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At least 631 records · Page 35Linked to original sources

USGS2023

Changes in chemical occurrence, concentration, and bioactivity in the Colorado River before and after replacement of the Moab, Utah wastewater treatment plant

Long-term (2010–19) water-quality monitoring on the Colorado River downstream from Moab Utah indicated the persistent presence of Bioactive Chemicals (BC), such as pesticides and pharmaceuticals. This stream reach near Canyonlands National Park provides critical habitat for federally endangered species. The Moab wastewater treatment plant (WWTP) outfall discharges to the Colorado River and is the nearest potential point-source to this reach. The original WWTP was replaced in 2018. In 2016–19, a study was completed to determine if the new plant reduced BC input to the Colorado River at, and downstream from, the outfall. Water samples were collected before and after the plant replacement at sites upstream and downstream from the outfall. Samples were analyzed for as many as 243 pesticides, 109 pharmaceuticals, 20 hormones, 51 wastewater indicator chemicals, 20 metals, and 8 nutrients. BC concentrations, hazard quotients (HQs), and exposure activity ratios (EARs) were used to identify and prioritize contaminants for their potential to have adverse biological effects on the health of native and endangered wildlife. There were 22 BC with HQs >1, mostly metals and hormones; and 23 BC with EARs >0.1, mostly hormones and pharmaceuticals. Most high HQs or EARs were associated with samples collected at the WWTP outfall site prior to its replacement. Discharge from the new plant had reduced concentrations of nutrients, hormones, pharmaceuticals, and other BC. For example, all 16 of the hormones detected at the WWTP outfall site had maximum concentrations in samples collected prior to the WWTP replacement. The WWTP replacement had less effect on instream concentrations of metals and pesticides, BC whose sources are less directly tied to domestic wastewater. Study results indicate that improved WWTP technology can create substantial reductions in concentrations of non-regulated BC such as pharmaceuticals, in addition to regulated contaminants such as nutrients.

Utah↗

USGS2007

Comparison of ion-exchange resin counterions in the nutrient measurement of calcareous soils: Implications for correlative studies of plant-soil relationships

For more than 40 years, ion-exchange resins have been used to characterize nutrient bioavailability in terrestrial and aquatic ecosystems. To date, however, no standardized methodology has been developed, particularly with respect to the counterions that initially occupy resin exchange sites. To determine whether different resin counterions yield different measures of soil nutrients and rank soils differently with respect to their measured nutrient bioavailability, we compared nutrient measurements by three common counterion combinations (HCl, HOH, and NaHCO 3 ). Five sandy calcareous soils were chosen to represent a range of soil characteristics at Canyonlands National Park, Utah, and resin capsules charged with the different counterions equilibrated in saturated pastes of these soils for one week. Data were converted to proportions of total ions of corresponding charge for ANOVA. Results from the different methods were not comparable with respect to any nutrient. Of eleven nutrients measured, all but iron (Fe 2+ ), manganese (Mn 2+ ), and zinc (Zn 2+ ) differed significantly ( p ≤0.05) as a function of soil×counterion interactions; Fe 2+ and Zn 2+ varied as functions of counterion alone. Of the counterion combinations, HCl-resins yielded the most net ion exchange with all measured nutrients except Na + , and the three of which desorbed in the greatest quantities from HOH-resins. Conventional chemical extractions using ammonium acetate generally yielded high proportional values of Ca 2+ , K + , and Na + . Further, among-soil rankings of nutrient bioavailability varied widely among methods. This study highlights the fact that various ion-exchange resin techniques for measuring soil nutrients may have differential effects on the soil-resin environment and yield data that should not be compared nor considered interchangeable. The most appropriate methods for characterizing soil-nutrient bioavailability depends on soil characteristics and likely on the physiological uptake mechanisms of plants or functional groups of interest. The effects of different extraction techniques on nutrient measures should be understood before selecting an extraction method. For example, in the calcareous soils used for this experiment, nutrient extraction methods that alter soil carbonates through dissolution or precipitation could compromise the accurate measurement of plant-available nutrients. The implications of this study emphasize the universal importance of understanding the differential effects of alternate methods on soil chemistry.

Communications in Soil Science and Plant Analysis↗

USGS2005

Macropolygon morphology, development, and classification on North Panamint and Eureka playas, Death Valley National Park CA

