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Research about Virginia

Source-linked reports with geographic coverage including Virginia.

At least 19 recordsLinked to original sources
USGS2026

Stream health shows indirect and threshold responses to implementation of agricultural conservation practices

Many agricultural conservation practices (hereafter conservation practices) are intended to protect streams from the deleterious effects of agriculture, but desired effects of their implementation are not always realized. Understanding the pathways through which conservation practices influence stream health can guide future implementation. Our goal was to quantify how conservation practices influence stream health in pastureland watersheds. We asked 4 research questions: R1) What are the effects of land use and conservation practices on instream conditions? R2) What are the effects of instream conditions on biota? R3) What are the relative effects of land use, conservation practices, and instream conditions on biota? R4) How do conservation practice density (no./ha) and agricultural land use interact to influence stream health? We collected data on water quality (total suspended solids, total N, total P, and Escherichia coli bacteria), instream habitat (substrate embeddedness and bank stability), and macroinvertebrate communities from 31 sites in the upper Tennessee River basin of southwest Virginia, USA. The sites collectively represented spatial analytical gradients of agricultural land use and density of conservation practices, with the dominant practices including prescribed grazing, brush management, and fencing. We found that conservation practice implementation was indirectly related to biotic assemblages through changes in water quality and habitat, but practice density in the study area was not associated with instream conditions that supported biotic communities representative of reference conditions. Further improving instream habitat conditions may require innovative conservation practices, targeted placement of practices in critical source areas of pollutants, or higher densities of practices.

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USGS2026

3D Elevation Program—Virginia

Using 3D Elevation Program data, a modern illustration of each State's landscape showcases its elevation differences in vivid detail. Each State has been consistently adjusted and colorized according to its highest and lowest elevations, accentuating differences even in States with low relief. To further emphasize landforms, shaded relief has been added on top of the elevation colors.

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USGS2026

Exploratory ecology of reintroduced elk in Virginia

Reintroductions of extirpated species are an important tool in wildlife conservation. Understanding how reintroduced populations acclimatize to novel environments can lend insight into social learning that in turn is valuable for assessing reintroduction success and maximizing efficacy of subsequent efforts. During 2012, 2013, and 2014, the Virginia Department of Wildlife Resources implemented soft releases of elk ( Cervus canadensis ) translocated to southwestern Virginia from eastern Kentucky. We investigated home range establishment and post-release movements of these reintroduced elk ( n = 60). We found adults moved farther from the release site than either yearlings or calves (F = 6.93, p = 0.001). Elk released in 2012 and 2013 took similar amounts of time to establish home ranges (median 181 days, range 108–214 days; and median 189 days, range 147–209 days, respectively), but individuals released in 2013 remained closer to the release site ( 𝑥 ̲ = 605.5 m, SD = 335.7 m, closer) presumably by joining established social groups. However, the 2014 cohort generally took longer to establish home ranges (median: 231 days; range: 56–258 days) and moved farthest from the release site ( 𝑥 ̲ = 1360.2 m, SD = 293.9 m, farther than 2012 individuals) possibly due to the larger cohort size and resulting intraspecific competition, or the earlier release date that year. Our findings suggest the number of consecutively released cohorts, the timing of the release, and the composition of age classes for released individuals are important considerations for reintroductions.

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USGS2026

Factors affecting benthic macroinvertebrate health in the City of Roanoke, Virginia, 2020–2023

