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At least 235 records · Page 13Linked to original sources
USGS2026

Investigation of drivers and sources of potential harmful algal blooms in Lake Anna, Virginia, 2023-24

Algal blooms in freshwater reservoirs are an increasing concern because of the risk to aquatic ecosystem health, recreational use, and water quality. Among the taxa that comprise an algal bloom, cyanobacteria are of particular concern due to the potential to produce toxic compounds which can cause acute and chronic illness in humans if ingested through contaminated water or shellfish. When toxins are above a toxin-specific threshold in the water column, the Commonwealth of Virginia categorizes the bloom as a harmful algal bloom (HAB), distinguishing it from an algal bloom without toxins present. Toxins are of particular concern in bodies of water which serve as major recreational areas, such as Lake Anna in central Virginia. Lake Anna is a 27 km-long and 47 km2 reservoir in central Virginia. Since the Commonwealth of Virginia revised the HAB monitoring framework in 2018, algal bloom advisories for potentially toxigenic blooms have been issued in the western, riverine zone of the reservoir. There were detections of microcystin and anatoxin production but no detections of cylindrospermopsin and saxitoxin production in Lake Anna; however, toxin concentrations were low, at values less than 0.65 µg/L. In 2023, the U.S. Geological Survey, in cooperation with Virginia Department of Environmental Quality, initiated a 19-month intensive and extensive study of western Lake Anna and its tributaries (North Anna River and Pamunkey Creek) to (1) characterize the algal community, biomass, and toxin production; (2) identify potential drivers leading to algal bloom initiation, persistence, and decline; and (3) assess the primary sources of the drivers contributing to algal blooms. Continuous and discrete monitoring of water quality within the lake, watershed inputs, meteorological conditions, and algal communities were monitored. Multiple modeling scenarios identified that the formation and persistence of algal blooms in Lake Anna are driven by interactions among chemical, macro- and micronutrient, and physical factors. Key drivers include total nitrogen, total phosphorus, water temperature, suspended sediment concentration, wind speed, copper, iron, molybdenum, nickel, sodium, and alkalinity. During this study, winter stormflow events delivered the highest loading of macro- and micronutrients from the tributaries to the lake. The lake is a sink for these nutrients in the water column or in the lake-bed sediments. During high-occupancy and recreation periods on the lake in the summer months, boating activity can promote internal loading by the resuspension of the lake-bed sediments, thereby increasing the nutrient availability for algal uptake. Thermal stratification and hypoxic conditions were observed, which can contribute to the passive release of nutrients into the water column, further facilitating algal bloom proliferation. These processes may create a positive feedback loop that supports the formation, persistence, and annual recurrence of algal blooms in the western region of Lake Anna. Continued water-quality monitoring of early warning indicators may improve the detection and forecasting of algal growth in the lake and help managers proactively manage water quality and algal growth.

EarthArXiv↗
USGS2026

End-user needs for remote sensing wetlands of the Prairie Pothole Region of North America

The Prairie Pothole Region (PPR) of North America comprises globally important grassland and wetland ecosystems critical for numerous populations of migratory birds. Due to the importance of this region for migratory birds, and particularly waterfowl, and the threats of habitat loss due to intensifying agriculture, there is a mature and diverse system of conservation organizations, agencies, and partnerships that spends hundreds of millions of dollars annually on habitat conservation to support migratory bird populations. Remote sensing can be a powerful tool for observing and evaluating global change at large scales as well as expanding inferences from field studies to the broader landscape with statistical models. However, development and utilization of these tools has lagged behind their demand for several reasons, including concerns over spatial and temporal resolution and accuracy of products; perception of a misalignment with decision-maker needs; technological barriers such as skill sets of conservation professionals, computing resources, data access, and usability. In this report, we summarize the needs of conservation professionals and scientists who use or want to use remote sensing data products to inform science about wetland change and conservation of wetlands in the PPR. We assembled this information through several methods leading up to, during, and following a January 2026 PPR Wetland Remote Sensing Workshop. The workshop included United States and Canadian scientists, conservation professionals, and policy experts. Our goal was to bring together end-users and remote sensing product developers jointly to explore reducing the lag between product development and utilization of products to inform science and conservation. Specifically, we aimed to identify gaps in wetland remote sensing that limit effective monitoring, management, and conservation in the PPR, and to develop a framework that outlines pathways to address these gaps by fostering collaboration, improving communication networks, encouraging discussion, and building on existing and ongoing efforts. This report summarizes our participants’ descriptions of end-user needs and the outcomes of the workshop.

