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At least 937 records · Page 52Linked to original sources
USGS2005

Aqueous stability of gadolinium in surface waters receiving sewage treatment plant effluent Boulder Creek, Colorado

In many surface waters, sewage treatment plant (STP) effluent is a substantial source of both regulated and unregulated contaminants, including a suite of complex organic compounds derived from household chemicals, pharmaceutical, and industrial and medical byproducts. In addition, STP effluents in some urban areas have also been shown to have a positive gadolinium (Gd) anomaly in the rare earth element (REE) pattern, with the Gd derived from its use in medical facilities. REE concentrations are relatively easy to measure compared to many organic wastewater compounds and may provide a more widely utilized tracer of STP effluents. To evaluate whether sewage treatment plant-associated Gd is a useful tracer of treatment plant effluent, an investigation of the occurrence, fate, and transport of rare earth elements was undertaken. The rare earth element patterns of four of five STP effluents sampled display positive Gd anomalies. The one site that did not have a Gd anomaly serves a small community, population 1200, with no medical facilities. Biosolids from a large metropolitan STP are not enriched in Gd even though the effluent is, suggesting that a substantial fraction of Gd remains in the aqueous phase through routine treatment plant operation. To evaluate whether STP-derived Gd persists in the fluvial environment, a 14-km study reach downstream of an STP was sampled. Gadolinium anomalies were present at all five downstream sites, but the magnitude of the anomaly decreased. Effluent from STPs is a complex mixture of organic and inorganic constituents, and to better understand the chemical interactions and their effect on REEs, the aqueous speciation was modeled using comprehensive chemical analyses of water samples collected downstream of STP input. These calculations suggest that the REEs will likely remain dissolved because phosphate and carbonate complexes dominate over free REE ions. This study supports the application of Gd anomalies as a useful tracer of urban wastewater.

Colorado↗
USGS2023

Bee species richness through time in an urbanizing landscape of the southeastern United State

Compared to non-urban environments, cities host ecological communities with altered taxonomic diversity and functional trait composition. However, we know little about how these urban changes take shape over time. Using historical bee (Apoidea: Anthophila) museum specimens supplemented with online repositories and researcher collections, we investigated whether bee species richness tracked urban and human population growth over the past 118 years. We also determined which species were no longer collected, whether those species shared certain traits, and if collector behavior changed over time. We focused on Wake County, North Carolina, United States where human population size has increased over 16 times over the last century along with the urban area within its largest city, Raleigh, which has increased over four times. We estimated bee species richness with occupancy models, and rarefaction and extrapolation curves to account for imperfect detection and sample coverage. To determine if bee traits correlated with when species were collected, we compiled information on native status, nesting habits, diet breadth, and sociality. We used non-metric multidimensional scaling to determine if individual collectors contributed different bee assemblages over time. In total, there were 328 species collected in Wake County. We found that although bee species richness varied, there was no clear trend in bee species richness over time. However, recent collections (since 2003) were missing 195 species, and there was a shift in trait composition, particularly lost species were below-ground nesters. The top collectors in the dataset differed in how often they collected bee species, but this was not consistent between historic and contemporary time periods; some contemporary collectors grouped closer together than others, potentially due to focusing on urban habitats. Use of historical collections and complimentary analyses can fill knowledge gaps to help understand temporal patterns of species richness in taxonomic groups that may not have planned long-term data.

North Carolina↗
USGS2015

Avian influenza ecology in North Atlantic sea ducks: Not all ducks are created equal

Wild waterfowl are primary reservoirs of avian influenza viruses (AIV). However the role of sea ducks in the ecology of avian influenza, and how that role differs from freshwater ducks, has not been examined. We obtained and analyzed sera from North Atlantic sea ducks and determined the seroprevalence in those populations. We also tested swab samples from North Atlantic sea ducks for the presence of AIV. We found relatively high serological prevalence (61%) in these sea duck populations but low virus prevalence (0.3%). Using these data we estimated that an antibody half-life of 141 weeks (3.2 years) would be required to attain these prevalences. These findings are much different than what is known in freshwater waterfowl and have implications for surveillance efforts, AIV in marine environments, and the roles of sea ducks and other long-lived waterfowl in avian influenza ecology.

