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At least 433 records · Page 24Linked to original sources

USGS2002

Transforming the Rockies: Human forces, settlement patterns, and ecosystem effects

The current ecological condition of the Rocky Mountains can be viewed from two somewhat opposing perspectives. The first is that human occupation has had relatively little effect on the Rockies: large natural, if not pristine, areas remain, and the region's open spaces provide wildlife habitat, majestic scenery, and a sense of wildness. Unlike the situation in, say, the Swiss Alps, where even high-elevation meadows have been mown and grazed intensively for as long as 500 years and many large mammals have been extirpated, most elements of Rocky Mountain landscapes and biota are reasonably unaltered. Even the presumption that Native Americans changed regional landscapes with deliberately set fires has been challenged by Baker and Ehle (2001) and others who think that most fires were lightning-caused or accidental ignitions. The second view is that humans have dramatically transformed the Rockies, at least since Euro-American settlement in the mid- to late 1800s. The slaughter of vast buffalo herds, the clearing of timber for railroad ties, and even the removal of whole hillsides in hydraulic placer mining represented substantial transformation. Ranch, resort, and residential development marks the latest incarnation of this transformation. Numerous, complex layers of land use have left landscape legacies, some of which may be unrecognized or underappreciated in modern assessments (Wohl 2001). Here we consider both perspectives because we are impressed with both the many effects of human use of the Rockies and the region's remaining wild landscapes. Ironically, much of the recent population growth and development in the Rockies is driven by the region's wild landscapes, which make the present widespread transformation seem all the more significant. It is, of course, the rapid clip of current human transformation—high population growth rates, pervasive rural residential development, and landscape fragmentation (Baron, Theobald, and Fagre 2000)—that worries ecologists and others concerned with Rocky Mountain ecosystems. So although we offer an overview of historical changes in the Rockies, especially since the 1800s, much of our attention here is on land uses, economies, and settlement patterns since the 1970s and on their future trends.

Book chapter↗

USGS2021

U.S. Geological Survey migratory bird science, 2020–21

Bird conservation as an endeavor engages a broad range of partners and a coordinated effort across State and Federal agencies, nongovernment organizations, universities and, at times, international partnerships. To understand information needs and respond to the many challenges in bird conservation, U.S. Geological Survey (USGS) scientists participate in Flyway committees, on Joint Venture boards and working groups, in professional organizations, and in other conservation partnerships. These activities connect USGS scientists to conservation partners with whom they work to address substantial challenges. More than one hundred USGS scientists are dedicated to the scientific study of migratory birds. This report presents the current (2021) representative breadth of activities of USGS scientists supporting the conservation and management of migratory birds. Ninety USGS scientists contributed to the project descriptions and other information detailing the work of the USGS. The science herein is organized and presented thematically by research strengths and by management topics. The report emphasizes the geographic framework of the North American Flyway councils through which USGS engages regularly with Federal and State government agencies and others who are responsible for managing migratory bird populations.

Circular↗

USGS2022

Characterization of the bathymetry, hydrodynamics, water quality, infrastructure, and channel condition of the Old Erie Canal from DeWitt to its junction with the current Erie Canal in Verona, near Rome, New York, 2018–19