Panamint and Eureka playas, both located within Death Valley National Park, exhibit a host of surficial features including fissures, pits, mounds, and plant-covered ridges, representing topographic highs and lows that vary up to 2 m of relief from the playa surface. Aerial photographs reveal that these linear strands often converge to form polygons, ranging in length from several meters to nearly a kilometer. These features stand out in generally dark contrast to the brighter intervening expanse of flat, plant-free, desiccated mud of the typical playa surface. Ground-truth mapping of playa features with differential GPS (Global Positioning System) was conducted in 1999 (North Panamint Valley) and 2002 (Eureka Valley). High-resolution digital maps reveal that both playas possess macropolygons of similar scale and geometry, and that fissures may be categorized into one of two genetic groups: (1) shore-parallel or playa-interior desiccation and shrinkage; and (2) tectonic-induced cracks. Early investigations of these features in Eureka Valley concluded that their origin may have been related to agricultural activity by paleo-Indian communities. Although human artifacts are abundant at each locale, there is no evidence to support the inference that surface features reported on Eureka Playa are anthropogenic in origin. Our assumptions into the genesis of polygons on playas is based on our fortuitous experience of witnessing a fissure in the process of formation on Panamint Playa after a flash flood (May 1999); our observations revealed a paradox that saturation of the upper playa crusts contributes to the establishment of some desiccation features. Follow-up visits to the same feature over 2 yrs' time are a foundation for insight into the evolution and possible longevity of these features. ?? 2005 Elsevier B.V. All rights reserved.

Earth-Science Reviews↗

USGS2014

Behavior of feral horses in response to culling and GnRH immunocontraception

Wildlife management actions can alter fundamental behaviors of individuals and groups,which may directly impact their life history parameters in unforeseen ways. This is especially true for highly social animals because changes in one individual’s behavior can cascade throughout its social network. When resources to support populations of social animals are limited and populations become locally overabundant, managers are faced with the daunting challenge of decreasing population size without disrupting core behavioral processes. Increasingly, managers are turning to fertility control technologies to supplement culling in efforts to suppress population growth, but little is quantitatively known about how either of these management tools affects behavior. Gonadotropin releasing hormone (GnRH) is a small neuropeptide that performs an obligatory role in mammalian reproduction and has been formulated into the immunocontraceptive GonaCon-BTM. We investigated the influences of this vaccine on behavior of feral horses ( Equus caballus ) at Theodore Roosevelt National Park, North Dakota, USA, for a year preceding and a year following nonlethal culling and GnRH-vaccine treatment. We observed horses during the breeding season and found only minimal differences in time budget behaviors of free-ranging female feral horses treated with GnRH and those treated with saline. The differences observed were consistent with the metabolic demands of pregnancy and lactation. We observed similar social behaviors between treatment groups, reflecting limited reproductive behavior among control females due to high rates of pregnancy and suppressed reproductive behavior among treated females due to GnRH-inhibited ovarian activity. In the treatment year, band stallion age was the only supported factor influencing herding behavior (P < 0.001), harem-tending behavior (P < 0.001), and agonistic behavior (P = 0.02). There was no difference between the mean body condition of control females (4.9 (95% CI = 4.7–5.1)) and treated females(4.8 (95% CI = 4.7–4.9)). Band fidelity among all females increased 25.7% in the year fol-lowing vaccination and culling, despite the social perturbation associated with removal of conspecifics. Herding behavior by stallions decreased 50.7% following treatment and culling (P < 0.001), while harem-tending behavior increased 195.0% (P < 0.001). The amount of available forage influenced harem-tending, reproductive, and agonistic behavior in the year following culling and treatment (P < 0.04). These changes reflected the expected nexus between a species with polygynous social structure and strong group fidelity and the large instantaneous change in population density and demography coincident with culling.Behavioral responses to such perturbation may be synergistic in reducing grazing pressure by decreasing energetically expensive competitive behaviors, but further investigation is needed to explicitly test this hypothesis.

Applied Animal Behaviour Science↗

USGS2025

Unlocking ecological insights from sub-seasonal visible-to-shortwave infrared imaging spectroscopy: The SHIFT campaign

We stand at the threshold of a transformative era in Earth observation, marked by space-borne visible-to-shortwave infrared (VSWIR) imaging spectrometers that promise consistent global observations of ecosystem function, phenology, and inter- and intra-annual change. However, the full value of repeat spectroscopy, the information embedded within different temporal scales, and the reliability of existing algorithms across diverse ecosystem types and vegetation phenophases have remained elusive due to the absence of suitable sub-seasonal spectroscopy data. In response, the Surface Biology and Geology (SBG) High-Frequency Time Series (SHIFT) campaign was initiated during late February 2022 in Santa Barbara County, California. SHIFT, designed to support NASA's SBG mission, addressed mission scoping, scientific advancement, applications development, and community building. This ambitious endeavor included weekly Airborne Visible InfraRed Imaging Spectrometer-Next Generation (AVIRIS-NG) imagery acquisitions for 13 weeks (spanning February 24 to May 29, 2022), accompanied by coordinated terrestrial vegetation and coastal aquatic data collection. We describe the rich datasets collected and illustrate how the complex sub-seasonal patterns of change can be linked to biological science and applications, surpassing insights from multispectral observations. Leveraging open-source processing methods and cloud-based analysis tools, the SHIFT campaign showcases the readiness of the scientific community to harness ecological insights from remotely sensed hyperspectral time series. We provide an overview of SHIFT's goals, data collections, preliminary results, and the collaborative efforts of early career scientists committed to unlocking the transformative potential of high-frequency time series data from space-borne VSWIR imaging spectrometers.

