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At least 955 records · Page 53Linked to original sources
USGS2007

Screening for the Pesticides Atrazine, Chlorpyrifos, Diazinon, Metolachlor, and Simazine in Selected Michigan Streams, March-November 2005

From March through November 2005, the U.S. Geological Survey, in cooperation with the Michigan Department of Environmental Quality (MDEQ), did a statewide screening to aid in understanding the occurrence and distribution of selected pesticides in Michigan streams. Stream-water samples were collected from 23 sites throughout Michigan. In all, 320 water samples were analyzed by use of rapid immunoassay methods for the herbicides atrazine, metolachlor, and simazine and the insecticides chlorpyrifos and diazinon. On one occasion (June, 2005), atrazine concentrations exceeded the Michigan water-quality value (7.3 micrograms per liter) at the Black River in St. Clair County. Neither chlorpyrifos nor diazinon was detected during April through September. MDEQ detected chlorpyrifos in streams throughout the state in November. Herbicide concentrations were highest in samples influenced by intensive agriculture; however, median herbicide concentrations were similar among agricultural and urban sites. Concentrations of herbicides were very low to undetected in undeveloped areas. Seasonal patterns were also evident during the sampling period. Increased concentrations generally occurred in late spring to early summer. At 11 sites, daily sampling was done every day for 5 days following a rainfall after herbicide application in the area. Substantial changes in concentrations of herbicides - greater than tenfold from the previous day - were observed during the daily sampling. No consistent relation was found between concentration and streamflow. Results of this study may be used to aid in the development of a more comprehensive pesticide monitoring study for the State of Michigan.

Michigan↗
USGS2012

Gene expression, glutathione status and indicators of hepatic oxidative stress in laughing gull (Larus atricilla) hatchlings exposed to methylmercury

Despite extensive studies of methylmercury (MeHg) toxicity in birds, molecular effects on birds are poorly characterized. To improve our understanding of toxicity pathways and identify novel indicators of avian exposure to Hg, the authors investigated genomic changes, glutathione status, and oxidative status indicators in liver from laughing gull (Larus atricilla) hatchlings that were exposed in ovo to MeHg (0.05–1.6 µg/g). Genes involved in the transsulfuration pathway, iron transport and storage, thyroid-hormone related processes, and cellular respiration were identified by suppression subtractive hybridization as differentially expressed. Quantitative polymerase chain reaction (qPCR) identified statistically significant effects of Hg on cytochrome C oxidase subunits I and II, transferrin, and methionine adenosyltransferase RNA expression. Glutathione-S-transferase activity and protein-bound sulfhydryl levels decreased, whereas glucose-6-phosphate dehydrogenase activity increased dose-dependently. Total sulfhydryl concentrations were significantly lower at 0.4 µg/g Hg than in controls. T ogether, these endpoints provided some evidence of compensatory effects, but little indication of oxidative damage at the tested doses, and suggest that sequestration of Hg through various pathways may be important for minimizing toxicity in laughing gulls. This is the first study to describe the genomic response of an avian species to Hg. Laughing gulls are among the less sensitive avian species with regard to Hg toxicity, and their ability to prevent hepatic oxidative stress may be important for surviving levels of MeHg exposures at which other species succumb.

Environmental Toxicology and Chemistry↗
USGS2016

Review and synthesis: Changing permafrost in a warming world and feedbacks to the Earth System

The permafrost component of the cryosphere is changing dramatically, but the permafrost region is not well monitored and the consequences of change are not well understood. Changing permafrost interacts with ecosystems and climate on various spatial and temporal scales. The feedbacks resulting from these interactions range from local impacts on topography, hydrology, and biology to complex influences on global scale biogeochemical cycling. This review contributes to this focus issue by synthesizing its 28 multidisciplinary studies which provide field evidence, remote sensing observations, and modeling results on various scales. We synthesize study results from a diverse range of permafrost landscapes and ecosystems by reporting key observations and modeling outcomes for permafrost thaw dynamics, identifying feedbacks between permafrost and ecosystem processes, and highlighting biogeochemical feedbacks from permafrost thaw. We complete our synthesis by discussing the progress made, stressing remaining challenges and knowledge gaps, and providing an outlook on future needs and research opportunities in the study of permafrost–ecosystem–climate interactions.

