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At least 811 records · Page 45Linked to original sources
USGS2017

Tectonic evolution of the Central Andean Plateau and implications for the growth of plateaus

Current end-member models for the geodynamic evolution of orogenic plateaus predict ( a ) slow and steady rise during crustal shortening and ablative subduction (i.e., continuous removal) of the lower lithosphere or ( b ) rapid surface uplift following shortening, which is associated with punctuated removal of dense lower lithosphere and/or lower crustal flow. This review integrates results from recent studies of the modern lithospheric structure, geologic evolution, and surface uplift history of the Central Andean Plateau to evaluate the geodynamic processes involved in forming it. Comparison of the timing, magnitude, and distribution of shortening and surface uplift, in combination with other geologic evidence, highlights the pulsed nature of plateau growth. We discuss specific regions and time periods that show evidence for end-member geodynamic processes, including middle–late Miocene surface uplift of the southern Eastern Cordillera and Altiplano associated with shortening and ablative subduction, latest Oligocene–early Miocene and late Miocene–early Pliocene punctuated removal of dense lower lithosphere in the Eastern Cordillera and Altiplano, and late Miocene–early Pliocene crustal flow in the central and northern Altiplano.

Annual Review of Earth and Planetary Sciences↗
USGS2009

Science-Based Strategies for Sustaining Coral Ecosystems

Coral ecosystems and their natural capital are at risk. Greenhouse gas emissions, overfishing, and harmful land-use practices are damaging our coral reefs. Overwhelming scientific evidence indicates that the threats are serious, and if they are left unchecked, the ecological and social consequences will be significant and widespread. Although the primary stressors to coral ecosystems are known, science-based strategies are needed to more accurately explain natural processes and forecast human-induced change. Collaborations among managers and scientists and enhanced mapping, monitoring, research, and modeling can lead to effective mitigation plans. U.S. Geological Survey scientists and their partners assess coral ecosystem history, ecology, vulnerability, and resiliency and provide study results to decisionmakers who may devise policies to sustain coral resources and the essential goods and services they provide.

Fact Sheet↗
USGS2008

Geologic resource evaluation of Pu'ukohola Heiau National Historic Site, Hawai'i; Part I, geology and coastal landforms

Geologic resource inventories of lands managed by the National Park Service (NPS) are important products for the parks and are designed to provide scientific information to better manage park resources. Park-specific geologic reports are used to identify geologic features and processes that are relevant to park ecosystems, evaluate the impact of human activities on geologic features and processes, identify geologic research and monitoring needs, and enhance opportunities for education and interpretation. These geologic reports are planned to provide a brief geologic history of the park and address specific geologic issues forming a link between the park geology and the resource manager. The Kona coast National Parks of the Island of Hawai'i are intended to preserve the natural beauty of the Kona coast and protect significant ancient structures and artifacts of the native Hawaiians. Pu'ukohola Heiau National Historic Site (PUHE), Kaloko-Honokohau National Historical Park (KAHO), and Pu'uhonua O Honaunau National Historical Park (PUHO) are three Kona parks studied by the U.S. Geological Survey (USGS) Coastal and Marine Geology Team in cooperation with the National Park Service. This report is one of six related reports designed to provide geologic and benthic-habitat information for the three Kona parks. Each geology and coastal-landform report describes the regional geologic setting of the Hawaiian Islands, gives a general description of the geology of the Kona coast, and presents the geologic setting and issues for one of the parks. The related benthic-habitat mapping reports discuss the marine data and habitat classification scheme, and present results of the mapping program. Pu'ukohola Heiau National Historic Site (PUHE) is the smallest (~86 acres) of three National Parks located on the leeward Kona coast of the Island of Hawai'i. The main structure at PUHE, Pu'ukohola Heiau, is an important historical temple that was built during 1790-91 by King Kamehameha I (also known as Kamehameha the Great) and is often associated with the founding of the Hawaiian Kingdom (Greene, 1993). The temple was constructed to incur the favor of the king's personal war god Kuka'ilimoku during the time that Kamehameha I waged several battles in an attempt to extend his control over all the Hawaiian Islands. The park is also the site of the older Mailekini Heiau, which was used by the ancestors of Kamehameha I, and an offshore, submerged temple, Hale O Kapuni Heiau, that was dedicated to the shark god. The park occupies the scenic Hill of the Whale overlooking Kawaihae Bay and Pelekane Beach. The seaward-sloping lands of PUHE lie at the convergence of lava flows formed by both Mauna Kea and Kohala Volcanoes. The park coastline is mostly rocky, with the exception of a small beach developed at the north boundary where an intermittent stream enters the sea. The park is bounded to the north by Kawaihae Harbor, to the south by Samuel M. Spencer Beach Park, and to the west by a broad submerged reef. The adjacent reef area is discussed in detail in the accompanying report by Cochran and others (2006). They mapped from the shoreline to depths of approximately 40 m, where the shelf drops off to a sand-covered bottom. PUHE park boundaries extend only to the mean high-tide line, however, landscape impacts created by development around the park are of concern to Park management.

