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At least 1,801 records · Page 100Linked to original sources
USGS2010

Modeling and mapping Golden-winged Warbler abundance to improve regional conservation strategies

Conservation planning requires identifying pertinent habitat factors and locating geographic locations where land management may improve habitat conditions for high priority species. I derived habitat models and mapped predicted abundance for the Golden-winged Warbler ( Vermivora chrysoptera ), a species of high conservation concern, using bird counts, environmental variables, and hierarchical models applied at multiple spatial scales. My aim was to understand habitat associations at multiple spatial scales and create a predictive abundance map for purposes of conservation planning for the Golden-winged Warbler. My models indicated a substantial influence of landscape conditions, including strong positive associations with total forest composition within the landscape. However, many of the associations I observed were counter to reported associations at finer spatial extents; for instance, I found Golden-winged Warblers negatively associated with several measures of edge habitat. No single spatial scale dominated, indicating that this species is responding to factors at multiple spatial scales. I found Golden-winged Warbler abundance was negatively related with Blue-winged Warbler ( Vermivora cyanoptera ) abundance. I also observed a north-south spatial trend suggestive of a regional climate effect that was not previously noted for this species. The map of predicted abundance indicated a large area of concentrated abundance in west-central Wisconsin, with smaller areas of high abundance along the northern periphery of the Prairie Hardwood Transition. This map of predicted abundance compared favorably with independent evaluation data sets and can thus be used to inform regional planning efforts devoted to conserving this species.

Avian Conservation and Ecology↗
USGS2011

Conservation of greater sage-grouse- a synthesis of current trends and future management

Recent analyses of Greater Sage-Grouse (Centrocercus urophasianus) populations indicate substantial declines in many areas but relatively stable populations in other portions of the species? range. Sagebrush (Artemisia spp.) habitats neces-sary to support sage-grouse are being burned by large wildfires, invaded by nonnative plants, and developed for energy resources (gas, oil, and wind). Management on public lands, which con-tain 70% of sagebrush habitats, has changed over the last 30 years from large sagebrush control projects directed at enhancing livestock grazing to a greater emphasis on projects that often attempt to improve or restore ecological integrity. Never-theless, the mandate to manage public lands to provide traditional consumptive uses as well as recreation and wilderness values is not likely to change in the near future. Consequently, demand and use of resources contained in sagebrush land-scapes plus the associated infrastructure to sup-port increasing human populations in the western United States will continue to challenge efforts to conserve Greater Sage-Grouse. The continued widespread distribution of sage-grouse, albeit at very low densities in some areas, coupled with large areas of important sagebrush habitat that are relatively unaffected by the human footprint, sug-gest that Greater Sage-Grouse populations may be able to persist into the future. We summarize the status of sage-grouse populations and habitats, provide a synthesis of major threats and chal-lenges to conservation of sage-grouse, and suggest a roadmap to attaining conservation goals.

Book chapter↗
USGS2017

Contaminants of emerging concern in the Great Lakes Basin: A report on sediment, water, and fish tissue chemistry collected in 2010-2012

