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At least 955 records · Page 53Linked to original sources
USGS2012

Demographics and run timing of adult Lost River ( Deltistes luxatus ) and shortnose ( Chasmistes brevirostris ) suckers in Upper Klamath Lake, Oregon, 2011

Executive Summary Data from a long-term capture-recapture program were used to assess the status and dynamics of populations of two long-lived, federally endangered catostomids in Upper Klamath Lake, Oregon. Lost River suckers ( Deltistes luxatus ) and shortnose suckers ( Chasmistes brevirostris ) have been captured and tagged with passive integrated transponder (PIT) tags during their spawning migrations in each year since 1995. In addition, beginning in 2005, individuals that had been previously PIT-tagged were re-encountered on remote underwater antennas deployed throughout sucker spawning areas. Captures and remote encounters during spring 2011 were used to describe the spawning migrations in that year and also were incorporated into capture-recapture analyses of population dynamics. Cormack-Jolly-Seber (CJS) open population capture-recapture models were used to estimate annual survival probabilities, and a reverse-time analog of the CJS model was used to estimate recruitment of new individuals into the spawning populations. In addition, data on the size composition of captured fish was examined to provide corroborating evidence of recruitment. Survival and recruitment estimates were used to derive estimates of changes in population size over time and to determine the status of the populations in 2010. Separate analyses were conducted for each species and also for each subpopulation of Lost River suckers (LRS). One subpopulation of LRS migrates into tributaries to spawn, similar to shortnose suckers (SNS), whereas the other subpopulation spawns at upwelling areas along the eastern shoreline of the lake. In 2011, we captured, tagged, and released 806 LRS at four lakeshore spawning areas and recaptured an additional 1,006 individuals that had been tagged in previous years. Across all four areas, the remote antennas detected 6,547 individual LRS during the spawning season. Spawning activity peaked in April and most individuals were encountered at Sucker Springs and Cinder Flats. In the Williamson River, we captured, tagged, and released 2,742 LRS and 123 SNS, and recaptured 376 LRS and 58 SNS that had been tagged in previous years. Remote PIT tag antennas in the traps at the weir on the Williamson River and remote antenna systems that spanned the river at four different locations on the Williamson and Sprague Rivers detected a total of 16,494 LRS and 5,450 SNS. Most LRS passed upstream between mid-April and mid-May when water temperatures were rising and near or greater than 10 °C. In contrast, the largest peaks in upstream passage of SNS occurred in early and mid-May when water temperatures were rising and near or greater than 12 °C. Finally, an additional 875 LRS and 1,600 SNS were captured in trammel net sampling at pre-spawn staging areas in the northeastern portion of the lake. Of these, 191of the LRS and 571 of the SNS had been PIT-tagged in previous years. For LRS, encounter histories showed that more than 90 percent of the fish captured at the staging areas were members of the subpopulation that spawns in the tributaries. Capture-recapture analyses for the LRS subpopulation that spawns at the shoreline areas included encounter histories for more than 10,500 individuals, and analyses for the subpopulation that spawns in the tributaries included more than 22,000 encounter histories. With a few exceptions, the survival of males and females in both subpopulations was high (greater than 0.9) between 1999 and 2009. Notably lower survival occurred for both sexes from the tributaries in 2000, for both sexes from the shoreline areas in 2002, and for males from the tributaries in 2006. Between 2001 and 2010, the abundance of males in the lakeshore spawning subpopulation decreased by 50–60 percent and the abundance of females decreased by 29–44 percent. Capture-recapture models suggested that the abundance of the river spawning subpopulation of LRS has increased substantially since 2006. The increase over this period was largely due to large estimated recruitment events in 2003, 2006, and 2008. We know that the estimate in 2006 is substantially biased in favor of recruitment due to a sampling issue. We are skeptical of the magnitude of recruitment indicated by the 2003 and 2008 estimates as well because very few small individuals that would indicate the presence of new recruits were captured in those years. If we assume that little or no recruitment has occurred, the abundance of both sexes in the river spawning subpopulation decreased by more than 40 percent between 2002 and 2010. Capture-recapture analyses for SNS included encounter histories for more than 15,500 individuals. The majority of annual survival estimates between 2001 and 2009 were high (greater than 0.8), but SNS did experience more years of low survival than either LRS subpopulation. The survival of both sexes was particularly low in both 2001 and 2004, and male survival also was somewhat low in 2002 and 2006. Capture-recapture models and size composition data indicated that recruitment of new individuals into the SNS spawning population was trivial in nearly all years between 2001 and 2009. As a result, the abundance of males decreased by 64–82 percent and the abundance of females decreased by 62–76 percent between 2001 and 2010. Despite relatively high survival in most years, both species have experienced substantial declines in the abundance of spawning fish because losses from mortality have not been balanced by recruitment of new individuals. Although capture-recapture data indicate substantial recruitment of new individuals into the adult spawning populations for SNS and river spawning LRS in some years, size data do not corroborate these estimates. In fact, fork length data indicate that all populations are largely comprised of fish that were present in the late 1990s and early 2000s. As a result, the status of the endangered sucker populations in Upper Klamath Lake remains worrisome, and the situation is most dire for shortnose suckers. Future investigations should explore the connections between sucker recruitment and survival and various environmental factors, such as water quality and disease. Our monitoring program provides a robust platform for estimating vital population parameters, evaluating the status of the populations, and assessing the effectiveness of conservation and recovery efforts.

