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USGS2010

Multilocus patterns of nucleotide polymorphism and demographic change in Taxodium distichum (Cupressaceae) in the lower Mississippi River alluvial valley

• Premise of the Study: Studies of the geographic patterns of genetic variation can give important insights into the past population structure of species. Our study species, Taxodium distichum L. (bald‐cypress), prefers riparian and wetland habitats and is widely distributed in southeastern North America and Mexico. We compared the genetic variation of T. distichum with that of its close relative, Cryptomeria japonica , which is endemic to Japan. • Methods: Nucleotide polymorphisms of T. distichum in the lower Mississippi River alluvial valley, USA, were examined at 10 nuclear loci. • Key Results: The average nucleotide diversity at silent sites, π sil , across the 10 loci in T. distichum was higher than that of C. japonica (π sil = 0.00732 and 0.00322, respectively). In T. distichum , Tajima's D values were each negative at 9 out of 10 loci, which suggests a recent population expansion. Maximum‐likelihood and Bayesian estimations of the exponential population growth rate ( g ) of T. distichum populations indicated that this species had expanded approximately at the rate of 1.7–1.0 × 10 –6 per year in the past. • Conclusions: Taxodium distichum had significantly higher nucleotide variation than C. japonica , and its patterns of polymorphism contrasted strikingly with those of the latter, which previously has been inferred to have experienced a reduction in population size.

Arkansas, Louisiana, Mississippi, Tennessee↗

USGS1989

Turkey vulture and California condor

Populations of turkey vultures in the western states appear stable, with no evidence of recent significant changes in distribution. Turkey vultures occupy a variety of habitats, nest in diverse situations and utilize a wide variety of carrion. Consequently, no particular limiting factor is likely to have a major effect on the total population. California condor numbers, in contrast, have continued to decline. With the capture of the last wild bird in 1987, the species has been extirpated from the wild. Reestablishment will depend on production and introduction of captive-reared birds, hopefully within the next 10 years. In the 18th century, condors inhabited areas along the Pacific coast from British Columbia to Baja California. Since 1950, the range has been restricted to a six county area adjacent to the southern San Joaquin Valley of California. Within this area, there appears to be no shortage of suitable nest sites; all recently used nest sites are within federally-controlled lands. Suitable foraging grounds have continued to diminish and are now largely limited to private rangelands and some Bureau of Land Management rangelands within the foothills of the San Joaquin Valley. Only these areas continue to supply the large mammal carcasses that the California condor needs for survival. The habitat of the condor is subject to a variety of land use practices and development pressures. Excessive mortality, coupled with low reproductive potential, continues to threaten the recovery of the species. Development of management practices to reduce mortality, particularly those that are contaminant-related, and of a preserve design to insure adequate habitat for the reintroduced population are still necessary for eventual recovery of the species.

Book chapter↗

USGS1987

Fall and winter foods of northern pintails in the Sacramento Valley, California

Food habits of northern pintails ( Anas acuta ) were investigated on 3 national wildlife refuges in the western portion of the Sacramento Valley, California, from August to March 1979-82. Pintails consumed >97% (aggregate % dry wt) plant food during diurnal foraging on national wildlife refuge rice, summer- irrigated, and summer-dry habitats from August through January. Invertebrate use increased to 28.9-65.6% of the diet in these habitats during February and March. Rice, swamp timothy ( Heleochloa schoenoides ), flatsedges ( Cyperus spp.), common barnyardgrass ( Echinochloa crusgalli ), southern naiad ( Najas guadalupensis ), and smartweed ( Polygonum spp.) seeds, miscellaneous vegetation, snails (Gastropoda), and midge (Diptera) and water beetle (Coleoptera) larvae were most important. These foods usually were taken proportional to or greater than availability. Rice was the most important food of pintails feeding nocturnally off the refuges in harvested rice fields from October through January (99.7%) and February and March (63%; barnyardgrass formed 31% of the diet). In August and October, some pintails consumed invertebrates or bulrush ( Scirpus spp.) seedlings in marshes soon after feeding in refuge rice (Aug) or harvested commercial rice fields (Oct), thereby increasing dietary protein. In late winter, females and males obtained similar (P > 0.05) percentages of invertebrates from refuge habitats. Important dietary seeds and invertebrates contained high protein or metabolizable energy content. Management should maintain adequate seed production in fall and mid-winter and invertebrate biomass in late winter.

