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17 recordsLinked to original sources
USGS2026

Climate-driven waterline variability along the North American West Coast

Sandy coasts are highly dynamic environments shaped by a myriad of hydro-sedimentary processes operating across various spatio-temporal scales. From seasonal to centennial timescales, sandy beach dynamics are strongly influenced by climate variability expressed in various forms, including seasonal cycles, climate modes (e.g., El Niño Southern Oscillation (ENSO)), and global warming. Satellite-based methods enable the observation of coastlines with unprecedented spatial and temporal coverage. However, over the past decade, as these methods have matured, coastal change studies have predominantly focused on long-term trends rather than on climate-driven cycles of shoreline change. In this study, we utilize a large dataset of monthly-sampled time series of waterline positions along the Pacific Coast of the United States and Baja California, Mexico. From these time series, we derived information on long-term trends and seasonal cycles of waterline change. Our analysis reveals clear contrasts in seasonal patterns of waterline variability across the study area, with greater amplitudes observed at higher latitudes. A shift in the dominant dynamics is evident in Southern Baja California, where shoreline variability is more influenced by intertropical dynamics and sea-level anomalies than by wave energy modulation, which dominates further north. ENSO is found to induce contrasting responses of the waterline along the study area. During El Niño events, shoreline retreat is observed in subtropical regions, while La Niña winters drive waterline retreat in higher latitudes, with southern regions either remaining stable or advancing.

Baja California, California, Oregon, Washington↗
USGS2025

Waterline responses to climate forcing along the North American West Coast

Understanding waterline variability at seasonal to interannual timescales is crucial for predicting coastal responses to climate forcing. However, relationships between large-scale climate variability and coastal morphodynamics remain underexplored beyond intensively monitored sites. This study leverages a newly developed 25-year (1997–2022) satellite-derived waterline dataset along the North American West Coast. Our results reveal distinct latitudinal patterns in seasonal waterline change, with excursions exceeding 25 m in the Pacific Northwest, decreasing to less than 10 m in Southern California and farther south. Waterline fluctuations strongly follow wave power in the Pacific Northwest ( R = −0.78), northern California ( R = −0.75), and Baja California ( R = −0.62), while Baja California Sur aligns more with sea-level variations ( R = −0.42). Interannually, waterline change exhibits latitudinal dependence: south of southern California, variability is low, with major erosion confined to strong El Niño-Southern Oscillation (ENSO) events, while northern regions show mixed responses. ENSO-driven storm track shifts modulate winter wave climate, resulting in enhanced (attenuated) erosion from southern California to Baja California Sur during El Niño (La Niña). However, further north, ENSO impacts are less consistent, reflecting a complex interplay of storm track displacement and intensification. These findings highlight the spatial complexity of ENSO-driven morphodynamics and provide a framework for assessing climate-induced coastal vulnerability.

North American West Coast↗
USGS2003

Tale of two pit lakes: initial results of a three-year study of the Main Zone and Waterline pit lakes near Houston, British Columbia, Canada

Pit lakes are becoming increasingly common in North America as well as in the rest of the world. They are created as openpit mines fill passively with ground water and surface inflows on cessation of mining activity. In many instances, the water quality in these pit lakes does not meet regulatory requirements due to a number of influences. The most important are the oxidation of sulfide minerals and the associated release of acid and metals and the flushing of soluble metals during pit filling. Examples of pit lakes with severe water-quality problems include the Berkeley Pit lake (Butte, MT) and the Liberty Pit lake (Nevada), whose waters are characterized by a pH near 3 and Cu concentrations as high as ~150 mg/L (Miller et al., 1996; Davis and Eary, 1997). The importance of the problem can be seen in the fact that some of these sites in the United States are Superfund sites.