California, Oregon↗
USGS2014

Demographics and run timing of adult Lost River ( Deltistes luxatus ) and short nose ( Chasmistes brevirostris ) suckers in Upper Klamath Lake, Oregon, 2012

Data from a long-term capture-recapture program were used to assess the status and dynamics of populations of two long-lived, federally endangered catostomids in Upper Klamath Lake, Oregon. Lost River suckers ( Deltistes luxatus ) and shortnose suckers ( Chasmistes brevirostris ) have been captured and tagged with passive integrated transponder (PIT) tags during their spawning migrations in each year since 1995. In addition, beginning in 2005, individuals that had been previously PIT-tagged were re-encountered on remote underwater antennas deployed throughout sucker spawning areas. Captures and remote encounters during spring 2012 were used to describe the spawning migrations in that year and also were incorporated into capture-recapture analyses of population dynamics. Cormack-Jolly-Seber (CJS) open population capture-recapture models were used to estimate annual survival probabilities, and a reverse-time analog of the CJS model was used to estimate recruitment of new individuals into the spawning populations. In addition, data on the size composition of captured fish were examined to provide corroborating evidence of recruitment. Model estimates of survival and recruitment were used to derive estimates of changes in population size over time and to determine the status of the populations in 2011. Separate analyses were conducted for each species and also for each subpopulation of Lost River suckers (LRS). Shortnose suckers (SNS) and one subpopulation of LRS migrate into tributary rivers to spawn, whereas the other LRS subpopulation spawns at groundwater upwelling areas along the eastern shoreline of the lake. In 2012, we captured, tagged, and released 749 LRS at four lakeshore spawning areas and recaptured an additional 969 individuals that had been tagged in previous years. Across all four areas, the remote antennas detected 6,578 individual LRS during the spawning season. Spawning activity peaked in April and most individuals were encountered at Cinder Flats and Sucker Springs. In the Williamson River, we captured, tagged, and released 3,376 LRS and 299 SNS, and recaptured 551 LRS and 125 SNS that had been tagged in previous years. Remote PIT tag antennas in the traps at the weir on the Williamson River and remote antenna systems that spanned the river at four different locations on the Williamson and Sprague Rivers detected a total of 19,321 LRS and 6,124 SNS. Most LRS passed upstream between late April and mid-May when water temperatures were increasing and greater than 10 °C. In contrast, most upstream passage for SNS occurred in early and mid-May when water temperatures were increasing and near or greater than 12 °C. Finally, an additional 1,188 LRS and 1,665 SNS were captured in trammel net sampling at pre-spawn staging areas in the northeastern part of the lake. Of these, 291 of the LRS and 653 of the SNS had been PIT-tagged in previous years. For LRS captured at the staging areas that had encounter histories that were informative about their spawning location, over 90 percent of the fish were members of the subpopulation that spawns in the rivers. Capture-recapture analyses for the LRS subpopulation that spawns at the shoreline areas included encounter histories for more than 12,150 individuals, and analyses for the subpopulation that spawns in the rivers included more than 29,500 encounter histories. With a few exceptions, the survival of males and females in both subpopulations was high (greater than 0.9) between 1999 and 2010. Notably lower survival occurred for both sexes from the rivers in 2000, for both sexes from the shoreline areas in 2002, and for males from the rivers in 2006. Between 2001 and 2011, the abundance of males in the lakeshore spawning subpopulation decreased by 53–65 percent and the abundance of females decreased by 36–48 percent. Capture-recapture models suggested that the abundance of both sexes in the river spawning subpopulation of LRS had increased substantially since 2006; increases were due to large estimated recruitment events in 2006 and 2008. We know that the estimates in 2006 are substantially biased in favor of recruitment because of a sampling issue. We are skeptical of the magnitude of recruitment indicated by the 2008 estimates as well because (1) few small individuals that would indicate the presence of new recruits were captured in that year, and (2) recapture probabilities in recruitment models based on just physical recaptures were lower than desired for robust inferences from capture-recapture models. If we assume that little or no recruitment occurred in 2006 or 2008, the abundance of both sexes in the river spawning subpopulation likely has decreased at rates similar to the rates for the lakeshore spawning subpopulation between 2002 and 2011. Capture-recapture analyses for SNS included encounter histories for more than 17,700 individuals. Most annual survival estimates between 2001 and 2010 were high (greater than 0.8), but SNS experienced more years of low survival than either LRS subpopulation. Annual survival of both sexes was particularly low in 2001, 2004, and 2010. In addition, male survival was somewhat low in 2002. Capture-recapture models and size composition data indicate that recruitment of new individuals into the SNS spawning population was trivial between 2001 and 2005. Models indicate substantial recruitment of new individuals into the SNS spawning population in 2006, 2008, and 2009. As a result, capture-recapture modeling suggests that the abundance of adult spawning SNS was relatively stable between 2006 and 2010. We are skeptical of the estimated recruitment in 2006, 2008, and 2009 because few small individuals that would indicate the presence of new recruits were captured in any of those years, and recapture probabilities in recruitment models were low. The best-case scenario for SNS, based on capture-recapture recruitment modeling, indicates that the abundance of males in the spawning population decreased by 71 percent and the abundance of females decreased by 69 percent between 2001 and 2011. The worst-case scenario, which assumes no recruitment and seems more likely, suggests an 86 percent decrease for males and an 81 percent decrease for females. Despite relatively high survival in most years, we conclude that both species have experienced substantial declines in the abundance of spawning fish because losses from mortality have not been balanced by recruitment of new individuals. Although capture-recapture data indicate substantial recruitment of new individuals into the adult spawning populations for SNS and river spawning LRS in some years, size data do not corroborate these estimates. In fact, fork length data indicate that all populations are largely comprised of fish that were present in the late 1990s and early 2000s. As a result, the status of the endangered sucker populations in Upper Klamath Lake remains worrisome, and the situation is especially dire for shortnose suckers. Future investigations should explore the connections between sucker recruitment and survival and various environmental factors, such as water quality and disease. Our monitoring program provides a robust platform for estimating vital population parameters, evaluating the status of the populations, and assessing the effectiveness of conservation and recovery efforts.