California↗

USGS2015

Integrated climate and land use change scenarios for California rangeland ecosystem services: wildlife habitat, soil carbon, and water supply

Context In addition to biodiversity conservation, California rangelands generate multiple ecosystem services including livestock production, drinking and irrigation water, and carbon sequestration. California rangeland ecosystems have experienced substantial conversion to residential land use and more intensive agriculture. Objectives To understand the potential impacts to rangeland ecosystem services, we developed six spatially explicit (250 m) climate/land use change scenarios for the Central Valley of California and surrounding foothills consistent with three Intergovernmental Panel on Climate Change emission scenario narratives. Methods We quantified baseline and projected change in wildlife habitat, soil organic carbon (SOC), and water supply (recharge and runoff). For six case study watersheds we quantified the interactions of future development and changing climate on recharge, runoff and streamflow, and precipitation thresholds where dominant watershed hydrological processes shift through analysis of covariance. Results The scenarios show that across the region, habitat loss is expected to occur predominantly in grasslands, primarily due to future development (up to a 37 % decline by 2100), however habitat loss in priority conservation errors will likely be due to cropland and hay/pasture expansion (up to 40 % by 2100). Grasslands in the region contain approximately 100 teragrams SOC in the top 20 cm, and up to 39 % of this SOC is subject to conversion by 2100. In dryer periods recharge processes typically dominate runoff. Future development lowers the precipitation value at which recharge processes dominate runoff, and combined with periods of drought, reduces the opportunity for recharge, especially on deep soils. Conclusion Results support the need for climate-smart land use planning that takes recharge areas into account, which will provide opportunities for water storage in dry years. Given projections for agriculture, more modeling is needed on feedbacks between agricultural expansion on rangelands and water supply.

California↗

USGS2022

Factors affecting spatiotemporal variation in survival of endangered winter-run Chinook Salmon outmigrating from the Sacramento River

Among four extant and declining Chinook salmon ( Oncorhynchus tshawytscha) runs in California’s Central Valley, none have declined as precipitously as Sacramento River winter-run Chinook Salmon. In addition to habitat loss, migratory winter-run employ a life history strategy to reside and feed in stopover habitats on their way from freshwaters to the ocean. This life history strategy is widely considered to be a key factor in the continued decline of winter-run. Using acoustic telemetry, we examined conditions that influenced reach-specific movement and survival of outmigrating juveniles during a prolonged, multi-year drought from 2013-2016, followed by one of the wettest years on record in 2017. We modeled how time-varying individual riverine covariates and reach-specific habitat features influenced smolt survival. Model selection favored a model with mean annual flow, intra-annual deviations from the mean flow at the reach scale, reach-specific channel characteristics, and travel time. Mean annual flow had the strongest positive effect on survival. A negative interaction between mean annual flow and intra-annual reach flow indicated that within-year deviations at the reach scale from annual mean flow had larger effects on survival in low flow years. These factors resulted in higher survival in years with pulse flows or high flows. Changes in movement behavior in response to small scale changes in velocity were negatively associated with survival. Covariates of revetment and wooded bank habitat were positively associated with survival but the effect of these fixed habitat features changed depending on whether they were situated in the upper or lower part of the river. Fish exhibited density dependent stopover behavior, with slowed downstream migration in the upper river in the wet years and extending to the lower river in the most critically dry year. This paper contributes two key findings for natural resource managers interested in flow management and targeted habitat restoration. The first is new insight to how the magnitude of pulse flows in dry and wet years affect survival of winter-run. The second is that density dependence influences where stopover habitat is used. Despite this, we identified an area of the river where fish consistently exhibited stopover behavior in all years.

California↗

USGS2024

An integrated analysis for estimation of survival, growth, and movement of unmarked juvenile anadromous fish

