results of the invertebrate model followed the same positive trend as species enumerations from the river basin. ?? 2007 Elsevier B.V. All rights reserved.

Ecological Engineering↗
USGS2015

A food web modeling analysis of a Midwestern, USA eutrophic lake dominated by non-native Common Carp and Zebra Mussels

Food web modeling is recognized as fundamental to understanding the complexities of aquatic systems. Ecopath is the most common mass-balance model used to represent food webs and quantify trophic interactions among groups. We constructed annual Ecopath models for four consecutive years during the first half-decade of a zebra mussel invasion in shallow, eutrophic Clear Lake, Iowa, USA, to evaluate changes in relative biomass and total system consumption among food web groups, evaluate food web impacts of non-native common carp and zebra mussels on food web groups, and to interpret food web impacts in light of on-going lake restoration. Total living biomass increased each year of the study; the majority of the increase due to a doubling in planktonic blue green algae, but several other taxa also increased including a more than two-order of magnitude increase in zebra mussels. Common carp accounted for the largest percentage of total fish biomass throughout the study even with on-going harvest. Chironomids, common carp, and zebra mussels were the top-three ranking consumer groups. Non-native common carp and zebra mussels accounted for an average of 42% of the total system consumption. Despite the relatively high biomass densities of common carp and zebra mussel, food web impacts was minimal due to excessive benthic and primary production in this eutrophic system. Consumption occurring via benthic pathways dominated system consumption in Clear Lake throughout our study, supporting the argument that benthic food webs are significant in shallow, eutrophic lake ecosystems and must be considered if ecosystem-level understanding is to be obtained.

Iowa↗
USGS2025

Application of transcriptomics concentration-response modeling for prioritization of contaminants detected in tributaries of the North American Great Lakes

As part of the Great Lakes Restoration Initiative, chemical monitoring and surveillance efforts have detected approximately 330 chemicals in surface water of Great Lakes tributaries. There were 140 chemicals for which no empirical toxicity data were available. The aim of this study was to generate transcriptomic points of departure (tPODs) for 10 of these compounds and demonstrate how they could be applied in a screening-level prioritization. Organisms representing three trophic levels of the aquatic food web ( Pimephales promelas , Daphnia magna , and Raphidocelis subcapitata ) were exposed for 24 hr to a half-log dilution series of nominal exposure concentrations typically ranging from 66.7–0.021 µM of each chemical. In addition to observations of apical effects (e.g., survival and morphology), whole body transcriptomic responses (tPODs) to each chemical were evaluated with targeted analysis using TempO-seq for P. promelas and D. magna and nontargeted RNA-seq for R. subcapitata . The tPODs ranged from 0.18–10.8 µM for P. promelas and 0.32–29 µM for D. magna , with the most potent of the chemicals tested being fipronil carboxamide for both species. For R. subcapitata , the tPODs ranged from 0.04–1.77 µM, with gabapentin as the most potent chemical tested. Empirically derived tPODs from these data-poor chemicals were compared with concentrations detected in the Great Lakes basin. Environmental concentrations were less than the tPODs except for R. subcapitata and 3,4-dichlorophenyl isocyanate. Similarly, tPODs from previously tested data-rich chemicals were compared with environmental concentrations, in which case tPODs from several chemicals overlapped environmental concentrations. This work demonstrates the potential utility of emerging ecological high-throughput transcriptomics assays to support screening and prioritization of data-poor environmental contaminants.