Hawaii↗
USGS2008

Geologic resource evaluation of Pu'uhonua O Honaunau National Historical Park, Hawai'i; Part I, geology and coastal landforms

Geologic resource inventories of lands managed by the National Park Service (NPS) are important products for the parks and are designed to provide scientific information to better manage park resources. Park-specific geologic reports are used to identify geologic features and processes that are relevant to park ecosystems, evaluate the impact of human activities on geologic features and processes, identify geologic research and monitoring needs, and enhance opportunities for education and interpretation. These geologic reports are planned to provide a brief geologic history of the park and address specific geologic issues forming a link between the park geology and the resource manager. The Kona coast National Parks of the Island of Hawai'i are intended to preserve the natural beauty of the Kona coast and protect significant ancient structures and artifacts of the native Hawaiians. Pu'ukohola Heiau National Historic Site (PUHE), Kaloko-Honokohau National Historical Park (KAHO), and Pu'uhonua O Honaunau National Historical Park (PUHO) are three Kona parks studied by the U.S. Geological Survey (USGS) Coastal and Marine Geology Team in cooperation with the National Park Service. This report is one of six related reports designed to provide geologic and benthic-habitat information for the three Kona parks. Each geology and coastal-landform report describes the regional geologic setting of the Hawaiian Islands, gives a general description of the geology of the Kona coast, and presents the geologic setting and issues for one of the parks. The related benthic-habitat mapping reports discuss the marine data and habitat classification scheme, and present results of the mapping program. Pu'uhonua O Honaunau National Historical Park ('Place of Refuge of Honaunau') is the southernmost of the three National Parks located on the leeward Kona coast of the Island of Hawai'i. It is a relatively small park originally 73 ha (182 acres), and was expanded in 2006 with the acquisition of an additional 96 ha (238 acres). The park is probably best known for the pu'uhonua (place of refuge) native Hawaiian cultural site. In addition to the pu'uhonua, the park contains palace grounds, royal fishponds, burial sites, prehistoric trails, a royal canoe landing area, stone house platforms and associated temple structures. A massive basalt rock wall (300 m long, 3 m high, and 5 m wide) separates the pu'uhonua from the areas used by Hawaiian royalty and other grounds. Honaunau Bay is a popular marine resource area adjacent to the park. The seaward-sloping lands of PUHO lie at the base of Mauna Loa volcano, which forms a bench of low-lying pahoehoe lava flows at Pu'uhonua Point. The park coastline is approximately 1.6 km long and is mostly rocky with the exception of a small artificially nourished beach at Keone'ele Cove at the northern boundary next to Honaunau Bay. The park is bounded to the south by Ki'ilae Bay and includes the coastal portions of three Hawaiian land divisions (ahupua'a): Honaunau, Keokea, and Ki'ilae. The western boundary is the high tide mark. The waters of Keone'ele Cove, the ancient royal canoe landing at PUHO, while not formally under NPS jurisdiction, are managed by the park under an agreement with the State of Hawai'i. This small embayment is a known haven for sea turtles, which are often found sunning themselves on the nearshore volcanic platform. Impacts to this area include frequent visits by scuba divers and snorkelers to Honaunau Bay and a small boat ramp located just to the north of Keone'ele Cove. There is an accompanying report that presents the results of benthic habitat mapping of the offshore waters for PUHO (Cochran and others, 2006b; linked below). They mapped from the shoreline to depths of approximately 40 m, where the shelf drops off to a sand-covered bottom. PUHO park boundaries extend only to the mean high-tide level; however, landscape impacts created by development around the park are of concern to