PLoS ONE↗
USGS2007

Aqueous exposure to 4-nonylphenol and 17β-estradiol increases stress sensitivity and disrupts ion regulatory ability of juvenile atlantic salmon

Population declines of wild Atlantic salmon have been attributed to an array of anthropogenic disturbances, including dams, commercial and recreational fishing, habitat loss, and pollution. Environmental contaminants in particular, can act as environmental stressors on fish, typically causing disruption of ion homeostasis due to their close association with the aquatic environment. To examine the effects of the xenoestrogen 4-nonylphenol (NP) or 17β-estradiol (E 2 ) on stress sensitivity and ion regulation, we exposed juvenile Atlantic salmon continuously for 21 d to either 10 or 100 μg/L NP (NP-L or NP-H), 2 μg/L E 2 (positive control), or vehicle control during the parr-smolt transformation in April. After treatment, fish were sampled in freshwater (FW), transferred to 30‰ seawater (SW) for 24 h, or subjected to a handling stress. Estradiol and NP-H increased plasma vitellogenin in males and females, and E 2 increased gonadosomatic index only in males. In FW, E 2 reduced sodium potassium–activated adenosine triphosphatase activity as well as plasma levels of growth hormone, insulin-like growth factor I, and triiodothyronine. Both E 2 and NP-H reduced plasma sodium in FW and increased plasma chloride in SW. Plasma Cortisol levels pre- and poststressor were significantly elevated by all treatments relative to controls, but only E 2 increased plasma glucose before and after the stressor. These results indicate that exposure of anadromous salmonids to environmental estrogens heightens sensitivity to external stressors, impairs ion regulation in both FW and SW, and disrupts endocrine pathways critical for smolt development.

Environmental Toxicology and Chemistry↗
USGS1986

Demography, environmental uncertainty, and the evolution of mate desertion in the snail kite

The Snail Kite (Rostrhamus sociabilis), an endangered hawk, has a unique mating system in Florida (Beissinger and Snyder 1987): when food is abundant, males or females desert their mates at nearly equal frequency (ambisexual mate desertion) in the midst of a nesting cycle. I examined the demographic and environmental constraints selecting for a clutch size that permits one parent to desert, yet optimizes the number of offspring produced by each parent. Demographic studies, conducted from 1979—1983, indicated that kites have (1) a very high nest failure rate (° = 68%) due most often to unstable nest sites and predation, (2) a variable nesting season (5—10 mo/yr), (3) an early age of first reproduction for a bird this size (10 mo), (4) a high degree of iteroparity (double and potentially triple clutching within a season), and (5) unstable populations. Both nesting success and population size were directly related to Everglades water levels and resultant snail densities. Kites responded to large annual changes in food abundance, not by adjusting clutch size but by deserting their mates and presumably attempting to renest. Kite demographic traits appear to be adaptations to or results of an uncertain environment. Based on 67 yr of Everglades water levels, environmental predictability, measured by spectral analysis and Colwell's (1974) index, was low and influenced by water management regimes: (1) water levels were lowered, (2) annual variation in levels increased and annual cycles became stronger, (3) the period length of long—term drought—flood cycles shifted from 10 or more yr toward 5 yr, and (4) levels became a less predictive cue for favorable nesting conditions. A potential evolutionary pathway from biparental care to mate desertion in Snail Kites is proposed. It is unlikely that mate desertion evolved solely from a context of conflict between the sexes, because kite nesting success is so low that it is probably maladaptive for a parent to desert and jeopardize the survival of any of its first brood. Instead, mate desertion behavior probably evolved in response to a smaller average clutch size; this would allow females to be highly iteroparous and avoid the costs of overinvestment, and should be strongly favored in a highly uncertain environment. Analysis of clutches in museum collections suggests that an apparent decline in clutch size may have occurred in Florida during the past century. The potential for ambisexual mate desertion to occur in other vertebrates is during the past century. The potential for ambisexual mate desertion to occur in other vertebrates is examined.

