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At least 1,243 records · Page 69Linked to original sources
USGS1972

Annual compilation and analysis of hydrologic data for Honey Creek, Trinity River Basin, Texas, 1970

The U.S. Soil Conservation Service is actively engaged in the installation of flood- and soil-erosion reducing measures in Texas under the authority of "The Flood Control Act of 1936 and 1944" and "Watershed Protection and Flood Prevention Act" (Public Law 566), as amended. The Soil Conservation Service has found a total of approximately 3,500 floodwater-retarding structures to be physically and economically feasible in Texas. As of September 30, 1970, 1,439 of these structures had been built. This watershed-development program will have varying but important effects on the natural surface- and ground-water resources of river basins, especially where a large number of the floodwater-retarding structures are built. Basic hydrologic data under natural and developed conditions are needed to appraise the effects of the structures on the yield and mode of occurrence of runoff. Hydrologic investigations of these small watershed study areas were begun by the U.S. Geological Survey in 1951 and are now being made in 12 areas (fig. 1). These investigations are being made in cooperation with the Texas Water Development Board, the Soil Conservation Service, the San Antonio River Authority, the city of Dallas, and the Tarrant County Water Control and Improvement District No. 1. The 12 study areas were chosen to sample watersheds having different rainfall, topography, geology, and soils. In five of the study areas (North, Little Elm, Mukewater, Little Pond-North Elm, and Pin Oak Creeks), streamflow and rainfall records were collected prior to construction of the floodwater-retarding structures, thus affording the opportunity for analyses of the conditions 'before and after" development. Structures have now been built in four of these study areas. A summary of the development of the floodwater-retarding structures in each study area as of September 30, 1970, is shown in table 1.

Texas↗
USGS2018

Assessing effects of nonnative crayfish on mosquito survival

Introductions of nonnative predators often reduce biodiversity and affect natural predator–prey relationships and may increase the abundance of potential disease vectors (e.g., mosquitoes) indirectly through competition or predation cascades. The Santa Monica Mountains (California, U.S.A.), situated in a global biodiversity hotspot, is an area of conservation concern due to climate change, urbanization, and the introduction of nonnative species. We examined the effect of nonnative crayfish (Procambarus clarkii) on an existing native predator, dragonfly nymphs (Aeshna sp.), and their mosquito larvae (Anopheles sp.) prey. We used laboratory experiments to compare the predation efficiency of both predators, separately and together, and field data on counts of dragonfly nymphs and mosquito larvae sampled from 13 local streams. We predicted a lower predation efficiency of crayfish compared with native dragonfly nymphs and a reduced predation efficiency of dragonfly nymphs in the presence of crayfish. Dragonfly nymphs were an order of magnitude more efficient predators than crayfish, and dragonfly nymph predation efficiency was reduced in the presence of crayfish. Field count data showed that populations of dragonfly nymphs and mosquito larvae were strongly correlated with crayfish presence in streams, such that sites with crayfish tended to have fewer dragonfly nymphs and more mosquito larvae. Under natural conditions, it is likely that crayfish reduce the abundance of dragonfly nymphs and their predation efficiency and thereby, directly and indirectly, lead to higher mosquito populations and a loss of ecosystem services related to disease vector control.

California↗
USGS2022

You can go your own way: No evidence for social behavior based on kinship or familiarity in captive juvenile box turtles

