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At least 1,189 records · Page 66Linked to original sources
USGS2026

Effects of storm surge exceedance value on overwash and inundation forecasts

Hurricane induced sediment transport and flooding can cause catastrophic damage to coastal communities. Forecasts test our understanding of the drivers of sediment transport and flooding, as well as quantify potential storm effects on coastlines. Real-time availability of forecasts allows emergency response and management decisions to be made with additional information. This study analyzed the skill of probabilistic forecasts of overwash and inundation along the Louisiana coastline from back-to-back Hurricanes Laura and Delta in 2020. To test skill, forecasts were compared with observations of mean water level relative to beach elevations and evidence of overwash and inundation identified in post-storm aerial imagery. We found that probabilistic forecasts accurately identified areas where overwash and inundation were likely to occur. In some cases, forecasts also produced a conservative estimation of overwash and inundation. For the first time, we explored the role of exceedance value in probabilistic forecasts of overwash and inundation and found that choice of exceedance value can influence forecasts. Additionally, we found that waves contributed up to 27% of the mean water level and up to 63% of the extreme water level during Hurricanes Laura and Delta.

Louisiana, Texas↗
USGS2005

A signal for independent coastal and continental histories among North American wolves

Relatively little genetic variation has been uncovered in surveys across North American wolf populations. Pacific Northwest coastal wolves, in particular, have never been analysed. With an emphasis on coastal Alaska wolf populations, variation at 11 microsatellite loci was assessed. Coastal wolf populations were distinctive from continental wolves and high levels of diversity were found within this isolated and relatively small geographical region. Significant genetic structure within southeast Alaska relative to other populations in the Pacific Northwest, and lack of significant correlation between genetic and geographical distances suggest that differentiation of southeast Alaska wolves may be caused by barriers to gene flow, rather than isolation by distance. Morphological research also suggests that coastal wolves differ from continental populations. A series of studies of other mammals in the region also has uncovered distinctive evolutionary histories and high levels of endemism along the Pacific coast. Divergence of these coastal wolves is consistent with the unique phylogeographical history of the biota of this region and re-emphasizes the need for continued exploration of this biota to lay a framework for thoughtful management of southeast Alaska.

Molecular Ecology↗
USGS2011

Seasonal Distribution and Movements of Atlantic and Shortnose Sturgeon in the Penobscot River Estuary, Maine

Relatively little is known about the distribution and seasonal movement patterns of shortnose sturgeon Acipenser brevirostrum and Atlantic sturgeon Acipenser oxyrinchus oxyrinchus occupying rivers in the northern part of their range. During 2006 and 2007, 40 shortnose sturgeon (66–113.4 cm fork length [FL]) and 8 Atlantic sturgeon (76.2–166.2 cm FL) were captured in the Penobscot River, Maine, implanted with acoustic transmitters, and monitored using an array of acoustic receivers in the Penobscot River estuary and Penobscot Bay. Shortnose sturgeon were present year round in the estuary and overwintered from fall (mid-October) to spring (mid-April) in the upper estuary. In early spring, all individuals moved downstream to the middle estuary. Over the course of the summer, many individuals moved upstream to approximately 2 km of the downstream-most dam (46 river kilometers [rkm] from the Penobscot River mouth [rkm 0]) by August. Most aggregated into an overwintering site (rkm 36.5) in mid- to late fall. As many as 50% of the tagged shortnose sturgeon moved into and out of the Penobscot River system during 2007, and 83% were subsequently detected by an acoustic array in the Kennebec River, located 150 km from the Penobscot River estuary. Atlantic sturgeon moved into the estuary from the ocean in the summer and concentrated into a 1.5-km reach. All Atlantic sturgeon moved to the ocean by fall, and two of these were detected in the Kennebec River. Although these behaviors are common for Atlantic sturgeon, regular coastal migrations of shortnose sturgeon have not been documented previously in this region. These results have important implications for future dam removals as well as for rangewide and river-specific shortnose sturgeon management.

