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At least 667 records · Page 37Linked to original sources
USGS2016

Wood decay in desert riverine environments

Floodplain forests and the woody debris they produce are major components of riverine ecosystems in many arid and semiarid regions (drylands). We monitored breakdown and nitrogen dynamics in wood and bark from a native riparian tree, Fremont cottonwood ( Populus deltoides subsp. wislizeni ), along four North American desert streams. We placed locally-obtained, fresh, coarse material [disks or cylinders (∼500–2000 cm 3 )] along two cold-desert and two warm-desert rivers in the Colorado River Basin. Material was placed in both floodplain and aquatic environments, and left in situ for up to 12 years. We tested the hypothesis that breakdown would be fastest in relatively warm and moist aerobic environments by comparing the time required for 50% loss of initial ash-free dry matter ( T 50 ) calculated using exponential decay models incorporating a lag term. In cold-desert sites (Green and Yampa rivers, Colorado), disks of wood with bark attached exposed for up to 12 years in locations rarely inundated lost mass at a slower rate ( T 50 = 34 yr) than in locations inundated during most spring floods ( T 50 = 12 yr). At the latter locations, bark alone loss mass at a rate initially similar to whole disks ( T 50 = 13 yr), but which subsequently slowed. In warm-desert sites monitored for 3 years, cylinders of wood with bark removed lost mass very slowly ( T 50 = 60 yr) at a location never inundated (Bill Williams River, Arizona), whereas decay rate varied among aquatic locations ( T 50 = 20 yr in Bill Williams River; T 50 = 3 yr in Las Vegas Wash, an effluent-dominated stream warmed by treated wastewater inflows). Invertebrates had a minor role in wood breakdown except at in-stream locations in Las Vegas Wash. The presence and form of change in nitrogen content during exposure varied among riverine environments. Our results suggest woody debris breakdown in desert riverine ecosystems is primarily a microbial process with rates determined by landscape position, local weather, and especially the regional climate through its effect on the flow regime. The increased warmth and aridity expected to accompany climate change in the North American southwest will likely retard the already slow wood decay process on naturally functioning desert river floodplains. Our results have implications for designing environmental flows to manage floodplain forest wood budgets, carbon storage, and nutrient cycling along regulated dryland rivers.

Arizona, Colorado, Nevada↗
USGS2017

Contribution of manipulable and non-manipulable environmental factors to trapping efficiency of invasive sea lamprey

We identified aspects of the trapping process that afforded opportunities for improving trap efficiency of invasive sea lamprey ( Petromyzon marinus ) in a Great Lake's tributary. Capturing a sea lamprey requires it to encounter the trap, enter, and be retained until removed. Probabilities of these events depend on the interplay between sea lamprey behavior, environmental conditions, and trap design. We first tested how strongly seasonal patterns in daily trap catches (a measure of trapping success) were related to nightly rates of trap encounter, entry, and retention (outcomes of sea lamprey behavior). We then tested the degree to which variation in rates of trap encounter, entry, and retention were related to environmental features that control agents can manipulate (attractant pheromone addition, discharge) and features agents cannot manipulate (water temperature, season), but could be used as indicators for when to increase trapping effort. Daily trap catch was most strongly associated with rate of encounter. Relative and absolute measures of predictive strength for environmental factors that managers could potentially manipulate were low, suggesting that opportunities to improve trapping success by manipulating factors that affect rates of encounter, entry, and retention are limited. According to results at this trap, more sea lamprey would be captured by increasing trapping effort early in the season when sea lamprey encounter rates with traps are high. The approach used in this study could be applied to trapping of other invasive or valued species.

Journal of Great Lakes Research↗
USGS2025

Abundance of microplastics in a typical urban wetland in China: Association with occurrence and carbon storage