Managers invest substantial resources to promote recovery of declining anadromous fish stocks. Recovery strategies are manifold and often include management actions intended to stimulate somatic growth, increase in-river survival, and motivate juvenile outmigration during favorable environmental conditions. Evaluating the efficacy of these management actions is difficult, however, because monitoring data that explicitly track individuals from egg deposition to juvenile outmigration are typically lacking. We developed an integrated population model that links two different and often collected types of anadromous fish monitoring data: spawning ground surveys and rotary screw trap juvenile catch data. The integrated model accounts for incomplete detection and uses the two sources of data to estimate juvenile demographic parameters in a multistate framework. We evaluated the model's performance using simulated data under a range of conditions typically encountered in similar surveys. Simulation results indicated that the model estimated juvenile survival, growth, and movement with no-to-minimal bias (i.e., ≥ 50 % of simulations ± 0–0.05). As an example case study, we fit the model to empirical fall-run Chinook Salmon ( Oncorhynchus tshawytscha ) monitoring data collected in California's Central Valley, U.S.A. In doing so, we evaluated the influence of environmental conditions (e.g., discharge, water temperature) and habitat availability on juvenile demographic rates. We demonstrated that through our integrated approach we could estimate state transition probabilities that are typically inestimable for naturally produced, unmarked juvenile fish when using traditional statistical approaches to analyze these types of monitoring data. Furthermore, the structure of our model can serve as a useful foundation for decision-support models within adaptive management programs by directly linking management actions, decision-support-model predictions, and monitoring.

California↗

USGS2003

True metabolizable energy for wood ducks from acorns compared to other waterfowl foods

Acorns of bottomland red oaks (Quercus spp.) are an important food of North American wood ducks (Aix sponsa). Barras et al. (1996) demonstrated that female wood ducks selected willow oak (Q. phellos) acorns over other species. We measured true metabolizable energy (TME) derived by captive, wild-strain, adult female wood ducks from acorns of willow oak, water oak (Q. nigra), cherrybark oak (Q. pagoda), and pin oak (Q. palustris) to determine whether female wood ducks ' preference for willow oak acorns was related to TME. Estimates of TME within acorn species were relatively precise, yet we did not detect variation in TME among acorn species (P=0.31); hence, we estimated TME across species (2.76±0.033 [SE] kcal/g dry mass; n=34). We concluded that TME apparently did not explain female wood ducks ' preference for willow oak acorns and hypothesized that morphological characteristics of willow oak acorns may be proximate cues related to selection by wood ducks . We also summarized known TME estimates for acorns fed to wood ducks and mallards (Anas platyrhynchos), and natural and agricultural foods fed to mallards, northern pintails (A. acuta), blue-winged teal (A. discors), and Canada geese (Branta canadensis). We found that acorns and moist-soil plant seeds and tubers provided, on average, about 76% of the TME in agricultural seeds. Thus, bottomland-hardwood and moist-soil habitats have potential to provide significant amounts of dietary energy , as well as greater diversity of foods and nutrients than croplands. Researchers should continue to determine TME of common foods (plant and animal) of waterfowl , and use TME in estimating waterfowl habitat carrying capacity (e.g., Reinecke et al. 1989). Additionally, large-scale, reliable estimates of plant and animal food availability in bottomland-hardwood and moist-soil habitats are needed to evaluate carrying capacity of landscapes important to waterfowl , such as the Mississippi Alluvial Valley (MAV).

Journal of Wildlife Management↗

USGS2001

Mourning dove productivity in California during 1992-95: Was it sufficient to balance mortality?

Mourning dove ( Zenaida macroura ) populations have declined steadily in the western United States since 1966. We investigated the role of recruitment in this long-term problem by studying nesting ecology of mourning doves from March to September 1992-95, in the northern Central Valley, California, USA. We studied nesting doves in blue oak woodlands ( Quercus douglasii ), willow-cottonwood riparian habitats ( Salix spp., Populus fremontii ), and commercial walnut, prune, pistachio, and cherry orchards. We used 3,047 nests for our analyses. Doves initiated nests from 14 March to 28 August; nesting season lengths ranged from 105 to 158 days. Only 2-5% of nests remained active after 1 September each year, and latest dates that young fledged ranged from 28 August to 21 September. Mayfield estimates of nest success rates varied inconsistently among study areas; annual success rates ranged from 35-59% for incubation, 49-79% for brooding, and 22-45% for total. Akaike's Information Criteria (AIC) analysis showed that total nest success was higher during years with relatively warm-dry springs (March-May, 1992 and 1994 [35-45% success]) than years with relatively cool-wet springs (1993 and 1995 [22-37% success]). Additionally, AIC analysis showed that fledglings produced/pair and fledglings/nesting attempt were highest during the warm-dry years. Likewise, we recorded more total pairs, nests, and total fledglings, and longer nesting seasons during the warm-dry years. The lower limit of the 95% confidence interval for fledglings produced/pair for all years exceeded the value of 2.5 previously estimated with banding data from 1967-74 as the value required to maintain breeding populations in California. Thus, if our productivity estimates reflected the general population, and annual survival rates had not changed, recruitment should have been adequate to produce an increasing population. Since this was not occurring, managers should complement population surveys with annual banding and harvest surveys to enable thorough examination of the relationships among survival, productivity, and abundance.