Maine↗
USGS2020

Occurrence of a suite of stream-obligate amphibians in timberlands of Mendocino County, California, examined using environmental DNA

Stream-obligate amphibians are important indicators of ecosystem health in the Pacific Northwest, but distributional information to improve forest management is lacking in many regions. We analyzed archived DNA extracted from water samples in 60 pools in streams on private timberlands in Mendocino County, California, for 3 California Species of Special Concern—Coastal Tailed Frogs ( Ascaphus truei ), Foothill Yellow-legged Frogs ( Rana boylii ), and Southern Torrent Salamanders ( Rhyacotriton variegatus )—to better understand their distributions in the region. Detection probabilities for eDNA of Foothill Yellow-legged Frogs and Coastal Tailed Frogs were positively influenced by water temperature. eDNA occurrence for both frogs was affected by whether silt or organic matter was a dominant substrate in the sampled pool, and Foothill Yellow-legged Frog eDNA occurrence was also affected by water temperature. Foothill Yellow-legged Frog eDNA occurrence had a strong, positive association with water temperature, with occurrence unlikely below 14°C and very likely above 16°C, and a positive association with silt or organic substrates in pools, which was likely an indicator of higher-order stream reaches. In contrast, Coastal Tailed Frogs had a negative association with silt or organic substrates. Historical visual detections were generally congruent with findings using eDNA, but differences highlight important areas for further study. We did not detect Southern Torrent Salamanders using eDNA at any sites. Our study reinforces that ecological relationships of these species are varied, and shows the importance of maintaining the integrity of streams with diverse characteristics for conserving stream amphibians.

California↗
USGS1998

Water quality in the Georgia-Florida coastal plain, Georgia and Florida, 1992-96

This report is intended to summarize major findings that emerged between 1992 and 1995 from the water-quality assessment of the Georgia-Florida Coastal Plain Study Unit and to relate these findings to water-quality issues of regional and national concern. The information is primarily intended for those who are involved in water-resource management. Yet, the information contained here may also interest those who simply wish to know more about the quality of water in the rivers and aquifers in the area where they live.

Florida, Georgia↗
USGS2016

Pacific walrus coastal haulout database, 1852-2016— Background report

Walruses are large benthic predators that rest out of water between foraging bouts. Coastal “haulouts” (places where walruses rest) are formed by adult males in summer and sometimes by females and young when sea ice is absent, and are often used repeatedly across seasons and years. Understanding the geography and historical use of haulouts provides a context for conservation efforts. We summarize information on Pacific walrus haulouts from available reports (n =151), interviews with coastal residents and aviators, and personal observations of the authors. We provide this in the form of a georeferenced database that can be queried and displayed with standard geographic information system and database management software. The database contains 150 records of Pacific walrus haulouts, with a summary of basic characteristics on maximum haulout aggregation size, age-sex composition, season of use, and decade of most recent use. Citations to reports are provided in the appendix and as a bibliographic database. Haulouts were distributed across the coasts of the Pacific walrus range; however, the largest (maximum >10,000 walruses) of the haulouts reported in the recent 4 decades (n=19) were concentrated on the Russian shores in regions near the Bering Strait and northward into the western Chukchi Sea (n=17). Haulouts of adult female and young walruses primarily occurred in the Bering Strait region and areas northward, with others occurring in the central Bering Sea, Gulf of Anadyr, and Saint Lawrence Island regions. The Gulf of Anadyr was the only region to contain female and young walrus haulouts, which formed after the northward spring migration and prior to autumn ice formation.