Environmental Research Letters↗
USGS2013

Conditions favouring Bromus tectorum dominance of endangered sagebrush steppe ecosystems

1. Ecosystem invasibility is determined by combinations of environmental variables, invader attributes, disturbance regimes, competitive abilities of resident species and evolutionary history between residents and disturbance regimes. Understanding the relative importance of each factor is critical to limiting future invasions and restoring ecosystems. 2. We investigated factors potentially controlling Bromus tectorum invasions into Artemisia tridentata ssp. wyomingensis communities across 75 sites in the Great Basin. We measured soil texture, cattle grazing intensity, gaps among perennial plants and plant cover including B. tectorum, biological soil crusts (BSCs) and bare soil. Using a priori knowledge, we developed a multivariate hypothesis of the susceptibility of Artemisia ecosystems to B. tectorum invasion and used the model to assess the relative importance of the factors driving the magnitude of such invasions. 3. Model results imply that bunchgrass community structure, abundance and composition, along with BSC cover, play important roles in controlling B. tectorum dominance. Evidence suggests abundant bunchgrasses limit invasions by limiting the size and connectivity of gaps between vegetation, and BSCs appear to limit invasions within gaps. Results also suggest that cattle grazing reduces invasion resistance by decreasing bunchgrass abundance, shifting bunchgrass composition, and thereby increasing connectivity of gaps between perennial plants while trampling further reduces resistance by reducing BSC. 4. Synthesis and applications. Grazing exacerbates Bromus tectorum dominance in one of North America's most endangered ecosystems by adversely impacting key mechanisms mediating resistance to invasion. If the goal is to conserve and restore resistance of these systems, managers should consider maintaining or restoring: (i) high bunchgrass cover and structure characterized by spatially dispersed bunchgrasses and small gaps between them; (ii) a diverse assemblage of bunchgrass species to maximize competitive interactions with B. tectorum in time and space; and (iii) biological soil crusts to limit B. tectorum establishment. Passive restoration by reducing cumulative cattle grazing may be one of the most effective means of achieving these three goals.

Journal of Applied Ecology↗
USGS2003

Fish biliary PAH metabolites estimated by fixed-wavelength fluorescence as an indicator of environmental exposure and effects

Biliary polynuclear aromatic hydrocarbon (PAH) metabolites have been studied since the mid 1980s as an indicator of exposure of fish to PAHs. However, the measurements of PAH metabolites are often costly and time-consuming. A simple and rapid method, fixed-wavelength fluorescence (FF), was used to measure the concentrations of benzo(a)pyrene (B[a]P)-type and naphthalene (NAPH)-type PAH metabolites in the bile of brown bullheads ( Ameiurus nebulosus ) collected from Old Woman Creek, Ottawa River, Cuyahoga River-harbor and Cuyahoga River-upstream. The biliary PAH metabolites in fish from the less contaminated Old Woman Creek were significantly lower than those from the industrially contaminated Ottawa and Cuyahoga rivers. The levels of biliary PAH metabolites were found to be related to the PAH sediment contamination for the four sites except Cuyahoga River-upstream, and to the prevalence of fish barbel abnormalities and external raised lesions observed in all rivers except Ottawa. Statistical analysis revealed a significant association between the occurrence of barbel abnormalities and concentrations of biliary NAPH-type metabolites and between the occurrence of raised lesions and concentrations of B[a]P-type metabolites. This study provides added evidence that FF is an effective bile analysis method for determining the exposure of fish to PAHs. This study also indicates that the measurement of PAH metabolites could help establish causal relationship between the chemical exposure and effects such as barbel abnormalities and raised lesions.

Journal of Great Lakes Research↗
USGS2019

The planktonic foraminiferal response to the Paleocene-Eocene thermal maximum on the Atlantic coastal plain

Planktonic foraminiferal assemblages in two cores from Maryland and New Jersey show evidence for significant changes in surface ocean habitats on the continental shelf during the Paleocene-Eocene Thermal Maximum (PETM). At both sites, significant assemblage shifts occur immediately before the onset of the event. These changes include the appearance of abundant triserial/biserial species as well as rare excursion taxa, which are limited to the interval of the carbon isotope excursion at deep-sea sites. The assemblage shifts signal the development of new habitats immediately prior to the onset of the PETM, likely involving warming, surface ocean acidification, increased stratification and oligotrophy. A sharp increase in diversity at the onset of the event is interpreted as a further increase in stratification and warming, as well as increased water depth and more eutrophic conditions. Finally, we observe variant morphologies of several planktonic foraminifera, which may also signal the response of the assemblage to environmental perturbation.