Environmental Toxicology and Chemistry↗
USGS2006

Development of allometric relations for three mangrove species in South Florida for use in the Greater Everglades Ecosystem restoration

Mathematical relations that use easily measured variables to predict difficult-to-measure variables are important to resource managers. In this paper we develop allometric relations to predict total aboveground biomass and individual components of biomass (e.g., leaves, stems, branches) for three species of mangroves for Everglades National Park, Florida, USA. The Greater Everglades Ecosystem is currently the subject of a 7.8-billion-dollar restoration program sponsored by federal, state, and local agencies. Biomass and production of mangroves are being used as a measure of restoration success. A technique for rapid determination of biomass over large areas is required. We felled 32 mangrove trees and separated each plant into leaves, stems, branches, and for Rhizophora mangle L., prop roots. Wet weights were measured in the field and subsamples returned to the laboratory for determination of wet-to-dry weight conversion factors. The diameter at breast height (DBH) and stem height were also measured. Allometric equations were developed for each species for total biomass and components of biomass. We compared our equations with those from the same, or similar, species from elsewhere in the world. Our equations explained ???93% of the variance in total dry weight using DBH. DBH is a better predictor of dry weight than is stem height and DBH is much easier to measure. Furthermore, our results indicate that there are biogeographic differences in allometric relations between regions. For a given DBH, stems of all three species have less mass in Florida than stems from elsewhere in the world. ?? Springer 2006.

Wetlands Ecology and Management↗
USGS2019

Diets of endangered silver chub (Macrhybopsis storeriana, Kirtland, 1844) in Lake Erie and implications for recovery

Silver chub ( Macrhybopsis storeriana , Kirtland, 1844) is a native Cyprinid in Lake Erie, one of the Laurentian Great Lakes of North America. It is listed as endangered by the US state of New York and Canada, which has a recovery plan, and as special concern by the state of Michigan. Silver chub faces a potential threat to recovery from control efforts for invasive Grass carp ( Ctenopharyngodon idella , Valenciennes 1844). Among the knowledge gaps for protection and restoration is current diet data. I describe the diet of silver chub from western Lake Erie in 2014, and I compare it to past studies to assess changes in diet through time. Silver chub captured in bottom trawls May–September 2014 were frozen in the field, and stomach contents were preserved in ethanol. Diet taxa were identified to the lowest practical taxonomic unit, then dried and weighed. Frequency of occurrence in silver chub diets was highest for Hexagenia spp. mayflies (79%). Dreissena spp. and Hexagenia spp. were both 41% of the diet by dry weight. Analysis of δ 13 C isotopes identified Hexagenia spp. as the primary source of carbon in silver chub. Compared to past studies, Dreissena spp. have mostly replaced Sphaeriidae and Gastropoda in silver chub diets. There also have been seasonal shifts in relative amounts of shelled organisms and Hexagenia spp. This study and past research suggest a functional link between silver chub and Hexagenia spp. abundance. Maintenance and recovery of silver chub may be dependent on maintaining Hexagenia spp. populations.

Ecology of Freshwater Fish↗
USGS2017

Spatial and temporal patterns in golden eagle diets in the western United States, with implications for conservation planning

Detailed information on diets and predatory ecology of Golden Eagles ( Aquila chrysaetos ) is essential to prioritize prey species management and to develop landscape-specific conservation strategies, including mitigation of the effects of energy development across the western United States. We compiled published and unpublished data on Golden Eagle diets to (1) summarize available information on Golden Eagle diets in the western U.S., (2) compare diets among biogeographic provinces, and (3) discuss implications for conservation planning and future research. We analyzed 35 studies conducted during the breeding season at 45 locations from 1940–2015. Golden Eagle diet differed among western ecosystems. Lower dietary breadth was associated with desert and shrub-steppe ecosystems and higher breadth with mountain ranges and the Columbia Plateau. Correlations suggest that percentage of leporids in the diet is the factor driving overall diversity of prey and percentage of other prey groups in the diet of Golden Eagles. Leporids were the primary prey of breeding Golden Eagles in 78% of study areas, with sciurids reported as primary prey in 18% of study areas. During the nonbreeding season, Golden Eagles were most frequently recorded feeding on leporids and carrion. Golden Eagles can be described as both generalist and opportunistic predators; they can feed on a wide range of prey species but most frequently feed on abundant medium-sized prey species in a given habitat. Spatial variations in Golden Eagle diet likely reflect regional differences in prey community, whereas temporal trends likely reflect responses to long-term change in prey populations. Evidence suggests dietary shifts from traditional (leporid) prey can have adverse effects on Golden Eagle reproductive rates. Land management practices that support or restore shrub-steppe ecosystem diversity should benefit Golden Eagles. More information is needed on nonbreeding-season diet to determine what food resources, such as carrion, are important for overwinter survival.