British Columbia;Texas↗
USGS2006

Ground-water/surface-water interaction in nearshore areas of Three Lakes on the Grand Portage Reservation, northeastern Minnesota, 2003-04

The U.S. Geological Survey (USGS), in cooperation with the Grand Portage Band of Chippewa Indians, applied three techniques to assess ground-water/surface-water interaction in nearshore areas of three lakes (North, Teal, and Taylor) on the Grand Portage Reservation in northeastern Minnesota. At each lake, analyses of existing aerial photographs, in-situ temperature measurements of shoreline lake sediment, and chemical analyses of surface water and pore water were conducted. Surface-water and pore-water samples were analyzed for major constituents, nutrients, and stable isotopes of oxygen and hydrogen. Bulk precipitation samples were collected and analyzed (1) for nutrient concentrations to determine nutrient input to the lakes through atmospheric deposition and (2) for stable isotope ratios of oxygen and hydrogen to determine a meteoric waterline that was needed for the stable isotope analyses of surface-water and pore-water samples. Total nitrogen concentrations in the precipitation samples ranged from 0.51 to 8.4 mg/L (milligrams per liter) as nitrogen at the North Lake precipitation station and from 0.42 to 2.3 mg/L as nitrogen at the Grand Portage precipitation station. Oxygen-18/oxygen-16 and deuterium/protium isotope ratios for the bulk precipitation samples lie relatively close to a meteoric waterline for northern Wisconsin, except for the ratios for samples collected on May 20, 2004. Analyses of existing aerial photographs, nearshore lake-sediment temperatures, and seasonal isotope ratios of surface-water and pore-water samples were the most valuable data for identifying locations of ground-water inflow and surface-water outseepage. Analyses of existing aerial photographs of the three lakes indicated the location of potential inflow channels and lineaments identifying potential ground-water inflow locations for pore-water sampling. Lake-sediment temperatures at potential ground-water inflow locations ranged from 4 to 16 ºC, varying between lakes, seasons, and climatic conditions. Major constituent chemistry was valuable at Taylor Lake, and to a limited extent at North and Teal Lakes, in confirming results from the isotope and lake-sediment temperature data. Ground-water inflow to North Lake likely occurs along the southwest and south shores, and along portions of the west, southeast, north, and northeast shores. Relatively cool lake-sediment temperatures along the southwest, south, west, and southeast shores, and in isolated beaver channels along the north and northeast shores of North Lake indicate potential ground-water inflow at these locations. Both localized ground-water inflow and surface-water outseepage occurs along portions of the north, northeast, southeast, and south shores, varying seasonally. Conflicting evidence for ground-water flow conditions exist for the northwest and north-northwest pore-water samples. Only minor differences in the major constituent concentrations were seen between the surface-water and pore-water samples from the North Lake area with the exception of iron and manganese concentrations. Ground-water inflow likely takes place along the south-southwest and north shores of Teal Lake, with a mixture of ground-water inflow and surface-water outseepage occurring in other areas of the lake. Cooler lake-sediment temperatures occurred along the south-southwest, west, and northwest shores, portions of the north shore, and in channels identified in aerial photographs throughout the lake, indicating potential ground-water inflow at those locations. Warmer lake-sediment temperatures along the northeast and portions of the southwest and northwest shores of Teal Lake indicate potential locations where surface-water outseepage or little ground- and surface-water interaction occurs. The major constituent concentrations were higher in the pore-water samples collected from the south-southwest and northeast shores of Teal Lake, indicating ground-water inflow. Cation adsorption, cation exchanges with hydrogen ions, and chelation with organic materials occurring in the fen surrounding the lake likely resulted in the low dissolved calcium, magnesium, and sodium concentrations in north, northwest, and west pore-water samples from the Teal Lake area. Pore-water samples from the south-southwest, north, and southwest shores of Teal Lake had isotopic compositions that plotted closest to the meteoric waterline, indicating that little evaporation or transpiration occurred in these samples and that ground-water inflow may be occurring at these locations. Surface-water outseepage from Teal Lake likely occurs along the northeast shore even though major constituent concentrations were high. Major constituent concentrations may be high because of a nearby beaver dam. Ground-water inflow to Taylor Lake likely occurs at the north and south pore-water sampling sites. Higher major constituent concentrations and the least evaporative isotope ratios were found in pore-water samples along the south, north, and west shores of Taylor Lake, indicating potential locations of ground-water inflow. However, a combination of warmer and cooler lake-sediment temperatures along the west lowland indicated that ground-water inflow and surface-water outseepage may occur at that location. Surface-water outseepage likely occurs from Taylor Lake along the south shore through a surface-water drainage channel to a downgradient bog. Warmer lake-sediment temperatures along portions of the south and southeast shores indicate that surface-water outseepage may occur at those locations. Both ground-water inflow and surface-water outseepage may occur along the west, southeast, and east shores of Taylor Lake, varying seasonally and with local precipitation. Knowledge of general water-flow directions in lake watersheds and how they may change seasonally can help water-quality specialists and lake managers address a variety of water-quality and aquatic habitat protection issues for lakes. Results from this study indicate that ground-water and surface-water interactions at the study lakes are complex, and the ability of the applied techniques to identify ground-water inflow and surface-water outseepage locations varied among the lakes. Measurement of lake-sediment temperatures proved to be a reliable and relatively inexpensive reconnaissance technique that lake managers may apply in complex settings to identify general areas of ground-water inflow and surface-water outseepage.