Ecology↗
USGS1992

Population recovery of the Whooping Crane with emphasis on reintroduction efforts: Past and future

The U.S. Fish and Wildlife Service (USFWS) began building a captive whooping crane (Grus americana) colony at Patuxent Wildlife Research Center (Patuxent), Maryland, in 1966. From 1976 to 1984, 73 eggs from this colony and 216 eggs from Wood Buffalo National Park (Wood Buffalo), Canada, nests were placed in sandhill crane (G. canadensis) nests at Grays Lake National Wildlife Refuge (Grays Lake), Idaho, the site of the first whooping crane reintroduction attempt. Although 84 chicks fledged from the 289 eggs, the egg transfer program has been discontinued because of inordinately high mortality (only ca. 13 birds remain in the wild in 1991) and lack of breeding in survivors. In recent decades new methods have emerged for introducing captive-produced offspring to the wild. Surrogate studies with sandhill cranes, particularly the endangered Mississippi sandhill cranes (G. c. pulla), have shown that young cranes, raised either by captive, conspecific foster parents, or by costumed humans and in close association with live cranes and lifelike crane taxidermic dummies, have high post-release survival rates. These techniques will likely be used in future whooping crane reintroduction programs. Current recovery objectives for the whooping crane include expansion of the 2 captive colonies, establishment of a third captive colony in Canada, and reintroduction of 2 additional wild populations. The Kissimmee Prairie in central Florida has been selected for the next release experiment. Evaluation of this site began in 1984, and risk assessment is expected to begin in 1992 with the transfer and monitoring of a group of captive-reared, juvenile whooping cranes. These 'tests of the environment' will, if results are favorable, be followed by a full-scale reintroduction effort of at least 20 birds/year beginning in 1994 or 1995.

Book chapter↗
USGS2008

Sunlight, season, snowmelt, storm, and source affect E. coli populations in an artificially ponded stream

Reducing fecal indicator bacteria, such as Escherichia coli (E. coli), in streams is important for many downstream areas. E. coli concentrations within streams may be reduced by intervening ponds or wetlands through a number of physical and biological means. A section of Dunes Creek, a small coastal stream of southern Lake Michigan, was impounded and studied for 30??months from pre-through post-construction of the experimental pond. E. coli reduction became more predictable and effective with pond age. E. coli followed the hydrograph and increased several-fold during both rainfall and snowmelt events. Seasonally, the pond was more effective at reducing E. coli during summer than winter. Late summer, non-solar reduction or inactivation of E. coli in the pond was estimated at 72% and solar inactivation at 26%. E. coli DNA fingerprinting demonstrated that the winter population was genetically more homogeneous than the summer population. Detection of FRNA coliphages suggests that there was fecal contamination during heavy rain events. An understanding of how environmental factors interact with E. coli populations is important for assessing anticipated contaminant loading and the reduction of indicator bacteria in downstream reaches. ?? 2007.

Science of the Total Environment↗
USGS2016

A methodology for quantifying trace elements in the exoskeletons of Florida stone crab ( Menippe mercenaria ) larvae using inductively coupled plasma optical emission spectrometry (ICP–OES)

The larvae of the Florida stone crab, Menippe mercenaria , migrate through a variety of habitats as they develop and, therefore, experience a broad range of environmental conditions through ontogeny. Environmental variability experienced by the larvae may result in distinct elemental signatures within the exoskeletons, which could provide a tool for tracking the environmental history of larval stone crab populations. A method was developed to examine trace-element ratios, specifically magnesium-to-calcium (Mg/Ca) and strontium-to-calcium (Sr/Ca) ratios, in the exoskeletons of M. mercenaria larvae. Two developmental stages of stone crab larvae were analyzed—stage III and stage V. Specimens were reared in a laboratory environment under stable conditions to quantify the average ratios of Mg/Ca and Sr/Ca of larval stone crab exoskeletons and to determine if the ratios differed through ontogeny. The elemental compositions (Ca, Mg, and Sr) in samples of stage III larvae (n = 50 per sample) from 11 different broods (mean Sr/Ca = 5.916 ± 0.161 millimole per mole [mmol mol −1 ]; mean Mg/Ca = 218.275 ± 59.957 mmol mol −1 ) and stage V larvae (n = 10 per sample) from 12 different broods (mean Sr/Ca = 6.110 ± 0.300 mmol mol −1 ; mean Mg/Ca = 267.081 ± 67.211 mmol mol –1 ) were measured using inductively coupled plasma optical emission spectrometry (ICP–OES). The ratio of Sr/Ca significantly increased from stage III to stage V larvae, suggesting an ontogenic shift in Sr/Ca ratios between larval stages. The ratio of Mg/Ca did not change significantly between larval stages, but variability among broods was high. The method used to examine the trace-element ratios provided robust, highly reproducible estimates of Sr/Ca and Mg/Ca ratios in the larvae of M. mercenaria , demonstrating that ICP–OES can be used to determine the trace-element composition of chitinous organisms like the Florida stone crab.