Behavioral interactions between conspecific animals can be influenced by relatedness and familiarity. Compared to other vertebrate taxa, considering such aspects of social behavior when housing captive reptiles has received less attention, despite the implications this could have for informing husbandry practices, enhancing welfare, and influencing outcomes of conservation translocations. In this study, to test how kinship and familiarity influenced social behavior in a reptile, we reared 16 captive-born Eastern Box Turtles ( Terrapene carolina ) under semi-natural conditions in four equally sized groups, where each group comprised pairs of siblings and non-siblings. Using separation distance between pairs of turtles in rearing enclosures as a measure of gregariousness, we found no evidence suggesting siblings more frequently interacted with one another compared to non-relatives over the first five months of life (β = -0.016, 95% CI: -0.117 to 0.084). Average pair separation distance decreased during this time (β = -0.146, 95% CI: -0.228 to -0.063) but may have been due to turtles aggregating around concentrated resources like heat and moist retreat areas as cold winter temperatures approached. When subject were eight months old, we measured repeated separation distances between unique pair combinations in an experimental environment and similarly found no support for gregariousness (associations) being influenced by kinship or familiarity (β = -1.554, 95% CI: -9.956 to 6.848). Additionally, differences in body size between pairs of turtles (β = -22.289, 95% CI: -68.448 to 23.870) nor the five-minute time interval during the 90-minute trial (P ≥ 0.18) had any apparent effect on associations. Agonistic interactions between individuals were never observed. Encouragingly, based on our results, group housing and rearing of juvenile box turtles did not appear to negatively impact their behavioral and physiological well-being. Unlike findings for other taxa, including some reptiles, our results suggest strategically housing groups of juvenile T. carolina to maintain social stability may not be an important husbandry consideration, or even a requirement, when planning releases of captive-reared individuals for conservation purposes.

Applied Animal Behaviour Science↗
USGS2020

Interaction between watershed features and climate forcing affects habitat profitability for juvenile salmon

Opportunities for growth and survival of aquatic organisms are spatially and temporally variable as habitat conditions across watersheds respond to interacting climatic, geomorphic, and hydrologic conditions. As conservation efforts often focus on identifying and protecting critical habitats, it is important to understand how this spatial and temporal variation in habitat quality affects the production dynamics of populations. Here, we use microchemical records preserved in otoliths to reconstruct juvenile habitat‐use by sockeye salmon that survived to spawn in a single population on the Alaska Peninsula. Successful individuals demonstrated a diverse array of juvenile behavioral strategies both within and among years. Importantly, the dominant juvenile behavioral strategy used by successful individuals changed among years, suggesting shifts in the relative benefits of different rearing habitats. The growth benefits of remaining in a more productive rearing lake were greatest in warm years indicating environmental influence on relative habitat quality. However, we found no strong relationship between the amount of growth accumulated in the productive rearing lake and overall population productivity across years. These results highlight the dynamic nature of habitat conditions and the beneficial effect of maintaining connectivity between diverse habitats for population productivity. When short‐term studies are used to demonstrate the relative values of different habitats to species of conservation concern, there is a distinct risk of under‐valuing habitats that may be critically important under alternative environmental conditions. In particular, land‐use decisions that reduce the range of habitat options available to species may erode a population’s ability to withstand environmental change over the long term.

Alaska↗
USGS2023

The context dependency of fish-habitat associations in separated karst ecoregions

Fish populations may be isolated via natural conditions in geographically separated ecoregions. Although reconnecting these populations is not a management goal, we need to understand how these populations persist across landscapes to develop meaningful conservation actions, particularly for species occupying sensitive karst ecosystems. Our study objective was to determine the physicochemical factors related to the occurrence of four spring-associated fishes. Arbuckle Uplift and Ozark Highlands ecoregions, USA. We used a hierarchical approach to identify habitat relationships at multiple spatial scales. We collected detection data using snorkeling and seining. We examined the physicochemical relationships related to the detection and occurrence of four spring-associated fishes using occupancy modeling in a Bayesian framework. We found physicochemical relationships that differed and were similar between ecoregions for several fishes. For three species, we found different water temperature relationships between ecoregions. Smallmouth bass were ubiquitous in their use of drainage areas in the Ozark Highlands but only associated with the lower network of the Arbuckle Uplift. There were several mirrored relationships between ecoregions, including an interaction between residual pool depth and water temperature, where sites with deeper pools were more likely to be occupied during warmer water temperatures. There were single-species occurrence relationships with percent vegetation and percent agriculture. Lastly, snorkeling was a more efficient sampling method compared to seining for all fishes. Our results indicate stream temperature mitigation may be possible via the maintenance of key channel morphologies, and we identify shared stressors between ecoregions. Channel mitigation to maintain reaches with deeper pools may be an important strategy for maintaining thermal refugia, particularly when considering climate change. Identifying the mechanistic underpinning of other multiscale ecological relationships would be helpful to discern if some of the different ecoregion relationships represent warning signals or interactions with unmeasured biotic or abiotic factors.