California↗

USGS2008

Ecosystem conceptual model- Mercury

Mercury has been identified as an important contaminant in the Delta, based on elevated concentrations of methylmercury (a toxic, organic form that readily bioaccumulates) in fish and wildlife. There are health risks associated with human exposure to methylmercury by consumption of sport fish, particularly top predators such as bass species. Original mercury sources were upstream tributaries where historical mining of mercury in the Coast Ranges and gold in the Sierra Nevada and Klamath-Trinity Mountains caused contamination of water and sediment on a regional scale. Remediation of abandoned mine sites may reduce local sources in these watersheds, but much of the mercury contamination occurs in sediments stored in the riverbeds, floodplains, and the Bay- Delta, where scouring of Gold-Rush-era sediment represents an ongoing source. Conversion of inorganic mercury to toxic methylmercury occurs in anaerobic environments including some wetlands. Wetland restoration managers must be cognizant of potential effects on mercury cycling so that the problem is not exacerbated. Recent research suggests that wettingdrying cycles can contribute to mercury methylation. For example, high marshes (inundated only during the highest tides for several days per month) tend to have higher methylmercury concentrations in water, sediment, and biota compared with low marshes, which do not dry out completely during the tidal cycle. Seasonally inundated flood plains are another environment experiencing wetting and drying where methylmercury concentrations are typically elevated. Stream restoration efforts using gravel injection or other reworking of coarse sediment in most watersheds of the Central Valley involve tailings from historical gold mining that are likely to contain elevated mercury in associated fines. Habitat restoration projects, particularly those involving wetlands, may cause increases in methylmercury exposure in the watershed. This possibility should be evaluated. The DRERIP mercury conceptual model and its four submodels (1. Methylation, 2. Bioaccumulation, 3. Human Health Effects, and 4. Wildlife Heath Effects) can be used to understand the general relationships among drivers and outcomes associated with mercury cycling in the Delta. Several linkages between important drivers and outcomes have been identified as important but highly uncertain (i.e. poorly understood). For example, there may be significant wildlife health effect of mercury on mammals and reptiles in the Delta, but there is currently very little or no information about it. The characteristics of such linkages are important when prioritizing and funding restoration projects and associated monitoring in the Delta and its tributaries.

Report↗

USGS2004

Instream flow characterization of upper Salmon River Basin streams, Central Idaho, 2003

Anadromous fish populations in the Columbia River Basin have plummeted in the last 100 years. This severe decline led to Federal listing of chinook salmon ( Oncorhynchus tshawytscha ) and steelhead trout ( Oncorhynchus mykiss ) stocks as endangered or threatened under the Endangered Species Act (ESA) in the 1990s. Historically, the upper Salmon River Basin (upstream from the confluence with the Pahsimeroi River) in Idaho provided migration corridors and significant habitat for these ESA-listed species, in addition to the federally listed bull trout ( Salvelinus confluentus ). Human development has modified the original streamflow conditions in many streams in the upper Salmon River Basin. Summer streamflow modifications, as a result of irrigation practices, have directly affected the quantity and quality of fish habitat and also have affected migration and (or) access to suitable spawning and rearing habitat for these fish. As a result of these ESA listings and Action 149 of the Federal Columbia River Power System Biological Opinion of 2000, the Bureau of Reclamation was tasked to conduct streamflow characterization studies in the upper Salmon River Basin to clearly define habitat requirements for effective species management and habitat restoration. These studies include the collection of habitat and streamflow information for the Physical Habitat Simulation (PHABSIM) model, a widely applied method to determine relations between habitat and discharge requirements for various fish species and life stages. Model results can be used by resource managers to guide habitat restoration efforts in the evaluation of potential fish habitat and passage improvements by increasing streamflow. Instream flow characterization studies were completed on Pole, Fourth of July, Elk, and Valley Creeks during 2003. Continuous streamflow data were collected upstream from all diversions on each stream. In addition, natural summer streamflows were estimated for each study site using regression equations. PHABSIM results are presented for bull trout, chinook salmon, and steelhead trout over a range of summer streamflows. Habitat/discharge relations are summarized for juvenile, adult, and spawning life stages at each study site. Adult fish passage and discharge relations are evaluated at specific transects identified as a potential low-streamflow passage barrier at each study site. Continuous summer water temperature data for selected study sites also are summarized and compared with Idaho Water Quality Standards and various temperature requirements of targeted fish species. Results of these habitat studies can be used to prioritize and direct cost-effective actions to improve fish habitat for ESA-listed anadromous and native fish species in the basin. These actions may include acquiring water during critical low-flow periods by leasing or modifying irrigation delivery systems to minimize out-of-stream diversions.