Major waterways in the City of Roanoke (City) have failed to meet Virginia’s aquatic life designated use since 1996. Segments of the upper Roanoke River lack healthy benthic macroinvertebrate communities which prompted a total maximum daily load (TMDL) study by the Virginia Department of Environmental Quality (VDEQ) to identify the most probable stressor(s) causing the impairment. Excess fine sediment was identified as the most probable stressor impairing benthic macroinvertebrates on portions of the Roanoke River in 2006, and a watershed implementation plan published in 2016 required communities within the impaired watershed to implement projects that would reduce the load of fine sediment entering the Roanoke River. Additional benthic macroinvertebrate sampling and stream habitat assessments along the Roanoke River and Tinker Creek (a tributary to the Roanoke River that flows through the City) revealed continued impaired conditions, and subsequent stressor identification analysis was completed in 2023. Samples collected downstream of the City on the Roanoke River and Tinker Creek generally showed more impaired conditions relative to samples collected at locations upstream of the City. Based on this evaluation, sediment and sediment-bound polychlorinated biphenyls (PCBs) were identified as probable stressors while specific conductance, total nitrogen, and sediment metals were possible stressors in Tinker Creek; however, only a sediment TMDL target was identified to address impaired benthic macroinvertebrate communities. In the Roanoke River upstream of the Niagara Dam, sediment and total phosphorus were identified as probable stressors, sediment polycyclic aromatic hydrocarbons and sediment PCB were considered possible stressors; however, the TMDL target was only for total phosphorus. The City partnered with the U.S. Geological Survey (USGS) in 2016 to continuously monitor water quality and streamflow conditions on a major tributary of Tinker Creek, Lick Run, and by 2020, four similar monitoring stations were installed on the Roanoke River and Tinker Creek near the locations of benthic macroinvertebrate sampling. Monitored parameters included streamflow and/or gage height (water level), water temperature, pH, dissolved oxygen, specific conductance, and turbidity. Turbidity is a measure of the relative clarity of the water and was previously used to model suspended-sediment concentrations at the monitoring stations. The City also contracted Kirk Environmental, LLP (KE) to collect benthic macroinvertebrate samples and stream habitat assessments near the locations of the water-quality monitoring stations. Identified benthic macroinvertebrates were used to calculate the Virginia Stream Condition Index (SCI), a multi-metric index composed of eight biological attributes that represent elements of the structure and function of the benthic macroinvertebrate community that measure diversity, composition, and tolerance to pollution. Study objective: In this report, benthic macroinvertebrate samples and stream habitat assessment scores collected at four locations on the Roanoke River and Tinker Creek by KE and the VDEQ between 2020 and 2023 were compared to measured water-quality and streamflow conditions prior to sampling to evaluate patterns between benthic macroinvertebrate health, water quality, and hydrology.

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USGS2026

Computation of regional groundwater budgets for the Virginia Coastal Plain aquifer system