Despite being detected at low levels in surface waters and sediments across the United States, contaminants of emerging concern (CECs) in the Great Lakes Basin are not well characterized in terms of spatial and temporal occurrence. Additionally, although the detrimental effects of exposure to CECs on fish and wildlife have been documented for many CECs in laboratory studies, we do not adequately understand the implications of the presence of CECs in the environment. Based on limited studies using current environmentally relevant concentrations of chemicals, however, risks to fish and wildlife are evident. As a result, there is an increasing urgency to address data gaps that are vital to resource management decisions. The U.S. Fish and Wildlife Service, in collaboration with the U.S. Geological Survey, is leading a Great Lakes Basin-wide evaluation of CECs (CEC Project) with the objectives to (a) characterize the spatial and temporal distribution of CECs; (b) evaluate risks to fish and wildlife resources; and (c) develop tools to aid resource managers in detecting, averting, or minimizing the ecological consequences to fish and wildlife that are exposed to CECs. This report addresses objective (a) of the CEC Project, summarizing sediment and water chemistry data collected from 2010 to 2012 and fish liver tissue chemistry data collected in 2012; characterizes the sampling locations with respect to potential sources of CECs in the landscape; and provides an initial interpretation of the variation in CEC concentrations relative to the identified sources. Data collected during the first three years of our study, which included 12 sampling locations and analysis of 134 chemicals, indicate that contaminants were more frequently detected in sediment compared to water. Chemicals classified as alkyphenols, flavors/ fragrances, hormones, PAHs, and sterols had higher average detection frequencies in sediment compared to water, while the opposite was observed for pesticides, pharmaceuticals, and plasticizers/flame retardants. The St. Louis River and Maumee River sampling locations had the most CEC detections in water and sediment, relative to other sites, as well as the largest number of maximum detected concentrations across all sites in the Basin. No consistent temporal CEC occurrence patterns were observed at locations sampled multiple times each day. Most appearances and increases in chemical concentrations in sediments occurred at sites immediately downstream from wastewater treatment plants and at sites with predominantly developed land use. The location with the most observed appearances and increases was the St. Louis River. Perfluorinated compounds were commonly detected in fish liver tissues with detections in 100% of both benthic and pelagic species. The occurrence of these chemicals in liver tissue of benthic and pelagic species was generally similar. Abstract

Great Lakes Basin↗
USGS2001

Spatial paradigms of lotic diatom distribution: A landscape ecology perspective

Spatial distributional patterns of benthic diatoms and their relation to current velocity were investigated in an unshaded cobble-bottom reach of White Creek (Washington County, NY). On 27 August 1999, diatoms were sampled and current velocity and depth were measured on a regular square sampling grid with a grain size of 0.01 m2, interval of 0.5 m, and extent of 16 m2. The relative abundance of the 18 common diatom species enumerated in the 81 samples was subjected to detrended correspondence analysis (DCA). The first axis (DCA1) explained 51% of the variance in diatom data and separated the samples according to current regimes. The spatial autocorrelation of DCA1 sample scores in deposition and erosion regions of White Creek was determined by Moran's I statistic to indicate patch size. In White Creek the patch length of all diatom communities was more than 3.1 m, whereas the patch width was 1 m in the deposition region and 0.5 m in the erosion region. There were 5 dominant diatom taxa, Achnanthes minutissima Ku??tz. et vars, Fragilaria capucina Dezmazie??res et vars, F. crotonensis Kitt., Diatoma vulgaris Bory, and Synedra ulna (Nitz.) Ehr. et vars. The patch length of the dominant species varied from 1 to more than 4.1 m, whereas the patch width, if defined, was 0.5 m. Achnanthes minutissima and F. capucina, the two diatom species with the highest relative abundance, displayed spatially structured patches of low abundance and comparatively random patches of high abundance, suggesting broad scale abiotic control of species performance in low abundance regions and finer scale biotic control of high abundance areas. Another objective of this study was to test the hypothesis that higher current velocities, which generally impede immigration, would increase randomness and complexity (i.e. homogeneity of diatom distributional patterns). The spatial complexity in low versus high velocity transects was determined by calculating the respective fractal dimension (D) of DCA1 scores. D of DCA1 was higher in the higher current velocity transects, suggesting that spatial complexity and homogeneity of diatom communities increased in faster currents. Partial canonical correspondence analysis was conducted on diatom, environmental, and spatial data to assess how much of the variance in species distribution could be attributed to environmental (current velocity and depth) versus spatial factors. The variance of species data, explained by the environment (exclusively current velocity), was 38%; whereas space alone contributed only 10%, indicating that 1) current velocity was the major factor that controlled diatom distribution in streams and 2) there were other spatially dependent variables, most likely biotic, but their role in shaping diatom communities was minor.