Oklahoma↗
USGS2020

Disturbance refugia within mosaics of forest fire, drought, and insect outbreaks

Disturbance refugia – locations that experience less severe or frequent disturbances than the surrounding landscape – provide a framework to highlight not only where and why these biological legacies persist as adjacent areas change but also the value of those legacies in sustaining biodiversity. Recent studies of disturbance refugia in forest ecosystems have focused primarily on fire, with a growing recognition of important applications to land management. Given the wide range of disturbance processes in forests, developing a broader understanding of disturbance refugia is important for scientists and land managers, particularly in the context of anthropogenic climate change. We illustrate the framework of disturbance refugia through the individual and interactive effects of three prominent forest disturbance agents: fire, drought, and insect outbreaks. We provide examples of disturbance refugia and related applications to natural resource management in western North America, demonstrate methods for characterizing refugia, identify research priorities, and discuss why a more comprehensive definition of disturbance refugia is relevant to conservation globally.

Frontiers in Ecology and the Environment↗
USGS2023

Quantifying the contributions of tributaries to large-river fish populations through mark-recapture modeling

Tributaries may play a vital role in maintaining populations of large river fishes, although the specific contributions of tributaries toward recruitment of river-wide populations are not often understood. Tributaries may experience fewer cumulative anthropogenic impacts relative to mainstem rivers and may offer more natural conditions supportive of native fish populations, which may provide opportunities for fish population restoration. Thus, an improved understanding of tributary-mainstem population dynamics may inform targeted conservation actions for spatially structured populations of large-river fishes. Colorado River tributaries in the Grand Canyon, Arizona, USA are a focus of imperiled Humpback Chub Gila cypha conservation, which includes translocations to enhance population redundancy and to expand the overall population. However, the fate of fish dispersed to the mainstem has not been thoroughly quantified. Using open population mark-recapture models, we quantified the relative contribution of three groups of Humpback Chub, including fish of confirmed tributary origin that were either translocated or produced in situ , and others presumed to be Colorado River mainstem origin fish, to three mainstem populations. Our specific study objectives were to 1) estimate Colorado River abundances of tributary and mainstem-origin fish over time, 2) compare relative group-specific contributions to three mainstem populations, and 3) compare group-specific survival rates of Humpback Chub in the Colorado River and in a tributary where a recent translocation has occurred. Tributaries contributed 26% and 43% of the overall abundance in two tributary inflow reach populations, and zero in a third, which we attributed to uncharacteristically low tributary survival immediately following translocation. In the mainstem, survival of tributary-origin fish was higher compared to mainstem-origin fish, suggesting an advantage of tributary residence. Our contrasting results from three different tributary inflow populations highlight the potential role for tributaries in sustaining large-river fish populations, which may have important implications for long-term maintenance of river metapopulations.

North American Journal of Fisheries Management↗
USGS2007

Revisiting the cape cod bacteria injection experiment using a stochastic modeling approach

Bromide and resting-cell bacteria tracer tests conducted in a sandy aquifer at the U.S. Geological Survey Cape Cod site in 1987 were reinterpreted using a three-dimensional stochastic approach. Bacteria transport was coupled to colloid filtration theory through functional dependence of local-scale colloid transport parameters upon hydraulic conductivity and seepage velocity in a stochastic advection - dispersion/attachment - detachment model. Geostatistical information on the hydraulic conductivity (K) field that was unavailable at the time of the original test was utilized as input. Using geostatistical parameters, a groundwater flow and particle-tracking model of conservative solute transport was calibrated to the bromide-tracer breakthrough data. An optimization routine was employed over 100 realizations to adjust the mean and variance ofthe natural-logarithm of hydraulic conductivity (InK) field to achieve best fit of a simulated, average bromide breakthrough curve. A stochastic particle-tracking model for the bacteria was run without adjustments to the local-scale colloid transport parameters. Good predictions of mean bacteria breakthrough were achieved using several approaches for modeling components of the system. Simulations incorporating the recent Tufenkji and Elimelech (Environ. Sci. Technol. 2004, 38, 529-536) correlation equation for estimating single collector efficiency were compared to those using the older Rajagopalan and Tien (AIChE J. 1976, 22, 523-533) model. Both appeared to work equally well at predicting mean bacteria breakthrough using a constant mean bacteria diameter for this set of field conditions. Simulations using a distribution of bacterial cell diameters available from original field notes yielded a slight improvement in the model and data agreement compared to simulations using an average bacterial diameter. The stochastic approach based on estimates of local-scale parameters for the bacteria-transport process reasonably captured the mean bacteria transport behavior and calculated an envelope of uncertainty that bracketed the observations in most simulation cases.