Alaska↗
USGS2014

Historical and contemporary imagery to assess ecosystem change on the Arctic coastal plain of northern Alaska

The Arctic Coastal Plain of northern Alaska is a complex landscape of lakes, streams, and wetlands scattered across low-relief tundra that is underlain by permafrost. This region of the Arctic has experienced a warming trend over the past three decades leading to thawing of on-shore permafrost and the disappearance of sea ice at unprecedented rates. The U.S. Geological Survey’s (USGS) Changing Arctic Ecosystems (CAE) research initiative was developed to investigate and forecast these rapid changes in the physical environment of the Arctic, and the associated changes to wildlife populations, in order to inform key management decisions by the U.S. Department of the Interior and other agencies. Forecasting future wildlife responses to changes in the Arctic can benefit greatly from historical records that inform what changes have already occurred. Several Arctic wildlife and plant species have already responded to climatic and physical changes to the Arctic Coastal Plain of northern Alaska. Thus, we located historical aerial imagery to improve our understanding of recent habitat changes and the associated response to such changes by wildlife populations. In this report, we describe and make available a set of 61 georectified aerial images of the Arctic Coastal Plain (taken from 1948 to 2010) that were obtained by the USGS to inform research objectives of the USGS CAE Initiative. Here, we describe the origins, metadata, and public availability of these images that were obtained within four main study areas on the Arctic Coastal Plain: Teshekpuk Lake Special Area, Chipp River, the Colville River Delta, and locations along the Dalton Highway Corridor between the Brooks Range and Deadhorse. We also provide general descriptions of observable changes to the geomorphology of landscapes that are apparent by comparing historical and contemporary images. These landscape changes include altered river corridors, lake drying, coastal erosion, and new vegetation communities. All original and georectified images and metadata are available through the USGS Alaska Science Center Portal (search under ‘Project Name’ using title of this report) or by contacting ascweb@usgs.gov .

Alaska↗
USGS2010

Trip report: pilot study of factors linking watershed function and coastal ecosystem health in American Samoa

Coral reef resources in the territory of American Samoa face significant problems from overfishing, non-point source pollution, global warming, and continuing population growth and development. The islands are still relatively isolated relative to other parts of the Pacific and have managed to avoid some of the more devastating invasive species that have reached other archipelagoes. As a result, there are opportunities for collaborative and integrative research and monitoring programs to help restore and maintain biodiversity and functioning natural ecosystem in the archipelago. We found that the “Ridge to Reef” paradigm already exists in American Samoa, with a high degree of interagency cooperation and efficient use of limited resources already taking place in the Territory. USGS may be able to make contributions as a partner organization in the Coral Reef Advisory Group (CRAG) through deployment of sediment monitoring instrumentation to supplement stream monitoring by the American Samoa Environmental Protection Agency, by providing high resolution vegetation and land-use maps of main islands, by providing additional support to the American Samoa Department of Marine and Wildlife Resources and the National Park Service for monitoring of invasive species, by working with members of CRAG to initiate sediment transport studies on Samoan reefs, and by developing new projects on the effects of bacterial contamination and pollutants on coral reef physiology and demography.

Open-File Report↗
USGS1994

The status of sea ducks in the North Pacific Rim: Toward their conservation and management

Sea ducks (tribe Mergini after Johnsgard 1960) are the most northerly distributed ducks, and species diversity is greatest in the North Pacific. They exploit a diversity of inshore and offshore marine habitats during the non-breeding season, and their use of habitat during breeding varies from coastal through freshwater wetlands of the tundra and taiga (Figure 1, Appendix 1). Non-breeding cohorts frequent marine habitats most of the year. Sea ducks thus are important indicators of the quality of freshwater and marine ecosystems of northern biomes. Of the 17 species discussed in this manuscript, at least 3 are reported to be declining (Appendix 2). However, the basis for many of those assessments is equivocal because there has been little effort to monitor populations. The efforts to more precisely assess their status point to catastrophic declines (Kertell 1991, Stehn et a 1993). Conservation problems related to sea ducks have a long history throughout the Holarctic. For example, the Labrador duck ( Camptorhynchus labradorius ) became extinct in 1875. (Phillips 1925); common eiders ( Somateria mollissima ) declined seriously throughout the northern hemisphere (Townsend 1914, Phillips 1925, Doughty 1979); harlequin ducks ( Histrionicus histrionicus ) experienced declines in Iceland and Greenland (Gudmundsson1971, Salomonson 1950), and more recently have been designated endangered in eastern Canada (Committee On the Status of Endangered Wildlife in Canada 1990). In Russia, all species of eider and harlequin ducks have been closed to sport hunting since 1981, and the Chinese mergansers ( Mergus squamatus ) presently are extremely rare and fully protected, i.e. category one of the red book (Solomonov 1987).