Computation of detailed groundwater flow budgets for subdivisions of the Virginia Coastal Plain aquifer system has enabled quantification and more thorough understanding of groundwater flow within this important water resource. A zone budget analysis based on previously published groundwater models of the Virginia Coastal Plain and Virginia Eastern Shore indicates that groundwater conditions vary substantially throughout the Coastal Plain aquifer system because of local variations in hydrogeology and historical and ongoing variations in groundwater use and management. Decades of substantial groundwater withdrawal from the Coastal Plain aquifer system have altered groundwater flow from predevelopment conditions. Rates of sustainable withdrawal are limited because the downward groundwater flow rate into confined aquifers is a relatively small part of the total groundwater budget for the aquifer system compared to the rate of recharge at the land surface. Analyses of groundwater budgets from the Virginia Coastal Plain model indicate that groundwater flow is generally outward from the surficial aquifer to rivers and coastal waterbodies and downward through a series of underlying aquifers and confining units to the Potomac aquifer, which is the deepest aquifer and the source of most groundwater withdrawals. Downward flow into the Potomac aquifer is estimated to be only 7 percent of total net precipitation-derived net recharge at the land surface but makes up about 66 percent of inflow to the aquifer in Virginia, with much of the remaining inflow occurring laterally from outside of defined groundwater budget regions in Virginia. For several decades prior to 2010, high rates of withdrawal from the Potomac aquifer resulted in substantial decline in groundwater storage in the aquifer and in most overlying aquifers and confining units. From 2010 to 2023, rates of withdrawal substantially lower than the historical maximum resulted in small net increases in groundwater storage in the confined aquifer system for most regions of the Virginia Coastal Plain. Nevertheless, for the same period, groundwater storage for the entire model domain continues to incrementally decline, indicating that storage recovery in Virginia is offset by a continued decrease in storage in areas beneath the Chesapeake Bay or adjacent areas of Maryland and North Carolina. Withdrawals from the Potomac aquifer have induced substantial downward flow which is a large part of groundwater budgets for confined aquifers such as the Potomac. For the most recent simulated conditions (2023) downward groundwater flow continues, but because vertical flow rates are a function of the difference between water pressure in the upper surficial systems and lower confined units, rates of downward flow are lower than those in earlier decades as the confined water levels partially recover from larger groundwater withdrawals in the past. Geographically, groundwater flow is generally inward from perimeter regions of the Virginia Coastal Plain toward central regions with the largest withdrawal rates. Groundwater inflow from coastal regions could be contributing to saltwater intrusion, even though that was not measured in this study. Analyses of groundwater budgets from the Virginia Eastern Shore peninsula, a geographic region of the Virginia Coastal Plain, indicate that groundwater flow for that isolated aquifer system is generally outward from the surficial aquifer to coastal water bodies and downward into the confined Yorktown-Eastover aquifer system, which is the source of most withdrawals. Downward groundwater flow into the confined Yorktown-Eastover aquifer system is estimated to be less than 2 percent of total recharge and less than 9 percent of net recharge at the water table but makes up more than 93 percent of all inflow to the confined aquifer system. Decades of substantial but relatively consistent groundwater withdrawals have induced greater downward flow rates into the confined aquifer system but also have resulted in loss of groundwater from storage. For the most recent simulated period (2023), estimated storage loss accounts for slightly under 7 percent of withdrawals from the confined aquifer system. The reported withdrawal rate for this period from the confined Yorktown-Eastover system is near the highest reported rate for the Virginia Eastern Shore, which means that the storage depletion is expected to continue, even though groundwater levels appear to be relatively stable. Estimated groundwater flow rates upward from the confining unit underlying the Yorktown-Eastover system and low rates of inflow from coastal water bodies underscore ongoing concerns about up-coning and lateral intrusion of salty groundwater.

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USGS2026

Assessment of natural gas pipeline construction on stream temperature and turbidity in southwestern Virginia, 2017–25

Despite the extensive natural gas pipeline network in the United States that intersects streams and other sensitive habitats, few case studies use a comparative upstream-to-downstream approach to evaluate potential short- and long-term effects of pipeline stream crossings from pre-construction through post-restoration. In 2017, the U.S. Geological Survey, in cooperation with the Virginia Department of Environmental Quality, deployed real-time continuous stream monitoring stations upstream and downstream from six proposed Mountain Valley Pipeline stream crossings in southwestern Virginia. Water temperature and turbidity data collected at the upstream and downstream sites were compared across three periods—before stream crossing construction, during stream crossing construction, and after stream crossing construction—to determine potential influences from the pipeline stream crossing. Additionally, the monitoring network was used to notify regulators of potentially anomalous conditions throughout the entire monitoring period. The results of this study indicate that pipeline stream crossing did not affect long-term or short-term upstream-to-downstream water temperature conditions or long-term upstream-to-downstream turbidity conditions in any of the six monitored streams. Some short-term anomalously elevated turbidity conditions were observed and attributable to pipeline stream crossing; however, the magnitudes and durations were not sufficient to alter the long-term turbidity regimes of the streams in which they were observed. The application of the monitoring network as a real-time alert system successfully alerted regulators to potentially anomalous conditions.