Journal of Raptor Research↗
USGS1989

Assessing the relationship between Section 404 and wetland losses: a feasibility study

The primary objective of the Clean Water Act of 1977 (33 U.S.C. 1251) is to restore and maintain the physical, chemical, and biological integrity of the Nation's waters. Section 404 of the Act regulates the discharge of dredged or fill materials into wetlands and represents the primary Federal authority for regulation of wetland alterations. Since its inception, the Section 404 program has been controversial in regard to the extent to which it was intended to provide wetlands regulation. Section 404 requires those who wish to discharge dredged or fill material into waters of the United States, which include many wetlands, to first obtain a Federal permit. The Environmental Protection Agency (EPA) has overall responsibility for administration of the Section 404 program and promulgates guidelines that must be followed in issuing permits. In addition, EPA has the final authority to prohibit specific discharges if the environmental impacts are unacceptable. The U.S. Army Corps of Engineers (Corps) issues Section 404 permits, which can be of two types. Individual Permits are issued following case-by-case reviews of proposed discharges. General Permits, which can be either nationwide or regional in scope, are authorized by the Corps for categories of activities that are similar in nature and that have only minimal individual and cumulative adverse environmental impacts. EPA, the National Marine Fisheries Service (NMFS), the Fish and Wildlife Service (Service), and State natural resource agencies review and comment on permit applications and offer recommendations on appropriate mitigation measures. Although comments from the Service and other natural resource agencies are advisory in nature (EPA's veto authority excepted), they can serve as the basis for modifying, conditioning, or denying a Section 404 permit. In 1986, in a survey conducted by the National Ecology Research Center, Service personnel indicated interest in additional information concerning both wetland trends and the impacts of activities authorized by the Corps under Section 404 (Roelle 1986). Although there is some information concerning wetland losses for certain geographic areas and for the Nation as a whole (Frayer et al. 1983; Tiner 1984), there appears to be little information on how these losses relate to the Section 404 permitting process. The primary objective of this study was to determine the feasibility of estimating wetland losses in relationship to Individual and General Permits issued under Section 404. A secondary objective was to assemble data on acceptance and implementation of specific mitigation recommendations offered by the Service and other natural resource agencies in connection with development activities on wetlands examined. At present, 26 categories of Nationwide permits have been authorized by the Corps. Nationwide permit 26 was of particular interest in this study because it specifically authorizes discharges into wetlands under certain circumstances (see Figure 1 and related text for a more complete discussion of circumstances under which Nationwide Permit 26 is applicable). All subsequent references to Nationwide or General permits pertain to Nationwide Permit 26.

Report↗
USGS2016

Genetic status and conservation of Westslope Cutthroat Trout in Glacier National Park