Prairie Pothole region↗
USGS2026

Resurvey of the Marble Canyon and Bridge Canyon dam sites in Grand Canyon National Park—Changes in sediment storage and evidence supporting the occurrence of bedrock incision through the mid-20th century

The Bureau of Reclamation developed an extensive plan for a network of dams, water tunnels, and hydropower plants in and around Grand Canyon, Arizona, in the 1940s through 1960s. The two largest of these planned dams were the Marble Canyon and Bridge Canyon Dams on the Colorado River. Though these dams were ultimately never built, Reclamation conducted extensive topographic, bathymetric, and subsurface exploration work at the sites proposed for these dams in the 1940s and 1950s. Resurveys of these dam sites were conducted between 1998 and 2021 to determine the changes in sediment storage at these dam sites caused by the upstream construction and operation of Glen Canyon Dam and by the recession of Lake Mead, the reservoir impounded by Hoover Dam. The resurveys of the Marble Canyon dam sites indicate that the post-1950s changes in sediment storage at these dam sites are broadly consistent with flux-based estimates of voluminous sand erosion from Marble Canyon since the 1963 closure of Glen Canyon Dam. These resurveys also suggest that the pre-dam longitudinal variation in sediment thickness over bedrock played a key role in determining the locations of the sand erosion induced by Glen Canyon Dam; more sand eroded from locations where more sand was present in the 1950s. The resurvey of the Bridge Canyon dam sites indicates that the Colorado River’s incision of the Lake Mead delta is regulated both by bed-sediment grain size and downstream hydraulic controls. Finally, analyses of bed-sediment thickness and sedimentological data at the dam sites, and observations of bed scour and gravel transport, suggest that sufficient bedrock was exposed to allow bedrock incision during commonly recurring pre-dam snowmelt floods that entrained small boulders into transport.

Arizona↗
USGS2026

Altitude of the potentiometric surface and depth to water in the Mississippi River Valley alluvial aquifer, spring 2024

Potentiometric-surface and depth-to-water maps for spring 2024 were created for the Mississippi River Valley alluvial aquifer using groundwater-altitude data from 1,151 wells completed in the Mississippi River Valley alluvial aquifer and from the altitude of the top of the water surface in area rivers from 160 U.S. Geological Survey and U.S. Army Corps of Engineers streamgages. The potentiometric-surface and depth-to-water maps for 2024 were created to support investigations to characterize the Mississippi River Valley alluvial aquifer as part of the U.S. Geological Survey Water Availability and Use Science Program. Sufficient data were available to map the potentiometric surface and depth to water of the Mississippi River Valley alluvial aquifer for spring 2024 for about 83 percent of the aquifer area. The potentiometric contours ranged from 0 to 330 feet (ft) above the North American Vertical Datum of 1988. The regional direction of the groundwater gradient was generally to the south-southwest, except in areas of groundwater-altitude depressions, where the groundwater gradient direction was into the depression, and near rivers, where the groundwater gradient direction was either from the aquifer to the river or from the river into the aquifer. Groundwater depressions in the potentiometric-surface map are in the lower one-half of the Cache region and in most of the Grand Prairie and Delta regions. Depth to water by well in the Mississippi River Valley alluvial aquifer in spring 2024 ranged from 0.27 ft above land surface to 145.65 ft below land surface.