The Old Erie Canal has undergone sedimentation and aquatic growth that have restricted flow and diminished the aesthetic quality of the canal during the nearly 200 years since its construction. During 2018–2019, the U.S. Geological Survey (USGS) in cooperation with the Madison County Planning Department and the New York State Canal Corporation conducted a study of the Old Erie Canal between the Town of DeWitt, New York, and its junction with the current Erie Canal of the New York State Canal System near Rome, N.Y. The study comprised bathymetric, velocity, and water-quality surveys and documentation of the canal infrastructure. The USGS established benchmarks and staff gages along the 30.8 miles of the canal study area to reference the water-surface level in the canal to the North American Vertical Datum of 1988 (NAVD 88). Bathymetric survey results indicated that during the time of the survey, the canal depths ranged from 1.26 feet (ft) to 7.33 ft between the Butternut and Durhamville aqueducts (with a mean depth of 3.52 ft). Shallow depths are located throughout the canal, but the section north of the Durhamville aqueduct was the shallowest, with depths ranging from 0.68 ft to 2.44 ft (and a mean depth of 1.36 ft). The reach-averaged water velocity was 0.28 feet per second. The system generally flows west to east from the Butternut aqueduct to the entrance to the Erie Canal. Water-quality data (dissolved oxygen, water temperature, specific conductance, pH, and turbidity) were collected concurrently with the bathymetric survey (spring 2018) to characterize changes in water quality along the length of the canal. Specific-conductance values measured upstream from the hamlet of Kirkville, Manlius, N.Y. may reflect road salts being flushed into the canal through the Butternut and Limestone feeder system (designed to divert water from nearby creeks to supply water for the Old Erie Canal) from recent stormwater runoff. Increases in pH in the downstream direction are possibly caused by increasing amounts of aquatic vegetation. During the time of the survey, turbidity was highest near inflows from the canal feeder system and tributary inputs which were elevated by stormwater runoff that transported sediment into the canal. The canal infrastructure was documented to provide a baseline assessment. The feeder system, designed to bring water into the canal, does not deliver flow when the creeks supplying water to those feeders are at base flow, but does bring water into the system when flows in the feeder creeks are elevated. A recent report provides an example of repair work completed on the Chittenango feeder to improve flow through the feeder into the canal (Welch and Madison County Planning Department, 1996). Two non-regulated tributaries, Meadow Brook and Pools Brook, consistently delivered flow to the canal. Outfalls where canal water discharges into nearby creeks were sealed in the Butternut and Limestone aqueducts. Outfalls in the Chittenango, Cowaselon, and Durhamville aqueducts were found with flashboards installed at an elevation that allows water to be discharged from the canal. These structures are designed to accept additional flashboards to raise the canal water surface with the potential to convey flow farther down the system. The general condition of the channel was open and navigable between Butternut aqueduct and Chittenago aqueduct. On the segment of the canal east of the Chittenango aqueduct, an increasing number of downed trees and tangled wads of vegetation affected flow and made navigation by boat difficult to the Durhamville aqueduct. North of the Durhamville aqueduct, numerous downed trees and an increased density of aquatic vegetation limited navigation by boat and reduced the flow rate.

New York↗

USGS2019

Chemical controls for an integrated pest management program

Chemical controls ranging from natural products to synthesized chemicals are widely used in aquatic pest management activities. Chemicals can be used to lure organisms to traps or can cause direct mortality by altering the physiological function of an organism. Much of what is known about controlling pests with chemicals is from research done on terrestrial pesticides. This paper focuses on how chemicals might be used as aquatic pesticides to control or eradicate aquatic invasive species. Current control tools are described, as are new technologies designed to selectively target the pest to reduce risks to nontarget organisms and the environment.

North American Journal of Fisheries Management↗

USGS2025

Comparing surgery time and short-term incision healing for Largemouth Bass using smooth- and barbed-absorbable sutures

Objective Barbed sutures have become increasingly favored over traditional smooth sutures in human medicine but remain understudied in fisheries biotelemetry applications. Our objectives were to (1) compare surgery time and recovery time for Largemouth Bass Micropterus nigricans when using smooth- versus barbed-absorbable sutures to close the incisions and (2) compare the short-term healing rates of incisions that were closed with the two sutures. Methods We conducted a surgical trial using two incision closure methods: a smooth suture method, which used three interrupted sutures, and a barbed suture method, which used a running style suture. Surgery and surgical recovery times were recorded for each surgery. At 14 d postsurgery, each incision was scored for openness and inflammation. Results Barbed sutures (median surgery time = 133.5 s) resulted in higher surgical efficiency than smooth sutures (median surgery time = 255.0 s). Surgical recovery time did not differ between the two suture types. Mortality did not differ between suture types (overall mortality = 21%) and was similar to previously reported mortality rates. Incision site inflammation and openness were variable but did not differ between suture types. Conclusions Our results indicate that barbed sutures may increase surgical efficiency while maintaining currently observed survival and healing rates for Largemouth Bass.