Minnesota↗
USGS2022

Where groundwater seeps: Evaluating modeled groundwater discharge patterns with thermal infrared surveys at the river-network scale

Predicting baseflow dynamics, protecting aquatic habitat, and managing legacy contaminants requires explicit characterization and prediction of groundwater discharge patterns throughout river networks. Using handheld thermal infrared (TIR) cameras, we surveyed 47 km of stream length across the Farmington River watershed (1,570 km 2 ; CT and MA, USA), mapping locations of bank and waterline groundwater discharges based on their thermal signature. Using the observed groundwater discharge locations and predicted groundwater discharge rates from 6 variations of a numerical groundwater-flow model (MODFLOW-NWT), we compared 1) predicted groundwater-discharge rates in areas with and without observed groundwater discharge, 2) spatial patterns of observed and predicted groundwater discharge locations, and 3) density of observed groundwater discharge locations with predicted discharge rates. Five of six models reasonably predicted the spatial patterns of discharge locations along the 5th order mainstem, but fewer models predicted groundwater discharge patterns in smaller streams. Our results highlight 1) the feasibility of using TIR observations to evaluate groundwater models, 2) model parameters that influence discharge prediction accuracy (riverbed sediment and bedrock hydraulic conductivity and river-aquifer connections), and 3) current strengths and future opportunities for improved modeling of groundwater-discharge patterns.

Connecticut, Massachusetts↗
USGS2023

Monitoring interdecadal coastal change along dissipative beaches via satellite imagery at regional scale

Coastal morphological changes can be assessed using shoreline position observations from space. However, satellite-derived waterline (SDW) and shoreline (SDS; SDW corrected for hydrodynamic contributions and outliers) detection methods are subject to several sources of uncertainty and inaccuracy. We extracted high-spatiotemporal-resolution (~50 m-monthly) time series of mean high water shoreline position along the Columbia River Littoral Cell (CRLC), located on the US Pacific Northwest coast, from Landsat missions (1984–2021). We examined the accuracy of the SDS time series along the mesotidal, mildly sloping, high-energy wave climate and dissipative beaches of the CRLC by validating them against 20 years of quarterly in situ beach elevation profiles. We found that the accuracy of the SDS time series heavily depends on the capability to identify and remove outliers and correct the biases stemming from tides and wave runup. However, we show that only correcting the SDW data for outliers is sufficient to accurately measure shoreline change trends along the CRLC. Ultimately, the SDS change trends show strong agreement with in situ data, facilitating the spatiotemporal analysis of coastal change and highlighting an overall accretion signal along the CRLC during the past four decades.