Oregon↗
USGS2018

Genetic integrity, population status, and long-term viability of isolated populations of shoal bass in the upper Chattahoochee River basin, Georgia

This report characterizes the status of multiple isolated Shoal Bass ( Micropterus cataractae ) populations in the upper Chattahoochee River basin (UCRB), Georgia. The Shoal Bass, a sport fish endemic to the Apalachicola-Chattahoochee-Flint River (ACF) basin, is a fluvial-specialist species considered vulnerable to local extirpations and extinction due to habitat fragmentation and introgression with non-native congeners. Perhaps one of the most isolated populations of Shoal Bass exists in a 2-km reach of Big Creek, a tributary of the Chattahoochee River located near Roswell, Georgia. Big Creek is partially contained within the Chattahoochee River National Recreation Area, although the Big Creek watershed is riddled with urban land cover. Roswell Mill Dam limits the upstream extent of the Shoal Bass population at Big Creek, and the downstream extent is presumably limited to the confluence of Big Creek and the Chattahoochee River. This reach of the Chattahoochee River is thermally depressed because of coldwater releases from Lake Lanier, and is considered unsuitable for Shoal Bass. Herein, we examine the genetic integrity, population status, and long-term viability of the Shoal Bass population in Big Creek. We also examine two additional Shoal Bass populations that occur in the UCRB, specifically the Chestatee River and the upper Chattahoochee River, both of which are impounded at Lake Lanier. Together, the Shoal Bass inhabiting these three stream systems comprise a distinct genetic stock of Shoal Bass (Taylor 2017), underscoring the importance of conserving these populations towards maintaining the overall diversity and adaptive potential of the species. We assessed genetic diversity and estimated effective population sizes within these three rivers by genotyping fish with 16 microsatellite DNA markers. Results demonstrated that the Shoal Bass population in Big Creek has experienced high rates of introgression with non-native Smallmouth Bass (M. dolomieu), purportedly introduced into the Chattahoochee River in the past 10-15 years. Alarmingly, only 24% (15 of 62) of putative Shoal Bass collected from Big Creek were genetically pure Shoal Bass, whereas the majority of fish were first-filial (F1) generation hybrids and unidirectional backcrosses towards Shoal Bass. Fleeting opportunity may remain to conserve the native genome of the Shoal Bass population in Big Creek. High hybridization rates prevented genetic diversity analysis for the Big Creek population. Shoal Bass populations in the Chestatee and Chattahoochee rivers displayed levels of genetic diversity similar to populations that persist in other rivers in the ACF basin, namely the Flint and Chipola rivers. Effective population sizes of 93.8– 197.4 for the Chestatee and Chattahoochee rivers (combined) suggest that the conservation status of these populations is stable for the short-term, but may be at risk of losing genetic diversity and adaptive potential in the long-term. To estimate age and mortality of the three populations, we used fish scales and capture-markrecapture (CMR) as complementary, non-lethal methods for age estimation. Estimated ages of phenotypic Shoal Bass ranged from 1-12 years in all three populations, demonstrating increased longevity compared to populations elsewhere within the native range. Catch-curve estimates of annual mortality ranged from 18.4-23.7%, which are markedly lower than those observed in other Shoal Bass populations in the ACF basin. These differences in life-history characteristics underscore the need for the development of population-specific management and conservation strategies for Shoal Bass in the UCRB. The lowest recruitment variability (i.e., the variation in year-class strength) was observed in the Chestatee River, a forested watershed, whereas the highest variability was observed in Big Creek, an urbanized watershed. Recruitment strength in Big Creek was negatively influenced by discharge variability in the summer months, suggesting that flashy, sediment-laden flows hinder survival of recently hatched young. Other statistically significant models from Big Creek and the Chattahoochee River indicated that over-winter survival could be an important pinch-point for recruitment in UCRB populations. A multi-agency sampling effort was conducted from May 2013-May 2016 to estimate the population size of Shoal Bass occupying the 1-km of wadeable shoal habitats in Big Creek. Using CMR models, we estimated that approximately 219-348 Shoal Bass (≥ 70 mm total length) occupied the area throughout the duration of our study. These estimates largely reflect abundance of individuals aged 0-2 years, as only 9% (36 of 408) tagged fish were aged ≥ 7 years. Local abundance appeared similar to that reported for a population that