Arkansas, Illinois, Kentucky, Louisiana, Mississip↗
USGS2026

Colored shaded relief bathymetry of Lake Chelan, Washington

In 2023, the U.S. Geological Survey (USGS) completed a 3-week field operation in Lake Chelan, Washington, the third deepest lake in the conterminous United States, to acquire sediment cores, high-resolution bathymetry data, and chirp sub-bottom profiles. The high-resolution bathymetry displayed in this map publication was collected using a Norbit Winghead i67-curved array multibeam system; raw data were cleaned and gridded (3 by 3 meters [m]) in the Teledyne CARIS software. In some locations where the slopes of Lake Chelan are near-vertical, multibeam returns were sparse, resulting in artifacts resembling holes that appear as grey dots within the color-shaded bathymetric relief. Although the 2023 bathymetric mapping of Lake Chelan resulted in similar morphometric characteristics to previous hydrographic campaigns (table 1; Kendra and Singleton, 1987; Pelletier and others, 1989), these new data provide a much more detailed understanding of the two physiographic basins that comprise Lake Chelan: the deeper (as deep as 445.8 m [fig. 1]; previously reported as 453 m) and narrower (1–2 kilometers [km] wide) Lucerne Basin to the north, and the shallower (as deep as 127.8 m [fig. 1]), and wider (2–3 km wide) Wapato Basin to the south. With this detailed imaging of Lake Chelan, we find pervasive morphological evidence of slope failure and mass-transport deposits (MTDs) in at least 89 locations within the lake and 63 subaqueous deltas (fig. 2). The deeper Lucerne Basin is dominated by steep slopes and numerous subaqueous deltas fed by steep fluvial catchments, whereas the Wapato Basin contains numerous landslide scarps, scars, and debris aprons along the more gently sloping lake margins, and abundant relict kettle structures from the Pleistocene deglaciation. Lake Chelan’s geomorphic, geophysical, and sediment data contain important records of glacial retreat and advance, regional volcanic eruptions, and earthquakes that generate ground motions severe enough to induce landslides recorded in the sediment as MTDs. The epicenter of the 1872 Washington State Earthquake (M 6.5–7.2; Bakun and others, 2002; Brocher and others, 2017; Sherrod and others, 2021) is along the Spencer Canyon Fault, near the southern end of Lake Chelan. Shaking from this earthquake was strong enough to affect local aquifers, induce liquefaction of unconsolidated sediments, produce large seiches (Brocher and others, 2018), and likely cause landslides within Lake Chelan.

Washington↗
USGS2026

Streamflow, base-flow, and precipitation trends and simulated effects of groundwater withdrawals from the North Fork Red River aquifer on base flows upgradient from Lake Altus, western Oklahoma, 1980–2022

The U.S. Geological Survey, in cooperation with the Bureau of Reclamation, used five scenarios created from a previously published numerical groundwater-flow model (1980–2013) and historical streamflow records (1980–2022) to investigate the relation between groundwater withdrawals from the North Fork Red River aquifer and inflows to Lake Altus from the North Fork Red River in western Oklahoma. The five scenarios were (1) a scaled-equal-proportionate-share (EPS) groundwater-withdrawal scenario, (2) a study-area-scaled-reported groundwater-withdrawal scenario, (3) a zonal-scaled-reported groundwater-withdrawal scenario, (4) a historical drought-threshold scenario, and (5) a base-flow and evapotranspiration depletion scenario. For the scaled-EPS groundwater-withdrawal scenario, EPS groundwater withdrawals were often much higher than reported groundwater withdrawals and greatly decreased base flows for most scale factors. For the study-area-scaled-reported groundwater-withdrawal scenario, base flows were reduced more but by smaller percentages during wet periods than during dry periods when scaling simulated reported groundwater withdrawals. For the zonal-scaled-reported groundwater-withdrawal scenario, scaling simulated reported groundwater withdrawals within selected zones with more groundwater withdrawals did not always affect base flows more than scaling reported groundwater withdrawals within zones with less groundwater withdrawals. For the historical drought-threshold scenario, curtailing groundwater withdrawals at the drought thresholds increased annual base flows to Lake Altus by about 1,169 to 3,665 acre-feet. For the base-flow and evapotranspiration depletion scenario, the distance between a groundwater well and a stream was a major factor affecting base flow to the North Fork Red River when increasing groundwater withdrawals; however, spatially variable hydrologic properties and saturated-zone evapotranspiration could also affect the relation between base flows and groundwater withdrawals.

Oklahoma↗
USGS2026

Methodology for quantitative spatial sensitivity analysis of volcanic geodetic networks

Introduction This report introduces a methodology for assessing the state of the U.S. Geological Survey Volcano Observatories’ geodetic monitoring networks that measure how volcanoes deform or change shape. This new method uses a model-based approach that considers the uniqueness of the instrument environments at each volcano. This report focuses on simplified volcanic sources, is independent of the shape or size of the volcano, or the network geometry, and thus highlights the strengths and potential vulnerabilities of each volcano’s geodetic network in an actionable visual format. This analysis can help observatories to make informed decisions about whether volcanoes have an adequate level of geodetic monitoring and indicate where improvements are needed.