North American Journal of Fisheries Management↗

USGS1998

Ontogenic and spatial patterns in diet and growth of lake trout in Lake Michigan

Lake trout Salvelinus namaycush in nearshore waters of Lake Michigan grow faster than lake trout residing offshore on Sheboygan Reef, which is in midlake. We examined the stomachs of lake trout, spanning ages 1 through 16, caught in both nearshore and offshore environments of Lake Michigan during 1994 and 1995 to determine whether diet differences may be responsible for the difference in growth rate. A comparison of the diets, coupled with bioenergetics modeling, indicated that juvenile lake trout on Sheboygan Reef experienced slow growth due to low food availability rather than to cold water temperatures. The availability of appropriate‐size prey appeared to regulate lake trout growth. Small prey fish were probably not readily available to small (200‐ to 399‐mm total length) lake trout on Sheboygan Reef, a substantial portion of whose diet consisted of invertebrates; in contrast, nearshore juveniles had a nearly 100% fish diet. Growth rate on the reef remained slow through intermediate lake trout sizes (400–599 mm total length), presumably due to low availability of rainbow smelt Osmerus mordax on the reef. Once lake trout achieved total lengths of approximately 600 mm, they grew slightly faster on Sheboygan Reef than near shore, indicating that large (>170‐mm total length) prey fish were readily available to lake trout in the reef area. On a wet‐weight basis, alewife Alosa pseudoharengus dominated the diet of large (≥600 mm total length) lake trout from both the nearshore and offshore regions of the lake, although bloater Coregonus hoyi composed over 30% of the diet on Sheboygan Reef and in southeastern nearshore Lake Michigan. Size of alewife prey increased with lake trout size. The bloater population currently represents the bulk of the biomass of the adult prey fish community, so our diet analysis suggests that large lake trout are continuing to select alewives.

Illinois, Indiana, Michigan, Wisconsin↗

USGS2022

Special section overview: Effects of ecosystem change on North American percid populations.

Walleye Sander vitreus , Sauger S. canadensis , and Yellow Perch Perca flavescens (referred to as percids herein) are collectively among the most culturally and ecologically important fish species in North America. As ecosystems change in response to environmental drivers, such as climate change, nutrient loading, and invasive species, there is a need to understand how percid populations respond to these changes. To address this need, a symposium was held during the 81st Annual Midwest Fish and Wildlife Conference to bring fishery scientists and managers together to describe and discuss percid population responses to ecosystem change. Prevailing symposium themes included the challenge of identifying mechanisms responsible for population-level changes, developing strategies to adaptively manage for resilient fisheries, and consideration of scale, context, and methods when interpreting variable results. Given the uncertainty of how ecosystem changes affect percid populations, participants emphasized the importance of communicating uncertainties to stakeholders, implementing data-driven management strategies, setting realistic goals, and revising management actions in an adaptive framework. There was universal agreement on both the challenge and necessity of facilitating constructive engagement among stakeholders in cooperative decision making. Symposium participants identified knowledge gaps and discussed future efforts to build on our current understanding of percid populations, including continuation of long-term monitoring, improved standardization of evaluation metrics, implementing adaptive management experiments to identify causal relationships, development of more robust analytical methods, use of historical data sources, and refining techniques to realistically convey management options to stakeholders.

North American Journal of Fisheries Management↗

USGS2007

Comparative performance of invasive and native Celastrus species across environmental gradients

The ability to understand and predict the success of invasive plant species in their new ranges is increased when there is a sympatric native congener available for comparison. Celastrus orbiculatus (oriental bittersweet) is a liana introduced into the United States in the mid-1800s from East Asia as an ornamental plant. Its native congener, Celastrus scandens (American bittersweet), ranges from the east coast of the United States as far west as Wyoming. In the Northeastern United States, C. orbiculatus is continuing to expand its range while C. scandens appears to be in serious decline. One hypothesis for this decline is that C. scandens does not have such a wide range of ecological tolerances in the current landscape as C. orbiculatus, which seems to tolerate a greater range of resource conditions. To investigate this hypothesis, we transplanted these two species into ten sites that spanned a full range of light and soil moisture conditions to compare their establishment and performance in terms of aboveground growth (biomass and height) and mortality. After two years, C. orbiculatus showed significantly lower mortality and greater biomass across all resource conditions compared to C. scandens. In addition, C. orbiculatus preferred more mesic soil moisture conditions, while C. scandens performed better in drier soil moisture conditions. Since much of the Northeastern United States is now forested, this preference for mesic soil conditions could make it more successful than C. scandens in the region. This study shows the utility of manipulative experiments, particularly those using congeneric native species as benchmarks, for assessing the causes and predicting the course of invasions. ?? 2007 Springer-Verlag.