Journal of Phycology↗
USGS2023

Wastewater reuse and predicted ecological risk posed by contaminant mixtures in Potomac River watershed streams

A wastewater model was applied to the Potomac River watershed to provide (i) a means to identify streams with a high likelihood of carrying elevated effluent-derived contaminants and (ii) risk assessments to aquatic life and drinking water. The model linked effluent discharges along stream networks, accumulated wastewater, and predicted contaminant loads of municipal wastewater constituents while accounting for instream dilution and attenuation. Simulations using 2016 data suggested that nearly 30% (8281 km) of streams were wastewater impacted. Low- to medium-order streams had the largest range of accumulated wastewater (ACCWW%) values. ACCWW% exceeded a 1% threshold at >39% of drinking-water intakes (varied by temporal condition). Risk assessments of municipal wastewater-contaminant mixtures indicated that 22% (1479 km) of streams impacted by municipal wastewater (5.5% of all reaches modeled) may pose high risk to aquatic organisms under mean-annual conditions, with fish more susceptible to chronic-exposure effects relative to other taxa. Risk varied temporally and by stream order, with the greatest risk occurring in the summer in small streams. These findings suggest that wastewater may be an important factor contributing to environmental degradation in the Potomac River watershed.

District of Columbia, Maryland, Pennsylvania, Virg↗
USGS2022

Context-dependent variation in persistence of host populations in the face of disease

Research Highlight : Valenzuela-Sánchez, A., Azat, C., Cunningham, A. A., Delgado, S., Bacigalupe, L. D., Beltrand, J., Serrano, J. M., Sentenac, H., Haddow, N., Toledo, V., Schmidt, B. R., & Cayuela, H. (2022). Interpopulation differences in male reproductive effort drive the population dynamics of a host exposed to an emerging fungal pathogen. Journal of Animal Ecology , 00 , 1– 12. https://doi.org/10.1111/1365-2656.13603 . Understanding the nuances of population persistence in the face of a stressor can help predict extinction risk and guide conservation actions. However, the exact mechanisms driving population stability may not always be known. In this paper, Valenzuela-Sánchez et al. (2022) integrate long-term mark–recapture data, focal measurements of reproductive effort, a population matrix model and inferences on life-history variation to reveal differences in demographic response to disease in a susceptible frog species ( Rhinoderma darwinii ). Valenzuela-Sánchez et al. found that demographic compensation via recruitment explained the positive population growth rate in their high disease prevalence population whereas the low disease prevalence population did not compensate and thus had decreasing population growth. Compensatory recruitment was likely due to the high probability of males brooding, and the high number of brooded larvae in the high prevalence population compared to low prevalence and disease-free populations. Valenzuela-Sánchez et al. also document faster generation times in the high prevalence population, which may indicate a faster life history that may be contributing to the population's ability to compensate for reduced survival. Lastly, the authors find a positive relationship between disease prevalence and the proportion of juveniles in a given population that suggest that there may be a threshold for disease prevalence that triggers increased reproductive effort. Altogether, their study provides novel support for increased reproductive effort as the pathway for compensatory recruitment leading to increasing population growth despite strong negative effects of disease on adult survival. Their results also caution the overgeneralization of the effects of stressors (e.g. disease) on population dynamics, where context-dependent responses may differ among host populations of a given species.

Journal of Animal Ecology↗
USGS2023

Performance evaluation of a channel rehabilitation project on the Lower Missouri River and implications for the dispersal of larval pallid sturgeon

In the Lower Missouri River, extensive channel modifications have altered hydraulic and morphologic conditions and reduced the river's ecological integrity. One species that has been adversely affected by these changes is the pallid sturgeon ( Scaphirhynchus albus ). Mainstem dams on the Missouri River restrict the upstream migration of adults and limit the downstream dispersal of larvae. Channelization to facilitate commercial barge traffic has also simplified the river. The self-dredging navigation channel is a highly efficient conduit for transporting sand, which has resulted in diminished rearing habitat along the lower river. Recently, a series of experimental projects was implemented to reengineer selected bends of the Lower Missouri River with the goal of increasing the interception and retention of passively drifting age-0 sturgeon into habitats more conducive to rearing. Here, we evaluate the hydraulic performance of one of these rehabilitation projects to gain insight on the implications of these interventions for age-0 pallid sturgeon dispersal. We conducted a dye-trace experiment and complementary hydraulic and particle-tracking modeling to examine the spatial and temporal patterns of passive dispersal in and around the rehabilitated study reach. Results from both the dye-trace experiment and particle-tracking model highlight the presence of several interception pathways from the navigation channel into more suitable rearing habitat on channel margins. Moreover, our results indicate that residence times within the rearing habitat are increased in comparison to the main channel. Although we cannot provide biological evaluation at this time to assess whether the rehabilitated study bend intercepts passively drifting age-0 pallid sturgeon, our analysis shows that hydraulic conditions within the rehabilitated bend would favor interception and retention of passively drifting particles (or, presumably, larvae) from the navigation channel and into slower moving, shallow-water habitat. Moreover, our particle-tracking model provides a new capability to explore important biological transport processes across a range of flows, organisms, and river environments.