Atlantic coastal plain↗
USGS2006

Sedimentation and Occurrence and Trends of Selected Chemical Constituents in Bottom Sediment, Empire Lake, Cherokee County, Kansas, 1905-2005

For about 100 years (1850-1950), the Tri-State Mining District in parts of southeast Kansas, southwest Missouri, and northeast Oklahoma was one of the primary sources of lead and zinc ore in the world. The mining activity in the Tri-State District has resulted in substantial historical and ongoing input of cadmium, lead, and zinc to the environment including Empire Lake in Cherokee County, southeast Kansas. The environmental contamination caused by the decades of mining activity resulted in southeast Cherokee County being listed on the U.S. Environmental Protection Agency's National Priority List as a superfund hazardous waste site in 1983. To provide some of the information needed to support efforts to restore the ecological health of Empire Lake, a 2-year study was begun by the U.S. Geological Survey in cooperation with the U.S. Fish and Wildlife Service and the Kansas Department of Health and Environment. A combination of sediment-thickness mapping and bottom-sediment coring was used to investigate sediment deposition and the occurrence of cadmium, lead, zinc, and other selected constituents in the bottom sediment of Empire Lake. The total estimated volume and mass of bottom sediment in Empire Lake were 44 million cubic feet and 2,400 million pounds, respectively. Most of the bottom sediment was located in the main body and the Shoal Creek arm of the reservoir. Minimal sedimentation was evident in the Spring River arm of the reservoir. The total mass of cadmium, lead, and zinc in the bottom sediment of Empire Lake was estimated to be 78,000 pounds, 650,000 pounds, and 12 million pounds, respectively. In the bottom sediment of Empire Lake, cadmium concentrations ranged from 7.3 to 76 mg/kg (milligrams per kilogram) with an overall median concentration of 29 mg/kg. Compared to an estimated background concentration of 0.4 mg/kg, the historical mining activity increased the median cadmium concentration by about 7,200 percent. Lead concentrations ranged from 100 to 950 mg/kg with an overall median concentration of 270 mg/kg. Compared to an estimated background concentration of 33 mg/kg, the median lead concentration was increased by about 720 percent as a result of mining activities. The range in zinc concentrations was 1,300 to 13,000 mg/kg with an overall median concentration of 4,900 mg/kg. Compared to an estimated background concentration of 92 mg/kg, the median zinc concentration was increased by about 5,200 percent. Within Empire Lake, the largest sediment concentrations of cadmium, lead, and zinc were measured in the main body of the reservoir. Within the Spring River arm of the reservoir, increased concentrations in the downstream direction likely were the result of tributary inflow from Short Creek, which drains an area that has been substantially affected by historical lead and zinc mining. Compared to nonenforceable sediment-quality guidelines, all Empire Lake sediment samples (representing 21 coring sites) had cadmium concentrations that exceeded the probable-effects guideline (4.98 mg/kg), which represents the concentration above which toxic biological effects usually or frequently occur. With one exception, cadmium concentrations exceeded the probable-effects guideline by about 180 to about 1,400 percent. With one exception, all sediment samples had lead concentrations that exceeded the probable-effects guideline (128 mg/kg) by about 10 to about 640 percent. All sediment samples had zinc concentrations that exceeded the probable-effects guideline (459 mg/kg) by about 180 to about 2,700 percent. Overall, cadmium, lead, and zinc concentrations in the bottom sediment of Empire Lake have decreased over time following the end of lead and zinc mining in the area. However, the concentrations in the most recently deposited bottom sediment (determined for 4 of 21 coring sites) still exceeded the probable-effects guideline by about 440 to 640 percent for cadmium, about 40 to 80 percent for lead, and about 580

Scientific Investigations Report↗
USGS2009

Geochemistry of inorganic nitrogen in waters released from coal-bed natural gas production wells in the Powder River Basin, Wyoming