Ecosphere↗

USGS2021

Stable isotopes used to infer trophic position of green turtles (Chelonia mydas) from Dry Tortugas National Park, Gulf of Mexico, United States

Evaluating resource use patterns for imperiled species is critical for understanding what supports their populations. Here we established stable isotope ( δ 13 "> δ13 C, δ 15 "> δ15 N) values for the endangered green sea turtle ( Chelonia mydas ) population found within the boundaries of Dry Tortugas National Park (DRTO), south Florida, USA. There is little gene flow between turtles sampled at DRTO and in other rookeries in Florida, underscoring the need to study this distinct population. Between 2008 and 2015 we collected multiple sample types (skin [homogenized epidermis/dermis], whole blood, red blood cells, plasma, carapace) from 151 unique green turtles, including 43 nesting females and 108 in-water captures; some individuals were resampled multiple times across years to evaluate consistency of isotope signatures. Isotopic ratios ranged from -27.3 to -5.4 for δ 13 "> δ 13 C and 3.7 to 10.6 for δ 15 "> δ 15 N. Using linear mixed models, we evaluated covariates (sample type, turtle size and year) that best explained the isotope patterns observed in turtle tissues. Predictions from the top model for δ 13 "> δ 13 C indicated a slight decrease over time and for δ 15 "> δ 15 N a slight increase in the middle sampling years (2010–2012); results indicated that turtle size appeared to be the driver behind the range in δ 13 "> δ 13 C and δ 15 "> δ 15 N observed in turtle skin. We found a pattern in stable carbon isotope values that are indicative of an ontogenetic change from an omnivorous diet in smaller turtles to a seagrass-based diet in larger turtles. When we compared the stable carbon and nitrogen isotope values of the samples collected from turtles with that of seagrasses found in DRTO, we found that turtles > 65 cm SCL had similar stable carbon isotope values to the seagrass species present. Results of this study suggest stable isotope analysis coupled with data for available resources can be useful for tracking and detecting future changes in green turtle resource shifts in DRTO.

Florida↗

USGS2022

Bedrock depth influences spatial patterns of summer baseflow, temperature and flow disconnection for mountainous headwater streams

In mountain headwater streams, the quality and resilience of summer cold-water habitat is generally regulated by stream discharge, longitudinal stream channel connectivity and groundwater exchange. These critical hydrologic processes are thought to be influenced by the stream corridor bedrock contact depth (sediment thickness), a parameter often inferred from sparse hillslope borehole information, piezometer refusal and remotely sensed data. To investigate how local bedrock depth might control summer stream temperature and channel disconnection (dewatering) patterns, we measured stream corridor bedrock depth by collecting and interpreting 191 passive seismic datasets along eight headwater streams in Shenandoah National Park (Virginia, USA). In addition, we used multi-year stream temperature and streamflow records to calculate several baseflow-related metrics along and among the study streams. Finally, comprehensive visual surveys of stream channel dewatering were conducted in 2016, 2019 and 2021 during summer low flow conditions (124 total km of stream length). We found that measured bedrock depths along the study streams were not well-characterized by soils maps or an existing global-scale geologic dataset where the latter overpredicted measured depths by 12.2 m (mean) or approximately four times the average bedrock depth of 2.9 m. Half of the eight study stream corridors had an average bedrock depth of less than 2 m. Of the eight study streams, Staunton River had the deepest average bedrock depth (3.4 m), the coldest summer temperature profiles and substantially higher summer baseflow indices compared to the other study steams. Staunton River also exhibited paired air and water annual temperature signals suggesting deeper groundwater influence, and the stream channel did not dewater in lower sections during any baseflow survey. In contrast, Paine Run and Piney River did show pronounced, patchy channel dewatering, with Paine Run having dozens of discrete dry channel sections ranging from 1 to greater than 300 m in length. Stream dewatering patterns were apparently influenced by a combination of discrete deep bedrock (20+ m) features and more subtle sediment thickness variation (1–4 m) depending on local stream valley hydrogeology. In combination, these unique datasets show the first large-scale empirical support for existing conceptual models of headwater stream disconnection based on spatially variable underflow capacity and shallow groundwater supply.