Microplastics (MPs) are gaining attention for their widespread presence and toxicity in ecosystems. However, their role as a carbon source in urban wetland carbon sinks is still unclear. In this study, the microplastic-carbon (MP-C) was firstly quantified based on the abundance and occurrence characteristics, including MP morphology, size and type in the Sanyang Wetland, a typical urban wetland of China. MP abundances ranged from 2.4 ± 0.6–14.9 ± 1.5 items/L in surface water and 6.6 ± 1.2 × 10 3 to 46.3 ± 5.9 × 10 3 items/kg in sediment. The predominant morphological characterization of MPs was fragments smaller than 200 μm in size, consisting of PP, PE, and PET, which suggests that the main source was domestic wastewater discharge nearby. Notably, in the Sanyang wetland, the contribution of MP-C to total organic carbon (TOC) was estimated to be 0.023 0.20 % in water and 0.026 0.28 % in sediment. With the continuous production of plastics globally, these values were predicted to increase to 0.12 0.71 % and 0.83 4.12 % by 2100, respectively. Although the estimations relied on simplified geometric assumptions for MP volume and theoretical carbon content, these approaches provide a reasonable basis for understanding MP-C dynamics in wetlands under current analytical constraints. The integration of MP-C characterization during environmental monitoring and management strategies would enhance our understanding of MP pollution's role in the carbon cycle.

Journal of Hazardous Materials↗
USGS2012

Thiamine deficiency: a viable hypothesis for paralytic syndrome in Baltic birds. Commentary on Sonne et al., 2012. A review of the factors causing paralysis in wild birds: implications for the paralytic syndrome observed in the Baltic Sea. Science of the Total Environment 416:32-39

In a recent assessment of hypotheses presented by Balk et al. (2009) regarding the etiology of a paralytic disease inflicting bird populations in Northern Europe, Sonne et al. (2012) “call for a major coordinated effort on research…” to “… integrate clinical, physiological, ecological and demographic investigations at all levels to better dissect the causes, the effects on ecosystems and potential impact on affected populations.” Further, they offer, “This should be undertaken before thiamine deficiency can be considered to constitute a serious problem to e.g. the Baltic ecosystems.” While we agree that holistic approaches to environmental research and management are essential, our experience suggests that waiting for definitive results from long-term research and monitoring programs prior to “consideration” of thiamine deficiency as a major factor in the paralytic disease observed in wild bird populations would hinder the ability of natural resource managers to understand and mitigate declining trends in avian population abundance.

Science of the Total Environment↗
USGS2003

Estimating rates of local extinction and colonization in colonial species and an extension to the metapopulation and community levels

Coloniality has mainly been studied from an evolutionary perspective, but relatively few studies have developed methods for modelling colony dynamics. Changes in number of colonies over time provide a useful tool for predicting and evaluating the responses of colonial species to management and to environmental disturbance. Probabilistic Markov process models have been recently used to estimate colony site dynamics using presence–absence data when all colonies are detected in sampling efforts. Here, we define and develop two general approaches for the modelling and analysis of colony dynamics for sampling situations in which all colonies are, and are not, detected. For both approaches, we develop a general probabilistic model for the data and then constrain model parameters based on various hypotheses about colony dynamics. We use Akaike's Information Criterion (AIC) to assess the adequacy of the constrained models. The models are parameterised with conditional probabilities of local colony site extinction and colonization. Presence–absence data arising from Pollock's robust capture–recapture design provide the basis for obtaining unbiased estimates of extinction, colonization, and detection probabilities when not all colonies are detected. This second approach should be particularly useful in situations where detection probabilities are heterogeneous among colony sites. The general methodology is illustrated using presence–absence data on two species of herons. Estimates of the extinction and colonization rates showed interspecific differences and strong temporal and spatial variations. We were also able to test specific predictions about colony dynamics based on ideas about habitat change and metapopulation dynamics. We recommend estimators based on probabilistic modelling for future work on colony dynamics. We also believe that this methodological framework has wide application to problems in animal ecology concerning metapopulation and community dynamics.