Lower Missouri River↗
USGS2015

Western juniper management: assessing strategies for improving greater sage-grouse habitat and rangeland productivity

Western juniper ( Juniperus occidentalis subsp. occidentalis ) range expansion into sagebrush steppe ecosystems has affected both native wildlife and economic livelihoods across western North America. The potential listing of the greater sage-grouse ( Centrocercus urophasianus ) under the U.S. Endangered Species Act has spurred a decade of juniper removal efforts, yet limited research has evaluated program effectiveness. We used a multi-objective spatially explicit model to identify optimal juniper removal sites in Northeastern California across weighted goals for ecological (sage-grouse habitat) and economic (cattle forage production) benefits. We also extended the analysis through alternative case scenarios that tested the effects of coordination among federal agencies, budgetary constraints, and the use of fire as a juniper treatment method. We found that sage-grouse conservation and forage production goals are somewhat complementary, but the extent of complementary benefits strongly depends on spatial factors and management approaches. Certain management actions substantially increase achievable benefits, including agency coordination and the use of prescribed burns to remove juniper. Critically, our results indicate that juniper management strategies designed to increase cattle forage do not necessarily achieve measurable sage-grouse benefits, underscoring the need for program evaluation and monitoring.

California, Oregon, Nevada↗
USGS2014

Opposing resonses to ecological gradients structure amphibian and reptile communities across a temperate grassland-savanna-forest landscape

Temperate savannas are threatened across the globe. If we prioritize savanna restoration, we should ask how savanna animal communities differ from communities in related open habitats and forests. We documented distribution of amphibian and reptile species across an open-savanna–forest gradient in the Midwest U.S. to determine how fire history and habitat structure affected herpetofaunal community composition. The transition from open habitats to forests was a transition from higher reptile abundance to higher amphibian abundance and the intermediate savanna landscape supported the most species overall. These differences warn against assuming that amphibian and reptile communities will have similar ecological responses to habitat structure. Richness and abundance also often responded in opposite directions to some habitat characteristics, such as cover of bare ground or litter. Herpetofaunal community species composition changed along a fire gradient from infrequent and recent fires to frequent but less recent fires. Nearby (200-m) wetland cover was relatively unimportant in predicting overall herpetofaunal community composition while fire history and fire-related canopy and ground cover were more important predictors of composition, diversity, and abundance. Increased developed cover was negatively related to richness and abundance. This indicates the importance of fire history and fire related landscape characteristics, and the negative effects of development, in shaping the upland herpetofaunal community along the native grassland–forest continuum.

Indiana↗
USGS2012

Management of surface water and groundwater withdrawals to maintain environmental stream flows in Michigan