inhabited Little Uchee Creek, a similar-sized tributary of the Chattahoochee River, prior to its recent functional extirpation. The low abundance of large, adult Shoal Bass further suggests the long-term viability of the Big Creek population may be in jeopardy. Perhaps most importantly, CMR estimates reflect abundance of phenotypic Shoal Bass – genetic analyses suggest the abundance of pure Shoal Bass could be an order of magnitude smaller. To evaluate the potential for adult Shoal Bass to emigrate from Big Creek into the mainstem Chattahoochee River, we tagged eight adults with acoustic telemetry tags and assessed their seasonal residency at two stationary receiver locations located in increasing proximity to the confluence with the Chattahoochee River. Fish took up residency near the confluence during the fall and winter months, during which time water temperatures in Big Creek were periodically colder than the Chattahoochee River. Although we were unable to document emigration, we conclude that the potential for emigration is highest during the winter months when the Chattahoochee River may be warmer than Big Creek. Two of the tagged fish were caught by anglers near the confluence, suggesting that angling pressure at Big Creek may be higher than previously suspected. Overall, this study observed unique life-history characteristics and characterized the population status of multiple Shoal Bass populations in the UCRB. Populations in the Chestatee and Chattahoochee rivers appear stable at present and likely represent the last remaining strongholds for pure Shoal Bass in the UCRB. Efforts to preserve forested watershed conditions, natural hydrology, and shoal habitats would contribute to the long-term persistence of Shoal Bass populations in these two rivers. Additionally, the detection of non-native Alabama Bass and their associated hybrids in both rivers is cause for concern. Diligent monitoring of hybridization dynamics between Alabama Bass and Shoal Bass is warranted, along with an assessment of Alabama Bass invasion extent upstream of Lake Lanier. The Shoal Bass population in Big Creek is threatened by elevated levels of introgression with nonnative Smallmouth Bass, recruitment variability, low abundance of adults, and isolation from other populations. Conservation intervention is urgently needed to restore and preserve this genetically distinct population, which would contribute to preservation of range wide genetic diversity and adaptability of the species. Additionally, an urban sport fishery for Shoal Bass at Big Creek has the potential to serve as a tool for increasing public awareness, engagement, and support of Shoal Bass conservation efforts in the UCRB. We suggest strategies for conservation of the remnant shoal habitats and Shoal Bass population in Big Creek, including potential development of a supplemental stocking program, selective removal of non-native congeners, and delivery of environmental education programs that could bolster awareness and appreciation.

Georgia↗
USGS2005

Post-harvest field manipulations to conserve waste rice for waterfowl

Rice seeds escaping collection by combines during harvest (hereafter, waste rice) provide quality forage for migrating and wintering waterfowl in the Lower Mississippi Alluvial Valley (MAV) and other rice growing regions in the United States. Recent sample surveys across the MAV have revealed abundance of waste rice in fields declined an average of 71% between harvest and late autumn. Thus, we evaluated the ability of common post-harvest, field-management practices to conserve waste rice for waterfowl until early winter via controlled experiments in Mississippi rice test plots in 2001 and 2003 and analyses of data from MAV-wide surveys of waste rice in rice production fields in 2000-2002. Our experiments indicated test plots with burned rice stubble that were not flooded during autumn contained more waste rice than other treatments in 2001 (P?0.10). Waste-rice abundance in test plots did not differ among postharvest treatments in 2003 (P = 0.97). Our analyses of data from the MAV sample surveys did not detect differences in abundance of waste rice among fields burned, rolled, disked, or left in standing stubble post-harvest (P?0.04; Bonferroni corrected critical ( a= 0.017). Because results from test-plot experiments were inconclusive, we based our primary inference regarding best post-harvest treatments on patterns of rice abundance identified from the MAV surveys and previously documented environmental and agronomic benefits of managing harvested rice fields for wintering waterfowl. Therefore, we recommend leaving standing stubble in rice fields after harvest as a preliminary beneficial management practice. We suggest future research evaluate potential of postharvest practices to conserve waste rice for waterfowl and reduce straw in production rice fields managed for wintering waterfowl throughout the MAV.