Open-File Report↗
USGS1979

Better utilization of ground water in the Piedmont and mountain region of the southeast

The development of water supplies for domestic consumption, and for those commercial and industrial uses requiring relatively pure water, has followed a pattern in the Piedmont and mountain areas of the southeast similar to that in most other humid areas. The first settlers utilized seepage springs on hillsides. Such springs occur along steep slopes where the water table intersects the land surface. As the population of the region grew, it became increasingly necessary to resort to shallow dug wells for domestic water supplies. Such wells also served as sources of water for the villages that developed, in time, around crossroad taverns. Seepage springs and dug wells are a satisfactory source of water in a virgin environment but are quickly polluted by careless waste-disposal practices. Thus disposal of domestic wastes in shallow pits resulted in epidemics of water-borne diseases as the villages grew into towns. This resulted in the third phase of water-supply development, which consisted of installing water lines and supplying water to homes from town-owned wells. In time, some of these wells became polluted and others failed to supply adequate water for the increasing needs of the larger urban areas. In the fourth phase these areas met their needs by drawing water from nearby streams. By the early years of this century it was possible to make this water palatable and relatively safe as a result of improvement in filtration methods. Streams, of course, have highly variable rates of flow and, as towns grew into small cities, the minimum flow of many streams was not adequate to meet the water-supply needs. This problem was solved in the fifth phase by building dams on the streams. We are still in this phase as we build larger and larger reservoirs to meet our growing water needs. Thus, through five phases of growth in the Piedmont and mountains we have advanced from the point where ground water was the sole source of supply to the point where it is the forgotten resource . For reasons to be explained below, a sixth phase can be foreseen in which ground water and surface water are recognized as parts of the hydrologic system with advantages in their conjunctive development and use.

Piedmont↗
USGS2017

Hazus® estimated annualized earthquake losses for the United States

Large earthquakes can cause social and economic disruption that can be unprecedented to any given community, and the full recovery from these impacts may or may not always be achievable. In the United States (U.S.), the 1994 M6.7 Northridge earthquake in California remains the third costliest disaster in U.S. history; and it was one of the most expensive disasters for the federal government. Internationally, earthquakes in the last decade alone have claimed tens of thousands of lives and caused hundreds of billions of dollars of economic impact throughout the globe (~90 billion U.S. dollars (USD) from 2008 M7.9 Wenchuan China, ~20 billion USD from 2010 M8.8 Maule earthquake in Chile, ~220 billion USD from 2011 M9.0 Tohoku Japan earthquake, ~25 billion USD from 2011 M6.3 Christchurch New Zealand, and ~22 billion USD from 2016 M7.0 Kumamoto Japan). Recent earthquakes show a pattern of steadily increasing damages and losses that are primarily due to three key factors: (1) significant growth in earthquake-prone urban areas, (2) vulnerability of the older building stock, including poorly engineered non-ductile concrete buildings, and (3) an increased interdependency in terms of supply and demand for the businesses that operate among different parts of the world. In the United States, earthquake risk continues to grow with increased exposure of population and development even though the earthquake hazard has remained relatively stable except for the regions of induced seismic activity. Understanding the seismic hazard requires studying earthquake characteristics and locales in which they occur, while understanding the risk requires an assessment of the potential damage from earthquake shaking to the built environment and to the welfare of people—especially in high-risk areas. Estimating the varying degree of earthquake risk throughout the United States is critical for informed decision-making on mitigation policies, priorities, strategies, and funding levels in the public and private sectors. For example, potential losses to new buildings may be reduced by proper land-use planning, applying most current seismic design codes and using new technologies and specialized construction techniques. However, decisions to spend money on any of those solutions require benefit and cost comparison against the perceived risk. Previous versions of the FEMA 366 studies are the only nationally accepted criteria and methodology for comparing seismic risk across regions.