Transactions of the North American Wildlife and Na↗
USGS2012

Population dynamics of king eiders breeding in northern Alaska

The North American population of king eiders (Somateria spectabilis) has declined by more than 50% since the late 1970s for unknown reasons. King eiders spend most of their lives in remote areas, forcing managers to make regulatory and conservation decisions based on very little information. We incorporated available published estimates of vital rates with new estimates to build a female, stage-based matrix population model for king eiders and examine the processes underlying population dynamics of king eiders breeding at 2 sites, Teshekpuk and Kuparuk, on the coastal plain of northern Alaska and wintering around the Bering Sea (2001–2010). We predicted a decreasing population ( λ = 0.981, 95% CI: 0.978–0.985), and that population growth was most sensitive to changes in adult female survival (sensitivity = 0.92). Low duckling survival may be a bottleneck to productivity (variation in ducking survival accounted for 66% of retrospective variation in λ ). Adult survival was high (0.94) and invariant ( σ = 0.0002, 95% CI: 0.0000–0.0007); however, catastrophic events could have a major impact and we need to consider how to mitigate and manage threats to adult survival. A hypothetical oil spill affecting breeding females in a primary spring staging area resulted in a severe population decline; although, transient population dynamics were relatively stable. However, if no catastrophic events occur, the more variable reproductive parameters (duckling and nest survival) may be more responsive to management actions.

Alaska↗
USGS2014

EAARL-B submerged topography: Barnegat Bay, New Jersey, pre-Hurricane Sandy, 2012

These remotely sensed, geographically referenced elevation measurements of lidar-derived submerged topography datasets were produced by the U.S. Geological Survey (USGS), St. Petersburg Coastal and Marine Science Center, St. Petersburg, Florida. This project provides highly detailed and accurate datasets for part of Barnegat Bay, New Jersey, acquired pre-Hurricane Sandy on October 18, 22, 23, and 26, 2012. The datasets are made available for use as a management tool to research scientists and natural-resource managers. An innovative airborne lidar, known as the second-generation Experimental Advanced Airborne Research Lidar (EAARL-B), was used during data acquisition. The EAARL-B system is a raster-scanning, waveform-resolving, green-wavelength (532-nm) lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL-B sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive lidar, down-looking red-green-blue (RGB) and infrared (IR) digital cameras, two precision dual-frequency kinematic carrier-phase GPS receivers, and an integrated miniature digital inertial measurement unit, which provide for sub-meter georeferencing of each laser sample. The nominal EAARL-B platform is a twin-engine Cessna 310 aircraft, but the instrument may be deployed on a range of light aircraft. A single pilot, a lidar operator, and a data analyst constitute the crew for most survey operations. This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Elevation measurements were collected over the survey area using the EAARL-B system. The resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed originally in a NASA-USGS collaboration. The exploration and processing of lidar data in an interactive or batch mode is supported using ALPS. Modules for presurvey flight-line definition, flight-path plotting, lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. The Airborne Lidar Processing System (ALPS) is used routinely to create maps that represent submerged or sub-aerial topography. Specialized filtering algorithms have been implemented to determine the "bare earth" under vegetation from a point cloud of last return elevations. For more information about similar projects, please visit the Lidar for Science and Resource Management Web site.

New Jersey↗
USGS2021

Does geomorphology determine vulnerability of mangrove coasts to sea-level rise?

