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USGS2020

Development and application of an empirical dune growth model for evaluating barrier island recovery from storms

Coastal zone managers require models that predict barrier island change on decadal time scales to estimate coastal vulnerability, and plan habitat restoration and coastal protection projects. To meet these needs, methods must be available for predicting dune recovery as well as dune erosion. In the present study, an empirical dune growth model (EDGR) was developed to predict the evolution of the primary foredune of a barrier island. Within EDGR, an island is represented as a sum of Gaussian shape functions representing dunes, berms, and the underlying island form. The model evolves the foredune based on estimated terminal dune height and location inputs. EDGR was assessed against observed dune evolution along the western end of Dauphin Island, Alabama over the 10 years following Hurricane Katrina (2005). The root mean square error with EDGR (ranging from 0.18 to 0.74 m over the model domain) was reduced compared to an alternate no-change model (0.69–0.96 m). Hindcasting with EDGR also supports the study of dune evolution processes. At Dauphin Island, results suggest that a low-lying portion of the site was dominated by overwash for ~5 years after Katrina, before approaching their terminal height and becoming growth-limited after 2010. EDGR’s computational efficiency allows dune evolution to be rapidly predicted and enables ensemble predictions to constrain the uncertainty that may result if terminal dune characteristics are unknown. In addition, EDGR can be coupled with an external model for estimating dune erosion and/or the long-term evolution of other subaerial features to allow decadal-scale prediction of barrier island evolution.

Alabama↗

USGS2017

Developing an effective Agassiz's Desert Tortoise monitoring program: Final report to the Coachella Valley Conservation Commission

Agassiz’s desert tortoise (Gopherus agassizii) is a conservation-reliant species with populations north and west of the Colorado River protected as threatened under the Endangered Species Act (Averill-Murray et al. 2012). Since it was listed under this category in 1990, a great deal has been learned about the natural history of the species, and it is now one of the best-studied turtles in the United States (Lovich and Ennen 2013). However, the accumulated body of scientific data available for the species has not yet been translated into recovery or delisting of the species. Successful conservation of any species requires knowledge of their natural history and how vital rates affect their ability to maintain stable populations in the face of natural and anthropogenic stresses. Agassiz’s desert tortoises occur from southwestern Utah to near the Mexican border in California – a distance of over 450 km – but population densities vary greatly across this immense landscape (U.S. Fish and Wildlife Service 2015). Tortoises occur in the Sonoran Desert of California, including the eastern and western ends of the Coachella Valley, where it is one of 27 species covered under the Coachella Valley Multiple Species Habitat Conservation Plan and Natural Community Conservation Plan (CVMSHCP/NCCP). The southern portion of Joshua Tree National Park (JTNP) lies within this 1.1 million acre planning area, and was predicted to be an area of low-density tortoise populations using habitat suitability modeling (Barrows 2011). JTNP is near the southern distributional limit of G. agassizii, yet very little has been published regarding the ecology of tortoises in the Sonoran Desert of California. Reproductive output is an important gross measure of the ability of a population to persist. When integrated with data on fertility and survivorship, this information forms a foundation for assessing population status and formulating effective management strategies (e.g., Congdon et al. 1993, 1994), especially for imperiled species. One aspect of the biology of G. agassizii that has been particularly well-studied is reproductive output. However, most of what we know about this topic comes from research in the Mojave Desert portion of the species’ range (Ernst and Lovich 2009). Comparatively little has been published on the reproductive ecology of populations living in the Sonoran Desert ecosystem of California. Publications by Lovich et al. (1999, 2011, 2012, 2014, 2015) constitute the main body of literature on desert tortoise reproductive ecology in the Sonoran Desert of California, with one study population located at the western end of the CVMSHCP/NCCP area. Collecting data on Agassiz’s desert tortoise ecology in the Sonoran Desert ecosystem is important due to significant differences between the two adjacent desert ecosystems, especially the timing and amounts of annual precipitation, and their potential effects on reproductive output (e.g., Lovich et al. 5 2015). There are also differences in the vulnerability of tortoises to the effects of a warming, drying climate between the two deserts (Barrows 2011; Zylstra et al. 2012). The overall goal of this study was to collect data on demography, reproductive output, and genetic affinities at a study site in the Sonoran Desert portion of JTNP in the eastern end of the CVMSHCP/NCCP area. Specific objectives included: 1) Collect data to establish baselines on tortoise populations and/or their habitat suitability in core habitat within the CVNCCP area, including biotic and abiotic variables affecting persistence of tortoise populations; 2) Compare and contrast with data collected on desert tortoises at USGS/BLM study site near Palm Springs over 16 years; 3) Support long-term modeling efforts needed to determine tortoise population viability; 4) Refine modeled relationships with identified threats such as fire, invasive species and climate change; and 5) Prioritize adaptive management needs for the desert tortoise in and beyond the CVNCCP area. The data from this study will aid in determining baseline estimates of the desert tortoise population size within the planning area as well as establish a marked population of Agassiz’s desert tortoises for future monitoring. Data will be integrated with habitat modeling in order to refine model output. Genetic data will be collected on both the north and south sides of Interstate 10 to determine the potential effects of habitat fragmentation and genetic mixing. Analyses are ongoing and results beyond those presented in this report will be published in peer-reviewed scientific journals following inclusion of additional data collected on the south side of Shavers Valley in 2017-2018.