Lassen Peak, Mount Shasta↗
USGS2026

A methods framework for evaluating measurement consistency across spectrometers for multispectral uncrewed aerial system vegetation mapping applications

The U.S. Geological Survey collects remote sensing data to support national scientific assessments of natural resources, hazards, and landscape change. Spectrometers and spectroradiometers are essential for gathering point-based spectral measurements used in applications such as uncrewed aerial systems (UAS) multispectral image calibration, validation, and analysis. Evaluating how different instruments perform in laboratory and field environments helps determine whether they provide consistent, interoperable measurements. Such verification can expand access to spectral ground data during UAS operations by allowing scientists to use alternative instruments when budgets, logistics, or field conditions limit options. We propose and test a methodological framework for evaluating spectrometers for measurement consistency during UAS multispectral vegetation mapping applications. There are three central evaluation components to the framework: laboratory, field, and relative to UAS multispectral imagery. By evaluating the instruments in both relatively controlled and uncontrolled environments, we thoroughly examine measurement consistency and when/why measurements may differ. We opportunistically selected two instruments for a case study in a coastal marsh setting: a compact laboratory spectrometer we modified for field use and a field-ready spectroradiometer. The instruments produced consistent measurements in both environments. We found differences between the field spectra and UAS spectra that likely reflect the perspectives of ground vs. aerial data and indicate that further radiometric calibration may be needed.

Massachusetts↗
USGS2026

Regional models for postfire debris-flow likelihood and rainfall thresholds across the western United States

The U.S. Geological Survey (USGS) uses an empirical model developed with logistic regression (the ‘M1’ model) to rapidly assess debris-flow likelihood and to identify quantitative rainfall thresholds for debris flows after wildfire in the western United States. The M1 model was calibrated to a debris-flow inventory from southern California (United States) and has been applied throughout the western United States. Limited spatial coverage in the calibration dataset has motivated evaluation of M1 model accuracy outside the calibration region (e.g., the Sierra Nevada or the eastern Cascade Range, United States). Previous test cases showed that M1 overpredicts debris-flow likelihood and underpredicts rainfall thresholds for some locations (e.g., Arizona, northern California, Colorado, New Mexico, United States). We sought to improve the regional applicability of a debris-flow likelihood model by expanding the debris-flow inventory used for calibration, testing multiple potential models and generating an updated model framework. The updated inventory includes 3788 observations from 67 burned areas paired with short duration rainfall ratios. The updated model framework consists of a modified model structure and sets of coefficients calibrated separately to the entire updated inventory and to subsets of the inventory that intersect three Environmental Protection Agency (EPA) Level 2 ecoregions (Mediterranean California, Upper Gila Mountains and Western Cordillera). Comparisons of predictions from the updated models with observed rainfall and debris-flow activity show that the updated models outperform the M1 model by ~15%–60% and improve the uniformity of predictive performance across the western United States. The updated models also reduce false positive rates relative to M1 and generate rainfall thresholds that are better aligned with relative differences in regional climatology and debris-flow activity.

Arizona, California, Colorado, Idaho, Montana, Nev↗
USGS2026

Cotton farming pesticides affect ileal microbiota activity expressions of virulome but not resistome or metabolic pathways in a sedentary wild passerine

The increased use of agrochemicals to enhance crop production has had detrimental environmental effects including implication in the sharp decline of North American farmland-breeding birds. Here, using a combination of deep shotgun metatranscriptomics and pesticide exposure data, we sought to assess whether exposure to cotton ( Gossypium spp.) production had a differential effect on ileum multi-kingdom microbial activity, metabolism, anti-microbial resistance, and virulence factors of sedentary northern mockingbirds ( Mimus polyglottos ) sampled from two cotton-producing areas (16 birds in total) and one uncultivated area (7 birds) in Texas, USA. Both Shannon Index values (Adj. r 2 = 0.174, F (1,21) = 5.633, p = 0.027) and a Mantel test (Spearman ρ = 0.184, p = 0.013) supported a relationship between metabolically active microbiota Bray–Curtis dissimilarities and differences in pesticide mixtures among study areas. Virulence factor richness (Adj. r 2 = 0.182, F (1,21) = 5.890, p = 0.024), Shannon Index (Adj. r 2 = 0.231, F (1,21) = 7.612, p = 0.012), and load (sum of virulence factor abundances; Adj. r 2 = 0.160, F (1,21) = 5.194, p = 0.033) were related to total pesticide load (total quantity of pesticides). We found no pesticide effects on expression of either antimicrobial resistance genes or metabolic pathways.