The greatest climate-based threat to coastlines worldwide is sea-level rise. We tested the hypothesis that tropical coasts fringed by mangroves and receiving high inputs of terrigenous sediment are less vulnerable to sea-level rise than biogenic systems dependent upon peat formation for vertical land development. An analysis of published data spanning a range of geomorphic settings showed that mineral accretion was a poor predictor of vulnerability to rising sea level. We additionally compared two oceanic island systems representing two extremes along this sediment gradient to further examine controls on elevation dynamics in minerogenic versus biogenic mangrove systems. Minerogenic systems characterized by intermediate to high rates of mineral sedimentation (Pacific high islands in Micronesia) were not better buffered against sea-level rise because of high subsidence rates. Peat-forming systems (Caribbean low islands in Belize) kept pace with relative sea-level rise (combined ocean and land movements) because of subsurface expansion driven by root matter accumulation. The data were not consistent with the paradigm that tropical coastlines characterized by peat-forming mangroves are generally more vulnerable to sea-level rise compared to minerogenic systems; however, they are not necessarily equally sensitive to the same external and internal forces controlling soil elevations. Our findings demonstrate that reliance on surface accretion data alone can lead to an inaccurate evaluation of coastal vulnerability and why all surface and subsurface land movements must be considered in relation to local sea-level trends to assess risk of submergence. Recognition of such differences is essential to proper management of tropical coastlines to ensure their resilience in the face of future sea-level rise.

Book chapter↗
USGS2026

Probabilistic forecasting of coastal wetland elevation and soil carbon response to sea-level rise

Tidal wetlands build soil as a dynamic response to inundation, resulting in carbon sequestration and resilience to sea-level rise. Process models can be used to make site-specific forecasts, anticipate future changes, and plan management responses. But to be actionable, forecasts from these models need to be accompanied by descriptions of their confidence. In this study, we demonstrate the application of ecological forecasting principles to the unique case of tidal wetland vulnerability and carbon storage, given accelerating and uncertain sea-level rise. We present a case study using the Cohort Marsh Equilibrium Model at the Global Change Research Wetland in Maryland, USA. We used meta-analyses to quantify lab- and sample-level measurement uncertainties for common soil measurements and to develop Bayesian model priors. Reanalysis of previous literature supported predictive relationships between belowground turnover and mean annual temperature, as well as between soil erodibility and suspended sediment concentration that could be transferable to other locations. The model forecasted a likely conversion of low-elevation marsh to open water by the 2060s, accompanied by a decrease in marsh carbon storage capacity. Forecasted uncertainty in elevation was dominated by structural uncertainty in the model, while carbon accumulation rates were more influenced by parameter uncertainty. After 2050, and increasingly as the forecast approached 2100, uncertainty in sea-level rise projections contributed to uncertainty in both forecasts. Forecasts were most sensitive to processes related to organic matter preservation, plant productivity (maximum aboveground biomass and belowground turnover), and organic soil packing density. The soil formed was an organic-rich peat (>70% organic matter according to the data), and model predictions were insensitive to parameters associated with mineral sedimentation. We identify additional field data collection, such as on decomposition trajectories and plant productivity, and data-model coupling of near-term elevation records as the most impactful strategies for reducing uncertainties in future forecasting efforts. Future work can build on this forecasting framework in other locations, using it for adaptive management, identifying appropriate interventions to mitigate wetland loss, and projecting future carbon removal capacity in response to accelerated sea-level rise.