Report↗

USGS2021

Growth of greater white-fronted goose goslings relates to population dynamics at multiple scales

The abundance of greater white-fronted geese ( Anser albifrons frontalis ) on the Arctic Coastal Plain (ACP) of northern Alaska, USA, has more than tripled since the late 1990s; however, recent rate of annual population growth has declined as population size increased, which may indicate white-fronted geese on the ACP are approaching carrying capacity. We examined rates of gosling growth in greater white-fronted geese at 3 sites on the ACP during 2012–2014 to assist with predictions of future population trends and assess evidence for density-dependent constraints on recruitment. We marked goslings at hatch with individually coded webtags and conducted brood drives during early August to capture, measure, and weigh goslings. Annual estimates of gosling mass at 32 days old (range = 1,190–1,685) indicate that goslings had obtained >60% of asymptotic size. This rate of growth corresponds with that of other goose species and populations with access to high-quality forage and no limitations on forage availability, and is consistent with the overall increase in abundance of white-fronted geese at the ACP scale. Contrary to most previous investigations, age-adjusted mass of goslings did not decline with hatch date. Goslings grew faster in coastal areas than at inland freshwater sites. Taken together, these findings suggest forage was not limiting gosling growth rates in either ecosystem, but forage was of greater quality in coastal areas where goose foraging habitat is expanding because of permafrost subsidence. Spatial patterns of gosling growth corresponded with local-scale patterns of population density and population change; the areas with greatest rates of gosling growth were those with the greatest population density and rates of population increase. We found little evidence to suggest forage during brood rearing was limiting population increase of white-fronted geese on the ACP. Factors responsible for the apparent slowing of ACP-wide population growth are likely those that occur in stages of the annual cycle outside of the breeding grounds.

Alaska↗

USGS2018

Population estimates of the Endangered Hawaiʻi ʻĀkepa (Loxops coccineus) in different habitats on windward Mauna Loa

Endangered Hawai‘i ʻĀkepas ( Loxops coccineus ) are endemic to Hawai‘i island, where they occur in five spatially distinct populations. Data concerning the status and population trends of these unique Hawaiian honeycreepers are crucial for assessing the effectiveness of recovery and management actions. In 2016, we used point‐transect distance sampling to estimate the abundance of Hawai‘i ʻĀkepas in portions of Hawai‘i Volcanoes National Park (HAVO) and the Kaʻū Forest Reserve (KFR) on Mauna Loa volcano. We then compiled the survey data from four other populations to provide a global population estimate. In our HAVO and KFR study area, we mapped habitat classes to determine the population densities in each habitat. Densities were highest (1.03 birds/ha) in open‐canopy montane ʻōhiʻa ( Metrosideros polymorpha ) woodland. In contrast, densities of the largest ʻĀkepa population on Mauna Kea volcano were highest in closed‐canopy ʻōhiʻa and koa ( Acacia koa ) forest where the species is dependent on nest cavities in tall (> 15 m), large (> 50‐cm diameter at breast height) trees. We surveyed potential nesting habitat in HAVO and KFR and found only one cavity in the short‐stature montane ʻōhiʻa woodland and five cavities in the tall‐stature forest. Differences in densities between the Mauna Kea and Mauna Loa populations suggest that Hawai‘i ʻĀkepas may exhibit different foraging and nesting behaviors in the two habitats. The estimated overall population density in the HAVO and KFR study area was 0.52 birds/ha, which equates to 3663 (95% CI 1725–6961) birds in their 11,377‐ha population range. We calculated a global population of 16,428 (95% CI 10,065–25,198) birds, which is similar to an estimate of 13,892 (95% CI 10,315–17,469) birds made in 1986. Our results suggest that populations are stable to increasing in the two largest populations, but the three other populations are smaller (range = 77–1443 birds) and trends for those populations are unknown.