Oikos↗
USGS2003

Factors affecting breeding dispersal of European ducks on Engure Marsh, Latvia

1. We used up to 35 years of capture-recapture data from nearly 3300 individual female ducks nesting on Engure Marsh , Latvia , and multistate modelling to test predictions about the influence of environmental, habitat and management factors on breeding dispersal probability within the marsh . 2. Analyses based on observed dispersal distances of common pochards and tufted ducks provided no evidence that breeding success in year t influenced dispersal distance between t and t + 1. 3. Breeding dispersal distances (year t to t + 1) of pochards and tufted ducks were associated with a delay in relative nest initiation dates in year t + 1. The delay was greater for pochards (c. 4 days) than for tufted ducks (c. 2 days) when females dispersed > 0.8 km. 4. Northern shovelers and tufted ducks moved from a large island to small islands at low water levels and from small islands to the large island at high water levels before the construction of elevated small islands (1960-82). Following this habitat management (1983-94), breeding fidelity was extremely high and not influenced by water level in the marsh for either species. 5. Because pochard nesting habitats in black-headed gull colonies were saturated during the entire study period, nesting females moved into and out of colonies with similar probabilities. Local survival probabilities and incubation body masses were higher for both yearlings (SY) and adults (ASY) nesting within gull colonies, suggesting that these females were of better quality than females nesting outside of the colonies. 6. Tufted ducks showed higher probabilities of moving from islands to emergent marshes when water levels were higher both before and after habitat management. However, rates of movement for a given water level were higher during the period before management than after. 7. Both pochards and tufted ducks exhibited asymmetric movement with respect to proximity to water, with higher movement probabilities to near-water nesting locations than away from these locations. 8. Multistate capture-recapture models provided analyses that were useful in investigating sources of variation in breeding dispersal probabilities.

Journal of Animal Ecology↗
USGS2003

Estimating natal dispersal movement rates of female European ducks with multistate modelling

1. We used up to 34 years of capture-recapture data from about 22 100 new releases of day-old female ducklings and multistate modelling to test predictions about the influence of environmental, habitat and management factors on natal dispersal probability of three species of ducks within the Engure Marsh, Latvia. 2. The mean natal dispersal distances were very similar (c. 0.6-0.7 km) for all three species and were on average 2.7 times greater than breeding dispersal distances recorded within the same study system. 3. We were unable to confirm the kinship hypothesis and found no evidence that young first-nesting females nested closer to their relatives (either mother or sister) than to the natal nest. 4. Young female northern shovelers, like adults, moved from small islands to the large island when water level was high and vice versa when water level was low before the construction of elevated small islands. Movement probabilities between the two strata were much higher for young shovelers than adults, suggesting that young birds had not yet developed strong fidelity to the natal site. Movements of young female tufted ducks , unlike those of shovelers, were not dependent on water level fluctuations and reflected substantial flexibility in choice of first nesting sites. 5. Data for young birds supported our earlier conclusion that common pochard nesting habitats in black-headed gull colonies were saturated during the entire study period. Young females, like the two adult age groups, moved into and out of colonies with similar probability. Fidelity probability of female pochards to each stratum increased with age, being the lowest (0.62) for young (DK) females, intermediate (0.78) for yearlings (SY) and the highest (0.84) for adult (ASY) females. 6. Young female tufted ducks , like adults, showed higher probabilities of moving from islands to emergent marshes when water levels were higher both before and after habitat management. The relationship between the spring water levels and movement was much weaker for young females than for adults. 7. Young female diving ducks exhibited much stronger (compared to adults) asymmetric movement with respect to proximity to water, with higher movement probabilities to near-water locations than away from these locations. 8. Local survival of day-old ducklings during the first year of life was time-specific and very low (means for different strata/states 0.01-0.08) because of high rates of emigration and prefledging mortality.

Journal of Animal Ecology↗
USGS2020

An overview of agent-based models in plant biology and ecology

Agent-based modeling (ABM) has become an established methodology in many areas of biology, ranging from the cellular to the ecological population and community levels. In plant science, two different scales have predominated in their use of ABM. One is the scale of populations and communities, through the modeling of collections of agents representing individual plants, interacting with each other and with the environment. The other is the scale of the individual plant, through the modeling, by functional-structural plant models (FSPMs), of agents representing plant building blocks, or metamers, to describe the development of plant architecture and functions within individual plants. The purpose of this review is to show key results and parallels in ABM for growth, mortality, carbon allocation, competition, and reproduction across the scales from the plant organ to populations and communities on a range of spatial scale to the whole landscape. Several areas of application of ABMs are reviewed, showing that some issues are addressed by both population-level ABMs and FSPMs. Continued increase in the relevance of ABM to environmental science and management will be helped by greater integration of ABMs across these two scales.