Virginia↗

USGS2014

Coastal tectonics on the eastern margin of the Pacific Rim: Late Quaternary sea-level history and uplift rates, Channel Islands National Park, California, USA

The Pacific Rim is a region where tectonic processes play a significant role in coastal landscape evolution. Coastal California, on the eastern margin of the Pacific Rm, is very active tectonically and geomorphic expressions of this include uplifted marine terraces. There have been, however, conflicting estimates of the rate of late Quaternary uplift of marine terraces in coastal California, particularly for the orthern Channel Islands. In the present study, the terraces on San Miguel Island and Santa Rosa Island were mapped and new age estimates were generated using uranium-series dating of fossil corals and amino acid geochronology of fossil mollusks. Results indicate that the 2nd terrace on both islands is ~120 ka and the 1st terrace on Santa Rosa Island is ~80 ka. These ages correspond to two global high-sea stands of the Last Interglacial complex, marine isotope stages (MIS) 5.5 and 51, respectively. The age estimates indicate that San Miguel Island and Santa Rosa Island have been tectonically uplifted at rates of 0.12e0.20 m/ka in the late Quaternary, similar to uplift rates inferred from previous studies on neighboring San Cruz Island. The newly estimated uplift rates for the northern Channel Islands are, however, an order of magnitude lower than a recent study that generated uplift rates from an offshore terrace dating to the Last Glacial period. The differences between the estimated uplift rates in the present study and the offshore study are explained by the magnitude of glacial isostatic adjustment (GIA) effects that were not known at the time of the earlier study. Set in the larger context of northeastern Pacific Rim tectonics, Channel Islands uplift rates are higher than those coastal localities on the margin of the East Pacific Rise spreading center, but slightly lower than those of most localities adjacent to the Cascadia subduction zone. The uplift rates reported here for the northern Channel Islands are similar to those reported for most other localities where strike-slip tectonics are dominant, but lower than localities where restraining bends (such as the Big Bend of the San Andreas Fault) result in crustal shortening.

California↗

USGS2002

Dieback of Acacia koa in Hawaii: Ecological and pathological characteristics of affected stands

Koa (Acacia koa) is an endemic Hawaiian tree that serves as a keystone species in the upper elevation forests of all the main islands. In the Mauna Loa Strip area of Hawaii Volcanoes National Park, mature koa stands are suffering from an unexplained dieback that has increased in severity since it was first noticed approximately 25 years ago. The dieback is often evident in patches, and generally spreads within stands in a radial fashion from a localized infection center. Entire crowns of affected trees become wilted, with foliage gradually progressing from an apparent healthy to a completely chlorotic condition. Although most trees die soon after the onset of symptoms, some trees are able to survive crown death by producing epicormic shoots on the lower portions of the trunk. Previously published studies reported that a vascular wilt fungus (Fusarium oxysporum f. sp. koae) was associated with koa seeds and the rhizosphere of healthy and dieback-affected koa stands. The purpose of this study was to characterize the stand structure, soil conditions, and physiological condition of dieback-affected trees, and to assess the possible role of F. oxysporum f. sp. koae in the current dieback stands. This fungus was isolated from branches of symptomatic koa in dieback-affected stands and roots from healthy and dieback-affected stands. Possible differences in the pathogenicity and virulence of F. oxysporum f. sp. koae isolates obtained from the roots of healthy koa in unaffected stands and those from branches of dieback-affected koa were determined by greenhouse inoculations of koa seedlings. Healthy koa saplings in stands unaffected by dieback were also inoculated to determine if disease symptoms could be induced by inoculation of injured roots in the field. Both branch and root isolates were pathogenic; with the percent mortality of inoculated seedlings ranging from 30 to 60% for all isolates. Disease severity between branch and root isolates was not significantly different. Wilt symptoms were not observed in field inoculations of koa saplings after 8 months. Investigation of the dieback stand structure determined that the larger size classes (i.e., DBH > 3 cm) were all affected equally, with the smallest size class (i.e., 0-3 cm DBH) having the lowest percentage of dieback at each site. Soil from dieback stands had higher water content and was more acidic than that from neighboring unaffected stands. Phyllodes on epicormic shoots of dieback trees had a reduced area, mass, and mass to area ratio. Phyllodes on dieback trees also had reduced stomatal conductance and higher (less negative) leaf water potential. Results from the greenhouse inoculations demonstrated that F. oxysporum f. sp. koae is pathogenic to koa, but the pathogen's activity in the field may be influenced by predisposing factors such as temperature fluctuations, water availability, soil type, and interactions with other soil organisms. F. oxysporum f. sp. koae appears to play an important role in regulating koa stand dynamics, growth, and physiology under environmental and edaphic conditions favorable for disease development. ?? 2002 Elsevier Science B.V. All rights reserved.