Report↗
USGS2009

Postmortem diagnostic investigation of disease in free-ranging marine turtle populations: A review of common pathologic findings and protocols

Over the past few decades, there have been increasing numbers of reports of diseases in marine turtles. Furthermore, in recent years, there have been documented instances of apparently new diseases emerging in these species of which the etiology and/or pathogenesis remain unknown. These instances i) raise concern for the survival of marine turtles, and ii) question the health and stability of the benthic marine environments in which turtles live. Knowledge of common disease processes and pathologic changes in lesions, along with a standardized approach to postmortem and sample collection are required to document and understand the host-agent-environment interactions in marine turtle health. This review combines, for the first time, a standardized approach to the postmortem of marine turtles for veterinary clinicians, with a concurrent descriptive review of the gross and microscopic pathologic changes in lesions commonly seen.

Journal of Veterinary Diagnostic Investigation↗
USGS2016

Genetic and phenotypic variation along an ecological gradient in lake trout Salvelinus namaycush

Background Adaptive radiation involving a colonizing phenotype that rapidly evolves into at least one other ecological variant, or ecotype, has been observed in a variety of freshwater fishes in post-glacial environments. However, few studies consider how phenotypic traits vary with regard to neutral genetic partitioning along ecological gradients. Here, we present the first detailed investigation of lake trout Salvelinus namaycush that considers variation as a cline rather than discriminatory among ecotypes. Genetic and phenotypic traits organized along common ecological gradients of water depth and geographic distance provide important insights into diversification processes in a lake with high levels of human disturbance from over-fishing. Results Four putative lake trout ecotypes could not be distinguished using population genetic methods, despite morphological differences. Neutral genetic partitioning in lake trout was stronger along a gradient of water depth, than by locality or ecotype. Contemporary genetic migration patterns were consistent with isolation-by-depth. Historical gene flow patterns indicated colonization from shallow to deep water. Comparison of phenotypic ( Pst ) and neutral genetic variation ( Fst ) revealed that morphological traits related to swimming performance (e.g., buoyancy, pelvic fin length) departed more strongly from neutral expectations along a depth gradient than craniofacial feeding traits. Elevated phenotypic variance with increasing water depth in pelvic fin length indicated possible ongoing character release and diversification. Finally, differences in early growth rate and asymptotic fish length across depth strata may be associated with limiting factors attributable to cold deep-water environments. Conclusion We provide evidence of reductions in gene flow and divergent natural selection associated with water depth in Lake Superior. Such information is relevant for documenting intraspecific biodiversity in the largest freshwater lake in the world for a species that recently lost considerable genetic diversity and is now in recovery. Unknown is whether observed patterns are a result of an early stage of incipient speciation, gene flow-selection equilibrium, or reverse speciation causing formerly divergent ecotypes to collapse into a single gene pool.

Lake Superior, Isle Royale↗
USGS2011

Abundance, stock origin, and length of marked and unmarked juvenile Chinook salmon in the surface waters of greater Puget Sound