Massachusetts↗
USGS2025

Reservoir operational strategies for sustainable sand management in the Colorado River

Climate change and increasing societal demands for water pose challenges for the management of dam-regulated rivers. Management decisions impact the environment of these rivers, creating the need to balance societal needs with environmental conservation. Here we present a modeling framework that optimizes resource benefits within imposed water use goals for the Colorado River in Grand Canyon, where sandbars are a valued natural feature. The current sand-management paradigm utilizes controlled dam-release floods to build and maintain sandbars without exhausting the limited sand supplied by tributaries downstream from Glen Canyon Dam, which blocks all sand supplied from upriver. High monthly releases outside of controlled floods erode sandbars and cause net sand export from Grand Canyon, reducing the sand available to build sandbars. Releases are high in some months owing to the need to adjust flows to meet annual delivery targets, which can be updated throughout the year. Here, we present alternative strategies for operations that avoid high releases, while meeting water storage and delivery goals. We test these strategies using a simplified reservoir model which accounts for forecast uncertainty. We show how these strategies affect sand mass balance and sandbar size using previously developed models. Strategies optimal for sustainable sandbar building maintained sufficient reservoir elevations for implementing controlled floods, avoided high monthly releases by relaxing annual release constraints, and implemented controlled floods in fall immediately following tributary sand inputs. Coordinated modeling of reservoir operations and environmental resources is valuable for managers seeking to balance societal and environmental needs in regulated rivers worldwide.

Arizona↗
USGS2016

Metapopulation viability of an endangered shorebird depends on dispersal and human-created habitats: Piping plovers ( Charadrius melodus ) and prairie rivers

Background Many species are distributed as metapopulations in dynamic landscapes, where habitats change through space and time. Individuals locate habitat through dispersal, and the relationship between a species and landscape characteristics can have profound effects on population persistence. Despite the importance of connectivity in dynamic environments, few empirical studies have examined temporal variability in dispersal or its effect on metapopulation dynamics. In response to this knowledge gap, we studied the dispersal, demography, and viability of a metapopulation of an endangered, disturbance-dependent shorebird. We examined three subpopulations of piping plovers ( Charadrius melodus ) on the lower Platte and Missouri rivers from 2008–2013. High flow events from an upstream dam on the Missouri River in 2010 and 2011 allowed us to assess the effect of total habitat loss and the subsequent creation of new habitat associated with a large disturbance at one ‘natural’ study location. The other two sites within the metapopulation, which were maintained by anthropogenic activities (e.g., mining, development, habitat restoration), were largely unaffected by this disturbance, resulting in a controlled natural experiment. Results High flow events were associated with increased emigration, decreased immigration, and decreased survival in the subpopulation that experienced high flows. Following the high flow event, immigration into that subpopulation increased. Dispersal rates among subpopulations were negatively correlated with distance. The metapopulation had a low probability of extinction over 100 years (0%) under the current disturbance interval and associated dispersal and survival rates. However, persistence depended on relatively stable, human-created habitats, not the dynamic, natural habitat (47.7 % extinction probability for this subpopulation). Conclusions We found that functional connectivity, as measured by the rate of dispersal among subpopulations, increased as a result of the high flow event in our study metapopulation. Plovers also increased reproductive output following this event. Although the study metapopulation had a low overall probability of extinction, metapopulation persistence depended on anthropogenically created habitats that provided a small but stable source of nesting habitat and dispersers through time. However, all subpopulations remained small, even if persistent, making them individually vulnerable to extinction through stochastic events. Given the highly dynamic nature of habitat availability in this system, maintaining several subpopulations within the metapopulation and stable sources of habitat will be critical, and this species will likely remain conservation-reliant.