Oecologia↗

USGS2026

A range-wide summary of western grebe and Clark’s grebe breeding lakes across North America

Western grebes ( Aechmophorus occidentalis ) and Clark’s grebes ( Aechmophorus clarkii ) are iconic waterbirds of North America that breed in colonies on inland lakes. Both species are patchily distributed and not surveyed well by the North American Breeding Bird Survey and, hence, we know relatively little about their population trends or the lakes that support the largest colonies. Knowing the distribution of western and Clark’s grebe breeding populations across their range is a critical first step to better monitor and manage these two waterbirds. We compiled published and unpublished data summarizing the status of current and historical western and Clark’s grebe breeding colonies on lakes across North America. We summarized count numbers for adults, nests, and chicks during the breeding season, including date of the most recent count from local survey efforts. We also summarized the most common threats to these birds at their breeding colonies. Sixty-seven percent of the Aechmophorus grebes during the breeding season were in 5% of the 770 breeding lakes identified range-wide, and 73% of the 770 breeding lakes supported < 100 breeding adults. The most common threats at breeding lakes were egg predation, wind and wave impact on nests, changes in populations of forage fish, anthropogenic disturbances, rapid fluctuation of water levels at breeding colonies, and decrease in nesting habitat availability. Our range-wide summary of the locations and sizes of breeding colonies and the presumed threats at these colonies provide a foundation for thorough range-wide survey efforts and conservation prioritizations for western and Clark’s grebes in North America.

North America↗

USGS1998

Origin of the Columbia River basalts: Melting model of a heterogeneous plume head

In order to study the origin of the Grande Ronde basalts (GRs) erupted in the climax stage of the Columbia River basalts (CRBs), we carried out high pressure melting experiments on four of the most primitive rock compositions representing the Yakima group of the CRBs. The voluminous GRs (constituting >80 vol% of CRBs) are totally aphyric basaltic andesites. GRs show very narrow and coherent chemical trends both in major and trace elements as well as isotopes. The silica-rich GRs (SiO 2 = 52–56 wt%) can be produced by direct partial melting of a MORB like source material (CRB72-31) at ∼2 GPa or ∼70 km depth. By 30–50% partial melting of the CRB72-31, the entire compositional range of the GRs can be produced in a narrow temperature interval (1300–1350°C) at ∼2 GPa. The aluminous clinopyroxene that appears in the above melting range is consistent as the major controlling phase of the GR trends. The partial melts are very similar to the GRs except for Al 2 O 3 and FeO which could be due to the mismatch in the source rock composition. Judging from the variation in REE, involvement of garnet in GR magma genesis can be ruled out. Small amounts of plagioclase (10–30 wt%) may be present in the partial melting residue. Judging from REE patterns and Nd isotopes of the GRs, the source rock should be unfractionated in REE. Based on the melting experiments, a heterogeneous plume model is proposed for the initial stage of the Yellowstone hot spot. Large lithologically distinct blobs of old oceanic crust components were included in the plume head. The GR magmas were produced by partial melting of the oceanic crust components at the bottom of the North American lithosphere. Similar melting processes of basalt/peridotite composite source may be operating in other LIPs (large igneous provinces). The GR type genuine oceanic crust derived melts may be seen where the ambient peridotite remains under subsolidus conditions. Volume and temperature of mantle plumes may have been overestimated, because contributions from the recycled oceanic crust is so large and the current mantle melting models concern only peridotite source.