Water originating from coal-bed natural gas (CBNG) production wells typically contains ammonium and is often disposed via discharge to ephemeral channels. A study conducted in the Powder River Basin, Wyoming, documented downstream changes in CBNG water composition, emphasizing nitrogen-cycling processes and the fate of ammonium. Dissolved ammonium concentrations from 19 CBNG discharge points ranged from 95 to 527 μM. Within specific channels, ammonium concentrations decreased with transport distance, with subsequent increases in nitrite and nitrate concentrations. Removal efficiency, or uptake, of total dissolved inorganic nitrogen (DIN) varied between channel types. DIN uptake was greater in the gentle-sloped, vegetated channel as compared to the incised, steep, and sparsely vegetated channel and was highly correlated with diel patterns of incident light and dissolved oxygen concentration. In a larger main channel with multiple discharge inputs ( n = 13), DIN concentrations were >300 μM, with pH > 8.5, after 5 km of transport. Ammonium represented 25−30% of the large-channel DIN, and ammonium concentrations remained relatively constant with time, with only a weak diel pattern evident. In July 2003, the average daily large-channel DIN load was 23 kg N day −1 entering the Powder River, an amount which substantially increased the total Powder River DIN load after the channel confluence. These results suggest that CBNG discharge may be an important source of DIN to western watersheds, at least at certain times of the year, and that net oxidation and/or removal is dependent upon the extent of contact with sediment and biomass, type of drainage channel, and time of day.

Wyoming↗
USGS1991

Report of 1st discussion group: The last interglacial in high latitudes of the Northern Hemisphere: Terrestrial and marine evidence

The paleoclimatic informations preserved at some selected sites from high northern latitudes correlative with the last interglacial maximum of Isotopic Substage 5e have been compiled on a hemisphere scale. The mapped compilation reveals much warmer climate conditions on average than present in both terrestrial and marine environments, and indicates a northward shift of subpolar and boreal bioclimatic zones. The data also suggest that temperature and precipitation gradients were significantly different than those of the Holocene, with particularly efficient latitudinal and eastward transport of warm air masses. The paleoenvironmental and paleoclimate trends through the last interglacial sensu lato (Isotopic Stage 5) are more difficult to assess because the chronostratigraphical framework is poorly constrained. Nevertheless, the data suggest important regionalism in the climatostratigraphical trends. In particular, the large amplitude climatic cyclicity that characterizes the last interglacial of Europe is barely observed elsewhere. Moreover, by the end of the last interglacial (Isotopic Substage 5a), conditions slightly cooler than present are recorded in western Europe, while relatively warm conditions, similar to today, apparently prevailed in circumpolar regions adjacent to the North Atlantic despite the onset of ice growth. The last interglacial provides paleosynoptic situations, unlike those of the present, that may contribute to understanding interactions within the environmental system on a hemispheric scale. There is, however, an imperative need for uniformization of data sets and for more accurate chronological control on regional scales.

Quaternary International↗
USGS2021

Global biotic events evident in the Paleogene marine strata of the eastern San Francisco Bay area, California

Paleogene marine strata in the eastern San Francisco Bay area are exposed in discontinuous outcrops in the various tectonic blocks. Although there are many missing intervals, the strata were previously thought to span most of the Paleocene and Eocene. Revision of biochronology and calibration to the international time scale as well as to the global oxygen isotope curve and sea-level curves indicate that the strata are latest Paleocene through middle Eocene in age and contain faunal changes that are linked to the overall global climate trends and hyperthermals of that time. The Paleocene-Eocene thermal maximum, third Eocene thermal maximum, early Eocene climatic optimum, and middle Eocene climatic optimum are all identified in the eastern San Francisco Bay marine strata. The dominance of smoothly finished, dissolution-resistant agglutinated benthic foraminiferal species corresponds with a rapid shoaling and rapid deepening (overcorrection) of the calcium compensation depth associated with the Paleocene-Eocene thermal maximum. The benthic foraminiferal extinction event was a dramatic turnover of benthic foraminiferal species that occurred shortly after the onset of the Paleocene-Eocene thermal maximum. Opportunistic species such as Bulimina , which indicate environmental stress and lower oxygen conditions, are commonly associated with the Paleocene-Eocene thermal maximum. Environmental changes similar to those observed during the Paleocene-Eocene thermal maximum also characterize the third Eocene thermal maximum, based on the agglutinated and opportunistic species. The early Eocene climatic optimum is noted by the presence of foraminiferal assemblages that indicate a stable, warmer water mass, abundant food, and an influx of terrigenous material. The onset and end of the middle Eocene climatic optimum are recognized by the dominance of siliceous microfossils. This research updates the age and environmental interpretations of the Paleogene formations occurring in the vicinity of Mount Diablo, eastern San Francisco Bay area. The revised interpretations, which are based on foraminifers and calcareous nannoplankton, make it possible to identify various global climatic and biotic events.