Nebraska↗
USGS2001

Reproductive ecology and demography of the 'Akohekohe

The ‘Ākohekohe ( Palmeria dolei ) is an endangered Hawaiian honeycreeper endemic to the montane rain forests of east Maui in the Hawaiian Islands. We investigated ‘Ākohekohe nesting ecology using color-banded birds for the first time as a background to understanding the species' conservation. From 1994–1997, we color-banded 78 individuals, located and monitored 46 active nests, and took behavioral data during 534 hr of nest observation at Hanawī Natural Area Reserve, near the center of the species' range. ‘Ākohekohe nesting behavior and life history closely resembled that of ‘Apapane ( Himatione sanguinea ) and related honeycreepers. The birds were monogamous within and among years, and we found no evidence of polyandry, polygyny, or helpers at the nest. The nesting season extended from November to early June. Females performed all incubation and brooding. Males provisioned females and nestlings, and they were more active than females in feeding fledglings during the two-week period of parental dependency. Modal clutch size, as determined from egg counts at three nests and by counting begging chicks at other nests, was two eggs, and parents frequently fledged two chicks. We found an overall nest success rate of 68% by the Mayfield method, a high rate compared with other Hawaiian honeycreepers and continental passerines. An average of 1.1 chicks fledged per active nest, and at least 42% of nesting pairs made two or more nesting attempts per season. Rats ( Rattus spp.) were abundant at the study site, and we confirmed their depredating some ‘Ākohekohe nests, so we did not expect to find such a high rate of nest success. The estimated annual probability of adult survival was also high, at 0.95 ± 0.10 (SE).

Condor↗
USGS1979

Federal onshore oil and gas lease bonus bids, 1972-1977: Statistical studies

We studied the statistical behavior of Federal onshore oil and gas lease bonus bids. Like offshore bids, these bids exhibited (a) occasional occurrences of low, noise bids, (b) apparent lognormality, (c) standard deviations (using natural logarithms) close to one, (d) apparent disparities between money left on the table given random lognormal bids consistent with flinching, and (e) wide ranges of aggressive and conservative biases of bidders in individual sales. In fact, the only substantive difference found was a far lesser proportion of joint bidding and larger company bidders bidding for these onshore leases which tended to receive lower bids than offshore bids.

Open-File Report↗
USGS2024

Estimated reductions in phosphorus loads from removal of leaf litter in the Lake Champlain drainage area, Vermont