Invasive hybridization is one of the greatest threats to the persistence of Westslope Cutthroat Trout Oncorhynchus clarkii lewisi . Large protected areas, where nonhybridized populations are interconnected and express historical life history and genetic diversity, provide some of the last ecological and evolutionary strongholds for conserving this species. Here, we describe the genetic status and distribution of Westslope Cutthroat Trout throughout Glacier National Park, Montana. Admixture between Westslope Cutthroat Trout and introduced Rainbow Trout O. mykiss and Yellowstone Cutthroat Trout O. clarkii bouvieri was estimated by genotyping 1,622 fish collected at 115 sites distributed throughout the Columbia, Missouri, and South Saskatchewan River drainages. Currently, Westslope Cutthroat Trout occupy an estimated 1,465 km of stream habitat and 45 lakes (9,218 ha) in Glacier National Park. There was no evidence of introgression in samples from 32 sites along 587 km of stream length (40% of the stream kilometers currently occupied) and 17 lakes (2,555 ha; 46% of the lake area currently occupied). However, nearly all (97%) of the streams and lakes that were occupied by nonhybridized populations occurred in the Columbia River basin. Based on genetic status (nonnative genetic admixture ≤ 10%), 36 Westslope Cutthroat Trout populations occupying 821 km of stream and 5,482 ha of lakes were identified as “conservation populations.” Most of the conservation populations ( N = 27; 736 km of stream habitat) occurred in the Columbia River basin, whereas only a few geographically restricted populations were found in the South Saskatchewan River ( N = 7; 55 km) and Missouri River ( N = 2; 30 km) basins. Westslope Cutthroat Trout appear to be at imminent risk of genomic extinction in the South Saskatchewan and Missouri River basins, whereas populations in the Columbia River basin are widely distributed and conservation efforts are actively addressing threats from hybridization and other stressors. A diverse set of pro-active management approaches will be required to conserve, protect, and restore Westslope Cutthroat Trout populations in Glacier National Park throughout the 21st century.

Glacier National Park↗
USGS2020

Patterns of smooth brome, Kentucky bluegrass, and shrub invasion in the northern Great Plains vary with temperature and precipitation

Biological diversity and ecological integrity in native prairies of the northern Great Plains are substantially modified from pre-Euro-American settlement. About 90,000 ha of native mixed-grass and tallgrass prairie are managed by the US Fish and Wildlife Service (Service) in North Dakota, South Dakota, and northeastern Montana. We used belt transects to classify floristic composition of all Service-owned prairies in the Dakotas and northeastern Montana. Prairies were significantly degraded, mainly by invasion of introduced grass and forb species and by native shrubs. In general, floristic integrity of Service-managed prairies was most compromised by smooth brome ( Bromus inermis ) and Kentucky bluegrass ( Poa pratensis ). The degradation was, in part, an unintended outcome of long-term management by the Service. The degree of degradation varied spatially across the broad geographic area defined by our study and was invader-specific, corresponding to geographic patterns in precipitation and temperature. Within the study area, floristic quality was relatively high on prairies toward the north and west, where plant growth sites generally were cooler and drier, based on long-term averages. In contrast, growth sites to the south and east generally were warmer, moister, and characterized by lower floristic quality, primarily because they were substantially invaded by smooth brome. Kentucky bluegrass was the most widespread invader of Service-owned prairies, with less frequent occurrence only in prairies dominated by smooth brome, especially in South Dakota or by native grass–forbs, especially in northwestern North Dakota and northeastern Montana. Improved knowledge of geographic and climate-related patterns of plant invasion enhances decision making for protecting northern mixed-grass and tallgrass prairies by focusing restoration efforts where probability of success is greater.

Montana, North Dakota, South Dakota↗
USGS2025

The effectiveness of wildfire at meeting restoration goals across a fire severity gradient in the Sierra Nevada