In 2008, the State of Michigan enacted legislation requiring that new or increased high-capacity withdrawals (greater than 100,000 gallons per day) from either surface water or groundwater be reviewed to prevent Adverse Resource Impacts (ARI). Science- based guidance was sought in defining how groundwater or surface-water withdrawals affect streamflow and in quantifying the relation between reduced streamflow and changes in stream ecology. The implementation of the legislation led to a risk-based system based on a gradient of risk, ecological response curves, and estimation of groundwater-surface water interaction. All Michigan streams are included in the legislation, and, accordingly, all Michigan streams were classified into management types defined by size of watershed, stream-water temperature, and predicted fish assemblages. Different streamflow removal percentages define risk-based thresholds allowed for each type. These removal percentages were informed by ecological response curves of characteristic fish populations and finalized through a legislative workgroup process. The assessment process includes an on-line screening tool that may be used to evaluate new or increased withdrawals against the risk-based zones and allows withdrawals that are not likely to cause an ARI to proceed to water-use registration. The system is designed to consider cumulative impacts of high-capacity withdrawals and to promote user involvement in water resource management by the establishment of water-user committees as cumulative withdrawals indicate greater potential for ARI in the watershed.

Michigan↗
USGS2015

Fire history of Everglades National Park and Big Cypress National Preserve, southern Florida

Fire occurs naturally in the environment on most continents, including Africa (Ryan and Williams, 2011), Asia (Kauhanen, 2008), Australia (Kutt and Woinarski, 2007), Europe (Eshel and others, 2000), South America (Fidelis and others, 2010), and North America (Van Auken, 2000). Antarctica appears to be the only continent that has no reported natural fires, although fire is common in grasslands of Patagonia and on islands in the Subantarctic region (Gonzalez and others, 2005; McGlone and others, 2007). Natural fires also have occurred over thousands of years, and the frequencies of these natural fires have changed (Power and others, 2008). This has resulted in altered ecosystems at landscape scales. Recent evidence suggests that the treeless desert pastures of Tibet once were forests and woodlands, and charcoal deposits indicate that fire was more frequent in the past (Miehe and others, 2006). Human cultural development has been influenced by changes in natural fire frequencies. Zong and others (2007) reported that human suppression of fires in coastal areas of China allowed the development of rice paddy cultivation and, thus, increased the size of human populations. In addition to its almost world-wide occurrence, fire plays a role in a wide variety of ecosystem types. Grassland, savanna, steppe, woodland, forest, and wetland ecosystems all have fire as part of their natural ecology (Veblen and Lorenz, 1988; Chokkalingam and others, 2007; Miller and others, 2009, Keith and others, 2010; Staver and others, 2011). Fires affect these ecosystems in various ways, the most obvious of which is the direct effect on plant biomass (for example, Van Wilgen, 1982; Mack and others, 2008). However, fire has many other effects on ecosystems. Plant species richness, diversity, and functional types can change in response to fire (Peterson and Reich, 2008). All properties of the surface soils (such as bulk density, particle size distribution, pH, and organic carbon and nitrogen content) can be altered by the frequency and severity of fire (Boerner and others, 2009). Faunal communities will respond to fire, with some species increasing (Fuhlendorf and others, 2006) and other species decreasing, after the fire (Vasconcelos and others, 2009).The position of the ecotone between differing ecosystems also is influenced by fire occurrence (Heisler and others, 2003; Briggs and others, 2005; Smith and others, 2013). Fire has been used as a management tool in various ecosystems around the world. Prairies, grasslands, and savannas are fire-maintained ecosystems where fire is used to deter invasion by shrubs and trees (Grant and others, 2009; Scheintaub and others, 2009). Similarly, fire plays an important role in woodlands and forests by influencing species composition and succession such, as the use of fire in coniferous forests to prevent encroachment by hardwoods (Phillippe and others, 2011). Fire also has been used to manage wetland ecosystems for more than 50 years (Lynch, 1941; Frost, 1995). Uses have included returning marshes to early successional states, increasing forage for wildlife (Lynch, 1941). In all fire-influenced ecosystems, prescribed burns are routinely used to reduce fuel loads, reducing the possibility of catastrophic fires.