Excess nutrient loading and other factors are driving eutrophication and other negative effects on water-quality conditions in Lake Champlain and other receiving waters in Vermont. Two common best management practices were evaluated to determine how these practices can be optimized by targeting maintenance and operation to align better with seasonally driven needs, specifically to help municipalities remove a greater proportion of seasonal leaves and organic debris, reduce nutrient loading, and achieve water-quality goals. To characterize solid materials typically removed by the municipal BMPs of catch-basin (CB) cleaning and street cleaning (SC), subsamples of CB and SC materials were collected each month from nine participating municipalities in central and northwestern Vermont between September 2017 and November 2018. Monthly and seasonal composites of CB and SC samples were created from the subsamples of available materials from all municipalities. Samples were analyzed for concentrations of total organic carbon, total Kjeldahl nitrogen, and total phosphorus (P), and separated into three particle-size fractions. Distribution of particle-size fractions was similar between CB and SC as both practices generally collect the coarser fraction of solid materials (greater than 125 micrometers in diameter). In the fall, however, the range of the coarser fraction of materials increased. This is attributed to the ability of SC to collect leaves and other light organic materials that commonly pass through a CB system designed to trap heavier materials. Total organic carbon, total Kjeldahl nitrogen, and total P concentrations were highest in the catch-basin samples in the fall of 2017, and concentrations in the SC samples were highest in the fall of 2018. The collection of fewer samples in 2017 may account for some of the variability between fall 2017 and fall 2018 results. A subset of SC samples collected from piles representing specific street-cleaning routes in September and November 2018 were also analyzed. Materials collected in November were dominated by leaves, and the concentrations of the analyzed species of carbon, nitrogen, and phosphorus in some samples were more than double those in samples collected on the same street-cleaning routes in September. The Vermont Department of Environmental Conservation and the University of Vermont developed estimates of load-reduction credits for CB and SC practices based on a policy developed by the Wisconsin Department of Natural Resources that determined the potential for credits associated with leaf-removal activities. This process also considered BMPs that were initiated during the U.S. Environmental Protection Agency’s Lake Champlain Basin Total Maximum Daily Load monitoring period (2000 to 2009) and adapted the Wisconsin Department of Natural Resources policies to apply to existing SC routes in the cooperating Vermont municipalities that possessed at least 17 percent tree cover. This exercise demonstrated that applying the Wisconsin Department of Natural Resources policy to existing street-cleaning routes possessing 17 percent or more tree cover would result in reductions in total P loads up to 65 percent of mandated target reductions, and about a 25 percent reduction on average. Continuous simulations of stormwater runoff volume, and of loads of suspended sediments and total P, also were created for Englesby Brook Basin, an urbanized basin in Burlington and South Burlington that drains to Lake Champlain. Although the basin is more developed than the average of the nine cooperating municipalities, streamflow and P loading data collected by the U.S. Geological Survey were available to evaluate model performance. Simulations based on a year of average climatic conditions projected potential small reductions in total P of 0.08 to 0.10 percent as a result of CB cleaning and SC practices. Simulated weekly SC practices, however, reduced street-solid loads by as much as 7 percent. When the proportion of total P seen in fall SC materials collected in Vermont was applied to these simulated street-solid loads, estimated reductions of total P were about 29 percent. The combination of analytical results, estimated load-reduction credits, and simulated reductions indicate that targeted increases of SC activities to reduce leaf loading in the fall have the potential to reduce loading to receiving waters and could help regulated communities meet their water-quality goals.

Vermont↗
USGS2004

Comparison of natural resource issues on tropical pacific ranges

The natural resources issues on tropical Pacific ranges are compared. If active management plan is in place, FWS may exempt those spp. from critical Habitat Prevention and control or invasive species essential. Wetlands are low-hanging fruit for restoration, but birds present mgmt. challenge. Marine sites may offer less potential for precise mgmt. of natural resources than terrestrial sites such as, lack of knowledge, observational limits, ecosystem complexity, mobile biota. It has been suggested that the tremendus public interest in helping with conservation activities - volunteer opportunities may offset staffing shortfalls.

Conference Paper↗
USGS2008

Subsurface fate and transport of sulfamethoxazole, 4-nonylphenol, and 17β-estradiol

Subsurface fate and transport of the antibiotic sulfamethoxazole (SX), the non-ionic surfactant degradation product 4-nonylphenol (NP), and the sex hormone 17β-estradiol (E2) were evaluated in a plume of contaminated groundwater at Cape Cod, Massachusetts, USA. The plume is the result of 60 years of wastewater treatment plant effluent disposal into rapid infiltration beds. Natural-gradient, in situ tracer experiments were used to evaluate subsurface transport of SX, NP, and E2 (injected at 300, 530, and 0.55 µg/L, respectively) relative to the conservative tracer bromide. Two geochemical zones were evaluated: (1) uncontaminated groundwater overlying the plume, and (2) contaminated groundwater within the plume that has recently become oxic after decades of anoxic conditions. The uncontaminated groundwater is characterized by a microbial community unacclimated to treated wastewater, whereas the contaminated groundwater is characterized by microbes acclimated to wastewater contaminants. Results from the tracer tests in both zones showed that the antibiotic SX was co-transported with the conservative tracer bromide, with little retardation or mass removal. In contrast, NP and E2, which are more hydrophobic and biodegradable, showed sorption (relative retardation factors ranged up to 5.9) and mass loss at both the uncontaminated and contaminated sites.