Annals of Botany↗
USGS2017

Unexpected stasis in a changing world: Lake nutrient and chlorophyll trends since 1990

The United States (U.S.) has faced major environmental changes in recent decades, including agricultural intensification and urban expansion, as well as changes in atmospheric deposition and climate—all of which may influence eutrophication of freshwaters. However, it is unclear whether or how water quality in lakes across diverse ecological settings has responded to environmental change. We quantified water quality trends in 2913 lakes using nutrient and chlorophyll (Chl) observations from the Lake Multi-Scaled Geospatial and Temporal Database of the Northeast U.S. (LAGOS-NE), a collection of preexisting lake data mostly from state agencies. LAGOS-NE was used to quantify whether lake water quality has changed from 1990 to 2013, and whether lake-specific or regional geophysical factors were related to the observed changes. We modeled change through time using hierarchical linear models for total nitrogen (TN), total phosphorus (TP), stoichiometry (TN:TP), and Chl. Both the slopes (percent change per year) and intercepts (value in 1990) were allowed to vary by lake and region. Across all lakes, TN declined at a rate of 1.1% year −1 , while TP, TN:TP, and Chl did not change. A minority (7%–16%) of individual lakes had changing nutrients, stoichiometry, or Chl. Of those lakes that changed, we found differences in the geospatial variables that were most related to the observed change in the response variables. For example, TN and TN:TP trends were related to region-level drivers associated with atmospheric deposition of N; TP trends were related to both lake and region-level drivers associated with climate and land use; and Chl trends were found in regions with high air temperature at the beginning of the study period. We conclude that despite large environmental change and management efforts over recent decades, water quality of lakes in the Midwest and Northeast U.S. has not overwhelmingly degraded or improved.

Global Change Biology↗
USGS2009

The ecology of dust

Wind erosion and associated dust emissions play a fundamental role in many ecological processes and provide important biogeochemical connectivity at scales ranging from individual plants up to the entire globe. Yet, most ecological studies do not explicitly consider dust‐driven processes, perhaps because most relevant research on aeolian (wind‐driven) processes has been presented in a geosciences rather than an ecological context. To bridge this disciplinary gap, we provide a general overview of the ecological importance of dust, examine complex interactions between wind erosion and ecosystem dynamics from the scale of plants and surrounding space to regional and global scales, and highlight specific examples of how disturbance affects these interactions and their consequences. It is likely that changes in climate and intensification of land use will lead to increased dust production from many drylands. To address these issues, environmental scientists, land managers, and policy makers need to consider wind erosion and dust emissions more explicitly in resource management decisions.

Frontiers in Ecology and the Environment↗
USGS2000

Mercury bioaccumulation in fish in a region affected by historic gold mining: The South Yuba River, Deer Creek, and Bear River watersheds, California, 1999

Mercury that was used historically for gold recovery in mining areas of the Sierra Nevada continues to enter local and downstream water bodies, including the Sacramento Delta and the San Francisco Bay of northern California. Methylmercury is of particular concern because it is the most prevalent form of mercury in fish and is a potent neurotoxin that bioaccumulates at successive trophic levels within food webs. In April 1999, the U.S. Geological Survey, in cooperation with several other agencies the Forest Service (U.S. Department of Agriculture), the Bureau of Land Management, the U.S. Environmental Protection Agency, the California State Water Resources Control Board, and the Nevada County Resource Conservation District began a pilot investigation to characterize the occurrence and distribution of mercury in water, sediment, and biota in the South Yuba River, Deer Creek, and Bear River watersheds of California. Biological samples consisted of semi-aquatic and aquatic insects, amphibians, bird eggs, and fish. Fish were collected from 5 reservoirs and 14 stream sites during August through October 1999 to assess the distribution of mercury in these watersheds. Fish that were collected from reservoirs included top trophic level predators (black basses, Micropterus spp.) intermediate trophic level predators [sunfish (blue gill, Lepomis macrochirus; green sunfish, Lepomis cyanellus; and black crappie, Poxomis nigromaculatus)] and benthic omnivores (channel catfish, Ictularus punctatus). At stream sites, the species collected were upper trophic level salmonids (brown trout, Salmo trutta) and upper-to-intermediate trophic level salmonids (rainbow trout, Oncorhynchus mykiss). Boneless and skinless fillet portions from 161 fish were analyzed for total mercury; 131 samples were individual fish, and the remaining 30 fish were combined into 10 composite samples of three fish each of the same species and size class. Mercury concentrations in samples of black basses (Micropterus spp.), including largemouth, smallmouth, and spotted bass, ranged from 0.20 to 1.5 parts per million (ppm), wet basis. Mercury concentrations in sunfish ranged from less than 0.10 to 0.41 ppm (wet). Channel catfish had mercury concentrations from 0.16 to 0.75 ppm (wet). The range of mercury concentrations observed in rainbow trout was from 0.06 to 0.38 ppm (wet), and in brown trout was from 0.02 to 0.43 ppm (wet). Mercury concentrations in trout were greater than 0.3 ppm in samples from three of 14 stream sites. Mercury at elevated concentrations may pose a health risk to piscivorous wildlife and to humans who eat fish on a regular basis. Data presented in this report may be useful to local, state, and federal agencies responsible for assessing the potential risks associated with elevated levels of mercury in fish in the South Yuba River, Deer Creek, and Bear River watersheds.