Texas↗
USGS2026

Impacts of cross-shore winds, waves, and sand ridges on inner shelf circulation

Understanding of circulation on inner continental shelves needs to be advanced to accurately predict the transport and connection between the shelves and nearshore. The circulation over the storm-dominated Fire Island Shelf, New York and a series of in situ shoreface connected sand ridges was investigated through high-resolution field observations, numerical simulations of hydrodynamics, and principal component analyses. The along-shelf subtidal flows were more energetic than the cross-shelf subtidal flows. Alongshore winds were driving the along-shelf subtidal flow and the variability of water levels. The cross-shelf subtidal flows were dominantly onshore near the seabed and offshore near the surface: the processes significant in this two-layer exchange were cross-shore winds which were commonly overlooked in literature, alongshore winds through Coriolis, and bottom friction. The ridges were significant in changing the magnitude and even the direction of the pressure gradients and associated flows. Wave impacts including water level changes, Stokes drift, vortex force, and breaking became significant in the inner shelf and the nearshore during wave-energetic events. Depending on the directions of waves and winds, waves caused to accelerate or decelerate and even reverse the wind-induced flow. In case of more shore-normal waves, the cross-shore Stokes drift became more significant; its interaction with Earth's rotation and flow vorticity generated significant Stokes-Coriolis impacts and vortex force, respectively, in the alongshore. With results applicable to other shelf settings, this study advanced the understanding of spatial and temporal variations of flows along and across inner shelves under varying forcing conditions.

New York↗
USGS2026

Diverging wildfire regimes and doubling of burn area in western United States water supply watersheds

Recent increases in western United States wildfire activity are raising concerns for regional water supplies. Analyzing the wildfire histories (1940-2024) of 3,100 watersheds, we identify a significant regime shift in the late 20th century. Watersheds with higher runoff ratios, critical for regional water provisioning, have significantly increasing burn area trends. The burned areas double following the late 20th century changepoints. Analysis of 17,000 watersheds reveals a diverging fire regime: a transition from moderate burns (1-20% area) towards minimal (<1%) and extensive (> 20%) events. Vulnerability is greatest in forested and mountainous regions, specifically those providing water to 100,000 or more downstream consumers. An integrated watershed management approach, one that considers land management and downstream water operations, may help secure water supplies and mitigate the cascading hazards from wildfire.

western United States↗
USGS2026

Using high frequency GPS data to assess wintering goose proximity to commercial poultry facilities on the Delmarva peninsula for avian influenza risk management and surveillance

The ongoing global outbreak of Highly Pathogenic Avian Influenza Virus (HPAIv) Clade 2.3.4.4 H5N1 in poultry, which was first detected in the United States (USA) in February 2022, underscores the importance of improving food biosecurity and wild bird surveillance. The Delmarva Peninsula is vital to wintering waterfowl and to poultry production, thereby increasing the risk of HPAIv outbreaks. By using fine-scale GPS tracking of Greater Snow Geese (GSGO, N = 59) and Canada Geese (CANG, N = 9) over four winters (2019–2023), we 1) demonstrate a risk ranking system for poultry facilities based on exposure to wintering waterfowl, and 2) model this exposure in relation to temporal, geographic, and land cover factors. We showed that an ordinal-percentile ranking system, based on goose points per hour (gp/h) at poultry facilities, effectively predicted HPAIv H5N1 outbreak risks in the Delmarva Peninsula. Seven facilities with outbreaks were in the 78–99th risk percentile, including one ranked among the top 25 of 6,021 facilities. Such ranking criteria could be used to guide biosecurity efforts when response teams’ resources are limited. Notably, one-third of Delmarva poultry facilities had GPS-marked waterfowl present during winters, indicating a significant presence despite our limited sample sizes. We analyzed the variability in goose exposure rates near poultry facilities over four winters. Time (week) during winter was the key predictor of exposure, with greater GSGO presence in mid-late winter (Dec 15 to Feb 28) and CANG exposure peaking in early winter (Nov 28 to Dec 11), then stabilizing until late winter (Feb to Mar 13), whereupon exposure increased again. Colder temperatures (below 0°C) significantly increased GSGO exposure as they sought waste grain for energy. Goose exposure for both species was high throughout the winter, necessitating 24-hour surveillance. Proximity to sewage treatment plants (≤2 km), National Wildlife Refuges (≤5 km), water bodies (≤5 km), and the coast (≤20 km) increased exposure levels. Additionally, inland areas with features such as reservoirs and lakes supported large numbers of geese near facilities.