California↗
USGS2008

Estuarine sediment transport by gravity-driven movement of the nepheloid layer, Long Island Sound

Interpretation of sidescan-sonar imagery provides evidence that down-slope gravity-driven movement of the nepheloid layer constitutes an important mode of transporting sediment into the basins of north-central Long Island Sound, a major US East Coast estuary. In the Western Basin, this transport mechanism has formed dendritic drainage systems characterized by branching patterns of low backscatter on the seafloor that exceed 7.4 km in length and progressively widen down-slope, reaching widths of over 0.6 km at their southern distal ends. Although much smaller, dendritic patterns of similar morphology are also present in the northwestern part of the Central Basin. Because many contaminants display affinities for adsorption onto fine-grained sediments, and because the Sound is affected by seasonal hypoxia, mechanisms and dispersal pathways by which inorganic and organic sediments are remobilized and transported impact the eventual fate of the contaminants and environmental health of the estuary.

Connecticut, Massachussetts, New York↗
USGS2019

The evolving threat of rapid Ohia death (ROD) to Hawaii’s native ecosystems and rare plant species

Hawai‘i’s most widespread native tree, ‘ōhi‘a lehua ( Metrosideros polymorpha ), has been dying across large areas of Hawai‘i Island mainly due to two fungal pathogens ( Ceratocystis lukuohia and Ceratocystis huliohia ) that cause a disease collectively known as Rapid ‘Ōhi‘a Death (ROD). Here we examine patterns of positive detections of C. lukuohia as it has been linked to the larger mortality events across Hawai‘i Island. Our analysis compares the environmental range of C. lukuohia and its spread over time through the known climatic range and distribution of ‘ōhi‘a. Analyses show this fungal pathogen generally encompassed the core, but not the extremes of the climatic range of ‘ōhi‘a. We further modeled the potential distribution of C. lukuohia across the Hawaiian Archipelago to estimate the risk of ROD to other islands. Given the potential for C. lukuohia to alter the structure of ‘ōhi‘a dominated forests, we used our projected potential distribution of C. lukuohia to assess the risk of ROD to threatened and endangered plant species across Hawai‘i. Many native plants are likely vulnerable to these types of large ‘ōhi‘a mortality events: of 234 endangered native plant species considered, 147 (62.8%) have more than half of their range within current and expanding C. lukuohia suitable areas. We also found evidence that protecting habitat by fencing out introduced feral ungulates reduces the prevalence of the disease likely by reducing physical damage caused by these animals to ‘ōhi‘a trees, a precondition for Ceratocystis infection. Given the ongoing spread of C. lukuohia , we developed a dynamic web portal to host our results online, where models and analyses are updated with new lab-confirmed detections to provide managers with a useful tool to help monitor and assess the risk of C. lukuohia as it continues to spread.

Hawaii↗
USGS2013

Coral reef resilience through biodiversity

Irrefutable evidence of coral reef degradation worldwide and increasing pressure from rising seawater temperatures and ocean acidification associated with climate change have led to a focus on reef resilience and a call to “manage” coral reefs for resilience. Ideally, global action to reduce emission of carbon dioxide and other greenhouse gases will be accompanied by local action. Effective management requires reduction of local stressors, identification of the characteristics of resilient reefs, and design of marine protected area networks that include potentially resilient reefs. Future research is needed on how stressors interact, on how climate change will affect corals, fish, and other reef organisms as well as overall biodiversity, and on basic ecological processes such as connectivity. Not all reef species and reefs will respond similarly to local and global stressors. Because reef-building corals and other organisms have some potential to adapt to environmental changes, coral reefs will likely persist in spite of the unprecedented combination of stressors currently affecting them. The biodiversity of coral reefs is the basis for their remarkable beauty and for the benefits they provide to society. The extraordinary complexity of these ecosystems makes it both more difficult to predict their future and more likely they will have a future.