Hawai'i↗

USGS2025

Population demographics of invasive Silver Carp in a Great Plains river network

Objective Knowledge of invasive Silver Carp Hypophthalmichthys molitrix population demographics and distributions may inform estimates of efforts necessary to achieve reductions in abundance and identify locations to conduct removal. Although extensively studied in other parts of their invasive range (e.g., Mississippi and Illinois rivers), less is known regarding Silver Carp population demographics in Great Plains rivers and streams. As such, this study characterized Silver Carp population demographics along an invasion gradient in a Great Plains river network containing multiple hydrologically unique river reaches and tributaries. Methods Boat and tote-barge electrofishing surveys were conducted within the lower Platte River basin in the spring, summer, and fall of 2022 and 2023. Lapilli otoliths were collected for assessment of age, growth, and annual mortality. Information on sex also was collected. A spatial assessment of differences in population demographics was performed between core and periphery regions of the population. Results There were 1,528 Silver Carp collected. A spatial difference in relative abundance was observed and was associated with changes in body condition and total length along the longitudinal gradient of the lower Platte River basin. Silver Carp sex ratios were male-skewed across the lower Platte River basin (1.6:1), particularly in reaches near the invasion front (10.1:1). Conclusions Silver Carp population demographics within the lower Platte River basin were aligned with an establishing population characterized by rapid individual growth and skewed sex ratios. Broadscale variation in population characteristics, including growth and size structure, suggested density-dependent processes. Silver Carp occurred throughout the study area, indicating that braided Great Plains streams are susceptible to invasion. This study provided insight into Silver Carp population demographics in the lower Platte River basin and may provide useful information for the development of Silver Carp management plans in similar Great Plains streams.

North American Journal of Fisheries Management↗

USGS2024

Nonbreeding waterfowl behavioral response to crewed and uncrewed aerial surveys on conservation areas in Missouri

Monitoring waterfowl populations provides the basis for improving habitat quantity and quality, establishing harvest regulations, and ensuring sustainable waterfowl populations through appropriate management. Waterfowl biologists currently use a variety of population and habitat monitoring methods ranging from informal ground observations to low-level occupied aircraft surveys. Although unoccupied aerial systems (UAS) may provide safer and more precise alternatives to traditional aerial survey techniques that are less disturbing to waterfowl, there is limited information on how waterfowl in winter respond to UAS. We compared the behavioral responses of waterfowl to helicopters and UAS on Missouri Department of Conservation wetland conservation areas October – February 2021-2022. Helicopter surveys were flown using an Airbus H125 helicopter at heights of 100 – 350 m, with UAS surveys flown using a DJI Mavic 2 Pro UAS at 15 – 90 m. Waterfowl behavior was categorized as alert, swim, fly, or abandonment using flock-scan surveys recorded for 10-minute periods before, during, and after the surveys. The percentage of time flocks spent in each behavior during- or post-survey were compared to time spent in those behaviors pre-survey. Waterfowl increased time spent swimming, flying, and abandonment in response to helicopter flights, whereas UAS flights did not influence overall waterfowl behavior. Additionally, waterfowl did not change behavior in response to UAS flights regardless of waterfowl guild (mallard, other duck, or goose) or hunting season (open or closed). Waterfowl did increase flight behavior during UAS flights at 30 m, however, there was no change in behavior at all other UAS survey altitudes. UAS may be a good alternative to traditional waterfowl survey methods and are not likely to affect waterfowl distributions or energy expenditures during the survey periods.