Idaho↗

USGS2012

Simulation of climate change in San Francisco Bay Basins, California: Case studies in the Russian River Valley and Santa Cruz Mountains

As a result of ongoing changes in climate, hydrologic and ecologic effects are being seen across the western United States. A regional study of how climate change affects water resources and habitats in the San Francisco Bay area relied on historical climate data and future projections of climate, which were downscaled to fine spatial scales for application to a regional water-balance model. Changes in climate, potential evapotranspiration, recharge, runoff, and climatic water deficit were modeled for the Bay Area. In addition, detailed studies in the Russian River Valley and Santa Cruz Mountains, which are on the northern and southern extremes of the Bay Area, respectively, were carried out in collaboration with local water agencies. Resource managers depend on science-based projections to inform planning exercises that result in competent adaptation to ongoing and future changes in water supply and environmental conditions. Results indicated large spatial variability in climate change and the hydrologic response across the region; although there is warming under all projections, potential change in precipitation by the end of the 21st century differed according to model. Hydrologic models predicted reduced early and late wet season runoff for the end of the century for both wetter and drier future climate projections, which could result in an extended dry season. In fact, summers are projected to be longer and drier in the future than in the past regardless of precipitation trends. While water supply could be subject to increased variability (that is, reduced reliability) due to greater variability in precipitation, water demand is likely to steadily increase because of increased evapotranspiration rates and climatic water deficit during the extended summers. Extended dry season conditions and the potential for drought, combined with unprecedented increases in precipitation, could serve as additional stressors on water quality and habitat. By focusing on the relationship between soil moisture storage and evapotranspiration pressures, climatic water deficit integrates the effects of increasing temperature and varying precipitation on basin conditions. At the fine-scale used for these analyses, this variable is an effective indicator of the areas in the landscape that are the most resilient or vulnerable to projected changes. These analyses have shown that regardless of the direction of precipitation change, climatic water deficit is projected to increase, which implies greater water demand to maintain current agricultural resources or land cover. Fine-scale modeling provides a spatially distributed view of locations in the landscape that could prove to be resilient to climatic changes in contrast to locations where vegetation is currently living on the edge of its present-day bioclimatic distribution and, therefore, is more likely to perish or shift to other dominant species under future warming. This type of modeling and the associated analyses provide a useful means for greater understanding of water and land resources, which can lead to better resource management and planning.

California↗

USGS2016

Forest structure of oak plantations after silvicultural treatment to enhance habitat for wildlife

During the past 30 years, thousands of hectares of oak-dominated bottomland hardwood plantations have been planted on agricultural fields in the Mississippi Alluvial Valley. Many of these plantations now have closed canopies and sparse understories. Silvicultural treatments could create a more heterogeneous forest structure, with canopy gaps and increased understory vegetation for wildlife. Lack of volume sufficient for commercial harvest in hardwood plantations has impeded treatments, but demand for woody biomass for energy production may provide a viable means to introduce disturbance beneficial for wildlife. We assessed forest structure in response to prescribed pre-commercial perturbations in hardwood plantations resulting from silvicultural treatments: 1) row thinning by felling every fourth planted row; 2) multiple patch cuts with canopy gaps of <1 0.25 – 2 ha; and 3) tree removal on intersecting corridors diagonal to planted rows. These 3 treatments, and an untreated control, were applied to oak plantations (20 - 30 years post-planting) on three National Wildlife Refuges (Cache River, AR; Grand Cote, LA; and Yazoo, MS) during summer 2010. We sampled habitat using fixed-radius plots in 2009 (pre-treatment) and in 2012 (post-treatment) at random locations. Retained basal area was least in diagonal corridor treatments but had greater variance in patch-cut treatments. All treatments increased canopy openness and the volume of coarse woody debris. Occurrence of birds using early successional habitats was greater on sites treated with patch cuts and diagonal intersections. Canopy openings on row-thinned stands are being filled by lateral crown growth of retained trees whereas patch cut and diagonal intersection gaps appear likely to be filled by regenerating saplings.