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USGS2026

Multiscale resource selection for a reintroduced elk population

Patterns of resource selection are driven by the decision-making processes of animals occurring at multiple scales from where to establish a home range (i.e., second order selection) to which resource patches to use within the home range (i.e., third order selection). Elk ( Cervus canadensis ) were reintroduced to southwestern Virginia, USA, from 2012 to 2014 following successful translocations onto reclaimed surface coal mines in the region. We sought to understand how elk have acclimated following their translocation using location data from GPS-collared adult female elk ( n = 33) collected from 2019 to 2022 along with remotely sensed terrain and land cover data. We utilized continuous-time movement models paired with generalized linear mixed-effects modeling to describe seasonal resource selection at second and third orders. At both scales of selection and throughout the year, female elk selected reclaimed surface mines, conifer forests, ridgetops, and areas with lower terrain roughness, while avoiding mixed hardwood and oak ( Quercus spp.) forests. Unmined open land was only selected at the third order during periods of forage scarcity (i.e., winter) and increased metabolic requirements (i.e., late gestation). Although surface coal mining leaves legacy environmental impacts on the landscape, management of these sites provides benefits to elk and maintains open habitat that is otherwise limited.

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USGS2026

Development of a SWAT+ model to improve conservation practice efficacy for protecting stream health in karst pasturelands

Placing appropriate conservation practices in critical source areas of pollutants can benefit stream health in karst environments susceptible to agricultural pollution. Watershed models, such as the Soil and Water Assessment Tool+ (SWAT+), can optimize both practice selection and placement across the landscape, but to our knowledge no studies have tested this model in karst pasturelands. Our goal was to understand pollutant dynamics in pasturelands with karst topography in southwest Virginia, United States. We built a SWAT+ model to predict streamflow and pollutant loads for four watersheds. SWAT+ predicted that streamflow estimates were most affected by setting the available water capacity to zero and increasing the hydraulic conductivity of the soil, revealing that water, and associated pollutants, move primarily through subsurface pathways. Predicted sediment yield was negatively associated with agricultural land cover and was strongly influenced by channel erodibility—indicating that the predominant sediment source may be streambanks. Therefore, practices that stabilize stream banks (e.g., fencing cattle out of streams) may be most effective at reducing sediment loads. The model unsatisfactorily predicted total nitrogen and total phosphorus loads. The utility of SWAT+ for cattle grazing operations in karst regions could be improved by more accurately representing the effects of cattle grazing on streambank erosion and the dynamic subsurface movement of pollutants.

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USGS2026

Transit time modeling framework for predicting freshwater salinization in urban catchments

The salinity of inland freshwaters is rising globally, particularly in urban watersheds where winter road deicers are widely applied. Attributing stream salinity dynamics to specific sources and transport pathways remains challenging due to episodic salt inputs, engineered drainage, and strong coupling between hydrology and subsurface storage. We present a modeling framework that couples climate-driven deicer build-up and wash-off with transient transit time distribution theory to simulate salt transport through drainage, interflow, and groundwater pathways. Applied to an urban watershed in Northern Virginia (USA), the model reproduces ten years of high-frequency stream salinity measurements across daily-to-decadal timescales. The calibrated model implies an average deicer application of 206 tonnes Cl −1 yr −1 , or roughly one 20 kg bag of rock salt person −1 yr −1 when normalized by the 20,000 people living in the watershed. In winter months, higher infiltration routes a large fraction of snowmelt and deicers into shallow subsurface pathways, enhancing vadose-zone and interflow contributions to stream salinity. Limited subsurface storage capacity and seasonal hydrologic turnover flush excess chloride from the vadose zone and groundwater during subsequent summer storms. By linking climate-driven deicer inputs, hydrologic connectivity, and stream water age, the framework provides a transferable basis for diagnosing and managing freshwater salinization in urban watersheds.