This study focuses on the use by juvenile Chinook salmon Oncorhynchus tshawytscha of the rarely studied neritic environment (surface waters overlaying the sublittoral zone) in greater Puget Sound. Juvenile Chinook salmon inhabit the sound from their late estuarine residence and early marine transition to their first year at sea. We measured the density, origin, and size of marked (known hatchery) and unmarked (majority naturally spawned) juveniles by means of monthly surface trawls at six river mouth estuaries in Puget Sound and the areas in between. Juvenile Chinook salmon were present in all months sampled (April–November). Unmarked fish in the northern portion of the study area showed broader seasonal distributions of density than did either marked fish in all areas or unmarked fish in the central and southern portions of the sound. Despite these temporal differences, the densities of marked fish appeared to drive most of the total density estimates across space and time. Genetic analysis and coded wire tag data provided us with documented individuals from at least 16 source populations and indicated that movement patterns and apparent residence time were, in part, a function of natal location and time passed since the release of these fish from hatcheries. Unmarked fish tended to be smaller than marked fish and had broader length frequency distributions. The lengths of unmarked fish were negatively related to the density of both marked and unmarked Chinook salmon, but those of marked fish were not. These results indicate more extensive use of estuarine environments by wild than by hatchery juvenile Chinook salmon as well as differential use (e.g., rearing and migration) of various geographic regions of greater Puget Sound by juvenile Chinook salmon in general. In addition, the results for hatchery‐generated timing, density, and length differences have implications for the biological interactions between hatchery and wild fish throughout Puget Sound.

Washington↗
USGS2004

Adaptive bleaching: A general phenomenon

Laboratory and field data bearing on the adaptive bleaching hypothesis (ABH) are largely consistent with it; no data of which we are aware refute it. We generalize the ABH in light of these data and observations. The population of zooxanthellae within an organism is dynamic, the diversity of zooxanthellae is both surprising and difficult to ascertain, and field experiments demonstrate both turn-over in zooxanthella types and habitat-holobiont correlations. Dynamic change in symbiont communities, and the idea of an equilibrium or optimal community that matches the environment at a particular place and time, are concepts that underlie or emerge from much of the recent literature. The mechanism we proposed to explain responses to acute bleaching appears to operate continuously, thereby enabling the host-symbiont holobiont to track even subtle environmental changes and respond promptly to them. These findings enhance the potential importance of the ABH in the outcomes of acute bleaching, which can (1) accelerate this process of holobiont change, and (2) change the set of possible trajectories for how symbiont communities might recover.

Conference Paper↗
USGS2003

Terrestrial activity and conservation of adult California red-legged frogs Rana aurora draytonii in coastal forests and grasslands

The federally threatened California red-legged frog Rana aurora draytonii occupies both aquatic and terrestrial habitats in its adult life stage. The terrestrial activities of this species are not well known and require documentation to assist in the development of appropriate levels of protection under the US Endangered Species Act. We studied the terrestrial activities of radio-tagged red-legged frogs (n = 8-26) inhabiting a coastal watershed in Santa Cruz County, California, during 1997-1998. In particular, we investigated (1) the use of terrestrial habitats by non-migrating adults in relation to season, breeding chronology, and precipitation, and (2) adult migration behavior, including seasonal timing, duration, distances traveled, and the use of corridors. Non-migrating red-legged frogs occupied terrestrial habitats briefly (median = 4-6 days) following infrequent summer rains, but resided nearly continuously on land (median = 20-30 days) from the onset of the winter wet-season until breeding activities commenced 1-2 months later. All of the non-migrating frogs remained within 130 m of their aquatic site of residence (median <25 m). Intervals spent on land were again brief during mid/late winter (median = 1-4 days), despite frequent and copious rainfall. Adult migration to and from breeding sites occurred from late October through mid-May (wet season). We monitored 25 migration events between aquatic sites that were 200-2800 m apart. Short distance movements ( <300 m) were completed in 1-3 days, longer movements required up to 2 months. Most migrating frogs moved overland in approximately straight lines to target sites without apparent regard to vegetation type or topography. Riparian corridors were neither essential nor preferred as migration routes. Frogs traveling overland occurred in upland habitats as far as 500 m from water. Approximately 11-22% of the adult population was estimated to migrate to and from breeding sites annually, whereas the bulk of the adult population was resident at these sites. Adequate protection of red-legged frog populations inhabiting relatively undeveloped landscapes is liable to be achieved by retaining an array of suitable habitat elements within at least 100 m of occupied aquatic sites, and by imposing seasonal limitations on detrimental human activities occurring within this zone. Specific protections for migrating frogs are probably unwarranted in forest and rangeland environments because dispersal habitat is ubiquitous and migrating frogs are widely distributed across the landscape in space and time. Published by Elsevier Science Ltd.