Proceedings of the Annual Conference of the Southe↗
USGS2024

Assessing potential habitat for freshwater mussels by transferring a habitat suitability model within the Ozark Ecoregion, Missouri

Habitat suitability models for freshwater mussels can inform conservation of these imperiled animals. Riverscape-scale hydrogeomorphic variables were previously used to predict suitable mussel habitat in the Meramec River basin, Missouri. We evaluated transferability of the Meramec River habitat suitability model to the Gasconade and Little Black rivers, in the Ozark Highlands ecoregion, Missouri. The best-fit models relied on transferring and adapting the original modeling framework to better represent the unique habitat characteristics of each river. Mussel bed occurrence in both rivers was associated with reaches that were classified as pools. Mussel beds in the Gasconade River were also associated with laterally stable reaches adjacent to small bluffs, distant from gravel bars, and with higher stream power indices. Mussel beds in the Little Black River were associated with reaches with higher surface water availability during low-flow conditions, lower stream power indices, and bluffs located downstream. Our results show that existing habitat models can be transferred to other streams with similar environmental conditions, but differences in watershed characteristics can affect transferability.

Missouri↗
USGS2011

Wind Turbines as Landscape Impediments to the Migratory Connectivity of Bats

Unprecedented numbers of migratory bats are found dead beneath industrial-scale wind turbines during late summer and autumn in both North America and Europe. Prior to the wide-scale deployment of wind turbines, fatal collisions of migratory bats with anthropogenic structures were rarely reported and likely occurred very infrequently. There are no other well-documented threats to populations of migratory tree bats that cause mortality of similar magnitude to that observed at wind turbines. Just three migratory species comprise the vast majority of bat kills at turbines in North America and there are indications that turbines may actually attract migrating individuals toward their blades. Although fatality of certain migratory species is consistent in occurrence across large geographic regions, fatality rates differ across sites for reasons mostly unknown. Cumulative fatality for turbines in North America might already range into the hundreds of thousands of bats per year. Research into the causes of bat fatalities at wind turbines can ascertain the scale of the problem and help identify solutions. None of the migratory bats known to be most affected by wind turbines are protected by conservation laws, nor is there a legal mandate driving research into the problem or implementation of potential solutions.

Environmental Law↗
USGS2013

Chronic toxicity of nickel-spiked freshwater sediments: variation in toxicity among eight invertebrate taxa and eight sediments

This study evaluated the chronic toxicity of Ni-spiked freshwater sediments to benthic invertebrates. A 2-step spiking procedure (spiking and sediment dilution) and a 2-stage equilibration period (10 wk anaerobic and 1 wk aerobic) were used to spike 8 freshwater sediments with wide ranges of acid-volatile sulfide (AVS; 0.94–38 µmol/g) and total organic carbon (TOC; 0.42–10%). Chronic sediment toxicity tests were conducted with 8 invertebrates ( Hyalella azteca, Gammarus pseudolimnaeus , Chironomus riparius, Chironomus dilutus , Hexagenia sp., Lumbriculus variegatus, Tubifex tubifex , and Lampsilis siliquoidea ) in 2 spiked sediments. Nickel toxicity thresholds estimated from species-sensitivity distributions were 97 µg/g and 752 µg/g (total recoverable Ni; dry wt basis) for sediments with low and high concentrations of AVS and TOC, respectively. Sensitive species were tested with 6 additional sediments. The 20% effect concentrations (EC20s) for Hyalella and Gammarus , but not Hexagenia , were consistent with US Environmental Protection Agency benchmarks based on Ni in porewater and in simultaneously extracted metals (SEM) normalized to AVS and TOC. For Hexagenia , sediment EC20s increased at less than an equimolar basis with increased AVS, and toxicity occurred in several sediments with Ni concentrations in SEM less than AVS. The authors hypothesize that circulation of oxygenated water by Hexagenia led to oxidation of AVS in burrows, creating microenvironments with high Ni exposure. Despite these unexpected results, a strong relationship between Hexagenia EC20s and AVS could provide a basis for conservative site-specific sediment quality guidelines for Ni.

Environmental Toxicology and Chemistry↗
USGS2019

Characteristics of feeding sites of California Condors (Gymnogyps californianus) in the human-dominated landscape of Southern California

Wildlife conservation is often improved by understanding the movement ecology of species and adapting management strategies to dynamic conditions associated with movement. Despite a remarkable recovery over the past 30 year, the establishment of self-sustaining populations of California Condors (Gymnogyps californianus) has been challenging in the human-dominated landscapes of southern California. Among these challenges are those imposed by condor ground-foraging behavior that exposes them to environmental contamination. These include lead poisoning from the ingestion of spent ammunition and micro-trash ingestion and, during takeoff and landing, collisions with human structures. We tracked 28 California Condors for 24 months with patagially mounted GPS telemetry units to investigate the characteristics of ground sites condors visited and to identify spatiotemporal trends that might aid in conservation of this critically endangered species. Ground sites occurred on a wide variety of land cover types, primarily on steep slopes, and those more frequently used were associated with open cover. Condors concentrated their visits to ground sites around a 3 h period near midday, and usage increased from winter to late summer. Our study is the first to use remotely sensed telemetry data to describe fine-scale ecological correlates of condor ground-foraging ecology and therefore has important relevance for ongoing conservation and management strategies for this species. The descriptions of ground sites we provide can be used to target conservation or management actions.