Forest Ecology and Management↗

USGS2024

Habitat and dissolved organic carbon modulate variation in the biogeochemical drivers of mercury bioaccumulation in dragonfly larvae at the national scale

We paired mercury (Hg) concentrations in dragonfly larvae with water chemistry in 29 U.S. national parks to highlight how ecological and biogeochemical context (habitat, dissolved organic carbon [DOC]) influence drivers of Hg bioaccumulation. Although prior studies have defined influences of biogeochemical variables on Hg production and bioaccumulation, it has been challenging to determine their influence across diverse habitats, regions, or biogeochemical conditions within a single study. We compared global (i.e., all sites), habitat-specific, and DOC-class models to illuminate how these controls on biotic Hg vary. Although the suite of important biogeochemical factors across all sites (e.g., aqueous Hg, DOC, sulfate [SO42−], and pH) was consistent with general findings in the literature, contrasting the restricted models revealed more nuanced controls on biosentinel Hg. Comparing habitats, aqueous (filtered) total mercury (THg) and SO42− were important in lentic systems whereas aqueous (filtered) methylmercury (MeHg), DOC, pH, and SO42− were important in lotic and wetland systems. The ability to identify important variables varied among habitats, with less certainty in lentic (model weight (W) = 0.05) than lotic (W = 0.11) or wetland habitats (W = 0.23), suggesting that biogeochemical drivers of bioaccumulation are more variable, or obscured by other aspects of Hg cycling, in these habitats. Results revealed a contrast in the importance of aqueous MeHg versus aqueous THg between DOC-classes: in low-DOC sites (<8.5 mg/L), availability of upstream inputs of MeHg appeared more important for bioaccumulation; in high-DOC sites (>8.5 mg/L) THg was more important, suggesting a link to in-situ controls on bioavailability of Hg for MeHg production. Mercury bioaccumulation (indicated by bioaccumulation factor) was more efficient in low DOC-class sites, likely due to reduced partitioning of aqueous MeHg to DOC. Together, findings highlight substantial variation in the drivers of Hg bioaccumulation and suggest consideration of these factors in natural resource management and decision-making.

Science of the Total Environment↗

USGS2026

Unveiling a legacy of fish introductions to mountain lakes using historical records and eDNA surveys in a National Park

Across the western United States, introductions of non-native fish into historically fishless mountain lakes have impacted native biota. Understanding the impacts of fish introductions is essential for conservation in Olympic National Park, a Biosphere Reserve. We reconstructed fish plantings using records dating back to 1930, followed by environmental DNA (eDNA) surveys to estimate the current distribution of fish and amphibians in 117 remote mountain lakes. We used Bayesian multiscale occupancy models to determine how lake attributes and planting history related to fish and amphibian occupancy. The most frequently detected species were Brook Trout, Rainbow Trout, Cascades Frog, and Northwestern Salamander. eDNA sampling revealed 52 lakes with amphibians only, 45 with fish and amphibians, 14 with fish only, and 6 unoccupied. Of the 53 lakes with planting records, 38 had fish eDNA detected. Fish eDNA was also detected in 21 lakes lacking planting records, which could reflect incomplete records, unauthorized plantings, and false positive detections. Of the three species planted, Cutthroat Trout had the highest failure rate and did not become established in 23 of 28 historically planted lakes. In a subset of 9 lakes sampled for up to 7 years, those with known fish and amphibian presence showed consistent eDNA detections over time. The number of times a lake was stocked was the best predictor of occupancy for Brook and Rainbow trout, while higher occupancy for Brook Trout was also associated with lower elevations, lower solar radiation, and larger lake area. We did not observe widespread negative associations between amphibian occupancy and fish presence, although there was a negative relationship between fish presence and Rough-skinned Newt and Long-toed Salamander occupancy. Cascades Frog occupancy showed no relationship to fish presence or lake traits. Our results suggest mechanisms of fish persistence over time and highlight areas where native amphibians are impacted by introduced fish. These results can guide management options like targeted fish removals that benefit native fauna while still supporting recreational fishing. More broadly, our work demonstrates the value of combining historical records with contemporary surveys and the utility of eDNA for broad-scale surveys of species distribution in remote wilderness areas.

Washington↗

USGS2022

Response of nutrient limitation to invasive fish suppression: How carcasses and analog pellets alter periphyton

The native Yellowstone Cutthroat Trout ( Oncorhynchus clarkii bouvieri Jordan and Gilbert, 1883) population in Yellowstone Lake, Yellowstone National Park, Wyoming, USA, is in decline because of competition from the introduced, invasive Lake Trout ( Salvelinus namaycush Walbaum in Artedi, 1792). Gillnetting is used to suppress adult Lake Trout; however, methods are being developed to suppress embryos, including adding Lake Trout carcasses and carcass-analog pellets to spawning sites. Decomposing carcasses and analog pellets cause decreased dissolved oxygen concentrations thereby leading to Lake Trout embryo mortality, but the effects of these methods on primary producers are unknown. We deployed in-situ nutrient diffusing substrates (NDS) at 3 spawning sites. The 1 st site was treated with carcasses, the 2 nd site was treated with analog pellets, and a 3 rd lacked treatment (control). To estimate how suppression measures may alter nutrient limitation, we measured algal biomass in 6 NDS amendments at each site: nothing (control), N, P, N + P, ground carcasses, or pulverized analog pellets. We deployed 5 replicates of each amendment at each site before and after treating whole sites. N and P co-limited periphyton before carcasses or analog pellets were added to spawning sites ( p < 0.01); however, nutrients were not limiting after the treatments were added to spawning sites ( p = 0.31–1). Algal biomass was 4× higher after whole-site carcass treatments. In contrast, analog pellets appeared to suppress algal biomass in the amendments (20% of NDS at the control site post-treatment) and in the treatment plot (33% of pre-treatment biomass at analog pellet site). We also measured how individual ingredients in analog pellets altered periphyton biomass, which suggested that vitamin E, estrogen, and soybean oil ingredients reduced the growth of primary producers. Suppression methods may stimulate or reduce algal biomass, depending on the methods used, which could have cascading effects on food webs and potentially reduce the success of the control measures. Estimating how different Lake Trout suppression methods may alter basal resources in the littoral zone of Yellowstone Lake will help natural resource agencies develop effective plans to control invasive predators at early life stages while minimally altering ecosystems.