As a consequence of both warming temperatures and over a century of fire suppression, wildfires in the historically frequent-fire forests of the western US have increased both in size and intensity, resulting in large patches of high severity fire that are well outside the historic range of variation. Postfire fuels research has often focused on such high severity patches because of the risk of both type conversion and repeated high severity fire. Yet a substantial portion of any given wildfire will likely still have burned at low to moderate severity. These areas generally retain live mature trees and surface fuels, suggesting that wildfire effects may be in keeping with some forest restoration goals. To better understand the range of postfire fuels conditions across severity classes and how well those conditions align with restoration targets, we sampled three wildfires in mixed conifer forests and giant sequoia groves of the southern Sierra Nevada. These wildfires appear to have met short-term restoration goals for surface fuel reduction, with burned areas having 79.5 % less fuels than unburned areas. Fine woody debris and litter and duff declined with severity, while coarse woody debris was more variable. Small tree density targets were roughly met after low and moderate severity fire, but large tree densities tended to be lower than restoration targets, possibly due to high levels of recent tree mortality. For long-term management, restoration plans set targets for the proportions of the landscape that should be in different fuel load categories, reflecting patterns shaped by many frequent and patchy fires. Observed post-wildfire surface fuels outside of groves were overwhelmingly in the lowest fuels category across severity classes, which is in keeping with short-term goals to reduce surface fuels but is not necessarily contributing to the heterogeneity desired at landscape scales. Surface fuels within giant sequoia groves were higher than those outside groves and therefore more closely matched long-term management targets for variation in fuel loads. However, for a highly valued species that has recently seen substantial losses to high severity fire, managers may find that these higher fuel loads are not desirable even in a landscape context. In summary, low and moderate severity wildfire appear to have beneficial effects in terms of meeting several management goals, however, the large amount of standing postfire fuels, the relative dearth of large trees, and the potential lack of postfire fuel heterogeneity may still pose potential management concerns.

California↗
USGS2022

Plant community trajectories following livestock exclusion for conservation vary and hinge on initial invasion and soil-biocrust conditions in shrub steppe

Adjustments or complete withdrawal of livestock grazing are among the most common conservation actions in semiarid uplands, but outcomes can vary considerably with ecological context. Invasion by exotic annual grasses and the excessive wildfire they promote are increasing threats to semiarid shrub-steppe, and plant-community response to livestock exclusion in these areas may be complicated by the rapid colonization ability of invaders. We evaluated vegetation-community changes over 14-year interval (2007–2021) in a shrub-steppe landscape where a >100-year history of livestock grazing had been terminated in 1996. Field surveys revealed that bare-soil exposure decreased >20% over the 14 years owing to biomass accumulation, but this was primarily due to large increases in exotic annual “cheatgrass” ( Bromus tectorum , +1.8-fold) and the litter it produces (+1.5-fold). Soil biocrusts increased 11.9% and perennial bunchgrasses increased 3% over the 14 years. These community changes varied at the patch scale and entailed inverse relationships of (1) both cheatgrass and biocrusts to plant-community basal cover, (2) cheatgrass to both biocrusts and perennial grasses, and (3) biocrusts to cheatgrass and litter. The spatiotemporal variability in vegetation constituted changes in plant-community states, according to cluster analysis. The modeled probability of a community transitioning to a cheatgrass state was (1) strongly and positively related to the initial (2007) cover of cheatgrass in hotspots where initial cheatgrass cover was >20%, and (2) negatively related to biocrust cover where initial biocrust cover was >4% of ground area. The decision space for this landscape can be framed as a shifting from acceptance towards resisting further degradation by removing livestock and their trampling of soil surfaces and utilization of perennial herbs. However, cheatgrass appears to be the most impactful agent of change and continued invasion appears imminent. Active restoration may help resist further degradation and direct change towards tolerable conditions.

Colorado↗
USGS2011

Engineering a future for amphibians under climate change

1. Altered global climates in the 21st century pose serious threats for biological systems and practical actions are needed to mount a response for species at risk. 2. We identify management actions from across the world and from diverse disciplines that are applicable to minimizing loss of amphibian biodiversity under climate change. Actions were grouped under three thematic areas of intervention: (i) installation of microclimate and microhabitat refuges; (ii) enhancement and restoration of breeding sites; and (iii) manipulation of hydroperiod or water levels at breeding sites. 3. Synthesis and applications. There are currently few meaningful management actions that will tangibly impact the pervasive threat of climate change on amphibians. A host of potentially useful but poorly tested actions could be incorporated into local or regional management plans, programmes and activities for amphibians. Examples include: installation of irrigation sprayers to manipulate water potentials at breeding sites; retention or supplementation of natural and artificial shelters (e.g. logs, cover boards) to reduce desiccation and thermal stress; manipulation of canopy cover over ponds to reduce water temperature; and, creation of hydrologoically diverse wetland habitats capable of supporting larval development under variable rainfall regimes. We encourage researchers and managers to design, test and scale up new initiatives to respond to this emerging crisis.