ISRN Oceanography↗
USGS2025

From subsidies to stressors: Shifting ecological baselines alter biological responses to nutrients in highly modified agricultural streams

Subsidy–stress gradients offer a useful framework for understanding ecological responses to perturbation and may help inform ecological metrics in highly modified systems. Historic, region-wide shifts from bottomland hardwood forest to row crop agriculture can cause positively skewed impact gradients in alluvial plain ecoregions, resulting in tolerant organisms that typically exhibit a subsidy response (increased abundance in response to environmental stressors) shifting to a stress response (declining abundance at higher concentrations). As a result, observed biological tolerance in modified ecosystems may differ from less modified regions, creating significant challenges for detecting biological responses to restoration efforts. Using the agriculturally dominated Mississippi Alluvial Plain (MAP) ecoregion in Mississippi, USA, as a case study, we tested the hypothesis that macroinvertebrate taxa that typically display a subsidy response to nutrient enrichment in less modified ecoregions (i.e., nutrient-tolerance) shift to a stress response to increasing nutrients in highly modified watersheds with elevated baseline nutrient conditions (i.e., nutrient intolerance). The abundance and diversity of MAP-specific intolerant taxa identified with threshold indicator taxa analysis were either unresponsive or exhibited a subsidy response to increasing nutrients in less modified ecoregions in Mississippi with less land alteration and lower nutrient concentrations, but declined at higher concentrations, providing evidence for a stress response to elevated nutrients in the MAP. Additionally, MAP-specific tolerant and intolerant taxa richness responded to increased nutrients predictably and consistently across space and time within the MAP. However, in MAP streams, elevated specific conductance was predicted to dampen the response of tolerant and intolerant taxa richness to increasing nutrient concentrations, highlighting the importance of considering multistressor interactions when interpreting biological data. Lastly, we demonstrate the efficacy of this approach with sediment bacterial communities characterized with amplicon sequencing, which lack sufficient life history characteristics necessary for the development of multimetric indices. Both macroinvertebrate and bacterial communities responded similarly to increasing nutrient concentrations, suggesting DNA-based approaches may provide an efficient biological assessment tool for monitoring water quality improvements in highly modified watersheds.

Mississippi↗
USGS2004

Decomposed gosling feet provide evidence of insecticide exposure

Canada goose goslings were exposed to turf sprayed with D · Z · N® diazinon 50W application (2.24 kg a.i./ha). The control plot was subjected to a water application. One foot from each bird was placed outdoors for 7 d to decompose and the other foot was kept frozen. Diazinon residues were analyzed on both feet. Results showed that diazinon was detected from undecomposed and decomposed feet of the birds. Diazinon residues were below the level of detection (<0.01 ppm, a.i.) on the feet from the control goslings. Decomposed feet may be used for determining insecticide exposure when the traditional matrices are not available.

Environmental Monitoring and Assessment↗
USGS2018

Effect of climate change on disease spread in wildlife

A growing body of evidence indicates that climate change alone, or acting synergistically with current anthropogenic threats, is affecting the health of wild populations of aquatic and terrestrial wildlife. Measurable by-products of climate change include elevated atmospheric concentrations of greenhouse gases, higher average global temperatures; variations in global precipitation patterns, rising and warming oceans, altered hydrographs of rivers, and increased mid-continental drying during summer. These consequences affect the terrestrial environment through shifts in phenology, vegetation cover, and fire regimes. Warmer ocean temperatures, increased acidification, rise in sea levels, and reduction in sea ice cover are also leading to widespread ecological changes in marine systems. Wildlife populations face a variety of climate-related pressures, such as changes in animal distribution or density, limitation of food resources, and alteration to critical habitats. The increased potential for emergence and resurgence of diseases that are responsive to environmental conditions also has implications for wildlife populations. Shifts in temperature or other climatic factors may directly affect the incidence of disease in wildlife by altering host-pathogen interactions, promoting vector populations or allowing new ranges for vectors, or reducing development times for parasites. A number of examples from both field and laboratory studies have demonstrated a clear link between warming environments and disease spread. Many climate-related environmental changes also influence wildlife health indirectly. For example, increasing temperatures, in combination with shifts in rainfall and humidity, may aggravate current trends for water resource limitation and habitat degradation or destruction and lead to increased crowding of animal populations, thereby promoting transmission opportunities of pathogens within populations or across species. Although it may be difficult to disentangle the influences of other anthropogenic changes from the direct effects of warming, some ecosystems provide especially useful models for studying climate-related disease spread in wildlife. For example, the effects of climate change on parasite dynamics may be easily observed in the Arctic, where environmental changes are occurring rapidly, anthropogenic influences are relatively limited, and biodiversity is generally low. Marine ecosystems are also undergoing rapid rates of change and may be vulnerable to a variety of natural and anthropogenic perturbations. Although many factors affect the health of organisms in ocean environments, temperature has been clearly linked to an increase in disease prevalence among sessile organisms such as corals. In this chapter, we discuss observed and predicted changes to wildlife health resulting from climate change. Our review will not include all aspects of wildlife health, but will instead focus on established or suspected links between climate drivers and disease spread and discuss examples from the current literature. Here, we define disease spread to include: 1) change in geographical or altitudinal distribution of pathogens, parasites, and vectors and the diseases they cause; 2) change in prevalence or severity of disease; and 3) emergence of novel diseases. Additionally, because wildlife species serve as reservoirs for zoonotic diseases that affect both animals and humans, we include select examples of the effect of climate change on the capacity of wildlife to harbor and spread these disease agents.