Missouri↗

USGS2013

Juvenile movement among different populations of cutthroat trout introduced as embryos to vacant habitat

Translocations are frequently used to increase the abundance and range of endangered fishes. One factor likely to affect the outcome of translocations is fish movement. We introduced embryos from five Westslope Cutthroat Trout Oncorhynchus clarkii lewisi populations (both hatchery and wild) at five different locations within a fishless watershed. We then examined the movement of age‐1 and age‐2 fish and looked for differences in movement distance among source populations and among introduction sites; we also examined the interactions among age, population, and introduction site. At age 1, most individuals (90.9%) remained within 1,000 m their introduction sites. By age 2, the majority of individuals (58.3%) still remained within 1,000 m of their introduction site, but considerably more individuals had moved downstream, some more than 6,000 m from their introduction site. We observed a significant interaction between age and source population ( F 4, 1077 = 15.45, P < 0.0001) as well as between age and introduction site ( F 41, 1077 = 11.39, P < 0.0008), so we presented results in the context of these interactions. Within age‐groups, we observed differences in movement behavior among source populations and among donor populations of Westslope Cutthroat Trout. We discuss these findings in light of previous research on juvenile salmonid movement.

Montana↗

USGS2025

Challenges and opportunities in mitigating sarcoptic mange in wild South American camelids

Vicuñas ( Vicugna vicugna ) and guanacos ( Lama guanicoe ) are the two species of wild South American camelids whose distributions range from Peru to northern Argentina and southern Peru to southern Argentina, respectively. Listed as critically endangered in the 1960s due to poaching, vicuña numbers had been gradually recovering; however, new concerns about population stability have arisen with recent observations of sarcoptic mange outbreaks in this species. Sarcoptic mange is an infectious skin disease caused by the microscopic burrowing mite, Sarcoptes scabiei , which infects nearly 150 mammalian species globally, including guanaco and vicuña. Wild camelid populations across Argentina, Bolivia, Chile, and Peru have been affected by sarcoptic mange, with the most severe outbreaks resulting in localized extirpation. Population declines have conservation and economic implications, as many local communities harvest vicuña and guanaco fiber for profit. We review the current literature on sarcoptic mange in wild camelids from Argentina, Bolivia, Chile, and Peru to establish a current state of knowledge on spatial prevalence, management, and therapeutics, and identify existing knowledge gaps. Critical next steps include 1) implementation of effective management strategies that limit the transmission of sarcoptic mange, 2) standardization of data collected during community capture (i.e., chaccu) events, 3) assessing the potential role of community captures in mite transmission, and 4) evaluation of treatment options and best practices for implementation. Further, there is a need for capacity building to improve disease diagnostics and surveillance in wild camelids. A multisectoral collaboration between governmental authorities, communities, academic institutions, and national and international organizations focusing on wild South American camelid conservation could contribute to building actions aimed at preventing future outbreaks and mitigating the current burden of sarcoptic mange disease.

Journal of Wildlife Management↗

USGS2014

A review of environmental impacts of salts from produced waters on aquatic resources

Salts are frequently a major constituent of waste waters produced during oil and gas production. These produced waters or brines must be treated and/or disposed and provide a daily challenge for operators and resource managers. Some elements of salts are regulated with water quality criteria established for the protection of aquatic wildlife, e.g. chloride (Cl − ), which has an acute standard of 860 mg/L and a chronic standard of 230 mg/L. However, data for establishing such standards has only recently been studied for other components of produced water, such as bicarbonate (HCO 3 − ), which has acute median lethal concentrations (LC50s) ranging from 699 to > 8000 mg/L and effects on chronic toxicity from 430 to 657 mg/L. While Cl− is an ion of considerable importance in multiple geographical regions, knowledge about the effects of hardness (calcium and magnesium) on its toxicity and about mechanisms of toxicity is not well understood. A multiple-approach design that combines studies of both individuals and populations, conducted both in the laboratory and the field, was used to study toxic effects of bicarbonate (as NaHCO 3 ). This approach allowed interpretations about mechanisms related to growth effects at the individual level that could affect populations in the wild. However, additional mechanistic data for HCO 3 − , related to the interactions of calcium (Ca 2 + ) precipitation at the microenvironment of the gill would dramatically increase the scientific knowledge base about how NaHCO 3 might affect aquatic life. Studies of the effects of mixtures of multiple salts present in produced waters and more chronic effect studies would give a better picture of the overall potential toxicity of these ions. Organic constituents in hydraulic fracturing fluids, flowback waters, etc. are a concern because of their carcinogenic properties and this paper is not meant to minimize the importance of maintaining vigilance with respect to potential organic contamination.