Conference Paper↗
USGS2015

A formalized approach to making effective natural resource management decisions for Alaska National Parks

A fundamental goal of the National Park Service (NPS) is the long-term protection and management of resources in the National Park System. Reaching this goal requires multiple approaches, including the conservation of essential habitats and the identification and elimination of potential threats to biota and habitats. To accomplish these goals, the NPS has implemented the Alaska Region Vital Signs Inventory and Monitoring (I&M) Program to monitor key biological, chemical, and physical components of ecosystems at more than 270 national parks. The Alaska Region has four networks—Arctic, Central, Southeast, and Southwest. By monitoring vital signs over large spatial and temporal scales, park managers are provided with information on the status and trajectory of park resources as well as a greater understanding and insight into the ecosystem dynamics. While detecting and quantifying change is important to conservation efforts, to be useful for formulating remedial actions, monitoring data must explicitly relate to management objectives and be collected in such a manner as to resolve key uncertainties about the dynamics of the system (Nichols and Williams 2006). Formal decision making frameworks (versus more traditional processes described below) allow for the explicit integration of monitoring data into decision making processes to improve the understanding of system dynamics, thereby improving future decisions (Williams 2011).

Alaska↗
USGS2005

Coastal forests of the Gulf of Mexico: A description and some thoughts on their conservation

Millions of Nearctic-Neotropical landbirds move through the coastal forests of the Gulf of Mexico each spring and autumn as they migrate across and around the gulf. Migration routes in the gulf region are not static—they shift year to year and season to season according to prevailing wind patterns. Given the dynamic nature of migration routes, coastal forests around the Gulf of Mexico potentially can provide important stopover habitat to en route migrants. The coastal forests from the Florida Keys to the Yucatan Peninsula include a wide range of habitat types that we have classified as 19 broad community types. From literature reviews, we determined that the majority of these coastal habitats have been lost or degraded due to the effects of development, agriculture, livestock grazing, timber industry activities, and the spread of exotic species. The continued loss and degradation of coastal forests pose a risk to migrating birds, and thus we need to develop a conservation strategy that maximizes the suitability of the remaining forested patches around the gulf. An effective conservation strategy will require considerations at the gulf-wide, regional, landscape and habitat levels. These considerations should include migrant movement and landfall patterns, migrant use of inland versus coastal fringe stopover sites, the creation of landscape mosaics that incorporate patch size and inter-patch distance, and the availability of within habitat resources.

Alabama, Florida, Louisiana, Mississippi, Texas↗
USGS2015

Status and conservation of interior Redband Trout in the western United States

In this article we describe the current status and conservation of interior (potamodromous) Redband Trout Oncorhynchus mykiss sspp. throughout its range in the western United States using extant data and expert opinion provided by fish managers. Redband Trout historically occupied 60,295 km of stream habitat and 152 natural lakes. Currently, Redband Trout occupy 25,417 km of stream habitat (42% of their historical range) and 124 lakes or reservoirs. Nonhybridized populations are assumed to occupy 11,695 km (46%) of currently occupied streams; however, fish from only 4,473 km (18%) have been genetically tested. Approximately 47% of the streams occupied by Redband Trout occur on private land, 45% on government lands, and 8% in protected areas. A total of 210 Redband Trout populations, occupying 15,252 km of stream habitat (60% of the current distribution) and 95,158 ha of lake habitat (52%), are being managed as “conservation populations.” Most conservation populations have been designated as weakly to strongly connected metapopulations (125; 60%) and occupy much more stream length (14,112 km; 93%) than isolated conservation populations (1,141 km; 7%). The primary threats to Redband Trout include invasive species, habitat degradation and fragmentation, and climate change. Although the historical distribution of interior Redband Trout has declined dramatically, we conclude that the species is not currently at imminent risk of extinction because it is still widely distributed with many populations isolated by physical barriers and active conservation efforts are occurring for many populations. However, the hybridization status of many populations has not been well quantified, and introgression may be more prevalent than documented here. We recommend (1) collecting additional genetic data and estimating distribution and abundance by means of a more rigorous spatial sampling design to reduce uncertainties, (2) collecting additional information to assess and predict the impacts of climate on populations, and (3) continuing to use this database to evaluate the status of Redband Trout and inform conservation efforts through time.

North American Journal of Fisheries Management↗