Book chapter↗
USGS1998

Field and laboratory evidence for intrinsic biodegradation of vinyl chloride contamination in a Fe(III)-reducing aquifer

Intrinsic bioremediation of chlorinated ethenes in anaerobic aquifers previously has not been considered feasible, due, in large part, to 1) the production of vinyl chloride during microbial reductive dechlorination of higher chlorinated contaminants and 2) the apparent poor biodegradability of vinyl chloride under anaerobic conditions. In this study, a combination of field geochemical analyses and laboratory radiotracer ([1,2-14C] vinyl chloride) experiments was utilized to assess the potential for intrinsic biodegradation of vinyl chloride contamination in an Fe(III)-reducing, anaerobic aquifer. Microcosm experiments conducted under Fe(III)-reducing conditions with material from the Fe(III)-reducing, chlorinated-ethene contaminated aquifer demonstrated significant oxidation of [1,2-14C] vinyl chloride to 14CO2 with no detectable production of ethene or other reductive dehalogenation products. Rates of degradation derived from the microcosm experiments (0.9-1.3% d-1) were consistent with field-estimated rates (0.03-0.2% d-1) of apparent vinyl chloride degradation. Field estimates of apparent vinyl chloride biodegradation were calculated using two distinct approaches; 1) a solute dispersion model and 2) a mass balance assessment. These findings demonstrate that degradation under Fe(III) reducing conditions can be an environmentally significant mechanism for intrinsic bioremediation of vinyl chloride in anaerobic ground-water systems.

Journal of Contaminant Hydrology↗
USGS2011

Multi-scale temporal and spatial variation in genotypic composition of Cladophora-borne Escherichia coli populations in Lake Michigan

High concentrations of Escherichia coli in mats of Cladophora in the Great Lakes have raised concern over the continued use of this bacterium as an indicator of microbial water quality. Determining the impacts of these environmentally abundant E. coli, however, necessitates a better understanding of their ecology. In this study, the population structure of 4285 Cladophora-borne E. coli isolates, obtained over multiple three day periods from Lake Michigan Cladophora mats in 2007-2009, was examined by using DNA fingerprint analyses. In contrast to previous studies that have been done using isolates from attached Cladophora obtained over large time scales and distances, the extensive sampling done here on free-floating mats over successive days at multiple sites provided a large dataset that allowed for a detailed examination of changes in population structure over a wide range of spatial and temporal scales. While Cladophora-borne E. coli populations were highly diverse and consisted of many unique isolates, multiple clonal groups were also present and accounted for approximately 33% of all isolates examined. Patterns in population structure were also evident. At the broadest scales, E. coli populations showed some temporal clustering when examined by year, but did not show good spatial distinction among sites. E. coli population structure also showed significant patterns at much finer temporal scales. Populations were distinct on an individual mat basis at a given site, and on individual days within a single mat. Results of these studies indicate that Cladophora-borne E. coli populations consist of a mixture of stable, and possibly naturalized, strains that persist during the life of the mat, and more unique, transient strains that can change over rapid time scales. It is clear that further study of microbial processes at fine spatial and temporal scales is needed, and that caution must be taken when interpolating short term microbial dynamics from results obtained from weekly or monthly samples.

Water Research↗