International Journal of Coal Geology↗

USGS2026

Sentinel-2 for chlorophyll-a water quality monitoring: A review of validation evidence and application potential

Water quality monitoring is integral to preserving the health of freshwater ecosystems, and satellite remote sensing has emerged as one monitoring method. Sentinel-2, in particular, has been valuable for water quality monitoring due to its 5-day global temporal revisit time and spatial resolution that ranges from 10 to 60 metres. Sentinel-2 can be used to measure and monitor chlorophyll-a, which historically has been used as an indicator of water quality, eutrophication and harmful algal blooms. Our goal was to review aquatic chlorophyll-a Sentinel-2 research to assess the types of validation evidence reported. Validation evidence is defined here as the set of information key to assessing algorithm performance, and include the spatial and temporal scales of satellite validation, reported in situ sampling method context information, demonstration of validation results through plots, and appropriate algorithm performance metrics. We highlight how the body of literature collectively contributes to advancing a national scale chlorophyll-a product that could support future resource management applications. Our review of 122 published studies indicated that much of the validation evidence corresponded to early stages, as defined by the NASA data maturity framework, due to a limited focus on individual lakes and limited detail on methodology for reproducibility. Prioritizing data accessibility for both in situ data and satellite workflows used in published studies; reporting methods with transparency and consistency; and using standard algorithm performance metrics could provide a consistent framework to support and enhance the utility of satellite inland water quality research. These three quality assurance mechanisms can promote effective evaluation of approaches for remote sensing of chlorophyll-a. Adopting these quality criteria could enable the integration of validation evidence from multiple studies, supporting more spatially and temporally representative products that would advance these approaches towards maturation for broader application.

International Journal of Remote Sensing↗

USGS2025

The relative influence of geographic and environmental factors on rare plant translocation outcomes

Conservation translocations are an established method for reducing the extinction risk of plant species through intentional movement within or outside the indigenous range. Unsuitable environmental conditions at translocation recipient sites and a lack of understanding of species–environment relationships are often identified as critical barriers to translocation success. However, previous syntheses have drawn these inferences from analyses of qualitative feedback rather than quantitative environmental data. In this study, we use a data set of 235 translocations conducted in the US to understand the influences of geographic and environmental factors on three metrics of translocation success: population persistence, next-generation recruitment and next-generation maturity. We use random forest models to quantify the relative importance of geographic and environmental factors that characterize dissimilarity between source and recipient locations, the position of recipient sites relative to species' ranges and niche metrics derived from these ranges. We also compare the importance of these variables with more conventional predictors (e.g. founder population size). Our results indicate that geographic and environmental variables can be as insightful as conventional variables for predicting plant translocation outcomes. The climate suitability of recipient sites, estimated using species distribution models, was the strongest relative predictor of whether a population persisted, with populations situated in more suitable climates displaying greater persistence. Next-generation recruitment and maturity were best predicted by niche metrics; species in more biotically limiting environments, including tropical regions and soils with high relative nutrient retention, as well as species with the broadest precipitation niches, were the least likely to attain these next-generation benchmarks. Synthesis and applications . Our study is one of the first to quantify the important role of spatial and climatic factors in rare plant translocation outcomes. We provide a novel geographic and environmental perspective on outcomes in plant translocations and demonstrate opportunities to improve translocation success not only by adhering to established best practice guidelines but also by integrating spatial modelling approaches into planning and management processes.