Idaho, Nevada, Oregon↗

USGS2004

Seismicity and tectonics of El Salvador

The large-scale plate-tectonics framework of El Salvador was defined in the “plate-tectonics revolution” of the 1960s and 1970s, but important issues related to seismic hazards depend on details that have been only recently, or are not yet, understood. Present evidence suggests that coupling across the interface-thrust zone beneath coastal El Salvador is sufficient to produce occasional interface-thrust earthquakes as large as M ∼8. The rate of such earthquakes is determined by the percentage of relative plate motion that is accumulated as elastic strain on the thrust-fault interface between the Cocos and Caribbean plates, which appears to be lower than in many other subduction zones, but is not well established. Earthquakes in the interior of the Cocos plate, such as the El Salvador earthquake of January 13, 2001, account for a significant percentage of Wadati-Benioff zone earthquakes. Separate consideration of the seismic hazard posed by, respectively, Cocos intraplate earthquakes and interface-thrust earthquakes is complicated by the difficulty of separating interface-thrust and Cocos intraplate events in earthquake catalogs. Earthquakes such as the San Vicente–San Salvador sequence of February 13–25, 2001, probably result from the motion of the Central American forearc northwestward with respect to the interior of the Caribbean plate; the geometry of the fault systems that accommodate the motion remains to be worked out. Understanding of this tectonic complexity and associated seismic hazards will be facilitated greatly by the long-term operation of high-sensitivity local seismograph networks, such as that operated by, and currently being upgraded by, the Servicio Nacional de Estudios Territoriales (SNET) of El Salvador.

Special Papers of the Geological Society of Americ↗

USGS2018

Flood-inundation maps for the Pawtuxet River in West Warwick, Warwick, and Cranston, Rhode Island

A series of 15 digital flood-inundation maps was developed for a 10.2-mile reach of the Pawtuxet River in the municipalities of West Warwick, Warwick, and Cranston, Rhode Island, by the U.S. Geological Survey (USGS), in cooperation with the Rhode Island Emergency Management Agency and the U.S. Army Corps of Engineers. The coverage of the maps extends downstream from Natick Pond dam near State Route 33/Providence Street bridge in West Warwick to the mouth of the river at Pawtuxet Cove (Broad Street bridge) on the border between Cranston and Warwick, R.I. A one-dimensional step-backwater hydraulic model created and calibrated for the Federal Emergency Management Agency Flood Insurance Studies for Kent and Providence Counties in 2015 was updated for this study. The updated hydraulic model reflects the removal of the Pawtuxet Falls dam during 2011 and the raised elevation of a levee surrounding the Warwick Sewer Authority wastewater treatment facility during 2014–17. The hydraulic model was calibrated by using the current (2018) stage-discharge relation at the USGS Pawtuxet River at Cranston, Rhode Island, streamgage (01116500) and documented high-water marks from the March 31, 2010, flood, which had a peak flow greater than the estimated 0.2-percent annual exceedance probability floodflow. The hydraulic model was used to compute water-surface profiles for 15 flood stages at 1-foot (ft) intervals referenced to the USGS Pawtuxet River at Cranston, Rhode Island, streamgage (01116500) and ranging from 8.0 ft (15.2 ft, North American Vertical Datum of 1988), which is the National Weather Service Advanced Hydrologic Prediction Service flood category “action stage,” to 22.0 ft (29.2 ft, North American Vertical Datum of 1988), which is the maximum stage of the stage-discharge relation at the streamgage and exceeds the National Weather Service Advanced Hydrologic Prediction Service flood category “major flood stage” of 13.0 ft. The simulated water-surface profiles were combined with a geographic information system digital elevation model derived from light detection and ranging (lidar) data with a 1.0-ft vertical accuracy to create flood-inundation maps. The flood-inundation maps depict estimates of the areal extent and depth of flooding corresponding to 15 selected flood stages at the streamgage. The flood-inundation maps depict only riverine flooding and do not depict any tidal backwater or coastal storm surge that might occur in the lower part of the river reach. The flood-inundation maps can be accessed through the USGS Flood Inundation Mapping Science website at https://water.usgs.gov/osw/flood_inundation . Near-real-time stages and discharges at the Pawtuxet River streamgage can be obtained from the USGS National Water Information System at https://waterdata.usgs.gov/ . The National Weather Service Advanced Hydrologic Prediction Service provides flood forecasts of stage for this site (CRAR1) at https:/water.weather.gov/ahps/ . The availability of flood-inundation maps referenced to current and forecasted water levels at the USGS Pawtuxet River at Cranston, Rhode Island, streamgage (01116500) can provide emergency management personnel and residents with information that is critical for flood response activities, such as evacuations and road closures, and postflood recovery efforts. The flood-inundation maps are nonregulatory but provide Federal, State, and local agencies and the public with estimates of the potential extent of flooding during flood events.