California↗
USGS2001

U.S. Geological Survey Appalachian region integrated science workshop proceedings, Gatlinburg, Tennessee, October 22-26, 2001

Some of nature's most magnificent creations on Earth are the picturesque landscape and the terrestrial and aquatic inhabitants of the Appalachian Mountains of the Eastern United States. Mother Nature has been kind to the region but man, often, has not. The Appalachian mountains and valleys have been home to a variety of human cultures, dating back approximately 12,000 years. A series of Native American peoples, including most recently the Cherokee Nation, inhabited the region prior to European settlement which began in the 1600's. All of these peoples have had the desire to reap the benefits of the land. Current and historic use of the land ranges from mineral extraction to agricultural development to timber production to industrial and residential development, all of which have now threatened the landscape. Many individuals and organizations desire to save the awe and beauty of the Appalachians for the generations to come, in a way that is environmentally and economically sustainable. They have tried for years to raise alarms that this area is threatened and worth the attention of all who are interested in an effort of restitution and preservation. Residents, environmental groups, land managers, scientists, business groups, and the multitude of visitors who pass through the national parks and other public lands located within the Appalachians have raised these same alarms. There is a need to not only identify the issues resulting from anthropogenic pressures on the landscape, but also to collect the information and conduct the science that will allow land managers and policy makers to become better informed and better able to execute their responsibilities.

Appalachia↗
USGS2007

Factors affecting the reproduction, recruitment, habitat, and population dynamics of pallid sturgeon and shovelnose sturgeon in the Missouri River

For more than a hundred years, human activities have modified the natural forces that control the Missouri River and its native fish fauna. While the ecological effects of regulation and channel engineering are understood in general, the current understanding is not sufficient to guide river restoration and management. The U.S. Geological Survey (USGS) is in the third year of a multiagency research effort to determine the ecological requirements for reproduction and survival of the endangered pallid sturgeon (Scaphirhynchus albus) and shovelnose sturgeon (Scaphirhynchus platorhynchus) in the Missouri River. The multidisciplinary research strategy includes components of behavior, physiology, habitat use, habitat availability, and population modeling of all life stages. Shovelnose sturgeon are used to design the strategy because they are closely related to the pallid sturgeon and are often used as a surrogate species to develop new research tools or to examine the effects of management actions or environmental variables on sturgeon biology and habitat use. During fiscal years 2005 and 2006, the U.S. Army Corps of Engineers (USACE) provided funds to USGS for tasks associated with the Comprehensive Sturgeon Research Program (CSRP) and for tasks associated with evaluation of the Sturgeon Response to Flow Modifications (SRFM). Because work activities of CSRP and SRFM are so integrated, we are providing information on activities that have been consolidated at the task level. These task activities represent chapters in this report.

Open-File Report↗
USGS2007

Project overview: Chapter A in Factors affecting the reproduction, recruitment, habitat, and population dynamics of pallid sturgeon and shovelnose sturgeon in the Missouri River

For more than a hundred years, human activities have modified the natural forces that control the Missouri River and its native fish fauna. While the ecological effects of regulation and channel engineering are understood in general, the current understanding is not sufficient to guide river restoration and management. The U.S. Geological Survey (USGS) is in the third year of a multiagency research effort to determine the ecological requirements for reproduction and survival of the endangered pallid sturgeon ( Scaphirhynchus albus ) and shovelnose sturgeon ( Scaphirhynchus platorhynchus ) in the Missouri River. The multidisciplinary research strategy includes components of behavior, physiology, habitat use, habitat availability, and population modeling of all life stages. Shovelnose sturgeon are used to design the strategy because they are closely related to the pallid sturgeon and are often used as a surrogate species to develop new research tools or to examine the effects of management actions or environmental variables on sturgeon biology and habitat use. During fiscal years 2005 and 2006, the U.S. Army Corps of Engineers (USACE) provided funds to USGS for tasks associated with the Comprehensive Sturgeon Research Program (CSRP) and for tasks associated with evaluation of the Sturgeon Response to Flow Modifications (SRFM). Because work activities of CSRP and SRFM are so integrated, we are providing information on activities that have been consolidated at the task level. These task activities represent chapters in this report.