Oregon, Washington↗
USGS2023

Accuracy and precision of sea-finding orientation as a function of dune proximity in hatchlings of two species of sea turtles

Context: Sea turtle hatchlings generally emerge at night from nests on sand beaches and immediately orient using visual cues, which are believed to entail the difference in brightness between the light seen in the seaward direction and that seen in the duneward direction. Aim: The aim of this study was to understand how dune proximity affected hatchling orientations in two sea turtle species that share a nesting beach 15 km long and 25.3 ± 9.4 m ( N = 215) from dune to waterline, with low to moderate artificial light nearby. Methods: For hatchling loggerhead and green turtles, we measured accuracy and precision of orientation, tested differences in distance from nest to dune, and investigated the effect of dune proximity on hatchling orientation. Key results: We found a significant decrease in hatchling orientation accuracy and precision in both species as the distance increased from nests to dune. Loggerhead and green turtles showed similar orientation ability when in the same proximity to the dune. Conclusions: We conclude that dune features provide important cues for hatchling orientation on sea turtle nesting beaches. Implications: Restoring and maintaining natural beach profiles, especially dune systems, is likely to increase the accuracy and precision of sea finding in hatchling sea turtles.

Florida↗
USGS1999

Maturation, fecundity, and intertidal spawning of Pacific sand lance in the northern Gulf of Alaska

Pacific sand lance Ammodytes hexapterus in Kachemak Bay, Alaska, showed no sexual dimorphism in length-to-weight (gonad-free) ratio or length-at-age relationship. Most matured in their second year, males earlier in the season than females, but females (31%) attained a higher gonadosomatic index than males (21%). Sand lance spawned intertidally once each year in late September and October on fine gravel or sandy beaches soon after the seasonal peak in water temperatures. Sand lance in Cook Inlet and Prince William Sound displayed similar maturation schedules. Schools were dominated 2: 1 by males as they approached the intertidal zone at a site where spawning has taken place for decades. Sand lance spawned vigorously in dense formations, leaving scoured pits in beach sediments. Fecundity of females (93–199 mm) was proportional to length, ranging from 1468 to 16 081 ova per female. About half of the overall spawning school fecundity was derived from age group 1 females (55% of the school by number). Spawned eggs were 1·02 mm in diameter, demersal, slightly adhesive, and deposited in the intertidal just below the waterline. Sand lance embryos developed over 67 days through periods of intertidal exposure and sub-freezing air temperatures.

Alaska↗
USGS2000

Origin of the 17 July 1998 Papua New Guinea tsunami: Earthquake or landslide

The tsunami that struck Papua New Guinea on 17 July 1998 shortly after a M w 7.0 earthquake ( Figure 1 ) was one of the deadliest tsunamis in this century. At least 2,200 people died from this event, essentially destroying an entire generation in some communities. In the months following the tsunami, several international survey teams collected data in an attempt to better understand the cause of this event. Elevations of waterline marks and displaced debris measured by the first International Tsunami Survey Team (ITST; Kawata et al., 1999 ) indicated an average runup of 10 m occurring over a 25 km length of coastline in the vicinity of Sissano Lagoon ( Figure 2 ). The maximum runup from this event was approximately 15 m. Tsunami runup heights of this size are commonly associated either with earthquakes of much larger magnitude or with “tsunami earthquakes” as defined by Kanamori ( 1972 ) and later discussed by Kanamori and Kikuchi ( 1993 ). Even for tsunami earthquakes, however, runup heights of 10-15 m seem only to occur for earthquakes M w > 7.5. Because these runup heights appear anomalously high for a M 7 earthquake, other sources have been postulated for the tsunami, including a submarine landslide or mass flow. Earlier this year, the bathymetry north of Papua New Guinea was surveyed by the Japan Marine Science and Technology Center (JAMSTEC) and the South Pacific Applied Geoscience Commission (SOPAC). In a report describing the preliminary results from these cruises ( Tappin et al. , 1999 ), bathymetric images are presented that show evidence both of a 40-km-long fault scarp and of collapse features within an approximately 10-km-wide bathymetric amphitheater ( Figure 2 ). The report suggests that a landslide was the sole cause for the tsunami. In this paper, I revisit the common assumption that local tsunami runup scales directly with moment magnitude and demonstrate that the tsunami generated by the earthquake cannot be disregarded to explain the runup observations.