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USGS2026

Environmental tradeoffs of urban stream restoration in Fairfax County, Virginia

Regulatory mandates to improve water quality and stream health have driven substantial investment in stream restoration. Most projects aim to improve channel-floodplain connectivity, reduce sediment erosion, and enhance habitat for aquatic organisms, yet few include adequate pre- and post-restoration monitoring to assess outcomes. Since 2007, Fairfax County, Virginia, and the U.S. Geological Survey have partnered to monitor and evaluate water-quality conditions in Flatlick Branch. In 2018, a 1.72-km reach of stream above the monitoring station was restored using a Natural Channel Design approach. This study applied the Stream Functions Pyramid (SFP) framework to evaluate restoration tradeoffs. Post-restoration, watershed hydrology remained largely unchanged, but channel modifications increased flow capacity, reduced velocity, and further disconnected the channel from the floodplain. Nutrient and sediment reductions exceeded expected amounts, but the removal of over 20 % of riparian tree canopy increased physicochemical variability and the frequency and magnitude of water temperature heatwaves. Post-restoration, state standards for low dissolved oxygen and elevated pH were exceeded 2.5 and 7.5 times more often, respectively. Gross primary production and ecosystem respiration increased and organic matter sources supporting metabolism shifted from allochthonous to autochthonous. Trends in several benthic macroinvertebrate metrics, which were improving prior to construction, have since plateaued or declined, and the fish assemblage shifted from a native minnow dominated community to non-native, warmwater tolerant taxa. This study highlights the need for comprehensive assessments of stream restoration and benefits of using the SFP to understand the consequences and possible tradeoffs of different ecosystem management decisions.

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USGS2026

Annual-cycle movement patterns of Eastern Brown Pelicans (Pelecanus occidentalis carolinensis) from the northern end of their breeding range

Understanding the variability in movement patterns of marine birds throughout their annual cycle is critical to ecosystem-based management in coastal regions. Tracking data from seabirds frequently demonstrates that movement patterns throughout the annual cycle are more complex and extensive than previously thought, and that factors that influence these movements differ throughout the species' range. During May of 2023, we deployed satellite tags on Eastern Brown Pelicans ( Pelecanus occidentalis carolinensis ) breeding in the Chesapeake Bay region, an area that supports commercial fisheries for forage fish, offshore energy production, and lies at the northern end of the species' breeding range. During the breeding season pelicans foraged throughout Chesapeake Bay and along the Atlantic coast up to 75 km from the breeding colony. Interannual shifts in use areas were linked to colony switching. Post-breeding, pelicans consistently staged in the mid-Chesapeake Bay before southward migration. Wintering locations extended from the Chesapeake Bay to Cuba. The study demonstrates that pelicans breeding in the Chesapeake Bay region exhibit high variability in movement patterns within and outside of the breeding season. Therefore, marine spatial plans within and beyond the Chesapeake region may need to account for intra-population variability in movement patterns to ensure long-term success.

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USGS2026

Characterization of the native freshwater mussel assemblage across a reach of the Rappahannock River, Virginia

Native freshwater mussels occur in rivers of all sizes, yet much of the literature focuses on small- to medium-sized rivers, likely because of logistic challenges of sampling deep, fast, and turbid large rivers. As large-river surveys become more common, the information resulting from a systematic sampling design can provide baseline data on population sizes to inform decision making by resource managers. We collected baseline data on mussel resources in the Rappahannock River, Virginia, in August 2024. This Atlantic coast river, which drains into the Chesapeake Bay, is ∼320 km long, up to 1.6 km wide, and up to 35 m deep. We conducted a systematic quantitative survey across the 75-km reach of the river from Fredericksburg to Leedstown, Virginia. Divers obtained 187 whole substrate samples to estimate the species richness, density, population size, size distribution, community composition, and longitudinal spatial distribution of the native mussel assemblage. Six species were found, and the community was dominated by Eastern Elliptio ( Elliptio complanata ). Mean reach density (± 1 standard error) and population size was 1.25 (0.21) mussels m 22 and 19.3 (3.3) million mussels, respectively. The presence of few fresh dead mussels indicated low to moderate natural mortality. Shell length ranged from 32 to 122 mm, and multiple size classes were observed in E. complanata . Species richness and density had similar longitudinal patterns, with the highest values in the middle of the sampled reach (river kilometers 60–95). These data provide resource managers with baseline information on the spatial distribution, density, length demography, diversity, and evenness of native freshwater mussels across this reach of the Rappahannock River. Identification of mussel occurrence, density, and evidence of reproduction can be used by managers to aid conservation and management decisions such as prioritizing areas for reintroductions and habitat restoration.