California↗
USGS2022

Using a multi-model ensemble approach to determine biodiversity hotspots with limited occurrence data in understudied areas: An example using freshwater mussels in México

Species distribution models (SDMs) are an increasingly important tool for conservation particularly for difficult-to-study locations and with understudied fauna. Our aims were to (1) use SDMs and ensemble SDMs to predict the distribution of freshwater mussels in the Pánuco River Basin in Central México; (2) determine habitat factors shaping freshwater mussel occurrence; and (3) use predicted occupancy across a range of taxa to identify freshwater mussel biodiversity hotspots to guide conservation and management. In the Pánuco River Basin, we modeled the distributions of 11 freshwater mussel species using an ensemble approach, wherein multiple SDM methodologies were combined to create a single ensemble map of predicted occupancy. A total of 621 species-specific observations at 87 sites were used to create species-specific ensembles. These predictive species ensembles were then combined to create local diversity hotspot maps. Precipitation during the warmest quarter, elevation, and mean temperature were consistently the most important discriminatory environmental variables among species, whereas land use had limited influence across all taxa. To the best of our knowledge, our study is the first freshwater mussel-focused research to use an ensemble approach to determine species distribution and predict biodiversity hotspots. Our study can be used to guide not only current conservation efforts but also prioritize areas for future conservation and study.

Pánuco↗
USGS2025

On the interface between cultural transmission, phenotypic diversity, demography and the conservation of migratory ungulates

Recent evidence indicates that green-wave surfing behaviour in ungulates and the migrations that stem from this behaviour are socially learned, culturally transmitted across generations and become more efficient via cumulative cultural evolution. But given a lack of corroborative evidence, whether ungulate migration is a cultural phenomenon remains a hypothesis deserving of further testing. In this opinion piece, we summarize the role memory and social learning play in the green-wave surfing that underlies ungulate migration, and when combined with the natural history of ungulates, we argue that the most likely mechanism for maintenance of ungulate migration is animal culture. We further our argument by providing a synopsis of processes that promote diversification of migratory behaviour and link these processes to their emergent ecological patterns, which are common in nature but have not historically been considered as potential cultural phenomena. The notion that diverse portfolios of migratory behaviour may buffer populations from environmental change emerges from this synthesis but requires empirical testing. Finally, we contend that, because the migratory behaviour of ungulates stems largely from cultural transmission as opposed to a genetic programme, the diversity of observed migratory strategies represents ‘culturally significant units’ deserving of the same conservation effort afforded to evolutionarily significant units.

Wyoming↗
USGS2023

Ecological associations of non-native ungulates on the Hawaiian Island of Lāna‘i

Sustained-yield hunting of introduced ungulates in the Hawaiian Islands often conflicts with the conservation of native species, but there is little reliable data to guide effective management. European mouflon sheep ( Ovis musimon ; mouflon) and axis deer ( Axis axis ; deer) were introduced on the island of Lāna‘i to provide additional hunting opportunities. Managers will require better information regarding the ecological associations of introduced ungulate species, relative to the habitats occupied, to resolve longstanding conflicts between native species conservation and sustained-yield hunting on islands. To address this information need, we modeled sheep and deer ecological associations, habitat-use, and suitability using data obtained from an intensive aerial survey completed in 2013 and temporally matching environmental data. In habitat suitability models evaluated by Receiver Operating Characteristic (ROC) metrics, predictor importance in a generalized linear model (GLM) of deer decreased in the following order: afternoon cloud cover, topographic slope, mean annual precipitation (MAP), elevation, normalized difference vegetation index (NDVI), and bare soil index. In a random GLM model of mouflon, predictor importance decreased in the following order: afternoon cloud cover, deer habitat suitability, NDVI, bare soil index, topographic slope, elevation, and MAP. Mouflon were restricted to lower elevation arid slopes, whereas deer were more broadly distributed throughout upland environments of the island. The presence of deer was also an important predictor for mouflon distribution, although mouflon was not an important predictor of deer, suggesting asymmetrical competition. Removal of the more abundant deer population may lead to an increase in abundance and distribution of mouflon without containment. This work represents the first habitat suitability analysis for all nonnative ungulates on any entire Hawaiian island. Our results are applicable to other islands where conflicts may arise with introduced ungulates, sustained-yield hunting, and native species conservation.