Florida↗
USGS2016

Science information to support Missouri River Scaphirhynchus albus (pallid sturgeon) effects analysis

The Missouri River Pallid Sturgeon Effects Analysis (EA) was commissioned by the U.S. Army Corps of Engineers to develop a foundation of understanding of how pallid sturgeon ( Scaphirhynchus albus ) population dynamics are linked to management actions in the Missouri River. The EA consists of several steps: (1) development of comprehensive, conceptual ecological models illustrating pallid sturgeon population dynamics and links to management actions and other drivers; (2) compilation and assessment of available scientific literature, databases, and models; (3) development of predictive, quantitative models to explore the system dynamics and population responses to management actions; and (4) analysis and assessment of effects of system operations and actions on species’ habitats and populations. This report addresses the second objective, compilation and assessment of relevant information. Scientific information on pallid sturgeon and its environment has grown substantially during the last decade. Presently available (2015) information indicates that stocked sturgeon are surviving and growing, and that wild and hatchery sturgeon are spawning in the wild. However, natural recruitment to age-1 and older has not been detected since systematic sampling began in 2005. Population models indicate the sensitivity of population growth to certain demographic variables, in particular early-life stage survival and perhaps adult fecundity. This report documents the existing population models for the pallid sturgeon, and the substantial quantities of information developed through the Pallid Sturgeon Population Assessment Program (PSPAP), the Habitat Assessment and Monitoring Program (HAMP), the Comprehensive Sturgeon Research Project (CSRP), range-wide genetics databases, and related research studies. The reference database compiled for the EA consists of over 190 peer-reviewed documents specifically related to pallid sturgeon and over 12,000 references on the Missouri River system and related species. Notwithstanding the large quantity of information available, the EA faces challenges in synthesizing the information into useful, quantitative models. In particular, critical demographic parameters for population models remain uncertain and the functional relationships between the two main categories of physical management action—changes in flow regime and reengineering channel form—and pallid sturgeon survival responses are obscure. In addition, there is an overarching uncertainty about how physical management actions interact with propagation management actions in view of evolving understanding of genetic structuring of the pallid sturgeon population. Synthesis efforts are also challenged by the fragmentation of information sources among projects and agencies; one objective of this report is to facilitate future assessments by providing documentation of what information is available and where.

Iowa, Kansas, Missouri, Montana, Nebraska, North D↗
USGS2015

Hydrogeology of the Ramapo River-Woodbury Creek valley-fill aquifer system and adjacent areas in eastern Orange County, New York

The hydrogeology of the valley-fill aquifer system and surrounding watershed areas was investigated within a 23-mile long, fault-controlled valley in eastern Orange County, New York. Glacial deposits form a divide within the valley that is drained to the north by Woodbury Creek and is drained to the south by the Ramapo River. Surficial geology, extent and saturated thickness of sand and gravel aquifers, extent of confining units, bedrock-surface elevation beneath valleys, major lineaments, and the locations of wells for which records are available were delineated on an interactive map. Currently (2013), groundwater is the primary source of water supply in the study area. Several public water-supply systems withdraw groundwater from production wells in valley areas; elsewhere, domestic wells are used for water supply. Community-supply wells tap both sand and gravel and fractured bedrock aquifers; most domestic wells tap fractured-bedrock aquifers. Thick, saturated sand and gravel deposits are limited in areal extent but form several localized, productive aquifer zones within the valley-fill sediments. Hydraulic interconnection among these zones is largely untested. Fine-grained lacustrine deposits form extensive confining units above some aquifer material. Till deposits that extend into valleys also confine sand and gravel or bedrock aquifers. The study area was divided into three sections—south, central, and north. The south section of the study area, from Harriman south to the Rockland County and New Jersey borders, includes the south-draining valleys of the Ramapo River and Summit Brook. South of the wide valley area at Harriman, the valleys are narrow and the valley-fill aquifers are largely untested; the most favorable aquifer conditions are likely at Arden and where major tributary streams enter the valley, between Southfields and We-Wah Lake. At Harriman, the Ramapo River valley fill has water-resource potential from ice-contact sand and gravel deposits. The central section of the study area encompasses the headwater drainage area of the Ramapo River, from Harriman to Monroe and Kiryas Joel. The valley-fill aquifer material is generally thin, mostly unconfined, and underlain by glacial till. Shallow production wells tap parts of this aquifer, and appear most productive when sited near surface-water bodies. Production wells in the section are frequently completed in the underlying bedrock. The north section of the study area encompasses the watershed of north-draining Woodbury Creek to just north of its confluence with Moodna Creek. The width of the valley bottom and type of valley-fill deposits vary considerably within the valley. The section likely has the greatest water-resource potential—both confined and unconfined aquifers are present and the village of Woodbury and town of Cornwall draw water supply from production wells. Aquifer potential appears most promising north of Central Valley, but several areas in this section are largely untested. Valley-fill aquifers are modest resources within the area, as indicated by the common practice of completing supply wells in the underlying bedrock rather than the overlying glacial deposits. Groundwater turbidity problems curtail use of the resource. However, additional groundwater resources have been identified by test drilling, and there are remaining untested areas. New groundwater supplies that stress localized aquifer areas will alter the groundwater flow system. Considerations include potential water-quality degradation from nearby land use(s) and, where withdrawals induce infiltration of surface-water, balancing withdrawals with flow requirements for downstream users or for maintenance of stream ecological health.