Seismological Research Letters↗
USGS2012

Assessing the vulnerability of public-supply wells to contamination: Rio Grande aquifer system in Albuquerque, New Mexico

This fact sheet highlights findings from the vulnerability study of a public-supply well in Albuquerque, New Mexico (hereafter referred to as “the study well”). The study well produces about 3,000 gallons of water per minute from the Rio Grande aquifer system. Water samples were collected at the study well, at two other nearby public-supply wells, and at monitoring wells installed in or near the simulated zone of contribution to the study well. Untreated water samples from the study well contained arsenic at concentrations exceeding the Maximum Contaminant Level (MCL) of 10 micrograms per liter (µg/L) established by the U.S. Environmental Protection Agency for drinking water. Volatile organic compounds (VOCs) and nitrate also were detected, although at concentrations at least an order of magnitude less than established drinking-water standards, where such standards exist. Overall, study findings point to four primary influences on the movement and (or) fate of contaminants and the vulnerability of the public-supply well in Albuquerque: (1) groundwater age (how long ago water entered, or recharged, the aquifer), (2) groundwater development (introduction of manmade recharge and discharge sources), (3) natural geochemical conditions of the aquifer, and (4) seasonal pumping stresses. Concentrations of the isotope carbon-14 indicate that groundwater from most sampled wells in the local study area is predominantly water that entered, or recharged, the aquifer more than 6,000 years ago. However, the additional presence of the age tracer tritium in several groundwater samples at concentrations above 0.3 tritium units indicates that young (post-1950) recharge is reaching the aquifer across broad areas beneath Albuquerque. This young recharge is mixing with the thousands-of-years-old water, is migrating to depths as great as 245 feet below the water table, and is traveling to some (but not all) of the public-supply wells sampled. Most groundwater samples containing a fraction of young water also contain manmade VOCs, including chloroform (a byproduct of drinking-water chlorination), which indicates that the source of young recharge is, at least in part, infiltration of chlorinated municipal-supply water from leaking waterlines and sewerlines or from turf watering. Other likely manmade, urban recharge sources are seepage from constructed ponds and unlined portions of a stormwater diversion channel. A regional-scale computer-model simulation of groundwater flow and transport to the public-supply well shows that manmade sources of recharge and discharge that were added after about 1930 have greatly altered directions of groundwater flow near Albuquerque and have caused water levels to decline by as much as 120 feet. Local-scale simulations show that seasonal changes in the pumping schedule of the study well affect the age and quality of water produced by the well. Increased pumping during the summer causes significant volumes of water to flow downward from the shallow to the intermediate zones of the aquifer, causing a higher fraction of young water to be produced by the well in the summer than in the winter months and a corresponding increase in VOC detections in the summer relative to the winter. During the winter when the study-well pump is idle for several hours each day, old, high-arsenic water from the deep zone of the aquifer travels up the wellbore and exits into the intermediate zone of the aquifer. When the pump is activated in the winter (for a relatively short time each day), some of the leaked, high-arsenic water is recaptured by the well. This results in a higher arsenic concentration (commonly more than 12 µg/L) in water produced in the winter than in the summer, and a smaller fraction of young water being produced by the well in the winter than in the summer (6 percent in the winter, compared to 11 percent in the summer). Knowledge of the vertical flow direction (both natural and pumping-enhanced) in the vicinity of a long-screened well, coupled with understanding of variations in contaminant concentrations with depth in the aquifer, can help water managers predict the positive or negative effect that wellbore flow will have on water quality and can lead to development of strategies to mitigate contamination (such as changes in pumping schedules or development of devices to inhibit wellbore flow when the pump is off).