Journal of Applied Ecology↗

USGS2020

High site fidelity does not equate to population genetic structure for common goldeneye and Barrow's goldeneye in North America

Delineation of population structure provides valuable information for conservation and management of species, as levels of demographic and genetic connectivity not only affect population dynamics but also have important implications for adaptability and resiliency of populations and species. Here, we measure population genetic structure and connectivity across the ranges of two sister species of sea ducks: Barrow's goldeneye Bucephala islandica and common goldeneye B. clangula . We use two different marker types: 7–8 nuclear microsatellite loci assayed across 229 samples and 3678 double digest restriction‐site associated DNA sequencing (ddRAD‐seq) loci assayed across 61 samples. First, both datasets found no evidence of genetic structure within common or Barrow's goldeneye, including between North American and European samples of common goldeneye. These results are in contrast with previous mitochondrial DNA, band recovery and telemetry data which suggest that goldeneyes are structured across their range. We posit that the discordance between autosomal genetic markers and other data types suggests that males, possibly subadult males, may be maintaining genetic connectivity across each species' respective ranges. Next, although mate choice consequences resulting from inter‐specific brood parasitism was hypothesized to cause some level of gene flow between goldeneye species, we only identified a single F1 hybrid with no further evidence of contemporary or historical gene flow. Despite ddRAD‐seq demographic analyses which recovered an optimum evolutionary model of split‐with‐migration (i.e. secondary contact), estimates of gene flow were <<1 migrant per generation in both directions. Together, we conclude that either strong ecological barriers or assortative mating are likely playing a role in preventing further backcrossing. Finally, demographic analyses estimated a relatively deep divergence time between Barrow's goldeneye and common goldeneye of ~1.6 million years before present and suggests that the genomes of both species have been under similar evolutionary constraints.

Journal of Avian Biology↗

USGS2021

The demographic contributions of connectivity versus local dynamics to population growth of an endangered bird

Conservation and management increasingly focus on connectivity, because connectivity driven by variation in immigration rates across landscapes is thought to be crucial for maintaining local population and metapopulation persistence. Yet, efforts to quantify the relative role of immigration on population growth across the entire range of species and over time have been lacking. We assessed whether immigration limited local and range‐wide population growth of the endangered snail kite Rostrhamus sociabilis in Florida, USA, over 18 years using multi‐state, reverse‐time modelling that accounts for imperfect detection of individuals and unobservable states. Demographic contributions of immigration varied depending on the dynamics and geographic position of the local populations, were scale‐dependent and changed over time. By comparing the relative contributions of immigration versus local demography for periods of significant change in local abundance, we found empirical evidence for a disproportionately large role of immigration in facilitating population growth of a centrally located population—a connectivity ‘hub’. The importance of connectivity changed depending of the spatial scale considered, such that immigration was a more important driver of population growth at small versus large spatial scales. Furthermore, the contribution of immigration was much greater during time periods when local population size was small, emphasizing abundance‐dependent rescue effects. Our findings suggest that efforts aimed at improving local breeding habitat will likely be most effective at increasing snail kite population growth. More broadly, our results provide much needed information on the role of connectivity for population growth, suggesting that connectivity conservation may have the greatest benefits when efforts focus on centrally located habitat patches and small populations. Furthermore, our results highlight that connectivity is highly dynamic over time and that interpreting the effects of connectivity at local scales may not transfer to region‐wide dynamics.