Journal of Applied Ecology↗
USGS2022

Greater sage-grouse respond positively to intensive post-fire restoration treatments

Habitat loss is the most prevalent threat to biodiversity in North America. One of the most threatened landscapes in the United States is the sagebrush ( Artemisia spp.) ecosystem, much of which has been fragmented or converted to non-native grasslands via the cheatgrass-fire cycle. Like many sagebrush obligates, greater sage-grouse ( Centrocercus urophasianus ) depend upon sagebrush for food and cover and are affected by changes to this ecosystem. We investigated habitat selection by 28 male greater sage-grouse during each of 3 years after a 113,000-ha wildfire in a sagebrush steppe ecosystem in Idaho and Oregon. During the study period, seeding and herbicide treatments were applied for habitat restoration. We evaluated sage-grouse responses to vegetation and post-fire restoration treatments. Throughout the 3 years post-fire, sage-grouse avoided areas with high exotic annual grass cover but selected strongly for recovering sagebrush and moderately strongly for perennial grasses. By the third year post-fire, they preferred high-density sagebrush, especially in winter when sagebrush is the primary component of the sage-grouse diet. Sage-grouse preferred forb habitat immediately post-fire, especially in summer, but this selection preference was less strong in later years. They also selected areas that were intensively treated with herbicide and seeded with sagebrush, grasses, and forbs, although these responses varied with time since treatment. Wildfire can have severe consequences for sagebrush-obligate species due to loss of large sagebrush plants used for food and for protection from predators and thermal extremes. Our results show that management efforts, including herbicide application and seeding of plants, directed at controlling exotic annual grasses after a wildfire can positively affect habitat selection by sage-grouse.

Ecology and Evolution↗
USGS2022

Wetland occupancy by duck broods in cropland-dominated landscapes of the United States Prairie Pothole Region

The Prairie Pothole Region (PPR) is globally important for breeding waterfowl but has been altered via wetland drainage and grassland conversion to accommodate agricultural land use. Thus, understanding the ecology of waterfowl in these highly modified landscapes is essential for their conservation. Brood occurrence is the cumulative outcome of key life-history events including pair formation and territory establishment, nest success, and early brood survival. We applied new technological advances in brood surveying methods to understand brood use of wetlands and how land use and wetland-specific factors influenced brood use of 413 wetlands in crop-dominated landscapes in the PPR of Iowa, Minnesota, North Dakota, and South Dakota, USA, during summers of 2018–2020. Dynamic occupancy models combining information from 2 visits throughout the year revealed no difference among the 4 states or between private and public lands, resulting in a region-wide annual wetland occupancy estimate of 0.41 (95% credible interval [CrI] = 0.26, 0.58). We assessed aquatic invertebrate forage availability, wetland and upland vegetation communities, and various water chemistry metrics in a subset ( n = 225) of these wetlands to evaluate how landscape and wetland-specific factors influenced occupancy. The amount of grassland surrounding wetlands was the only variable to influence occupancy at a landscape scale, while wetland size, invertebrates, fish, and vegetation communities influenced occupancy at finer scales. Closer scrutiny of wetland area revealed occupancy was greater in small wetlands after controlling for total wetland area. Our results indicate the greatest constraint on brood occupancy across crop-dominated landscapes of the PPR in the United States was the occurrence of semipermanent wetlands suitable for brood rearing. Other factors, such as wetland vegetation or surrounding land use, had minor intervening influences on duck brood use and ducks were distributed invariant of wetland ownership or broad spatial processes occurring among states. These results demonstrated wetland conservation and restoration strategies are likely to yield gains in annual duck broods across this vast, altered, and highly modified landscape.