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USGS2025

Landowners' cognitions and motivations coupled with practice durability influence persistence in grazing agricultural conservation practices in southwest Virginia

Agricultural conservation practices are often used to protect stream health while continuing food production. However, recovery of stream health is often not as rapid or extensive as planned. The efficacy of practices may be improved by promoting their continued use by landowners (i.e., persistence) after cost-share contracts with government agencies end. Persistence rates and their drivers are typically unknown. Therefore, we mail-surveyed 889 landowners to understand persistence in grazing practices in southwest Virginia. Survey responses were analyzed quantitatively using logistic regression and qualitatively via coding. We found that persistence rates for vegetative practices, cattle-exclusion fencing, off-stream watering structures, and pasture management were 74%, 84%, 94%, and 94%, respectively. Both the quantitative and qualitative analyses indicated that landowner cognitions (i.e., attitudes toward practices, environment, and agencies), environmental motivations, and practice durability influence persistence. Our results highlight that persistence could be encouraged by: (1) providing targeted messaging that demonstrates persistence benefits and aligns with landowners' motivations, (2) ensuring that responsibility to maintain practices is transferred during land-tenure changes, and (3) allocating more agency funding to practice maintenance.

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USGS2025

A 10-year continuous daily simulation of chloride flux from a suburban watershed in Fairfax County, Virginia, USA

Increasing levels of chloride in surface water are associated with detrimental effects on water quality, aquatic ecosystems, infrastructure, and human health. Numerous mass-balance studies have inferred watershed transport processes by interpreting chloride inputs and outputs, but few represent internal dynamics explicitly. We constructed a coupled water/chloride mass balance model to gain insights into storage, residence time, and transport processes in a 10-km 2 urban watershed. The model, which operates over a 10-year period at a daily time scale, represents storage in a dynamic soil-moisture reservoir, quick-flow runoff from storm events, and slow-flow runoff that sustains streamflow in dry weather. The calibrated model accurately represented (a)the observed transition from a streamflow enrichment regime in cold months to a dilution regime in warmer months, (b) the observed tendency for late-summer concentrations to be higher after winters with heavy snowfall, and (c) a period-of-record downward trend in chloride concentration likely associated with a downward trend in annual snowfall. Estimated chloride inputs averaged 195 metric tons per year, while the average output was 270 metric tons per year. In contrast, estimated storage was only 107 metric tons. The estimated mean residence time in groundwater was 1.27 years. This short residence time indicates that efforts to reduce inputs will manifest as decreased concentrations in streamflow on a management-relevant time scale of several years. The coupled mass balance model yielded insights into internal watershed dynamics that would not be possible from simple input/output analysis; such models can be useful tools for gaining insight into small watershed hydrology and pollutant transport.

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USGS2025

Using satellite imagery and soil data to understand occurrences and migration of soil conditions harmful to archaeological sites on Jamestown Island, Virginia