Hawaii↗
USGS2015

Environmental assessment of water, sediment, and biota collected from the Bear Creek watershed, Colusa County, California

The Cache Creek watershed lies within California's North Coast Range, an area with abundant geologic sources of mercury (Hg) and a long history of Hg contamination (Rytuba, 2000). Bear Creek, Cache Creek, and the North Fork of Cache Creek are the major streams of the Cache Creek watershed, encompassing 2978 km 2 . The Cache Creek watershed contains soils naturally enriched in Hg as well as natural springs (both hot and cold) with varying levels of aqueous Hg (Domagalski and others, 2004, Suchanek and others, 2004, Holloway and others 2009). All three tributaries are known to be significant sources of anthropogenically derived Hg from historic mines, both Hg and gold (Au), and associated ore storage/processing sites and facilities (Slotton and others, 1995, 2004; CVRWQCB, 2003; Schwarzbach and others, 2001; Gassel and others, 2005; Suchanek and others., 2004, 2008a, 2009). Historically, two of the primary sources of mercury contamination in the upper part of Bear Creek have been the Rathburn and Petray Hg Mines. The Rathburn Hg mine was discovered and initially mined in the early 1890s. The Rathburn and the more recently developed Petray open pit mines are localized along fault zones in serpentinite that has been altered and cut by quartz and chalcedony veins. Cold saline-carbonate springs are located perepheral to the Hg deposits and effluent from the springs locally has high concentrations of Hg (Slowey and Rytuba, 2008). Several ephemeral tributaries to Bear Creek drain the mine area which is located on federal land managed by the U.S. Bureau of Land Management (USBLM). The USBLM requested that the U.S. Geological Survey (USGS) measure and characterize Hg and other geochemical constituents in sediment, water, and biota to establish baseline information prior to remediation of the Rathburn and Petray mines. Samples sites were established in Bear Creek upstream and downstream from the mine area. This report is made in response to the USBLM request, the lead agency mandated to conduct a Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) - Removal Site Investigation (RSI). The RSI applies to the possible removal of Hg-contaminated mine waste from Bear Creek. This report summarizes data obtained from field sampling of water, sediment, and biota in Bear Creek, above input from the mine area and downstream from the Rathburn-Petray mine area to the confluence with Cache Creek. Our results permit a preliminary assessment of the chemical constituents that could elevate levels of monomethyl Hg (MMeHg) in Bear Creek and its uptake by biota and provide baseline information for comparison to conditions after mine remediation is completed.

California↗
USGS2014

Assessing effects of variation in global climate data sets on spatial predictions from climate envelope models