New Mexico↗
USGS1974

Map showing the thickness of loosely packed sediments and the depth to bedrock in the Sugar House quadrangle, Salt Lake County, Utah

This map provides information on the location and distribution of three general types of geologic materials in part of Salt Lake County, including the southeastern part of Salt Lake City, Utah. These materials have different physical properties that are pertinent to comprehensive planning and zoning, land-use studies, and engineering usage. The map should be of use in preliminary studies to determine the depth to different general types of foundation material and to determine the potential for settlement of the ground surface during major earthquakes, which could result in damage to waterlines, gaslines, large buildings, and other major engineering structures. The lines on the map are generalized. Lines showing the thickness of loosely packed sediments are based on drillers’ logs of 27 water wells in and near the 35-square-mile part of the quadrangle west of the mountains – less than one data point for each square mile. Lines showing the depth to bedrock are based on indirect geophysical data, and the data points are more widely scattered. The map may be useful as a general guide in planning, but investigations by qualified specialists should be made for detailed evaluations of specific areas. references to other reports of possible interest to the reader are included at the end of this text.

Utah↗
USGS2015

Accuracy testing of electric groundwater-level measurement tapes

Electric tapes are used to measure groundwater levels and to verify the accuracy of pressure transducers installed in wells. Electric tapes are generally assumed to be accurate to ±0.01 foot (ft), but little information is available from the manufacturers and no accuracy studies have been conducted to confirm this value. This study measured the accuracy of six popular models of electric groundwater tapes. The tapes tested include models from Durham Geo, Geotech, Heron, In-Situ, Solinst, and Waterline that are commonly used by the U.S.Geological Survey (USGS). The accuracy tests compared the length of each electric tape to a calibrated-steel reference tape and measured each probe’s activation accuracy and displacement volume. The tape-length accuracy combined with the probe-activation accuracy gave the overall measurement accuracy of the tape. The accuracy tests demonstrated that none of the electric-tape models tested consistently met the suggested USGS accuracy of ±0.01 ft. The test data show that the tape models in the study should give a water-level measurement that is accurate to roughly ±0.05 ft per 100 ft without additional calibration. To meet USGS accuracy guidelines, the electric-tape models tested will need to be individually calibrated. Specific conductance also plays a part in tape accuracy. The probes will not work in water with specific conductance values near zero, and the accuracy of one probe was unreliable in very high conductivity water (10,000 microsiemens per centimeter).

Open-File Report↗
USGS2018

Bathymetric contour map, surface area and capacity table, and bathymetric difference map for Clearwater Lake near Piedmont, Missouri, 2017

Clearwater Lake, on the Black River near Piedmont in Reynolds County, Missouri, was constructed in 1948 and is operated by the U.S. Army Corps of Engineers for flood-risk reduction, recreation, and fish and wildlife habitat. The lake area is about 1,800 acres with about 34 miles of shoreline at the conservation pool elevation of 498 feet. Since the completion of the lake in 1948, sedimentation likely has caused the storage capacity of the lake to decrease gradually. The loss of storage capacity can decrease the effectiveness of the lake to mitigate flooding, and excessive sediment accumulation also can reduce aquatic habitat in some areas of the lake. Many lakes operated by the U.S. Army Corps of Engineers have periodic bathymetric and sediment surveys to monitor the status of the lake. The U.S. Geological Survey completed one such survey of Clearwater Lake in 2008 during a period of high lake level using bathymetric surveying equipment consisting of a multibeam echosounder, a singlebeam echosounder, 1/3 arc-second National Elevation Dataset data (used outside the multibeam echosounder survey extent), and the waterline derived from 2008 aerial light detection and ranging (lidar) data. In May 2017, the U.S. Geological Survey, in cooperation with the U.S. Army Corps of Engineers, surveyed the bathymetry of Clearwater Lake to prepare an updated bathymetric map and a surface area and capacity table. The 2008 survey was contrasted with the 2017 survey to document the changes in the bathymetric surface of the lake.