Rhode Island↗

USGS2013

Measuring environmental change in forest ecosystems by repeated soil sampling: a North American perspective

Environmental change is monitored in North America through repeated measurements of weather, stream and river flow, air and water quality, and most recently, soil properties. Some skepticism remains, however, about whether repeated soil sampling can effectively distinguish between temporal and spatial variability, and efforts to document soil change in forest ecosystems through repeated measurements are largely nascent and uncoordinated. In eastern North America, repeated soil sampling has begun to provide valuable information on environmental problems such as air pollution. This review synthesizes the current state of the science to further the development and use of soil resampling as an integral method for recording and understanding environmental change in forested settings. The origins of soil resampling reach back to the 19th century in England and Russia. The concepts and methodologies involved in forest soil resampling are reviewed and evaluated through a discussion of how temporal and spatial variability can be addressed with a variety of sampling approaches. Key resampling studies demonstrate the type of results that can be obtained through differing approaches. Ongoing, large-scale issues such as recovery from acidification, long-term N deposition, C sequestration, effects of climate change, impacts from invasive species, and the increasing intensification of soil management all warrant the use of soil resampling as an essential tool for environmental monitoring and assessment. Furthermore, with better awareness of the value of soil resampling, studies can be designed with a long-term perspective so that information can be efficiently obtained well into the future to address problems that have not yet surfaced.

Journal of Environmental Quality↗

USGS2011

Passage and behavior of adult American shad in an experimental louver bypass system

We tested 436 adult American shad Alosa sapidissima in an experimental louver bypass system, which was similar to a system operating at Holyoke Dam, Massachusetts, to determine guidance and passage efficiency and to study fish response to stimuli from physical structures, light intensity, and water velocity. Groups of 5–29 fish were exposed to combinations of two bypass exits (wide-shallow and vertical-slot sharp-crested weirs) and two louver arrays (7.6- and 15.2-cm slat spacing) oriented 20° to water flow direction. Underwater video observations showed fish responded to louvers as a physical barrier during the day, when they stayed 30–55 cm (1.3 cm/5 klx) away from and oriented parallel to louvers, and as a behavioral barrier at night, when they moved closer to louvers and oriented into the current. Both louver arrays guided fish effectively, (i.e., prevented fish from passing through the slats) 100% for narrow spacing and 97% for wide spacing. Adults avoided moving closer than 0.5 m to either exit type; instead, fish remained 0.8–1.4 bodylengths upstream, depending on light intensity (farther upstream during daytime, similar to behavior at louvers). At exits, water velocity increased from 0.4 m/s to 0.8 m/s or more in a distance of 0.9 m (rate of velocity increase, 0.44 m/s per meter). This rapid velocity increase elicited an avoidance response by fish that resulted in few fish (5%) passing. Our results provide behavioral explanations for the efficient guidance of adult American shad by louvers and for the fishes' avoidance of the exit at the Holyoke Dam. From this, we provide suggestions on how to prevent fish avoidance of exits.

Massachusetts↗

USGS2007

Abiotic influences on the biomass of Vallisneria americana Michx. In the Upper Mississippi River

American wildcelery, Vallisneria americana Michx. is an ecologically important component of aquatic communities in the Upper Mississippi River (UMR). We conducted a study in 2002 to determine the association of several abiotic factors on the vegetative growth of Vallisneria in Navigation Pool 8 (Pool 8) of the UMR. We measured turbidity, percent light absorbance, surface water ammonium, surface water nitrate, current velocity, conductivity, pH and water depth throughout one growing season at 56 stratified sites based on where Vallisneria occurred in previous years. Sediment and aboveground biomass samples were collected during peak growth. Sediment was analysed for organic content, particle size, pore water nitrate and pore water ammonium. Vallisneria biomass samples were dried to constant mass. Because some sites were without water for much of the growing season, only data from 52 sites were reported. Biomass was associated with depth, percent light absorbance, turbidity and wind fetch. Vallisneria was abundant in the depth range of 0.55 to 1.03 m, in areas receiving at least 38% of surface light and in areas exposed to greater wind fetch (>2000 m). Our results suggest that the primary abiotic variable associated with Vallisneria americana in the UMR is light, not nutrients.