Climate change poses new challenges for natural resource managers. Predictive modeling of species–environment relationships using climate envelope models can enhance our understanding of climate change effects on biodiversity, assist in assessment of invasion risk by exotic organisms, and inform life-history understanding of individual species. While increasing interest has focused on the role of uncertainty in future conditions on model predictions, models also may be sensitive to the initial conditions on which they are trained. Although climate envelope models are usually trained using data on contemporary climate, we lack systematic comparisons of model performance and predictions across alternative climate data sets available for model training. Here, we seek to fill that gap by comparing variability in predictions between two contemporary climate data sets to variability in spatial predictions among three alternative projections of future climate. Overall, correlations between monthly temperature and precipitation variables were very high for both contemporary and future data. Model performance varied across algorithms, but not between two alternative contemporary climate data sets. Spatial predictions varied more among alternative general-circulation models describing future climate conditions than between contemporary climate data sets. However, we did find that climate envelope models with low Cohen's kappa scores made more discrepant spatial predictions between climate data sets for the contemporary period than did models with high Cohen's kappa scores. We suggest conservation planners evaluate multiple performance metrics and be aware of the importance of differences in initial conditions for spatial predictions from climate envelope models.

Journal of Fish and Wildlife Management↗
USGS2005

Managing Fire in the Northern Chihuahuan Desert: A Review and Analysis of the Literature

Executive Summary This report began as a literature review (Gebow and Halvorson 2001) conducted for fire planners at Carlsbad Caverns National Park who were seeking information about (1) the natural state of park vegetation, (2) northern Chihuahuan Desert natural fire regimes, and (3) fire effects on park plant species. It is the goal of managers there to continue to refine the wildland and prescribed fire program as they learn more about the ecosystems at the park.The park has a history of grazing and then fire suppression in the 20th century. The current effort revisits questions asked by earlier workers at the park, Walter Kittams and Gary Ahlstrand, who began fire studies in the 1970s. This document addresses ecosystems and historical change to those systems in Chihuahuan Desert areas of southeast Arizona, southern New Mexico, west Texas, or in neighboring regions that share the same plant species. It examines fire literature for situations possibly analogous to those at Carlsbad Caverns. It also includes papers that offer advice on extrapolating future ecological trends from past ones (Swetnam et al. 1999) and on resource management decision-making (Grumbine 1997), and other pieces that address broader aspects of fire or landscape change (Goldman 1994; Marston 1996; Mutch 1994, 1995). These more philosophical works were included in the original review at the park's request and have been retained here because they discuss other issues relevant to fire management. Individual reviews of 35 papers, as requested originally by Carlsbad Caverns, appear in Appendix 1. The results section-summary of key findings-discusses historical changes to plant communities then focuses on burn intervals observed or recommended by workers for particular plant communities. Results from a search of the USDA Forest Service's Fire Effects Information System (www.fs.fed.us/database/feis) are also included in this report, supplemented with information from a review conducted by Ahlstrand (1981b) that included much of his own work. This database contains comprehensive plant species accounts and fire effects data. Entries are available for a number of the dominant species at Carlsbad Caverns, though the information frequently applies to the plants in other parts of their ranges. The literature presents highly variable fire effects and observed/recommended burn intervals for similar plant communities in the northern Chihuahuan Desert region. While local and longer-term fire-effects studies are still needed to guide resource managers, the variability seen in the literature itself translates into a fire management goal. Preserving the irregularity in time and space of fires would likely best replicate 'natural' fire regimes.