Missouri River↗
USGS2010

Mercury in Sediment, Water, and Biota of Sinclair Inlet, Puget Sound, Washington, 1989-2007

Historical records of mercury contamination in dated sediment cores from Sinclair Inlet are coincidental with activities at the U.S. Navy Puget Sound Naval Shipyard; peak total mercury concentrations occurred around World War II. After World War II, better metallurgical management practices and environmental regulations reduced mercury contamination, but total mercury concentrations in surface sediment of Sinclair Inlet have decreased slowly because of the low rate of sedimentation relative to the vertical mixing within sediment. The slopes of linear regressions between the total mercury and total organic carbon concentrations of sediment offshore of Puget Sound urban areas was the best indicator of general mercury contamination above pre-industrial levels. Prior to the 2000-01 remediation, this indicator placed Sinclair Inlet in the tier of estuaries with the highest level of mercury contamination, along with Bellingham Bay in northern Puget Sound and Elliott Bay near Seattle. This indicator also suggests that the 2000/2001 remediation dredging had significant positive effect on Sinclair Inlet as a whole. In 2007, about 80 percent of the area of the Bremerton naval complex had sediment total mercury concentrations within about 0.5 milligrams per kilogram of the Sinclair Inlet regression. Three areas adjacent to the waterfront of the Bremerton naval complex have total mercury concentrations above this range and indicate a possible terrestrial source from waterfront areas of Bremerton naval complex. Total mercury concentrations in unfiltered Sinclair Inlet marine waters are about three times higher than those of central Puget Sound, but the small numbers of samples and complex physical and geochemical processes make it difficult to interpret the geographical distribution of mercury in marine waters from Sinclair Inlet. Total mercury concentrations in various biota species were compared among geographical locations and included data of composite samples, individual specimens, and caged mussels. Total mercury concentrations in muscle and liver of English sole from Sinclair Inlet ranked in the upper quarter and third, respectively, of Puget Sound locations. For other species, concentrations from Sinclair Inlet were within the mid-range of locations (for example, Chinook salmon). Total mercury concentrations of the long-lived and higher trophic rockfish in composites and individual specimens from Sinclair Inlet tended to be the highest in Puget Sound. For a given size, sand sole, graceful crab, staghorn sculpin, surf perch, and sea cucumber individuals collected from Sinclair Inlet had higher total mercury concentrations than individuals collected from non-urban estuaries. Total mercury concentrations in individual English sole and ratfish were not significantly different than in individuals of various sizes collected from either urban or non-urban estuaries in Puget Sound. Total mercury concentrations in English sole collected from Sinclair Inlet after the 2000-2001 dredging appear to have lower total mercury concentrations than those collected before (1996) the dredging project. The highest total mercury concentrations of mussels caged in 2002 were not within the Bremerton naval complex, but within the Port Orchard Marina and inner Sinclair Inlet.

Open-File Report↗
USGS2012

Alaska Geochemical Database - Mineral Exploration Tool for the 21st Century - PDF of presentation

The U.S. Geological Survey has created a geochemical database of geologic material samples collected in Alaska. This database is readily accessible to anyone with access to the Internet. Designed as a tool for mineral or environmental assessment, land management, or mineral exploration, the initial version of the Alaska Geochemical Database - U.S. Geological Survey Data Series 637 - contains geochemical, geologic, and geospatial data for 264,158 samples collected from 1962-2009: 108,909 rock samples; 92,701 sediment samples; 48,209 heavy-mineral-concentrate samples; 6,869 soil samples; and 7,470 mineral samples. In addition, the Alaska Geochemical Database contains mineralogic data for 18,138 nonmagnetic-fraction heavy mineral concentrates, making it the first U.S. Geological Survey database of this scope that contains both geochemical and mineralogic data. Examples from the Alaska Range will illustrate potential uses of the Alaska Geochemical Database in mineral exploration. Data from the Alaska Geochemical Database have been extensively checked for accuracy of sample media description, sample site location, and analytical method using U.S. Geological Survey sample-submittal archives and U.S. Geological Survey publications (plus field notebooks and sample site compilation base maps from the Alaska Technical Data Unit in Anchorage, Alaska). The database is also the repository for nearly all previously released U.S. Geological Survey Alaska geochemical datasets. Although the Alaska Geochemical Database is a fully relational database in Microsoft® Access 2003 and 2010 formats, these same data are also provided as a series of spreadsheet files in Microsoft® Excel 2003 and 2010 formats, and as ASCII text files. A DVD version of the Alaska Geochemical Database was released in October 2011, as U.S. Geological Survey Data Series 637, and data downloads are available at http://pubs.usgs.gov/ds/637/ . Also, all Alaska Geochemical Database data have been incorporated into the interactive U.S. Geological Survey Mineral Resource Data web portal, available at http://mrdata.usgs.gov/ .