Wyoming↗

USGS2026

Population densities and trends of landbirds in the National Park of American Samoa

The National Park of American Samoa (NPSA), which protects some of the most intact tropical rainforest in the South Pacific, is exposed to recurring, intense tropical cyclones, including Tropical Cyclone Gita in 2018. In combination with other anthropogenic pressures, cyclones represent a potential source of disturbance to landbird populations, particularly native frugivorous and seed-dispersing species. Long-term monitoring provides a means to evaluate population trajectories following disturbance events and to identify potential management gaps. Landbird surveys were conducted in the Tutuila and Taʻū units of NPSA in 2011, 2018, and 2023 using point-transect distance sampling, with vegetation composition and structure quantified at each sampling station. Species-specific detection functions were fitted to count data to estimate densities by unit, with variance estimated using bootstrap procedures. Comparisons of 2018 and 2023 density estimates using two-sample z-tests indicated that changes in most landbird populations were inconclusive. Since 2018, increases in density were observed for the Pacific Imperial Pigeon ( Ducula pacifica ) and Crimson-crowned Fruit Dove ( Ptilinopus porphyraceus ) on Tutuila, while decreases were observed for the Pacific Kingfisher ( Todiramphus sacer ) on Tutuila, and for the Polynesian Wattled Honeyeater ( Foulehaio carunculatus ), Polynesian Starling ( Aplonis tabuensis ), and Samoan Starling ( Aplonis atrifusca ) on Taʻū. The Many-colored Fruit Dove ( Ptilinopus perousii ) remained rare in both units, and the Manuʻa Shrikebill (Clytorhynchus vitiensis powelli) was narrowly distributed on Taʻū, with insufficient detections of either species to estimate density. The cryptic Spotless Crake ( Zapornia tabuensis ) was detected only in 2018. Changes in tree canopy cover and height did not exhibit patterns clearly associated with a major disturbance event and likely reflected differences in sampling frames among surveys. Invasive non-native plants, most notably Miconia crenata , were widespread in both units. Although many landbird populations in NPSA remain abundant, inference from current monitoring is constrained by limited information on vital rates and species-specific responses to invasive species, disease, habitat change, and extreme weather. As climate change is projected to increase tropical cyclone intensity in the South Pacific, sustained monitoring and targeted management will be important for understanding and conserving landbird populations in American Samoa.

National Park of American Samoa, Ta'u, Tutuila↗

USGS2012

Using geochemistry to identify the source of groundwater to Montezuma Well, a natural spring in Central Arizona, USA: Part 2

Montezuma Well is a unique natural spring located in a sinkhole surrounded by travertine. Montezuma Well is managed by the National Park Service, and groundwater development in the area is a potential threat to the water source for Montezuma Well. This research was undertaken to better understand the sources of groundwater to Montezuma Well. Strontium isotopes ( 87 Sr/ 86 Sr) indicate that groundwater in the recharge area has flowed through surficial basalts with subsequent contact with the underlying Permian aged sandstones and the deeper, karstic, Mississippian Redwall Limestone. The distinctive geochemistry in Montezuma Well and nearby Soda Springs (higher concentrations of alkalinity, As, B, Cl, and Li) is coincident with added carbon dioxide and mantle-sourced He. The geochemistry and isotopic data from Montezuma Well and Soda Springs allow for the separation of groundwater samples into four categories: (1) upgradient, (2) deep groundwater with carbon dioxide, (3) shallow Verde Formation, and (4) mixing zone. δ 18 O and δD values, along with noble gas recharge elevation data, indicate that the higher elevation areas to the north and east of Montezuma Well are the groundwater recharge zones for Montezuma Well and most of the groundwater in this portion of the Verde Valley. Adjusted groundwater age dating using likely 14 C and δ 13 C sources indicate an age for Montezuma Well and Soda Springs groundwaters at 5,400–13,300 years, while shallow groundwater in the Verde Formation appears to be older (18,900). Based on water chemistry and isotopic evidence, groundwater flow to Montezuma Well is consistent with a hydrogeologic framework that indicates groundwater flow by (1) recharge in higher elevation basalts to the north and east of Montezuma Well, (2) movement through the upgradient Permian and Mississippian units, especially the Redwall Limestone, and (3) contact with a basalt dike/fracture system that provides a mechanism for groundwater to flow to the surface. While the exact nature of the groundwater flow connections is still uncertain, the available data indicate that flow to Montezuma Well may be more susceptible to future groundwater development in the Redwall Limestone than from any other geologic unit. Overall, the shallow groundwater in the surrounding Verde Formation appears to be largely disconnected from deeper groundwater flowing to Montezuma Well.