Conference Paper↗

USGS2014

The historical distribution of Gunnison Sage-Grouse in Colorado

The historical distribution of Gunnison Sage-Grouse ( Centrocercus minimus ) in Colorado is described based on published literature, observations, museum specimens, and the known distribution of sagebrush ( Artemisia spp.). Historically, Gunnison Sage-Grouse were widely but patchily distributed in up to 22 counties in south-central and southwestern Colorado. The historical distribution of this species was south of the Colorado-Eagle river drainages primarily west of the Continental Divide. Potential contact areas with Greater Sage-Grouse ( C. urophasianus ) were along the Colorado-Eagle river system in Mesa, Garfield, and Eagle counties, west of the Continental Divide. Gunnison Sage-Grouse historically occupied habitats that were naturally highly fragmented by forested mountains and plateaus/mesas, intermountain basins without robust species of sagebrush, and river systems. This species adapted to use areas with more deciduous shrubs (i.e., Quercus spp., Amelanchier spp., Prunus spp.) in conjunction with sagebrush. Most areas historically occupied were small, linear, and patchily distributed within the overall landscape matrix. The exception was the large intermountain basin in Gunnison, Hinsdale, and Saguache counties. The documented distribution east of the Continental Divide within the large expanse of the San Luis Valley (Alamosa, Conejos, Costilla, and Rio Grande counties) was minimal and mostly on the eastern, northern, and southern fringes. Many formerly occupied habitat patches were vacant by the mid 1940s with extirpations continuing to the late 1990s. Counties from which populations were recently extirpated include Archuleta and Pitkin (1960s), and Eagle, Garfield, Montezuma, and Ouray (1990s).

Colorado↗

USGS2004

Potential exposure of larval and juvenile delta smelt to dissolved pesticides in the Sacramento-San Joaquin Delta, California

The San Francisco Estuary is critical habitat for delta smelt Hypomesus transpacificus, a fish whose abundance has declined greatly since 1983 and is now listed as threatened. In addition, the estuary receives drainage from the Central Valley, an urban and agricultural region with intense and diverse pesticide usage. One possible factor of the delta smelt population decline is pesticide toxicity during vulnerable larval and juvenile stages, but pesticide concentrations are not well characterized in delta smelt spawning and nursery habitat. The objective of this study was to estimate the potential exposure of delta smelt during their early life stages to dissolved pesticides. For 3 years (1998-2000), water samples from the Sacramento-San Joaquin Delta were collected during April-June in coordination with the California Department of Fish and Game's delta smelt early life stage monitoring program. Samples were analyzed for pesticides using solid-phase extraction and gas chromatography/mass spectrometry. Water samples contained multiple pesticides, ranging from 2 to 14 pesticides in each sample. In both 1999 and 2000, elevated concentrations of pesticides overlapped in time and space with peak densities of larval and juvenile delta smelt. In contrast, high spring outflows in 1998 transported delta smelt away from the pesticide sampling sites so that exposure could not be estimated. During 2 years, larval and juvenile delta smelt were potentially exposed to a complex mixture of pesticides for a minimum of 2-3 weeks. Although the measured concentrations were well below short-term (96-h) LC50 values for individual pesticides, the combination of multiple pesticides and lengthy exposure duration could potentially have lethal or sublethal effects on delta smelt, especially during early larval development.

American Fisheries Society Symposium↗

USGS2015

Waterbird use of catfish ponds and migratory bird habitat initiative wetlands in Mississippi

Aquaculture can provide important surrogate habitats for waterbirds. In response to the 2010 Deepwater Horizon oil spill, the National Resource Conservation Service enacted the Migratory Bird Habitat Initiative through which incentivized landowners provided wetland habitats for migrating waterbirds. Diversity and abundance of waterbirds in six production and four idled aquaculture facilities in the Mississippi Alluvial Valley were estimated during the winters of 2011–2013. Wintering waterbirds exhibited similar densities on production (i.e., &sim;22 birds/ha) and idled (i.e., &sim;20 birds/ha) sites. A total of 42 species were found using both types of aquaculture wetlands combined, but there was considerable departure in bird guilds occupying the two wetland types. The primary users of production ponds were diving and dabbling ducks and American coots. However, idled ponds, with varying water depths (e.g., mudflats to 20 cm) and diverse emergent vegetation-water interspersion, attracted over 30 species of waterbirds and, on average, had more species of waterbirds from fall through early spring than catfish production ponds. Conservation through the Migratory Bird Habitat Initiative was likely responsible for this difference. Our results suggest production and idled Migratory Bird Habitat Initiative aquaculture impoundments produced suitable conditions for various waterbird species and highlight the importance of conservation programs on private lands that promote diversity in vegetation structure and water depths to enhance waterbird diversity.