Biological Conservation↗
USGS2012

Parasite invasion following host reintroduction: a case of Yellowstone’s wolves

Wildlife reintroductions select or treat individuals for good health with the expectation that these individuals will fare better than infected animals. However, these individuals, new to their environment, may also be particularly susceptible to circulating infections and this may result in high morbidity and mortality, potentially jeopardizing the goals of recovery. Here, using the reintroduction of the grey wolf (Canis lupus) into Yellowstone National Park as a case study, we address the question of how parasites invade a reintroduced population and consider the impact of these invasions on population performance. We find that several viral parasites rapidly invaded the population inside the park, likely via spillover from resident canid species, and we contrast these with the slower invasion of sarcoptic mange, caused by the mite Sarcoptes scabiei. The spatio-temporal patterns of mange invasion were largely consistent with patterns of host connectivity and density, and we demonstrate that the area of highest resource quality, supporting the greatest density of wolves, is also the region that appears most susceptible to repeated disease invasion and parasite-induced declines. The success of wolf reintroduction appears not to have been jeopardized by infectious disease, but now shows signs of regulation or limitation modulated by parasites.

Wyoming↗
USGS2024

Diminishing productivity and hyperstable harvest in northern Wisconsin walleye fisheries

Managing fisheries in a changing socio-ecological environment may require holistic approaches for identifying and adapting to novel ecosystem dynamics. Using 32 years of Ceded Territory of Wisconsin (CTWI) walleye (Sander vitreus) data, we estimated production (P), biomass (B), biomass turnover (P/B), yield (Y), and yield over production (Y/P) and tested for hyperstability in walleye yield. Most CTWI walleye populations showed low P, and B, and Y/P < 1. Yet, production overharvest (Y/P > 1) was prevalent among Wisconsin walleye recruitment-based management approaches (natural recruitment [NR], sustained only by stocking, combination). Production, B, and P/B have declined in NR populations, while Y and Y/P have remained constant. Walleye Y was hyperstable along a production gradient among all management approaches and fishery types (i.e., angling only, angling/tribal harvest combined). Diminishing productivity and hyperstable yield may be jointly contributing to observed walleye declines. We classified lakes into management groups of low, moderate, or high vulnerability to harvest based on Y/P and P/B dynamics and recommend that exploitation may need to decline to maintain or increase the adaptive capacity of CTWI walleye.

Wisconsin↗
USGS2012

Weather effects on avian breeding performance and implications of climate change

The influence of recent climate change on the world’s biota has manifested broadly, resulting in latitudinal range shifts, advancing dates of arrival of migrants and onset of breeding, and altered community relationships. Climate change elevates conservation concerns worldwide because it will likely exacerbate a broad range of identified threats to animal populations. In the past few decades, grassland birds have declined faster than other North American avifauna, largely due to habitat threats such as the intensification of agriculture. We examine the effects of local climatic variations on the breeding performance of a bird endemic to the shortgrass prairie, the Lark Bunting ( Calamospiza melanocorys ) and discuss the implications of our findings relative to future climate predictions. Clutch size, nest survival, and productivity all positively covaried with seasonal precipitation, yet relatively intense daily precipitation events temporarily depressed daily survival of nests. Nest survival was positively related to average temperatures during the breeding season. Declining summer precipitation may reduce the likelihood that Lark Buntings can maintain stable breeding populations in eastern Colorado although average temperature increases of up to 38C (within the range of this study) may ameliorate declines in survival expected with drier conditions. Historic climate variability in the Great Plains selects for a degree of vagility and opportunism rather than strong site fidelity and specific adaptation to local environments. These traits may lead to northerly shifts in distribution if climatic and habitat conditions become less favorable in the drying southern regions of the Great Plains. Distributional shifts in Lark Buntings could be constrained by future changes in land use, agricultural practices, or vegetative communities that result in further loss of shortgrass prairie habitats.

Colorado↗