Many know Jamestown Island, Virginia, hereafter referred to as “the Island,” located near the mouth of the James River into the Chesapeake Bay, as the home of the first permanent English settlement in North America. However, the Island is home to 15,000 years’ worth of cultural artifacts and archaeological sites. In addition to its rich history, the Island is home to a variety of native plants and animals, including many rare, threatened, and endangered species. Preserving historical and natural resources is part of Colonial National Historic Park’s (COLO) enabling legislation. To this end, COLO has been seeking data to inform management decisions on how to prioritize resources to preserve archaeological sites and anticipate changes to natural systems from sea-level rise and other effects of climate change. The U.S. Geological Survey (USGS), in partnership with COLO, collected and analyzed data to help determine soil conditions detrimental to archaeological sites across the Island using a combination of soil samples and assessments of vegetative health as a proxy for soil conditions. This study combined normalized difference vegetative index raster grids spanning 8 years, 2010 to 2018, and soil data from 50 sites sampled in dry (June 2021) and wet months (March 2022) at two different soil horizons to investigate potential hazards to plant health and corrosive conditions in the unsaturated subsurface. The data suggest that access to the James River drives soil pH and soil conductivity. Areas of the Island that are subject to frequent inundation were observed to have both higher soil conductivity (as high as 4,845 millisiemens per meter [mS/m]) and lower pH (as low as 3.84). Higher soil conductivity, or salinity, and more acidity create corrosive environment, which can destroy buried artifacts and are detrimental to vegetative health. These conditions were not limited to the edges of the Island, like Black Point. Inland locations, such as the Pitch and Tar Swamp, were observed to have some of the highest conductivity values, which were likely caused by from a combination of inflow of James River water along Back Creek into the Pitch and Tar Swamp and proximity to the Visitor Center and other high-traffic areas of the Island. A difference of normalized difference vegetative index values from 2010 to 2018 raster grid appears to support this, showing an apparent loss of vegetative health in marsh grass in the Pitch and Tar Swamp. These data may inform COLO about areas of the Island that are currently most threatened by corrosive conditions and how those conditions are likely to migrate in the future.

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USGS2025

Calcareous nannofossil biostratigraphy and floral response to environmental changes recorded in the Pliocene Yorktown Formation, southeastern Virginia, USA

The Pliocene Yorktown Formation, deposited on the U.S. Mid-Atlantic Coastal Plain, has played an important role in advancing our knowledge of Pliocene paleoclimate. To refine the age and paleoenvironment of the Yorktown Formation, we analyzed the calcareous nannofossil assemblage and compared it with variations in lithology and calculated sea surface temperature (SST) from previous studies. The Yorktown Formation in the studied sections consists of, in ascending order, the Sunken Meadow, Rushmere, Morgarts Beach, and Moore House members. Sediment samples were collected from these units and analyzed for calcareous nannoplankton assemblages. The last occurrences of both Reticulofenestra pseudoumbilicus (3.82 Ma) and Sphenolithus spp. (3.61 Ma) were recognized within the Sunken Meadow Member. Discoaster tamalis and Discoaster surculus sporadically occurred within the Rushmere Member, but no specimens of the genus Sphenolithus were recorded, suggesting that this unit was deposited sometime between 3.61–2.76Ma. Rare occurrences of the genus Discoaster made it difficult to constrain the age of the Morgarts Beach and Moore House members, but they are most likely deposited before re-entrance of small Gephyrocapsa (ca. 2.5 Ma), supporting previous age estimates based on planktic foraminiferal biostratigraphy and variation in alkenone-based sea-surface temperature estimates. The abrupt decline of both cold-water species ( Coccolithus pelagicus ) and coastal species ( Helicosphaera spp.) is associated with a rise in SST within the Rushmere Member just below the Morgarts Beach Member, and it may reflect a rapid transgression following the global sea-level low stand associated with Marine Isotope Stage (MIS)M2.

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USGS2025

Hiding in plain sight: Genomic characterization of a novel nackednavirus and evidence of diverse adomaviruses in a hyperpigmented lesion of a largemouth bass (Micropterus salmoides)

Largemouth bass (LMB; Micropterus nigricans ) are popular both as a sportfish and an aquaculture species. At present, six described viruses are associated with LMB, of which two are typically considered in cases of LMB mortality events. Advances in discovery and diagnostic capabilities using next-generation sequencing have augmented surveillance efforts and subsequently led to the discovery of novel cryptogenic viruses. Here, we present evidence of three novel viruses from a single skin sample collected from a hyperpigmented melanistic lesion of an LMB with blotchy bass syndrome associated with MnA-1 co-infection. These viruses represent recently described groups of viruses (adomaviruses and nackednaviruses) that infect fish. Both are markedly understudied and of unknown significance to fish health. This work highlights the diversity of viruses associated with LMB and further advances our understanding of the LMB virome. Application of de novo sequencing approaches presents an opportunity to explore a new frontier of host–pathogen relationships and microbes associated with changing environments.

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