Mississippi↗

USGS2020

Co-occurence of Chiricahua leopard frogs (Lithobates chiricahuensis) with sunfish (Lepomis)

Invasive species are a major threat to the persistence of native species, particularly in systems where ephemeral aquatic habitats have been replaced by permanent water and predators, such as fish, have been introduced. Within the Altar Valley, Arizona, the invasive American bullfrog, Lithobates catesbeianus (formerly Rana catesbeianus ), has been successfully eradicated to help recover Chiricahua leopard frogs ( Lithobates chiricahuensis ). However, other nonnative predators including sunfish ( Lepomis ) are present in some permanent water bodies. During four consecutive years (2014–2017), we detected both the federally threatened Chiricahua leopard frog and sunfish at one permanent water body in the Altar Valley. This suggests that despite the potential negative effect of predatory fish on amphibians, there may be conditions where the Chiricahua leopard frog can co-occur with this nonnative predator. A better understanding of rare situations of co-occurrence with nonnative predators may contribute to our understanding of why co-occurrence happens in some, but not all, systems and whether conservation strategies can be developed in situations where eradication of nonnative predators is infeasible.

Arizona↗

USGS1996

Water Quality in a Wet Meadow, Platte River Valley, Central Nebraska

The Platte River Valley in Nebraska, and in particular the reach from Kearney to Grand Island, is an extremely important natural habitat area. Over 300 migratory bird species, including several threatened and endangered species, have been observed along the Platte River. In the spring, nearly 500,000 sandhill cranes, along with millions of ducks and geese, use this reach as a staging and feeding area during their northerly migration. Wet meadows (grasslands which have waterlogged soils much of the year) are a critical part of this migratory-bird habitat. However, the area of wet meadows between Kearney and Grand Island has declined nearly 50 percent due to the activities of man. The condition of the remaining wet meadows is of vital importance. The U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program is designed to describe the status and trends in the quality of the Nation's surface water and groundwater resources and to provide a sound understanding of the natural and human factors that affect the quality of these resources. A study of the groundwater beneath a selected wet meadow was undertaken as part of the Central Nebraska Basins NAWQA study unit. Observation wells were installed in the wet meadow at various distances along two transects downgradient from the edge of a corn field. One to five wells completed at depths of about 15 to 100 feet were located at each of the 5 sites. The wells were completed in the Platte River alluvium or the underlying Ogallala Formation. The depth to the water table ranges from 0 to 5 feet below land surface. The general direction of groundwater flow is parallel to flow in the Platte River. Selected wells were sampled in February, March, June, and December 1994 for major cations and anions, nutrients, and organonitrogen herbicides. Pesticides and fertilizers are used extensively in Nebraska to enhance the production of row crops. Some of these pesticides and fertilizers have migrated into the groundwater. Atrazine was detected in water from all of the wells sampled in February and June and most of the wells sampled at other times, but only in concentrations of 0.1 to 0.6 micrograms per liter. Concentrations of the other pesticides analyzed, including alachlor, cyanazine, and metolachlor, were at or below the detection limit of 0.05 micrograms per liter. The highest concentrations of nitrate were found in water from the shallow wells (about 15 feet deep). The concentrations of nitrate as nitrogen in water from these wells ranged from 5 to 13 milligrams per liter in June. Concentrations of major cations and anions decreased and their ratios varied with depth. The major cations were calcium and sodium, and the major anions were sulfate and bicarbonate. Water from the shallowest wells was a mixed calcium sodium sulfate type, whereas the deepest alluvial-aquifer water was a calcium sulfate type. The water from the Ogallala Formation was a calcium bicarbonate type. The variability of the groundwater quality reflects seasonal changes in recharge to and evaporation from the alluvial aquifer and rates of movement and mixing within and between the aquifers.