Florida↗

USGS2024

Comparison of two otolith processing methods for silver carp age estimation

Accurate age estimates are critical in the development, implementation, and assessment of silver carp ( Hypophthalmichthys molitrix ) management plans. Lapilli otoliths are the most commonly used calcified structures for silver carp age estimation, but studies on the precision of two established preparation methods [i.e., grind-and-burn (GB), thin-section (TS)] are lacking. Therefore, we assessed within-reader, between-reader, and between-method precision for 125 silver carp collected from six rivers throughout the Lower Mississippi River Basin (Arkansas, Cache, Mississippi, St. Francis, White, and Yazoo). Additionally, we compared the effort and material costs associated with each method. Overall, younger ages were estimated with the GB method (median estimated age = 6 yr, range = 3–12) than the TS method (median estimated age = 7 yr, range = 3–13). Between-method comparisons revealed low agreement (average CV = 16.40) and significant bias (Evans-Hoenig χ2 = 31.81, P < 0.01) between the two methods, particularly in older individuals. The TS method (average CV = 12.50) displayed similar between-reader precision to the GB method (average CV = 11.75). Younger age estimates for the GB method may be a result of misidentification of annuli near the otolith margin as both readers reported that TS otoliths offered clearer views than GB otoliths. Processing effort (TS method = 6.7 min otolith–1; GB method = 4.6 min otolith–1) and material costs (TS method = US$0.37 otolith–1; GB method = $0.34 otolith–1) were similar for the two methods and are likely not a factor when choosing an age estimation protocol. Our results indicate that use of the TS method for silver carp age estimation may lead to less biased age estimates, especially in established populations with greater abundances of older individuals, assuming putative additional annuli observed in thin-sections are true annuli.

Journal of the Southeastern Association of Fish an↗

USGS2015

Status and conservation of interior Redband Trout in the western United States

In this article we describe the current status and conservation of interior (potamodromous) Redband Trout Oncorhynchus mykiss sspp. throughout its range in the western United States using extant data and expert opinion provided by fish managers. Redband Trout historically occupied 60,295 km of stream habitat and 152 natural lakes. Currently, Redband Trout occupy 25,417 km of stream habitat (42% of their historical range) and 124 lakes or reservoirs. Nonhybridized populations are assumed to occupy 11,695 km (46%) of currently occupied streams; however, fish from only 4,473 km (18%) have been genetically tested. Approximately 47% of the streams occupied by Redband Trout occur on private land, 45% on government lands, and 8% in protected areas. A total of 210 Redband Trout populations, occupying 15,252 km of stream habitat (60% of the current distribution) and 95,158 ha of lake habitat (52%), are being managed as “conservation populations.” Most conservation populations have been designated as weakly to strongly connected metapopulations (125; 60%) and occupy much more stream length (14,112 km; 93%) than isolated conservation populations (1,141 km; 7%). The primary threats to Redband Trout include invasive species, habitat degradation and fragmentation, and climate change. Although the historical distribution of interior Redband Trout has declined dramatically, we conclude that the species is not currently at imminent risk of extinction because it is still widely distributed with many populations isolated by physical barriers and active conservation efforts are occurring for many populations. However, the hybridization status of many populations has not been well quantified, and introgression may be more prevalent than documented here. We recommend (1) collecting additional genetic data and estimating distribution and abundance by means of a more rigorous spatial sampling design to reduce uncertainties, (2) collecting additional information to assess and predict the impacts of climate on populations, and (3) continuing to use this database to evaluate the status of Redband Trout and inform conservation efforts through time.

North American Journal of Fisheries Management↗

USGS2016

Effects of salt pond restoration on benthic flux: Sediment as a source of nutrients to the water column

Understanding nutrient flux between the benthos and the overlying water (benthic flux) is critical to restoration of water quality and biological resources because it can represent a major source of nutrients to the water column. Extensive water management commenced in the San Francisco Bay, Beginning around 1850, San Francisco Bay wetlands were converted to salt ponds and mined extensively for more than a century. Long-term (decadal) salt pond restoration efforts began in 2003. A patented device for sampling porewater at varying depths, to calculate the gradient, was employed between 2010 and 2012. Within the former ponds, the benthic flux of soluble reactive phosphorus and that of dissolved ammonia were consistently positive (i.e., moving out of the sediment into the water column). The lack of measurable nitrate or nitrite concentration gradients across the sediment-water interface suggested negligible fluxes for dissolved nitrate and nitrite. The dominance of ammonia in the porewater indicated anoxic sediment conditions, even at only 1 cm depth, which is consistent with the observed, elevated sediment oxygen demand. Nearby openestuary sediments showed much lower benthic flux values for nutrients than the salt ponds under resortation. Allochthonous solute transport provides a nutrient advective flux for comparison to benthic flux. For ammonia, averaged for all sites and dates, benthic flux was about 80,000 kg/year, well above the advective flux range of −50 to 1500 kg/year, with much of the variability depending on the tidal cycle. By contrast, the average benthic flux of soluble reactive phosphorus was about 12,000 kg/year, of significant magnitude, but less than the advective flux range of 21,500 to 30,000 kg/year. These benthic flux estimates, based on solute diffusion across the sediment-water interface, reveal a significant nutrient source to the water column of the pond which stimulates algal blooms (often autotrophic). This benthic source may be augmented further by bioturbation, bioirrigation and episodic sediment resuspension events.