Open-File Report↗
USGS2004

Data and understanding

In the year 1534 when Cabeza de Vaca escaped from the aborigines of southern Texas by whom he had been enslaved for six years, he made his way on foot from the vicinity of Galveston to the west coast of Mexico. Although his Relación was not printed until 1542, the verbal report of Cabeza de Vaca gave impetus to the growing interest in exploration of New Spain. Estevanico, the black, one of de Vaca's companions, served as guide to Fray Marcos de Niza on the first Spanish reconnaissance to reach the village of Zuni in New Mexico. The earliest Spanish exploring parties hoped to find riches, but expected to acquire, at the least, facts. These "gentlemen of high quality," as Castaneda called them, wanted to see for themselves whether the cities of Cibola had streets of silver. Hearsay was not enough. Rumor was to be replaced by first-hand knowledge. Without discounting the hope for personal gain, these men presumably were fired with some further intellectual and spiritual motivation, among which must have been the desire for facts about these parts where we are assembled. Inscription Rock, only a few miles west of Albuquerque, bears illuminating tidbits of history. Don Diego de Vargas, says the carved inscription of 1692, came here "A su costa"—at his own expense. We are attempting to survey and correlate some of the facts which people have gained about the nature of semi-arid lands. We are better off than the early Spanish explorers, for in the intervening period data and information have been accumulated in scope and in detail beyond the imagination of our predecessors. We have available excellent maps, knowledge of the soils and of the rocks, both at the surface and below the ground, measurements of precipitation, descriptions of the vegetation, data on the flow of streams, experience in the use, if not the husbandry, of the land. It is true that for the purposes of our complex civilization, the need for additional data has far outstripped the programs of fact-finding. But it appears that an indefinite expansion of the collection of routine measurements would still leave something lacking. I draw the distinction between measurement data and understanding; between the collection of facts and knowledge of processes and interrelationships. Although we have a wealth of data, our understanding of the semi-arid environment is poor. Understanding the physical and biologic processes operating in an environment is important for living in and with the land. As an example, let us look briefly at the interrelation of the water and sediment in ephemeral streams, and the problem of valley trenching or arroyo cutting.

Conference Paper↗
USGS2016

Ecological resistance in urban streams: the role of natural and legacy attributes

Urbanization substantially changes the physicochemical and biological characteristics of streams. The trajectory of negative effect is broadly similar around the world, but the nature and magnitude of ecological responses to urban growth differ among locations. Some heterogeneity in response arises from differences in the level of urban development and attributes of urban water management. However, the heterogeneity also may arise from variation in hydrologic, biological, and physicochemical templates that shaped stream ecosystems before urban development. We present a framework to develop hypotheses that predict how natural watershed and channel attributes in the pre-urban-development state may confer ecological resistance to urbanization. We present 6 testable hypotheses that explore the expression of such attributes under our framework: 1) greater water storage capacity mitigates hydrologic regime shifts, 2) coarse substrates and a balance between erosive forces and sediment supply buffer morphological changes, 3) naturally high ionic concentrations and pH pre-adapt biota to water-quality stress, 4) metapopulation connectivity results in retention of species richness, 5) high functional redundancy buffers trophic function from species loss, and 6) landuse history mutes or reverses the expected trajectory of eutrophication. Data from past comparative analyses support these hypotheses, but rigorous testing will require targeted investigations that account for confounding or interacting factors, such as diversity in urban infrastructure attributes. Improved understanding of the susceptibility or resistance of stream ecosystems could substantially strengthen conservation, management, and monitoring efforts in urban streams. We hope that these preliminary, conceptual hypotheses will encourage others to explore these ideas further and generate additional explanations for the heterogeneity observed in urban streams.

Freshwater Science↗
USGS2020

An analysis of the factors that control fault zone architecture and the importance of fault orientation relative to regional stress

The moment magnitude 7.2 El Mayor−Cucapah (EMC) earthquake of 2010 in northern Baja California, Mexico produced a cascading rupture that propagated through a geometrically diverse network of intersecting faults. These faults have been exhumed from depths of 6−10 km since the late Miocene based on low-temperature thermochronology, synkinematic alteration, and deformational fabrics. Coseismic slip of 1−6 m of the EMC event was accommodated by fault zones that displayed the full spectrum of architectural styles, from simple narrow fault zones (<100 m in width) that have a single high-strain core, to complex wide fault zones (>100 m in width) that have multiple anastomosing high-strain cores. As fault zone complexity and width increase the full spectrum of observed widths (20−200 m), coseismic slip becomes more broadly distributed on a greater number of scarps that form wider arrays. Thus, the infinitesimal slip of the surface rupture of a single earthquake strongly replicates many of the fabric elements that were developed during the long-term history of slip on the faults at deeper levels of the seismogenic crust. We find that factors such as protolith, normal stress, and displacement, which control gouge production in laboratory experiments, also affect the architectural complexity of natural faults. Fault zones developed in phyllosilicate-rich metasedimentary gneiss are generally wider and more complex than those developed in quartzo-feldspathic granitoid rocks. We hypothesize that the overall weakness and low strength contrast of faults developed in phyllosilicate rich host rocks leads to strain hardening and formation of broad, multi-stranded fault zones. Fault orientation also strongly affects fault zone complexity, which we find to increase with decreasing fault dip. We attribute this to the higher resolved normal stresses on gently dipping faults assuming a uniform stress field compatible with this extensional tectonic setting. The conditions that permit slip on misoriented surfaces with high normal stress should also produce failure of more optimally oriented slip systems in the fault zone, promoting complex branching and development of multiple high-strain cores. Overall, we find that fault zone architecture need not be strongly affected by differences in the amount of cumulative slip and instead is more strongly controlled by protolith and relative normal stress.