Fact Sheet↗

USGS2007

Longitudinal patterns of fish assemblages, aquatic habitat, and water temperature in the Lower Crooked River, Oregon

The Lower Crooked River is a remarkable groundwater-fed stream flowing through vertical basalt canyons in the Deschutes River Valley ecoregion in central Oregon (Pater and others, 1998). The 9-mile section of the river between the Crooked River National Grasslands boundary near Ogden Wayside and river mile (RM) 8 is protected under the National Wild and Scenic Rivers Act (16 U.S.C. 1271-1287) for its outstandingly remarkable scenic, recreational, geologic, hydrologic, wildlife, and botanical values (ORVs), and significant fishery and cultural values. Groundwater springs flow directly out of the canyon walls into the Lower Crooked River and create a unique hydrologic setting for native coldwater fish, such as inland Columbia Basin redband trout (Oncorhynchus mykiss gairdneri). To protect and enhance the ORVs that are the basis for the wild and scenic designation, the Bureau of Land Management (BLM) has identified the need to evaluate, among other conditions, fish presence and habitat use of the Lower Crooked River. The results of this and other studies will provide a scientific basis for communication and cooperation between the BLM, Oregon Water Resources Department, Oregon Department of Fish and Wildlife (ODFW) and all water users within the basin. These biological studies initiated by the BLM in the region reflect a growing national awareness of the impacts of agricultural and municipal water use on the integrity of freshwater ecosystems. Biological surveys are needed to better understand the aquatic ecosystem of the Lower Crooked River. This baseline information will be valuable to public land managers whose task is to balance resource use while protecting the unique attributes (that is, ORVs) of the Lower Crooked River. The habitat requirements of coldwater fishes in this section of stream are of particular interest due to state and federal regulation of water temperature in order to protect and restore fish populations. Historical data on the distribution and abundance of stream fishes in the Lower Crooked River are limited to point observations by fishermen and local biologists because steep canyon walls have limited access to most of the river. Surveys of aquatic habitat (channel morphology and substrate composition) have been conducted for the BLM by the ODFW (Oregon Department of Fish and Wildlife, 1997), U.S. Forest Service (United States Forest Service, 2003), and the U.S. Fish and Wildlife Service (USFWS), but fish surveys using electrofishing gear have never been conducted in the isolated 11-mile section of the Crooked River Gorge, and visual observations with mask and snorkel have only been made at isolated point locations where hiking trails provide access to the river (K. Jones, Steve Marx, and Brett Hodgson, ODFW; P. Lickwar, USFWS; pers. comm.). Thus, there is a poor understanding of stream fish presence and distribution throughout Lower Crooked River. Information on fish assemblages is available for the Deschutes River basin and applies generally to the Lower Crooked River because the two rivers were connected historically (Zimmerman and Ratliff 2003). The construction of dams throughout the Deschutes River basin has eliminated historic runs of salmon and steelhead and prevented migration of bull trout and Pacific lamprey into the Crooked River system. Native fish species expected to occur in the Lower Crooked River include Columbia Basin redband trout ( Oncorhynchus mykiss gairdneri ), mountain whitefish ( Prosopium williamsoni ), sculpin ( Cottus spp.), two species of dace ( Rhinichthys spp.), two species of sucker ( Catostomus spp.), northern pikeminnow ( Ptychocheilus oregonensis ), chiselmouth ( Acrocheilus alutaceus ), and redside shiner ( Richardsonius balteatus ). Threespine stickleback ( Gasterosteus aculeatus ), a species native to western Oregon, also occurs in the basin but is believed to be introduced (D. Markle, Department of Fisheries and Wildlife, Oregon State University, personnel commun.). Extensive stocking of rainbow trout has contributed to a large population of naturalized fish of hatchery origin in the Lower Crooked River. Due to the difficulty of differentiating between wild redband trout and naturalized rainbow trout of hatchery origin, the general classification of rainbow trout ( Oncorhynchus mykiss ) is used throughout this report to describe the fish that were observed in the Lower Crooked River. Exotic fish species expected to occur in the Lower Crooked River include large- and smallmouth bass ( Micropterus spp.), yellow perch ( Perca flavescens ), and brown bullhead (Ameiurus nebulosis) (Zimmerman and Ratliff 2003). The goal of this project was to examine longitudinal patterns in fish assemblages, aquatic habitat, and water temperature in the Lower Crooked River during summer conditions. Specific objectives were to (1) characterize the spatial distribution of native and non-native fishes, (2) describe variation in channel morphology, substrate composition, and water temperature, and (3) evaluate the associations between fishes, aquatic habitat, and water temperature.

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