California↗

USGS2012

Quantifying anthropogenically driven morphologic changes on a barrier island: Fire Island National Seashore, New York

Beach scraping, beach replenishment, and the presence of moderate development have altered the morphology of the dune–beach system at Fire Island National Seashore, located on a barrier island on the south coast of Long Island, New York. Seventeen communities are interspersed with sections of natural, nonmodified land within the park boundary. Beach width, dune elevation change, volume change, and shoreline change were calculated from light detection and ranging (LIDAR), real-time kinematic global positioning system (RTK GPS), and beach profile data sets at two ∼4 km long study sites. Each site contains both modified (developed, replenished, and/or scraped) and nonmodified (natural) areas. The analysis spans 9 years, from 1998 to 2007, which encompasses both scraping and replenishment events at Fire Island. The objectives of this study were to quantify and compare morphological changes in modified and nonmodified zones, and to identify erosional areas within the study sites. Areas of increased volume and shoreline accretion were observed at both sites and at the western site are consistent with sand replenishment activities. The results indicate that from 1998 to 2007 locations backed by development and that employed beach scraping and/or replenishment as erosion control measures experienced more loss of volume, width, and dune elevation as compared with adjacent nonmodified areas. A detailed analysis of one specific modification, beach scraping, shows distinct morphological differences in scraped areas relative to nonscraped areas of the beach. In general, scraped areas where there is development on the dunes showed decreases in all measured parameters and are more likely to experience overwash during storm events. Furthermore, the rapid mobilization of material from the anthropogenic (scraped) dune results in increased beach accretion downcoast. National park lands are immediately adjacent to developed areas on Fire Island, and even relatively small human-induced modifications can affect park resources and beach–dune response to storms. This study is the first to conduct a systematic analysis on how anthropogenic modifications affect resources at Fire Island National Seashore and provides essential information for effective management and preservation of coastal resources within the park.

New York↗

USGS2021

Effects of winter ticks and internal parasites on moose survival in Vermont, USA

Moose ( Alces alces ) have experienced considerable declines along the periphery of their range in the northeastern United States. In Vermont, the population declined 45% from 2010 to 2017 despite minimal hunter harvest and adequate habitat. Similarly, nearby populations recently experienced epizootics characterized by >50% mortality. Declines have largely been associated with the effects of winter ticks ( Dermacentor albipictus ), but uncertainty exists about the effects of environmental and other parasite-related conditions on moose survival. We examined patterns of moose survival among a radio-collared population ( n = 127) in Vermont from 2017 to 2019. Our objectives were to estimate causes of mortality and model survival probability as a function of individual and landscape variables for calves (<1 yr) and adults (≥1 yr). Observed adult survival was 90% in 2017, 84% in 2018, and 86% in 2019, and winter calf survival was 60% in 2017, 50% in 2018, and 37% in 2019. Winter tick infestation was the primary cause of mortality (91% of calves, 25% of adults), and 32% of all mortalities had evidence of meningeal worm ( Parelaphostrongylus tenuis ). Other sources of mortality such as vehicles, harvest, predation, deep snow, and other parasitic infections were negligible. The best supported calf model included sex differences and negative effects of tick engorgement (%/week) and parasite level (roundworm and lungworm). The best supported adult model included the effect of cumulative tick engorgement (cumulative %/week), which negatively affected survival. Our results indicate that winter tick engorgement strongly affects survival, and is probably compounded by the presence of meningeal worm and other parasites. Reduced tick effects may be achieved by decreasing moose density through harvest and managing late winter habitat to minimize tick density. Management of white-tailed deer ( Odocoileus virginianus ) density may also affect the transmission of meningeal worm.

Vermont↗