Delaware, Maryland, Virginia↗
USGS2026

Site fidelity of American Oystercatcher Haematopus palliatus in the Cape Romain Region, South Carolina, United States of America

Site fidelity of American Oystercatchers Haematopus palliatus to both high-tide roosts and nesting habitats remains less-well studied than other aspects of their ecology. During high tides, shorebirds concentrate at roosts primarily to sleep and preen, and the loss of high-quality roost habitat has been linked to population declines in several species. Similarly, high-quality nesting habitat reduces risks from predation, flooding, and intraspecific competition. Strong site fidelity provides additional benefits by allowing individuals to become familiar with local resources and threats. We evaluated intra- and inter-annual fidelity to nonbreeding roosts, fidelity to breeding sites, and natal philopatry in a largely undeveloped coastal landscape, the Cape Romain Region in South Carolina. This region supports one of the largest resident breeding populations of American Oystercatchers along the Atlantic coast of the USA and roughly one third of the nation’s wintering population. From 2001–2014, on 713 days, we banded 290 adults and 141 chicks and conducted resighting surveys during spring high tides across beaches and shell rake roosts. Both resident and migrant birds exhibited strong fidelity to nonbreeding sites, while resident birds were even more faithful to their breeding locations. The mean distance between successive nest sites was just over 1 km, compared to an average shift of about 3 km among nonbreeding sites (maximum 43 km). Movements between breeding and nonbreeding sites averaged approximately 4 km. Natal fidelity was also high: birds first observed paired on a breeding site did so on average 5 km from their natal site (maximum 18 km), at a mean age of 5 years. In a region characterized by abundant oyster-reef foraging habitat and low disturbance, these patterns likely reflect the predictability of prey resources and the availability of protected roosts.

South Carolina↗
USGS2026

Adult sicydiine gobies visually communicate via a spectacular array of signals, ornaments, and behaviours

Arguably, the most striking aspect of rock-climbing gobies of the subfamily Sicydiinae is their display of colour. Conversely, the taxonomy, biogeography, and migratory aspects of sicydiine biology have progressed much more than has the science of their visual communication and behaviour. Here, we form a virtual team to consolidate and offer our collective experiences in observing sicydiines across many islands, countries, and continental margins, primarily focusing on intraspecific interactions. We provide a framework of visible morphological features of male and female fish, along with natural history commentary, and make preliminary interpretations of the behaviours, their functions, and the circumstances that appear to underlie different types of visual communication by these gobies. We also make use of learning from both (a) studies of sicydiine evolution and ecology where it relates to in-stream migration and predation, and (b) visual communication science which has been derived from studies of other taxa including coral reef fishes ( e.g., wrasses, goatfishes) and model freshwater fish groups such as cichlids, darters, guppies and sticklebacks to interpret some of what we have observed sicydiines doing in streams. We then identify priorities for research and management, contending that this group of fishes represents a very promising model animal group for enhancing understanding of animal visual communication. Whilst tropical streams face a range of threatening processes, sicydiine gobies specifically, are additionally vulnerable to overharvest for the aquarium trade as a function of their attractiveness and spectacular visual displays. The latter is a matter of global conservation relevance.