New York↗
USGS2016

Hydrologic effects on diameter growth phenology for Celtis laevigata and Quercus lyrata in the floodplain of the lower White River, Arkansas

Bottomland hardwood (BLH) forests represent an extensive wetland system in the Mississippi Alluvial Valley and southeastern USA, and it is currently undergoing widespread transition in species composition. One such transition involves increased establishment of sugarberry (Celtis laevigata), and decreased establishment of overcup oak (Quercus lyrata). The ecological mechanisms that control this transition are not well understood. We measured monthly diameter growth with dendrometer bands on 86 sugarberry and 42 overcup oak trees at eight sites in the floodplain of the White River (AR, USA) with differing hydrologic regimes. For both species, growth attenuated earlier at drier sites compared to wetter sites. Overcup oak grew slightly longer through late August, suggesting its growth period extends across both wet and dry periods. In contrast, sugarberry growth rate decreased substantially by mid-July. While these results did not necessarily indicate a mechanism for increased prominence of sugarberry, they suggest sugarberry growing season does not as much coincide with the typically drier period of late summer and may be less affected by these conditions. Overcup oak grows later into the dry season and water table conditions during this period may determine if overcup oak benefits from this relatively extended growth period.

Conference Paper↗
USGS2016

Effects of microhabitat and large-scale land use on stream salamander occupancy in the coalfields of Central Appalachia

Large-scale coal mining practices, particularly surface coal extraction and associated valley fills as well as residential wastewater discharge, are of ecological concern for aquatic systems in central Appalachia. Identifying and quantifying alterations to ecosystems along a gradient of spatial scales is a necessary first-step to aid in mitigation of negative consequences to aquatic biota. In central Appalachian headwater streams, apart from fish, salamanders are the most abundant vertebrate predator that provide a significant intermediate trophic role linking aquatic and terrestrial food webs. Stream salamander species are considered to be sensitive to aquatic stressors and environmental alterations, as past research has shown linkages among microhabitat parameters, large-scale land use such as urbanization and logging, and salamander abundances. However, there is little information examining these relationships between environmental conditions and salamander occupancy in the coalfields of central Appalachia. In the summer of 2013, 70 sites (sampled two to three times each) in the southwest Virginia coalfields were visited to collect salamanders and quantify stream and riparian microhabitat parameters. Using an information-theoretic framework, effects of microhabitat and large-scale land use on stream salamander occupancy were compared. The findings indicate that Desmognathus spp. occupancy rates are more correlated to microhabitat parameters such as canopy cover than to large-scale land uses. However, Eurycea spp . occupancy rates had a strong association with large-scale land uses, particularly recent mining and forest cover within the watershed. These findings suggest that protection of riparian habitats is an important consideration for maintaining aquatic systems in central Appalachia. If this is not possible, restoration riparian areas should follow guidelines using quick-growing tree species that are native to Appalachian riparian areas. These types of trees would rapidly establish a canopy cover, stabilize the soil, and impede invasive plant species which would, in turn, provide high-quality refuges for stream salamanders.