Alaska↗
USGS2016

Users and uses of Landsat 8 satellite imagery—2014 survey results

Executive Summary In 2013, Landsat 8 began adding high quality, global, moderate-resolution imagery to the more than 40-year archive of Landsat imagery. To assess the potential effects of the availability of Landsat 8 imagery on users and their work, the U.S. Geological Survey (USGS) Land Remote Sensing Program (LRS) initiated a survey of Landsat users. The objectives of the survey were to 1. Characterize various Landsat user groups, such as United States (U.S.) and international users and Landsat 8 and non-Landsat 8 users; 2. Identify any differences among user groups in uses and preferences; 3. Measure the importance of and satisfaction with Landsat 8 attributes; 4. Assess the importance to users of the frequency of usable imagery; and 5. Determine any challenges in using Landsat 8. The online survey was sent to 51,617 Landsat users registered with USGS in May 2014. Almost 13,000 people responded to the survey for a response rate of 25 percent (n = 12,966). Current Landsat users (users who had used Landsat in their work in the year prior to the survey) composed 89 percent of the sample (n = 11,549) and past Landsat users composed 11 percent (n = 1,417). The results reported here apply to current Landsat users registered with the USGS Earth Resources Observation and Science (EROS) Center. Users from 161 countries responded to the survey. Of those, 19 percent were citizens or permanent residents of the United States and 81 percent resided in other countries. More than 70 percent of current users had used Landsat 8 in the year prior to the survey. The majority of Landsat 8 users (65 percent) were established users who used Landsat imagery regularly both before and after Landsat 8 imagery became available. The average current Landsat user was male, 36 years old, and highly educated, with 9 years of experience using satellite imagery or geographic information system (GIS) software. Landsat 8 users had, on average, two more years of experience than non-Landsat 8 users. Users were employed predominantly by academic institutions (65 percent), followed by private businesses (13 percent), Federal governments (10 percent), State and local governments (6 percent), and nonprofit organizations (6 percent). Of the Landsat imagery obtained in the past year by current users, on average 31 percent came from a Landsat 8 sensor. An equivalent amount came from the Landsat 7 ETM+ sensor (33 percent); slightly less came from Landsats 4 and 5 TM sensors (27 percent). Much less came from Landsats 1 through 5 MSS sensors (5 percent). Overall, more than a third of users’ work used Landsat imagery (38 percent). Of this work, on average, 37 percent of the work was operational. Landsat 8 users considered a greater proportion of their work operational than non-Landsat 8 users (39 percent compared with 29 percent). Environmental sciences and management were the most commonly selected primary applications (selected by 42 percent of users). Land use/land cover (23 percent) was the second most commonly selected primary application, followed by education (12 percent), agriculture (9 percent), and planning and development (6 percent). Landsat 8 users were asked to rank the importance of certain attributes in determining whether to use Landsat 8 imagery in their work. The archive was ranked most important, followed by cost, spatial resolution, extent of coverage, data quality, and frequency of revisit. Users were asked how satisfied they were with these same attributes as they currently apply to Landsat 8 imagery. On average, users were most satisfied with lack of cost, extent of coverage, data quality, and the archive, but they were satisfied with all attributes. Users were asked how often they needed Landsat imagery to meet various requirements for their primary application. The survey question specifically asked how often users needed usable imagery, which differs from how often they would like the Landsat satellites to acquire an image. Users were asked to identify their needed frequency of usable imagery for the following levels: 1. Threshold level—the minimum frequency of usable imagery needed to be of any value to their primary application. 2. Breakthrough level—the frequency of usable imagery that would result in a significant improvement for their primary application of the imagery. 3. Target level—the frequency of usable imagery that would only provide a limited additional increase in the expected performance for their primary application. To meet the threshold level, three-quarters of users needed usable imagery every 17 days or less frequently. At the breakthrough level, two-thirds of users (64 percent) needed a usable image every 5–16 days. The current constellation of two satellites (Landsat 7 and 8) is capable of meeting the threshold and breakthrough needs of most users at least some of the time, but a single satellite would be highly unlikely to do so. Two-fifths of users (40 percent) felt that usable imagery provided every 4 days or more frequently would meet their target level which the current Landsat constellation cannot provide. Landsat 8 users were significantly more likely than non-Landsat 8 users to need usable imagery more frequently to meet their target levels. Additionally, U.S. Landsat 8 users were significantly more likely than other Landsat users to need usable imagery more frequently in order meet both their breakthrough and target levels. To explore the effect of the availability of Landsat 8 imagery on Landsat imagery use in general, established users (those who had consistently used Landsat imagery both before and after Landsat 8 imagery became available) using Landsat 8 imagery were asked about changes in the amount of Landsat imagery they used. The majority of established users using Landsat 8 imagery (60 percent) reported an average increase of 51 percent in the number of scenes obtained after Landsat 8 imagery became available. Landsat 8 users were asked if they had encountered challenges in using Landsat 8 whereas non-Landsat 8 users were asked if such challenges had played a role in why they were not using Landsat 8 imagery. Although many users did not encounter challenges when using or trying to use Landsat 8 data, slightly less than 30 percent did encounter issues with processing the data to a usable point. The most common issue reported was not being able to create or have access to a surface reflectance corrected product. Other challenges were related to the file sizes of images being too large to download, store, or analyze. There were no statistically significant differences between Landsat 8 and non-Landsat 8 users in terms of challenges encountered when using or trying to use the imagery, which indicates that users were not unduly discouraged by the challenges they may have encountered. When asked about potential consequences of not using Landsat 8, more than half of the non-Landsat 8 users did not report detrimental effects on their work from not using the imagery. Of those who did report detrimental effects, decreased quality of work, decreased scope of work, and increased time spent on work were the most common.