Hawaii↗
USGS2023

Is now the time? Review of genetic rescue as a conservation tool for brook trout

Brook trout populations have been declining throughout their native range in the east coast of the United States. Many populations are now distributed in small, isolated habitat patches where low genetic diversity and high rates of inbreeding reduce contemporary viability and long-term adaptive potential. Although human-assisted gene flow could theoretically improve conservation outcomes through genetic rescue, there is widespread hesitancy to use this tool to support brook trout conservation. Here, we review the major uncertainties that have limited genetic rescue from being considered as a viable conservation tool for isolated brook trout populations and compare the risks of genetic rescue with other management alternatives. Drawing on theoretical and empirical studies, we discuss methods for implementing genetic rescue in brook trout that could yield long-term evolutionary benefits while avoiding negative fitness effects associated with outbreeding depression and the spread of maladapted alleles. We also highlight the potential for future collaborative efforts to accelerate our understanding of genetic rescue as a viable tool for conservation. Ultimately, while we acknowledge that genetic rescue is not without risk, we emphasize the merits that this tool offers for protecting and propagating adaptive potential and improving species' resilience to rapid environmental change.

Ecology and Evolution↗
USGS2020

Combining physical and species‐based approaches improves refugia identification

Climate‐change refugia – locations likely to facilitate species persistence under climate change – are increasingly important components of conservation planning. Recent approaches for identifying refugia at broad scales include identifying regions that are projected to experience less severe changes (climatic exposure), that contain a diversity of physical and topographic features (environmental diversity), and that either retain or remain close to suitable climatic conditions (climate tracking, including both “species‐neutral” and species‐based approaches). We compared the degree of agreement between these approaches – with respect to their spatial coverage and other characteristics – across much of North America. This analysis found that approaches based on environmental diversity and species‐neutral climatic gradients both favored topographically complex regions, whereas climatic exposure and species‐based approaches identified regions with a range of topographic characteristics. Species‐based approaches targeting specific habitat groups identified unique regions missed by other approaches, emphasizing the importance of asking the question “refugia for what?” when prioritizing refugia. Our results highlight the necessity of including climatic exposure and species‐based information in addition to topographic diversity and climatic gradients in refugia analyses.

Frontiers in Ecology and the Environment↗
USGS2026

Predicted genetic consequences of alternative population control strategies for North American plains bison in Yellowstone National Park

North American plains bison ( Bison bison bison ) in Yellowstone National Park are descendant from a population low of 23 indigenous individuals from the late 1800s, and 21 individuals introduced from outside herds in the early 1900s to strengthen the possibility of recovery. Within the park, the herd has rebounded and now averages around 5,000 animals. The herd is managed as a closed population within the park and adjacent areas in Montana, USA, which involves annual removals of animals to control numbers. We used genetic simulation to first isolate the effects of population size on retention of genetic diversity, and second to predict the genetic consequences of different population control strategies that vary in the number of bison removed annually, and their relatedness, while considering varying degrees of male dominance and environmental catastrophes. We found through simulation of a stable population that a herd size >2,500 had a high probability (>0.9) of retaining genetic diversity at levels compatible with long-term conservation (>90% of the initial genetic variation over 200 years), but a herd of 3,500 or more had a high likelihood (>0.9) of retaining levels of genetic variation (95%) suggested for maintaining evolutionary potential. When simulating the removals based on plausible management strategies available to the National Park Service, we found that maintaining a herd size of 3,500 or more, limiting removals to less than 40% of the population at a time, keeping a balanced sex ratio, and preferentially removing related individuals would likely retain more than 95% of existing genetic variation. With a herd size of 3,500 animals or more, population catastrophes and male dominance only influenced genetic retention in the most extreme cases, such as a catastrophic population decline of over 95%, a prolonged decline from 90% to 10% over 5 years, or extreme male dominance where 1% of males produced all offspring each year.

Idaho, Montana, Wyoming↗
USGS2018

Variation in DNA methylation is associated with migratory phenotypes of lake sturgeon (Acipenser fulvescens) in the St. Clair River

Lake sturgeon populations show a variety of movement patterns, but this variation is poorly understood. To compare two migratory phenotypes of lake sturgeon in the St. Clair River, multiple data types were analyzed. Individual fish were classified into migratory phenotypes based on acoustic telemetry data from 2012-2015. Lake sturgeon consistently showed movement from the St. Clair River upriver into Lake Huron or downriver into Lake St. Clair. The two migratory phenotypes were then compared for differences in morphometrics, genetics, and epigenetics. Morphological differences based on linear measurements were not detected between phenotypes. Microsatellite data from 11 loci suggested one population with no genetic differentiation between migratory phenotypes. Our epigenetic results indicated that the migratory phenotypes are differentially methylated (P=0.036), thus epigenetics may be associated with migratory differences in lake sturgeon. Only one restriction site was identified to be driving the differential methylation (P=0.012). While little evidence at neutral loci occurred for genetic differentiation of lake sturgeon, DNA methylation may play a role in the observed movement pattern variation. When combined with microsatellite and morphometric analyses, our results suggested that different migratory patterns may reflect phenotypic plasticity, allowing lake sturgeon to acclimate to short-term environmental variability. Without an integrated approach, the role of epigenetics in the migratory phenotype of lake sturgeon may have been overlooked. Further characterization of migratory phenotypes could be important for management to conserve behavioral variation across the distribution of lake sturgeon and for design of stocking guidelines.