Arizona↗

USGS2025

Analysis of trends in terrestrial vegetation at Mediterranean Coast Network Parks: Channel Islands National Park

The five islands comprising Channel Islands National Park (CHIS) experience natural gradients in temperature and moisture driven by ocean currents. Additionally, the islands were used as ranchlands and military land before becoming a national park, resulting in widespread erosion and vegetation change. As a result, CHIS spans gradients in climate as well as ranching duration and time since animal removal. Vegetation monitoring was initiated in 1984 on three islands (Anacapa, Santa Barbara, San Miguel), in 1990 on Santa Rosa Island, and in 1998 on Santa Cruz Island, with the goal of documenting the long-term response of island vegetation to ranch animal removal and climate fluctuations. Since that time, monitoring has documented the range of natural fluctuation in island environments over decades and provided insights into vegetation change in ecosystems unencumbered by ongoing development. Long-term vegetation monitoring at CHIS is therefore a rare example of an ecosystem experiment that demonstrates the results of management actions and serves as a baseline for land managers and scientists worldwide. Terrestrial vegetation data collected between 1984 and 2018 were modeled to estimate trends over time and to characterize relationships with covariates related to site characteristics, nonnative mammal removal programs, and water balance metrics. Data were analyzed for trends in vegetation cover, woody plant density, and plant community diversity grouped by life form and nativity across all islands and within individual islands, as well as for several individual species that dominate plant communities or present challenges to native plant recovery. In all, a total of 162 trend and covariate models were tested in this study, the details of which are provided in this report. Briefly, results reflect a decline in nonnative annual disturbance-thriving species with the reduction in animal grazing and trampling. Increasing trends were observed in native shrub density and native shrub recruitment density, as well as native shrub cover across all islands averaged together and on Santa Cruz Island. However, opposite trends were seen on the smaller islands of Santa Barbara and Anacapa, where increasing seabird activity may be damaging vegetation. Further results indicate the importance of soil moisture, relative humidity, fog, precipitation, site exposure, and solar radiation for vegetation patterns and trends. In many instances, there are apparent interacting effects of environmental variables with trends related to nonnative mammal removal and site location. Vegetation patterns in space and time emerge in the dataset as nuanced responses to interacting drivers.

Calfornia↗

USGS2024

Modelling effects of flow withdrawal scenarios on riverine and riparian features of the Yampa River in Dinosaur National Monument

The National Park Service (NPS) is charged with maintaining natural riverine resources and processes in its parks along the Yampa River and downstream along the Green River. This mission requires information on how proposed water withdrawals would affect resources. We present a methodology that quantifies the impact on natural riverine and riparian features of Dinosaur National Monument based on alternative withdrawals that vary in volume and timing. This methodology uses a reverse quantification and develops tools to enable the NPS to ensure that if withdrawals must occur, the adverse impacts would be minimized by prescribing or constraining the timing, magnitude, and duration of withdrawal. The reverse quantification, well-suited for unregulated rivers such as the Yampa, strives to protect all flows minus extractions from daily flows based on three parameters: 1) a minimum flow, below which water diversion does not occur; 2) the percentage of the flow above the minimum that is diverted; 3) the maximum daily flow that is diverted. We apply 350 flow extraction scenarios, each defined by a unique set of parameters, to the 99 historic annual hydrographs of daily flows (water year (WY) 1922–2020), and to the more recent 20 years (WY 2001–2020). We also consider how hydrologic year type (wet to dry) influences the flow volume extracted and impact to the resource. Recognizing the seasonal differences in flow and ecological and geomorphic response, we divide each year into four distinct seasonal periods and use relations from the literature between flow, channel change, riparian vegetation and fish behavior, physiology, and habitat to define hydrograph and resource metrics used to evaluate impacts to the resource. While our analysis demonstrates that all withdrawals will damage the resource, extractions during the Early Runoff Period (March 15 – April 30) are least detrimental and extractions during the Summer Baseflow Period (July 16 – October 31) are most detrimental. We find that most aspects of the resource are more sensitive to increasing extractions during drier years than during wetter years. Recent decades have seen a shift towards more frequent drier years, resulting in less water in most periods. As a result, our analysis suggests that extractions in recent decades would have had a greater impact on the resource when compared to similar extractions during the full historical record. Finally, we demonstrate how the NPS may use these results to develop limits on extractions for resource protection.