Iowa, Minnesota, North Dakota, South Dakota↗
USGS2025

Shifts in suitability of pinyon-juniper communities: A climate adaptation framework for range-wide management of arid woodland resources

Pinyon-juniper (PJ) woodlands are a diverse ecosystem type providing a wealth of ecosystem services across western North America. Managing PJ woodlands in the 21st century entails balancing multiple conservation objectives, and resource managers and policy-makers working to sustain PJ woodlands need spatially explicit information about current PJ woodland conditions and how they may be impacted in coming decades in the context of wildfire risk and changing climate. Here, we address knowledge gaps and provide information that improves the long-term value of conservation and restoration actions in PJ woodlands. To this end, we merged projections of future environmental suitability for nine PJ species with wildfire risk and locations of mature and old-growth (MOG) woodlands to assess spatial variation in PJ woodlands with differing threats and management opportunities. We identified potential climate refugia with enduring high community suitability and low burn probability (3 % of study area ) that may persist with relatively little management. We found promising locations of PJ-MOG forest type with high future suitability (12 % of areas) that could be prioritized for fire risk reduction to maintain high-value woodlands. Despite a 38 % mean community suitability decline under future climate conditions, some locations (7 % of areas) may act as climate refugia where future climate conditions can support current PJ woodland composition and structure. We conclude by demonstrating how this information can be integrated into a conceptual framework to help prioritize conservation and climate adaptation in PJ woodlands.

western North America↗
USGS2019

Age and growth of Freshwater Drum and Gizzard Shad occupying two reservoir-river complexes with different groundwater contributions

Restoring groundwater flow is a management option that improves water temperature regimes and benefits fishes. Although this strategy applies more readily to river systems, the thermal character of reservoirs is heavily influenced by inflowing rivers. We examined differences in age, structure, and growth of both Freshwater Drum Aplodinotus grunniens and Gizzard Shad Dorosoma cepedianum that occupy catchments with varying groundwater contributions in the south‐central United States. Seepage run data indicated that the Kiamichi River was losing surface water to groundwater in summer 2016, whereas groundwater inflows were apparent in the Elk River basin. Summer 2016 data showed that the Elk River had cooler water temperatures than the Kiamichi River and Grand Lake O’ the Cherokees water temperatures were similar to those in the incoming Elk River. We found higher densities of older Freshwater Drum and Gizzard Shad (maximums of 32 and 8 years old, respectively) in samples from the Grand basin than among fish that were sampled from the Kiamichi River basin (21 and 6 years old, respectively). Freshwater Drum grew at similar rates in both basins even though they reached larger maximum lengths in the Grand basin (649 mm TL) than in the Kiamichi River basin (600 mm). The average asymptotic length was greater for the Kiamichi population ( L ∞ = 613 mm) than for the Grand population ( L ∞ = 557 mm). Gizzard Shad from the Grand basin were larger than those from the Kiamichi River basin, though the latter population grew faster initially (Brody growth coefficient: K = 0.787 versus K = 0.179, respectively), but they had smaller asymptotic length ( L ∞ = 206 mm versus L ∞ = 343 mm). The role that groundwater plays in temperature regulation in these basins partially explains the observed differences. Our results suggest that the metabolic theory of ecology can be applied to fisheries management at a finer spatial scale.