Maryland↗
USGS2011

Biological dimensions of tern management-a case study of the least tern in Sonora, Mexico, and a comparative analysis of reproductive investment in terns

Least terns (Sternula antillarum) are threatened by rapid human development on the northern coast of Sonora, Mexico. Terns are bellwethers for changes along the world's coastlines, as their coastal breeding habitat is vulnerable to flooding and development. We conducted targeted ground and aerial surveys for least tern colonies along 160 kilometers of coast, and document our findings on colony sizes at nine sites over 3 years in the first portion of this report. Like many taxa, terns lay larger clutches at higher latitudes. In the second portion of this report, we evaluate least tern breeding lifespan, food availability, and nest predation as potential ecological reasons behind this differing clutch-size pattern. After correcting for phylogenetic relationships, we found that food availability, not breeding lifespan or nest predation rate, was related to reproductive investment across 46 species and populations of terns. We conclude that coastal development may have a greater impact on nesting terns in tropical regions as compared to temperate breeding locations, because global oceanic patterns of decreased food availability reduce reproductive investment in the tropics.

Open-File Report↗
USGS2013

Mapping polar bear maternal denning habitat in the National Petroleum Reserve -- Alaska with an IfSAR digital terrain model

The National Petroleum Reserve–Alaska (NPR-A) in northeastern Alaska provides winter maternal denning habitat for polar bears ( Ursus maritimus ) and also has high potential for recoverable hydrocarbons. Denning polar bears exposed to human activities may abandon their dens before their young are able to survive the severity of Arctic winter weather. To ensure that wintertime petroleum activities do not threaten polar bears, managers need to know the distribution of landscape features in which maternal dens are likely to occur. Here, we present a map of potential denning habitat within the NPR-A. We used a fine-grain digital elevation model derived from Interferometric Synthetic Aperture Radar (IfSAR) to generate a map of putative denning habitat. We then tested the map’s ability to identify polar bear denning habitat on the landscape. Our final map correctly identified 82% of denning habitat estimated to be within the NPR-A. Mapped denning habitat comprised 19.7 km2 (0.1% of the study area) and was widely dispersed. Though mapping denning habitat with IfSAR data was as effective as mapping with the photogrammetric methods used for other regions of the Alaskan Arctic coastal plain, the use of GIS to analyze IfSAR data allowed greater objectivity and flexibility with less manual labor. Analytical advantages and performance equivalent to that of manual cartographic methods suggest that the use of IfSAR data to identify polar bear maternal denning habitat is a better management tool in the NPR-A and wherever such data may be available.

Alaska↗
USGS2025

Infection by the marine cestode Hepatoxylon trichiuri in returning Chinook salmon (Oncorhynchus tshawytscha) spawners in Patagonia: Implications for a novel fishery

Parasitological information may be useful for managing economically important fisheries by providing insights into population dynamics and health effects. The Chinook salmon ( Oncorhynchus tshawytscha ), an invasive species with high socio-ecological importance in South America, supports recreational and incipient artisanal fisheries. In Southern Chile, the recent approval of coastal fisheries for returning Chinook salmon in some regions highlights the importance of understanding salmon foraging, habitat use, and commercial value. However, such information is lacking. Parasites have been extensively used as cost-effective biological tags to identify fish stocks. We conducted the first parasitological examination of the marine tapeworm Hepatoxylon trichiuri larvae in returning adult Chinook salmon from the Cisnes River to assess its potential as a biological tag for returning Chinook salmon in Patagonia. Of 61 Chinook salmon from the Cisnes River, 52.46% were infected by H. trichiuri , with 1.65 ± 1.26 parasites per infected salmon (mean ± SD). Infection prevalence and intensity did not differ significantly between males and females. Infection intensity was higher in larger salmon but decreased with increasing salmon condition. Infection intensity was not significantly related to length, mass, or body condition. Infection prevalence and intensity of H. trichiuri varied spatially among Patagonian river-basin populations of Chinook salmon, thereby supporting the use of H. trichiuri as a biological tag. Our findings provide important parasitological metrics that may enhance future management practices by informing geographic variability in foraging locations of adult salmon and their commercial value for human consumption.