Journal of Ecology and the Natural Environment↗
USGS2017

Temporal constraints on the potential role of fry odors as cues of past reproductive success for spawning lake trout

Deciding where to reproduce is a major challenge for most animals. Many select habitats based upon cues of successful reproduction by conspecifics, such as the presence of offspring from past reproductive events. For example, some fishes select spawning habitat following odors released by juveniles whose rearing habitat overlaps with spawning habitat. However, juveniles may emigrate before adults begin to search for spawning habitat; hence, the efficacy of juvenile cues could be constrained by degradation or dissipation rates. In lake trout ( Salvelinus namaycush ), odors deposited by the previous year's offspring have been hypothesized to guide adults to spawning reefs. However, in most extant populations, lake trout fry emigrate from spawning reefs during the spring and adults spawn during the fall. Therefore, we postulated that the role of fry odors in guiding habitat selection might be constrained by the time between fry emigration and adult spawning. Time course chemical, physiological, and behavioral assays indicated that the odors deposited by fry likely degrade or dissipate before adults select spawning habitats. Furthermore, fry feces did not attract wild lake trout to constructed spawning reefs in Lake Huron. Taken together, our results indicate fry odors are unlikely to act as cues for lake trout searching for spawning reefs in populations whose juveniles emigrate before the spawning season, and underscore the importance of environmental constraints on social cues.

Ecology and Evolution↗
USGS2017

A computational fluid dynamics modeling study of guide walls for downstream fish passage

A partial-depth, impermeable guidance structure (or guide wall) for downstream fish passage is typically constructed as a series of panels attached to a floating boom and anchored across a water body (e.g. river channel, reservoir, or power canal). The downstream terminus of the wall is generally located nearby to a fish bypass structure. If guidance is successful, the fish will avoid entrainment in a dangerous intake structure (i.e. turbine intakes) while passing from the headpond to the tailwater of a hydroelectric facility through a safer passage route (i.e. the bypass). The goal of this study is to determine the combination of guide wall design parameters that will most likely increase the chance of surface-oriented fish being successfully guided to the bypass. To evaluate the flow field immediately upstream of a guide wall, a parameterized computational fluid dynamics model of an idealized power canal was constructed in © ANSYS Fluent v 14.5 (ANSYS Inc., 2012). The design parameters investigated were the angle and depth of the guide wall and the average approach velocity in the power canal. Results call attention to the importance of the downward to sweeping flow ratio and demonstrate how a change in guide wall depth and angle can affect this important hydraulic cue to out-migrating fish. The key findings indicate that a guide wall set at a small angle (15° is the minimum in this study) and deep enough such that sweeping flow dominant conditions prevail within the expected vertical distribution of fish approaching the structure will produce hydraulic conditions that are more likely to result in effective passage.

Ecological Engineering↗
USGS2011

Breeding bird response to partially harvested riparian management zones

We compared avian communities among three timber harvesting treatments in 45-m wide even-age riparian management zones (RMZs) placed between upland clearcuts and along one side of first- or second-order streams in northern Minnesota, USA. The RMZs had three treatments: (1) unharvested, (2) intermediate residual basal area (RBA) (targeted goal 11.5 m 2 /ha, realized 16.0 m 2 /ha), and (3) low RBA (targeted goal 5.7 m 2 /ha, realized 8.7 m 2 /ha). Surveys were conducted one year pre-harvest and three consecutive years post-harvest. There was no change in species richness, diversity, or total abundance associated with harvest but there were shifts in the types of birds within the community. In particular, White-throated Sparrows ( Zonotrichia albicollis ) and Chestnut-sided Warblers ( Dendroica pensylvanica ) increased while Ovenbirds ( Seiurus aurocapilla ) and Red-eyed Vireos ( Vireo olivaceus ) decreased. The decline of avian species associated with mature forest in the partially harvested treatments relative to controls indicates that maintaining an unharvested RMZ adjacent to an upland harvest may aid in maintaining avian species associated mature forest in Minnesota for at least three years post-harvest. However, our observations do not reflect reproductive success, which is an area for future research.

Minnesota↗

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