Cybium↗
USGS2026

Soil seed banks of invasive plant species of the Lower Mississippi River Delta

The invasion routes of non-native species into estuaries can be difficult to determine. Purple loosestrife (Lythrum salicaria) is an invasive species in North America and occurs sporadically in the remote freshwater marshes of the Lower Mississippi River Delta in Louisiana, U.S.A. The origin of L. salicaria in this region, however, is not known. This species has been documented in the Lower Mississippi River in Louisiana since the 1980s but these observed individuals have disappeared and reappeared in the vicinity in subsequent years. We collected soil samples (i.e., soil seed banks) from all known past and present individuals at the time of sampling and attempted to germinate them in a greenhouse under different water regimes, but we did not find germinable seeds of L. salicaria. The lack of a persistent soil seed bank suggests that the establishment of new populations may be from plant fragments originating in either local or upstream sources in the river (e.g., Wisconsin glaciation region). Alternatively, the individuals could be spread from locally developed seeds that do not persist for long periods of time in the soil seed bank. We found only one other non-native species in the soil seed banks of this estuary (Cyperus difformis), although many non-native species exist in the standing vegetation. Knowledge of soil seed bank composition can give insight into the origin of regenerative material for vegetative establishment and inform management approaches to control non-native species.

EarthArXiv↗
USGS2026

Geolocator devices did not affect chick growth or adult return rates in Wedge-tailed Shearwaters (Ardenna pacifica) despite interannual variation in chick development

Although biologging has transformed seabird ecology, bird-borne devices could alter the behaviors being studied, including parental care. We tested for effects of leg-mounted light-level geolocators (< 1% of body mass) on chick growth and adult return rates in Wedge-tailed Shearwaters (‘ua‘u kani, Ardenna pacifica ) breeding on O‘ahu, Hawai‘i during two consecutive breeding seasons that coincided with contrasting El Niño Southern Oscillation (ENSO) years. Accounting for hatching phenology, we compared three responses of two tagging groups (tagged and non-tagged controls): (1) chick growth rates (mass, wing chord, 10th primary), (2) chick survival to fledging, and (3) adult return rates in the following breeding season. We found a significant effect of year on overall chick growth patterns, but no effect of tagging or sex-specific impacts. Chick survival did not differ between groups in either year. Regardless of the tagging group, all chicks in 2023 grew wing chords more slowly and reached lower peak body mass compared to chicks in 2022. However, growth rates did not differ between tagging groups within either season. Despite these interannual differences in chick growth, geolocator deployments did not impact breeding performance or adult return rates to the colony. These results emphasize the importance of evaluating device effects to avoid misinterpreting interannual variability as a tagging impact, and reinforce the value of even small-scale comparisons of tagged and non-tagged groups.

Hawaii↗
USGS2026

An evaluation of transmitter effects on the return rate of adult and juvenile Common Terns to a breeding colony

Advancements in technology have facilitated a rapid expansion in the range of species for which tracking studies can be implemented. Such efforts often require unique attachment methods or materials for which careful evaluation is required to fully understand potential tagging effects and subsequent implications. During the 2021 breeding season, our research team affixed two types of light-weight transmitters to adult and pre-fledgling juvenile Common Terns ( Sterna hirundo ) with leg-loop harnesses made of elastic cord. Our initial observations of these marked birds detected minimal differences in behavior and nesting success of marked adults, and failed to detect any notable impacts on the growth rate or behavior of marked juveniles, but were limited to a single year of data. To provide further insight into the potential effects of these tagging methods, we evaluated return and nesting rates for the 2022 through 2025 breeding seasons. We found that all individuals observed on the breeding grounds in the years following transmitter attachment had not retained the transmitter. The observed tag loss suggest that tag retention could be considered when planning future efforts, and limits our analyses to understanding lagged effects of the unknown duration of actual attachment. With this limitation in mind, we found that birds marked as adults with center-weighted and rear-weighted tags were 1.00 and 0.76 times as likely, respectively, to return to the colony site, and 1.09 and 0.77 times as likely, respectively, to be observed nesting when compared with unmarked controls. Similarly, birds marked as juveniles with rear-weighted transmitters were 0.54 as likely to return, and 0.72 times as likely to nest in subsequent years. These results suggest no negative impacts of center-weighted attachment on return or nesting rates, but moderate support declines in both metrics for birds marked with rear-weighted transmitters.

Maryland↗