Oklahoma↗
USGS2026

Linking scale-specific sinuosity to hydrogeomorphic domains in Alaska watersheds

River meander patterns arise from geomorphological processes influenced by climate, geology, terrain, and hydrology. These processes produce a wide spectrum of sinuous channel and meander forms, and understanding them is essential for land management practices, such as natural channel restoration (Dominguez et al., 2018), flood and erosion control, bank stabilization (U.S. Department of Interior, 2015), and riparian corridor and agricultural land management (Ran, et al., 2022; Yu, et al., 2023; Zhu et al., 2022). Studies of meander migration provide insight into sediment dynamics and river ecosystem health (Ielpi et al. 2023, Constantine et al., 2014). A river’s natural ability to clean itself, or reduce pollutants, through physical, chemical, and biological processes, also termed self-purification capacity, has been linked to river sinuosity (Xiao et al, 2019, 2025). Scale-specific sinuosity (S3) is an easily computed metric for characterizing planform meander bend geometry across a range of measurement scales (Stanislawski et al., 2023). Unlike the traditional single summary value of sinuosity for a stream section, S3 estimates the relative distribution of meander‑bend sizes, such as peak‑to‑trough lengths, within a planform linear representation of a stream section, along with the relative contributions of these bend sizes to its overall sinuosity. The aim of this study is to assess the potential of S3 as a diagnostic geomorphic metric with applications to process-based river and fluvial domain classification. Rivers vary widely in their sensitivity to change depending on sediment and bedload materials, landscape position, and hydroclimatic variability, including flooding or drought. River classification systems were developed to organize the diversity of river forms and processes in ways that support both scientific understanding and management needs. Classification provides a framework for geomorphological analyses related to resource assessment, habitat evaluation, and mitigation of natural or human-driven disturbances. Process-based classification systems help predict how channels respond to changes in flow or sediment regimes (Buffington and Montgomery, 2022), and also support resource exploration because ecological habitats, mineral deposits, and other natural resources often correspond to sediment characteristics that vary systematically across channel types (Rosgen, 1994; Wheaton et al., 2013; Wheaton et al., 2015). Planform-based metrics such as channel sinuosity have long been components of river classification systems (Rosgen, 1994; Wheaton et al., 2015; Buffington and Montgomery, 2022), where sinuosity is measured as a simple ratio of path length over end-to-end distance.

Alaska↗
USGS2018

Remaining populations of an upland stream fish persist in refugia defined by habitat features at multiple scales

Aim Conserving stream biota could require strategies that preserve habitats conveying resistance to ecological impacts of changing land use and climate. Retrospective analyses of species’ responses to anthropogenic disturbances can inform such strategies. We developed a hierarchical framework to contrast environmental conditions underlying persistence versus extirpation of an imperilled stream fish, Candy Darter ( Etheostoma osburni ), over decades of changing land use. The decline of E. osburni may broadly represent the challenge of conserving sensitive freshwater species in intensively used upland environments. Location New River drainage, Appalachian Mountains, USA. Methods We surveyed fish and habitat in historically occupied sites to identify population refugia, and used multivariate and spatial analyses to address three questions: (a) what are the environmental correlates of refugia? (b) are the pathways by which land use impacts instream habitat constrained by catchment- and/or segment-scale features? and (c) are E. osburni distributional dynamics spatially structured and explained by fine sediment and warm stream temperatures? Results We confirmed a recently localized distribution similar to other upland species, marked by at least seven extirpations from streams throughout E. osburni 's southern range. Catchment-scale features primarily constrained land use and finer-scale habitat, leading to either extirpations or population-supporting refugia defined by features at multiple scales. Refugium habitats contained cooler temperatures and less fine sediment. Rare mismatches between persistence and habitat suitability were explained by network location , suggesting unmeasured environmental gradients and/or dispersal contributed to distributional dynamics. Main conclusions We provided insight at multiple spatial scales into how aquatic species’ distributions become fragmented and localized. Our results demonstrate that natural landscape heterogeneity imparts spatially variable resistance of sensitive species to intensive land uses. By recognizing the scale-specific features that buffer populations from extirpation, conservation strategies could be tailored to protect naturally occurring refugium habitats and focus restoration in systems where such habitats are broadly lacking.

Virginia, West Virginia↗