Baja California↗
USGS2012

Estimating westslope cutthroat trout ( Oncorhynchus clarkii lewisi ) movements in a river network using strontium isoscapes

We used natural variation in the strontium concentration (Sr:Ca) and isotope composition ( 87 Sr: 86 Sr) of stream waters and corresponding values recorded in otoliths of westslope cutthroat trout ( Oncorhynchus clarkii lewisi ) to examine movements during their life history in a large river network. We found significant spatial differences in Sr:Ca and 87 Sr: 86 Sr values (strontium isoscapes) within and among numerous spawning and rearing streams that remained relatively constant seasonally. Both Sr:Ca and 87 Sr: 86 Sr values in the otoliths of juveniles collected from nine natal streams were highly correlated with those values in the ambient water. Strontium isoscapes measured along the axis of otolith growth revealed that almost half of the juveniles had moved at least some distance from their natal streams. Finally, otolith Sr profiles from three spawning adults confirmed homing to natal streams and use of nonoverlapping habitats over their migratory lifetimes. Our study demonstrates that otolith geochemistry records movements of cutthroat trout through Sr isoscapes and therefore provides a method that complements and extends the utility of conventional tagging techniques in understanding life history strategies and conservation needs of freshwater fishes in river networks.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS2010

Hydrological connectivity for riverine fish: measurement challenges and research opportunities

In this review, we first summarize how hydrologic connectivity has been studied for riverine fish capable of moving long distances, and then identify research opportunities that have clear conservation significance. Migratory species, such as anadromous salmonids, are good model organisms for understanding ecological connectivity in rivers because the spatial scale over which movements occur among freshwater habitats is large enough to be easily observed with available techniques; they are often economically or culturally valuable with habitats that can be easily fragmented by human activities; and they integrate landscape conditions from multiple surrounding catchment(s) with in‐river conditions. Studies have focussed on three themes: (i) relatively stable connections (connections controlled by processes that act over broad spatio‐temporal scales >1000 km 2 and >100 years); (ii) dynamic connections (connections controlled by processes acting over fine to moderate spatio‐temporal scales ∼1–1000 km 2 and <1–100 years); and (iii) anthropogenic influences on hydrologic connectivity, including actions that disrupt or enhance natural connections experienced by fish. We outline eight challenges to understanding the role of connectivity in riverine fish ecology, organized under three foci: (i) addressing the constraints of river structure; (ii) embracing temporal complexity in hydrologic connectivity; and (iii) managing connectivity for riverine fishes. Challenges include the spatial structure of stream networks, the force and direction of flow, scale‐dependence of connectivity, shifting boundaries, complexity of behaviour and life histories and quantifying anthropogenic influence on connectivity and aligning management goals. As we discuss each challenge, we summarize relevant approaches in the literature and provide additional suggestions for improving research and management of connectivity for riverine fishes. Specifically, we suggest that rapid advances are possible in the following arenas: (i) incorporating network structure and river discharge into analyses; (ii) increasing explicit consideration of temporal complexity and fish behaviour in the scope of analyses; and (iii) parsing degrees of human and natural influences on connectivity and defining acceptable alterations. Multiscale analyses are most likely to identify dominant patterns of connections and disconnections, and the appropriate scale at which to focus conservation activities.