Missouri↗
USGS2011

Construction of shipping channels in the Detroit River: History and environmental consequences

The Detroit River is one of the most biologically diverse areas in the Great Lakes basin. It has been an important international shipping route since the 1820s and is one of the busiest navigation centers in the United States. Historically, it supported one of the most profitable Lake Whitefish (Coregonus clupeaformis) commercial fisheries in the Great Lakes. Since 1874, the lower Detroit River has been systematically and extensively modified, by construction of deepwater channels, to facilitate commercial shipping. Large-scale dredging, disposal of dredge spoils, and construction of water-level compensating works has greatly altered channel morphology and flow dynamics of the river, disrupting ecological function and fishery productivity of the river and influencing Great Lakes water levels. From 1874 to 1968, major construction projects created 96.5 kilometers (60 miles) of shipping channels, removed over 46,200,000 m 3 of material, covered 4,050 hectares (40.5 square kilometers) of river bottom with dredge spoils, and built 85 hectares of above-waterline compensating works at a total cost of US$283 million. Interest by industries and government agencies to develop the river further for shipping is high and increasing. Historically, as environmental protection agencies were created, construction impacts on natural resources were increasingly addressed during the planning process and, in some cases, assessments of these impacts greatly altered or halted proposed construction projects. Careful planning of future shipping-channel construction and maintenance projects, including a thorough analysis of the expected environmental impacts, could greatly reduce financial costs and ecological damages as compared to past shipping-channel construction projects.

Michigan↗
USGS2017

Testing the effect of water in crevasses on a physically based calving model

A new implementation of a calving model, using the finite-element code Elmer, is presented and used to investigate the effects of surface water within crevasses on calving rate. For this work, we use a two-dimensional flowline model of Columbia Glacier, Alaska. Using the glacier's 1993 geometry as a starting point, we apply a crevasse-depth calving criterion, which predicts calving at the location where surface crevasses cross the waterline. Crevasse depth is calculated using the Nye formulation. We find that calving rate in such a regime is highly dependent on the depth of water in surface crevasses, with a change of just a few meters in water depth causing the glacier to change from advancing at a rate of 3.5 km a -1 to retreating at a rate of 1.9 km a -1 . These results highlight the potential for atmospheric warming and surface meltwater to trigger glacier retreat, but also the difficulty of modeling calving rates, as crevasse water depth is difficult to determine either by measurement in situ or surface mass-balance modelling.

Alaska↗
USGS2026

Evaluating treatment methods to control the egg masses of the crop pest Pomacea maculata

Pomacea maculata is an invasive aquatic apple snail species that poses serious ecological, agricultural, and public health threats across the southeastern United States. Its spread, particularly in Louisiana, has heavily impacted rice and crayfish farming, an industry producing over 90% of U.S. crayfish and valued at more than $250 million annually. The snail damages seedling rice, clogs crayfish traps, reduces yields, and increases labor for farmers. Moreover, it is a known host of rat lungworm ( Angiostrongylus cantonensis ), a parasite harmful to humans, making its presence in food production environments a public health concern. Controlling P. maculata is challenging due to its life cycle and reproductive strategies. The species lays large clutches of eggs above the waterline, where traditional aquatic molluscicides are ineffective. This study aimed to assess low-cost, practical methods for reducing egg hatch rates, specifically water submersion and vegetable oil application, on newly laid (day 1) and older (day 7) egg clutches. Laboratory trials on 125 egg clutches revealed that water submersion significantly reduced hatch rates and the development of dormant hatchlings, regardless of clutch age. Oil treatment only reduced hatch rates for day 1 clutches and had no effect on dormant hatchlings. These results suggest that water treatment is more broadly effective and feasible for farmers to apply without needing to determine egg age when applied on a routine, weekly basis. While oil showed limited use, its time-sensitive application limits practicality in the field. Water-based approaches offer a scalable solution for reducing P. maculata populations, but do not completely eliminate the potential for hatching and spreading. Without comprehensive control strategies targeting all life stages, the apple snail’s spread and associated impacts are expected to worsen, underscoring the urgency of continued management innovation.

Florida↗