Cisnes River, Patagonia↗
USGS1975

Water and the South Florida environment

Ecological problems are a major concern to Florida as well as to the Nation. National attention was focused on these problems in September 1968, when the Port Authority of Dade County began to con- struct a jetport for supersonic aircraft on a 39-square-mile tract 6 miles north of Everglades National Park and on the east edge of the Big Cypress Swamp. Conservation groups and citizens raised questions as to the effects of a regional jetport and the attendant satellite growth on the water resources and biological communities of the National Park. The Department of the Interior began studies to investigate the situation. One study, Leopold (1969), reported on the unfavorable ecological effects of the attendant satellite growth. Then Secretary of the Interior, Walter J. Hickel, directed the U.S. Geological Survey to study the water resources of the Big Cypress to determine which parts of the Big Cypress contribute the major part of the water necessary to maintain adequate water supplies for Everglades National Park. This was done in a report by Klein and others (1970). At about the same time, the Departments of interior and Transportation, the State of Florida, and the Dade County Port Authority con-curred in assigning to the Secretary of the Interior certain responsibilities for planning, developing, and coordinating an ecological study of south Florida. A primary objective of the ecological study is to provide information that will assist in the formulation of land-use policy consistent with the protection of the environment of Everglades National Park, the adjacent estuaries, and the public water supplies. The part of the investigation describing the surface-water and ground-water resources of south Florida was assigned to the Geological Survey. The quantity and quality of surface water and ground water and their interrelation with estuarine and marine waters are here considered. Also considered are the problems, present or future, related to the hydrologic environment that involve human, animal, and plant life. Changes taking place, apparent trends, and projections for the future are also considered, as well as alternatives for water management. The Geological Survey effort began in January 1971, when aerial photography and selected qualitative hydrologic data were obtained. However, most of the information upon which this report Is based was obtained by the Geological Survey in cooperative programs with several local, State, and Federal agencies since about 1940. The long-term support of the U.S. Army Corps of Engineers, the National Park Service, U.S. Navy, Florida Department of Natural Resources, Central and Southern Florida Flood Control District, Dade, Broward, Palm Beach and Collier Counties, Miami and Miami Beach, Ft. Lauderdale, Naples and others in the collection of data is gratefully acknowledged. A prolonged drought throughout south Florida from September 1970 to May 1971 accentuated the importance and timeliness of the study. The drought brought about a readvance of sea-water intrusion in many coastal areas, which necessitated restrictions on water use. The effect of drought on the regional water supply, continued population growth and increased water demands, and deterioration of the water quality in many of the canals and waterways of the urban areas accentuated the need for improved water management and land-use planning. As a result of the water crisis, the Governor of Florida called a special conference in September 1971. The conference, attended by foremost scientific and government personnel, proposed creation of an agency that would develop and implement comprehensive land and water-use plans for south Florida that would minimize environmental degradation.

Florida↗
USGS2025

Monitoring Pacific walrus coastal haulouts by satellite to estimate herd abundance and distribution

The Pacific walrus ( Odobenus rosmarus divergens ) has a single, panmictic stock that ranges across the Bering and Chukchi Seas. However, its seasonal distribution is incompletely described, particularly in autumn when herds gather on shore, and abundance is of interest to management entities. We monitored walrus herds using satellite imagery on shore across their summer and autumn range in the Chukchi Sea to provide insights on seasonal distribution and abundance. During each study year (2017–2024), we documented walrus herd abundance at 8 Chukchi Sea haulouts based on the herd area detected in satellite imagery multiplied by herd density estimates derived from aerial survey data. In contrast to historical seasonal use, we found large herds on shore at only 3 sites, 1 in Alaska and 2 in northern Chukotka (Russia). In 2022, we observed a very large herd with an abundance (and 90% prediction interval) of 184,000 (min–max = 153,000–214,000) northwest of the Bering Strait, which enabled us to estimate a minimum population size (N min ) by correcting the abundance estimate by the proportion of walruses that may be hauled out and available for detection. Our estimate of 250,000 was commensurate with the N min estimate (214,000) from a 2013–2017 Pacific walrus genetic mark-recapture study.

Alaska↗