Freshwater Biology↗
USGS2002

Landscape ecology of plague in the American southwest, September 19-20, 2000, Fort Collins, Colorado

During September 19-20, 2000, a workshop titled "Landscape Ecology of Plague in the American Southwest" was held in Fort Collins, Colorado. The workshop was funded by the U.S. Geological Survey (USGS)-Earth Surface Processes Team and sponsored by the USGS National Wildlife Health Center. Forty scientists and natural resource managers and administrators representing 8 federal agencies, 4 state agencies, 6 universities, and other local agencies and nongovernment organizations met to discuss historical and current status of plague in the United States, current activities in plague surveillance, research, and management in wildlife, and research and information needs relative to plague control and management. Eleven individual presentations on plague history, status, and trends; diagnostic technologies; epizootiological studies and observations; and control and management strategies and studies, followed by a panel discussion on the impact of plague on wildlife and ecosystems, led the way to extensive group discussions on important plague-related questions, issues and problems. Workshop attendees participated in identifying important research and information needs relevant to control and management of plague in wildlife, and in the process, established new cooperative and collaborative partnerships and enhanced existing relationships upon which future research and information needs can be met. The proceedings from this workshop are intended to be used by the natural resource managers and researchers from the various participating agencies, research facilities, as well as other stakeholders to aid in the development of future research and information programs and funding initiatives related to both zoonotic and sylvatic plague.

American Southwest↗
USGS2025

Endemic and invasive species: A history of distributional trends in the fish fauna of the lower New River drainage

Invasive species are often central to conservation efforts, particularly when concerns involve potential impacts on rare, endemic native species. The lower New River drainage of the eastern United States is a watershed that warrants conservation assessment, as the system is naturally depauperate of native fish species and it is nearly saturated with non-native fish species: there are 31 natives, including at least nine endemic taxa, and 63 non-natives. For endemic taxa, we examined temporal distribution shifts (range expansions or contractions) based on percent change in the occupied watershed area. We contrasted these findings with time series analyses on distribution trends of non-native minnows (Leuciscidae) and darters (Percidae) based on growth curve models of the cumulative sum of the total area of occupied 12-digit hydrologic unit codes. We documented range reductions for six of nine endemic taxa. We determined that 11 of 18 non-native minnows and 6 of 8 non-native darters were invasive based on range expansions and associated invasion curve models. The endemic taxa are of conservation concern given the limited distribution ranges and documented population declines. Although among-species comparisons of range shifts do not support causal inference, documentation of changes in distribution ranges of endemic and invasive species is critical to inform conservation efforts.

North Carolina, Tennessee, Virginia, West Virginia↗
USGS2022

Large-scale fire management restores grassland bird richness for a private lands ecoregion

Of all terrestrial biomes, grasslands are losing the most biodiversity the most rapidly, so there is a critical need to document and learn from large-scale restoration successes. In the Loess Canyons ecoregion of the Great Plains, USA, an association of private ranchers and natural resource agencies has led a multi-decadal, ecoregion-scale initiative to combat the loss of grasslands to woody plant encroachment by restoring large-scale fire regimes. Here, we use 14 years of fire treatment history with 6 years of grassland bird monitoring and remotely sensed tree cover data across 136,767 ha of privately owned grassland to quantify outcomes of large-scale grassland restoration efforts. Grassland bird richness increased across 65% (90,032 ha) of the Loess Canyons, and woody plant cover decreased up to 55% across 25% (7408 ha) of all fire-treated areas. This was accomplished with extreme fire treatments that killed mature trees, were large (mean annual area burned was 3100 ha), spatially clustered and straddled boundaries between invasive woodlands and remaining grasslands – not heavily infested woodlands. Findings from this study provide the first evidence of human management reversing the impacts of woody encroachment on grassland birds at an ecoregion scale.