Michigan↗
USGS2007

Chinook salmon use of spawning patches: Relative roles of habitat quality, size, and connectivity

Declines in many native fish populations have led to reassessments of management goals and shifted priorities from consumptive uses to species preservation. As management has shifted, relevant environmental characteristics have evolved from traditional metrics that described local habitat quality to characterizations of habitat size and connectivity. Despite the implications this shift has for how habitats may be prioritized for conservation, it has been rare to assess the relative importance of these habitat components. We used an information-theoretic approach to select the best models from sets of logistic regressions that linked habitat quality, size, and connectivity to the occurrence of chinook salmon (Oncorhynchus tshawytscha) nests. Spawning distributions were censused annually from 1995 to 2004, and data were complemented with field measurements that described habitat quality in 43 suitable spawning patches across a stream network that drained 1150 km 2 in central Idaho. Results indicated that the most plausible models were dominated by measures of habitat size and connectivity, whereas habitat quality was of minor importance. Connectivity was the strongest predictor of nest occurrence, but connectivity interacted with habitat size, which became relatively more important when populations were reduced. Comparison of observed nest distributions to null model predictions confirmed that the habitat size association was driven by a biological mechanism when populations were small, but this association may have been an area-related sampling artifact at higher abundances. The implications for habitat management are that the size and connectivity of existing habitat networks should be maintained whenever possible. In situations where habitat restoration is occurring, expansion of existing areas or creation of new habitats in key areas that increase connectivity may be beneficial. Information about habitat size and connectivity also could be used to strategically prioritize areas for improvement of local habitat quality, with areas not meeting minimum thresholds being deemed inappropriate for pursuit of restoration activities. ?? 2007 by the Ecological Society of America.

Ecological Applications↗
USGS2022

Database of biodiversity, habitat, and aquatic-resource quantification tools used in market-based conservation — 2022 update

Market-based conservation makes use of economic incentives to promote actions that avoid, minimize, or compensate for detrimental effects on natural resources and the environment. Examples of market-based conservation mechanisms include aquatic-resource (such as, streams, wetlands, and estuaries) compensatory mitigation, conservation banking, habitat exchanges, and payments for ecosystem services. A critical component in the operation of these market-based conservation mechanisms is the methods (hereafter referred to as “quantification tools”) used to assess existing (sometimes referred to as “baseline”) or potential site conditions. Quantification tools are used to assign values to the benefits provided by preservation, restoration, or enhancement actions, as well as the negative effects of human activities (for example, infrastructure development, energy extraction, and anthropogenic disasters). In 2018, the U.S. Geological Survey (USGS) published a database describing the attributes of 69 quantification tools developed for United States conservation markets. The database focused on tools used for species-based mitigation, payments for ecosystem services, and ecolabel programs (Chiavacci and Pindilli, 2020). Recently, the USGS, in collaboration with the U.S. Environmental Protection Agency, revised the original database by updating the existing tool information, adding newly developed tools, and broadening the scope to include tools developed for compensatory mitigation under the Clean Water Act Section 404 Regulatory Program.

Fact Sheet↗
USGS2006

A simulation model of land-use change in the Lake Tahoe Basin of California and Nevada, as used in a decision-support system

The Tahoe Land-Use Change model is a stochastic, spatially explicit simulation of future land-use change—in particular, development and retirement of individual parcels—in the Lake Tahoe Basin of California and Nevada. The Federal, State, and regional management agencies responsible for the basin are revising and integrating their 20-year plans to meet various goals, including maintaining or improving several environmental (e.g., lake clarity, forest health) and socioeconomic (e.g., affordable housing) characteristics. To assist this effort, the model projects the long-term outcomes of land-use-management decisions, including those relating to existing and potential government regulations, development activities, and conservation practices. The model results are probabilistic maps of parcel-specific changes in land use and the resulting changes in the amount and locations of developed parcels and land-use change. To capture the uncertainties and variation in the exact parcels of land selected for development or retirement by individuals acting in the basin, a single model run includes multiple iterations, from which cumulative statistics are taken to describe the results. The purpose of the model is to generate changes in the amounts and types of land use and land cover that form inputs to a basinwide model of pollutant loading to Lake Tahoe, which, in turn, generates inputs to a lake-clarity model. Together, these three models form a chain of tools that link land-use decisions to changes in a critical environmental quality—the clarity of Lake Tahoe—within a decision-support context. Eventually, these three models will become part of a larger, more complete decision-support system.

California, Nevada↗