River Research and Applications↗

USGS2025

Precipitation timing mediates life-stage and population-level associations with climate for an indicator species

Global climate change is contributing to declines in biodiversity, although changes vary across geographic regions and species. The iconic greater sage-grouse (Centrocercus urophasianus; sage-grouse) is central to conservation within the North American sagebrush ecosystem, yet its vulnerability to climate effects remains poorly understood. We used hierarchical models to explore weather and climatic influences on sage-grouse across nearly four decades, focusing first on pattern (population change), then process (demographic life stage). We quantified eight indicators of temperature and/or moisture conditions across time lags of 0–1.5 years leading up to current year breeding activities. Sage-grouse population growth tended to increase following above-average growing season precipitation. Precipitation or drought timing influenced whether process effects were positive or negative. More summer and/or fall moisture corresponded with increases in subsequent year brood and adult survival, while concurrent seasonal drought led to reductions in nest survival. Positive concurrent spring drought associations with adult and brood survival were largely outweighed by positive prior year moisture effects. Density-dependence and indirect effects of precipitation through vegetation and forage resource pathways likely contributed to nuanced responses across life stages. Our research improves mechanistic understanding of this indicator species’ sensitivity to climatic factors, while reinforcing the importance of large-scale conservation initiatives for sagebrush ecosystems.

Scientific Reports↗

USGS2021

What have we lost? Modeling dam impacts on American shad populations through their native range

American shad ( Alosa sapidissima ) are native to the east coast of North America from the St. Johns River, Florida, to the St. Lawrence River region in Canada. Since the 1800s, dams have reduced access to spawning habitat. To assess the impact of dams, we estimated the historically accessed spawning habitat in coastal rivers (485,618 river segments with 21,113 current dams) based on (i) width, (ii) distance from seawater, and (iii) slope (to exclude natural barriers to migration) combined with local knowledge. Estimated habitat available prior to dam construction (2,752 km 2 ) was 41% greater than current fully accessible habitat (1,639 km 2 ). River-specific population models were developed using habitat estimates and latitudinally appropriate life history parameters (e.g., size at age, maturity, iteroparity). Estimated coast-wide annual production potential was 69.1 million spawners compared with a dammed scenario (41.8 million spawners). Even with optimistic fish passage performance assumed for all dams (even if passage is completely absent), the dam-imposed deficit was alleviated by fewer than 3 million spawners. We estimate that in rivers modeled without dams, 98,000 metric tons of marine sourced biomass and nutrients were annually delivered, 60% of which was retained through carcasses, gametes and metabolic waste. Damming is estimated to have reduced this by more than one third. Based on our results, dams represent a significant and acute constraint to the population and, with other human impacts, reduce the fishery potential and ecological services attributed to the species.

Frontiers in Marine Science↗

USGS1986

Alaska goose populations: Past, present and future

Many people think Alaska remains a pristine wilderness and that wildlife populations are still at prehistoric levels. This very likely is not true for the 11 species and subspecies of geese that nest in Alaska. Large, widely dispersed populations of geese were observed near the turn of the century. Even in the early 1970s, it was estimated that Alaskan habitats were used by 915,000 nesting and 100,000 additional migrating geese each year (King and Lensink 1971). Since then the Alaskan populations of most of these species have declined, some to dramatically low levels (Raveling 1984), even though habitats within the state have remained largely unaltered by man. The U.S. has treaties with Canada, Mexico, Japan and the Soviet Union to protect geese and other shared migratory birds, confirming international concern for the welfare of this resource. Cooperative research on Alaskan geese during the past several decades has given understanding of their migration corridors, staging and wintering habitats, and the principle places where they are hunted, thereby providing information needed to develop effective management plans. The only attempt to re-introduce geese in Alaska has been in the Aleutian Islands. Other opportunities exist. It is our intent here to: (1) review the historic and current status and important habitats of geese that occur in Alaska; (2) identify existing and potential threats to these populations; and (3) offer alternative management approaches for geese in Alaska.

Alaska↗