Open-File Report↗
USGS2019

The risk reduction benefits of the Mesoamerican Reef in Mexico

Coastal development and climate change are dramatically increasing the risks of flooding, erosion, and extreme weather events. Coral reefs and other coastal ecosystems act as natural defenses against coastal hazards, but their degradation increases risk to people and property. Environmental degradation, however, has rarely been quantified as a driver of coastal risk. In Quintana Roo, Mexico, a region on the Mexican Caribbean coast with an annual tourism economy of 10 billion USD, coral reefs constitute a natural barrier against flooding from hurricanes. This study spatially quantifies the risk reduction benefits of the Mesoamerican Reef in Quintana Roo for people, buildings, and hotel infrastructure. The risk reduction benefits are substantial. For example, the reefs prevented 43% additional damage during Hurricane Dean in (2007) and provide nowadays hazard risk reduction for 4.3% of the people, 1.9% of the built capital, and 2.4% of the hotel infrastructure, per year. The annual benefits are estimated in 4,600 people, 42 million USD damage prevention for buildings, and 20.8 million USD for hotel infrastructure. The study also compares the risk reduction of coral reefs with (i) the protection offered by dunes and (ii) the increase in coastal risk from sea-level rise (SLR). The risk reduction of dunes is more critical where there are no coral reefs offshore and for small return-periods storms. Sea-level rise, however, will make the more frequent storms more impactful and will drive significant increases in annual expected damages across the region. However, we demonstrate that, in coral reef environments, the contribution of reef degradation to coastal risk is larger than the expected increase in risk from SLR. However, the spatial distribution of the risk reduction benefits from reefs differs for people and infrastructure, and in particular for hotels, which receive the most protection from reefs. Furthermore, many sections present larger benefits than the typical costs of restoration. This valuation makes a compelling case for protecting and maintaining this natural infrastructure for its risk reduction service, but also allows the development of piloting innovative strategies, such as risk finance and insurance strategies, that can align environmental and risk management goals.

Mesoamerican Reef↗