Nebraska↗
USGS2010

A model‐data intercomparison of CO2 exchange across North America: Results from the North American Carbon Program site synthesis

Our current understanding of terrestrial carbon processes is represented in various models used to integrate and scale measurements of CO 2 exchange from remote sensing and other spatiotemporal data. Yet assessments are rarely conducted to determine how well models simulate carbon processes across vegetation types and environmental conditions. Using standardized data from the North American Carbon Program we compare observed and simulated monthly CO 2 exchange from 44 eddy covariance flux towers in North America and 22 terrestrial biosphere models. The analysis period spans ∼220 site‐years, 10 biomes, and includes two large‐scale drought events, providing a natural experiment to evaluate model skill as a function of drought and seasonality. We evaluate models' ability to simulate the seasonal cycle of CO 2 exchange using multiple model skill metrics and analyze links between model characteristics, site history, and model skill. Overall model performance was poor; the difference between observations and simulations was ∼10 times observational uncertainty, with forested ecosystems better predicted than nonforested. Model‐data agreement was highest in summer and in temperate evergreen forests. In contrast, model performance declined in spring and fall, especially in ecosystems with large deciduous components, and in dry periods during the growing season. Models used across multiple biomes and sites, the mean model ensemble, and a model using assimilated parameter values showed high consistency with observations. Models with the highest skill across all biomes all used prescribed canopy phenology, calculated NEE as the difference between GPP and ecosystem respiration, and did not use a daily time step.

Journal of Geophysical Research: Biogeosciences↗
USGS2025

Stock composition of cryptic Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) in the Restigouche River and estuary, Canada

The Atlantic sturgeon ( Acipenser oxyrinchus oxyrinchus ) is an important species in eastern North America due to its conservation status and cultural significance. Local Mi'gmaw fishers have reported an increase in sturgeon sightings over the last decade in the Restigouche River and estuary. Mi’gmaw Knowledge, oral history, and archaeological finds attest to their historical presence in the region; however, the river is not a documented habitat for Atlantic sturgeon in Western literature. Based on community interest and concern, the Gespe’gewa’gi Institute of Natural Understanding co-developed a Two-Eyed Seeing collaboration to learn more about these sturgeon. Here, we investigate their genetic origin via microsatellite analyses and hypothesized that they would originate from the closest spawning habitat, the St. Lawrence River. We found that, overall, the largest contributor to our Atlantic sturgeon sampled from the Restigouche River system was the St. Lawrence River (85.7% of samples), followed by the Wolastoq (3.6%), then a mixture of the St. Lawrence, the Wolastoq, the Kennebec, and/or the Hudson River populations (10.7%). Improving our understanding of the distribution of Atlantic sturgeon through microsatellite analyses and leveraging range-wide genetic baselines directly assesses the genetic origin of unknown stock compositions and can support the future co-management of the species.

Restigouche River and estuary↗
USGS2008

Effects of salinity on freshwater fishes in coastal plain drainages in the southeastern U.S.

This review focuses on the influence of salinity on freshwater fishes in coastal rivers and estuaries of the southeastern U.S. Influences of salinity on freshwater fish species can be explained partly through responses evidenced by behavior, physiology, growth, reproduction, and food habits during all aspects of life history. Factors influencing the rate of salinity change affect the community structure and dynamics of freshwater fishes in brackish environments. Our understanding of the relation between salinity and the life history of freshwater fishes is limited because little ecological research has been conducted in low-salinity habitats that we consider an “interface” between freshwater streams and the estuary proper. Much of the available data are descriptive in nature and describe best general patterns, but more specific studies are required to better determine the influence of salinity on freshwater fishes. Improved understanding of the influence of human-induced changes on the productivity and viability of these important systems will require a new research focus.

Reviews in Fisheries Science↗