Colorado, Utah↗

USGS2020

Spatial and temporal variations in SO2 and PM2.5 levels around Kīlauea volcano, Hawai'i during 2007–2018

Among the hazards posed by volcanoes are the emissions of gases and particles that can affect air quality and damage agriculture and infrastructure. A recent intense episode of volcanic degassing associated with severe impacts on air quality accompanied the 2018 lower East Rift Zone (LERZ) eruption of Kīlauea volcano, Hawai'i. This resulted in a major increase in gas emission rates with respect to usual emission values for this volcano, along with a shift in the source of the dominant plume to a populated area on the lower flank of the volcano. This led to reduced air quality in downwind communities. We analyse open-access data from the permanent air quality monitoring networks operated by the Hawai'i Department of Health (HDOH) and National Park Service (NPS), and report on measurements of atmospheric sulfur dioxide (SO 2 ) between 2007 and 2018 and PM 2.5 (aerosol particulate matter with diameter <2.5 μm) between 2010 and 2018. Additional air quality data were collected through a community-operated network of low-cost PM 2.5 sensors during the 2018 LERZ eruption. From 2007 to 2018 the two most significant escalations in Kīlauea's volcanic emissions were: the summit eruption that began in 2008 (Kīlauea emissions averaged 5–6 kt/day SO 2 from 2008 until summit activity decreased in May 2018) and the LERZ eruption in 2018 when SO 2 emission rates reached a monthly average of 200 kt/day during June. In this paper we focus on characterizing the airborne pollutants arising from the 2018 LERZ eruption and the spatial distribution and severity of volcanic air pollution events across the Island of Hawai'i. The LERZ eruption caused the most frequent and severe exceedances of the Environmental Protection Agency (EPA) PM 2.5 air quality threshold (35 μg/m 3 as a daily average) in Hawai'i in the period 2010–2018. In Kona, for example, the maximum 24-h-mean mass concentration of PM 2.5 was recorded as 59 μg/m 3 on the twenty-ninth of May 2018, which was one of eight recorded exceedances of the EPA air quality threshold during the 2018 LERZ eruption, where there had been no exceedances in the previous 8 years as measured by the HDOH and NPS networks. SO 2 air pollution during the LERZ eruption was most severe in communities in the south and west of the island, as measured by selected HDOH and NPS stations in this study, with a maximum 24-h-mean mass concentration of 728 μg/m 3 recorded in Ocean View (100 km west of the LERZ emission source) in May 2018. Data from the low-cost sensor network correlated well with data from the HDOH PM 2.5 instruments, confirming that these low-cost sensors provide a robust means to augment reference-grade instrument networks.

Hawaii↗

USGS2024

Abundance and distribution of white-tailed deer on First State National Historical Park and surrounding lands

We estimated both abundance and distribution of white-tailed deer ( Odocoileus virginianus ) on the Brandywine Valley unit of First State National Historical Park (FRST) and the Brandywine Creek State Park (BCSP) during 2020 and 2021 with two widely used field methods — a road-based count and a network of camera traps. We conducted 24 road-based counts, covering 260 km of roadway, and deployed up to 16 camera traps, processing over 82,000 images representing over 5,000 independent observations. In both years, we identified bucks based on their body and antler characteristics, tracking their movements between baited camera trap locations. We tested seven estimators commonly reported in the literature, comparing the relative merits for managers of small, protected natural areas like FRST. Deer densities estimated from conventional road-based distance sampling were approximately 10 deer/km 2 lower than densities estimated from camera-trapping surveys. We attribute the bias in roadbased distance sampling to the difficulty of recording the precise effort expended to obtain the counts. Modifying the distance sampling method addressed many of the issues associated with the conventional approach. Despite little substantive differences in land cover types between the two methods, a clear spatial segregation of male and female deer at camera trap locations could bias roadbased counts if the sexes are not encountered in proportion to their abundances. There was a distinct gradient in deer distribution across the study area, with higher proportions of deer recorded in camera traps at FRST than BCSP, which harvests 20–60 deer annually during a regulated, hunting season. The most reliable (i.e., low bias, acceptable precision) methods, Spatial Capture Recapture (SCR) and Density Surface Modeling (DSM), produced deer densities of approximately 50 deer/km 2 in each year — a number which is consistent with previous estimates for New Castle County, Delaware, and our experience in similar, unhunted natural areas. Across both FRST and BCSP, these densities translated into area-wide (~1000 ha) population sizes between 650–1000 deer, with about one-half to two-thirds comprising the FRST population. Density surface modeling of mapped locations of deer detected during surveys, combined with camera-trapping and a time-to-event data analysis might be the only practical means of reliably assessing white-tailed deer abundance in small (<2000 ha), protected natural areas like FRST. Most other approaches are either too time-consuming, require identification and tracking of individual deer, the use of bait, or require intervention by a subject-area expert.

Delaware, Pennsylvania↗