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At least 415 records · Page 23Linked to original sources
USGS2013

On estimating the economic value of insectivorous bats: Prospects and priorities for biologists

Bats are among the most economically important nondomesticated mammals in the world. They are well-known pollinators and seed dispersers, but crop pest suppression is probably the most valuable ecosystem service provided by bats. Scientific literature and popular media often include reports of crop pests in the diet of bats and anecdotal or extrapolated estimates of how many insects are eaten by bats. However, quantitative estimates of the ecosystem services provided by bats in agricultural systems are rare, and the few estimates that are available are limited to a single cotton-dominated system in Texas. Despite the tremendous value for conservation and economic security of such information, surprisingly few scientific efforts have been dedicated to quantifying the economic value of bats. Here, we outline the types of information needed to better quantify the value of bats in agricultural ecosystems. Because of the complexity of the ecosystems involved, creative experimental design and innovative new methods will help advance our knowledge in this area. Experiments involving bats in agricultural systems may be needed sooner than later, before population declines associated with white-nose syndrome and wind turbines potentially render them impossible.

Book chapter↗
USGS2020

Introduction: Ecological subsidies as a framework for understanding contaminant fate, exposure, and effects at the land-water interface

Ecologists have long recognized that ecological subsidies (the flow of organic matter, nutrients, and organisms between ecosystems) can strongly affect ecosystem processes and community structure in the recipient ecosystem. Animal movements, organic matter flows, and food web dynamics between linked aquatic and terrestrial systems can also influence contaminant fate, exposure, and effects at the land-water interface. Here and in this book, we develop a broad framework that highlights two important ways that ecological subsidies and contaminants interact. Ecological subsidies from the donor system can drive exposure to recipient systems, and contaminant exposures in the donor system can control subsidies and contaminant fluxes to the recipient systems. In the case of prey movement between ecosystems, subsidies drive exposure when contaminants present in aquatic environments bioaccumulate in the tissues of prey organisms at levels that are relatively non-toxic to the prey themselves. Conversely, exposure in the aquatic system can limit subsidies when pollutants are relatively toxic to prey organisms themselves and the magnitude of the subsidy (i.e., biomass of aquatic insects emerging to the terrestrial environment) is reduced. These effects of contaminants on subsidies are shaped by other global stressors that are ubiquitous in aquatic-riparian ecosystems (e.g., climate and land use change, species extinction and invasion, and eutrophication). As our understanding of these ecological and toxicological processes advances, there are increasing opportunities to make landscape-scale predictions of contaminant and animal fluxes and to integrate this knowledge of aquatic-riparian linkages into managing contaminant risks. Through these efforts to integrate the fields of ecology and ecotoxicology on this subject, we expect to gain greater insight on the ecological effects of contaminants on linked ecosystems as well as the ways in which food web dynamics and ecosystem processes can themselves govern the fate, transport, and exposure to contaminants in the environment.

Book chapter↗
USGS2020

Metamorphosis and the impact of contaminants on ecological subsidies

Animals with complex life histories such as aquatic insects and amphibians link freshwater and terrestrial ecosystems when they transition from water to land during development. This transition requires metamorphosis from juvenile to adult life stages. Metamorphosis is a stressful and ecologically sensitive life history event. Exposure to contaminants during juvenile development (before or during metamorphosis) can disrupt the complex process of metamorphosis, thereby altering the flow of organisms from water to land. This chapter reviews how ecological stressors impact the timing and success of metamorphosis. Key ideas include: (1) metamorphosis is a key event in the movement of subsidies from water to land, (2) mortality during metamorphosis is enhanced in the presence of contaminants, and (3) juvenile responses to contaminants may not predict adult responses, due to death during metamorphosis. Metamorphosis is a critical life history stage that should be accounted for in ecotoxicological studies.

Book chapter↗
USGS2021

Trophic ecology

The trophic ecology of lake charr Salvelinus namaycush morphotypes from small and large lakes within their native and introduced ranges is reviewed over the past 50 years. The lake charr is an apex predator in most habitats it occupies, where it plays a significant role in defining food webs. While often considered piscivores, lake charr feed on a range of aquatic prey throughout their life history, including zooplankton, benthic invertebrates, and fish, as well as terrestrial insects, mammals, birds, amphibians, and reptiles. Lake charr diets that vary within morphotypes among lakes and among sympatric morphotypes reflect differences in habitat use, prey availability, and individual preferences. Temporal variability in diet can result from seasonal prey pulses, thermal barriers, and long-term prey dynamics. Lake charr adapt quickly to consume invasive prey fishes, and often decimate native prey fishes and other piscivores in lakes into which they are introduced. Salient research topics in lake charr trophic ecology include: (1) how best to quantify spatial and temporal trophic niche space; and, (2) how changing environmental conditions, such as invasive species and lake warming, will influence lake charr feeding and broader lake food-web dynamics.

Book chapter↗
USGS2019

Historical range and variation (HRV)

Fire-prone landscapes are experiencing rapid and potentially persistent changes as the result of complex and potentially novel interactions of anthropogenic climate changes, shifting fire regimes, exotic plant, insect, and pathogen invasions, and industrial, agricultural, and urban development. Are these landscapes fully departed from historical conditions? Should they be managed as novel environments or as landscapes in transition? Historical range and variation is a benchmark representation of the conditions that describe fully functional, healthy ecosystems or landscapes. The HRV can provide an ecological reference against which contemporary and future conditions can be evaluated to determine status, trend, and magnitude of departure. This text describes the concepts of HRV, methods for developing HRV data sets, and application of HRV for fire management. We discuss the limitations of HRV, and its use under future climates that are no longer representative of historical conditions.

Book chapter↗
USGS2017

Effects of climate change on forest vegetation in the northern Rockies

Increasing air temperature, through its influence on soil moisture, is expected to cause gradual changes in the abundance and distribution of tree, shrub, and grass species throughout the Northern Rockies, with drought tolerant species becoming more competitive. The earliest changes will be at ecotones between lifeforms (e.g., upper and lower treelines). Ecological disturbance, including wildfire and insect outbreaks, will be the primary facilitator of vegetation change, and future forest landscapes may be dominated by younger age classes and smaller trees. High-elevation forests will be especially vulnerable if disturbance frequency

Rocky Mountains↗
USGS2018

Linking animals aloft with the terrestrial landscape

Despite using the aerosphere for many facets of their life, most flying animals (i.e., birds, bats, some insects) are still bound to terrestrial habitats for resting, feeding, and reproduction. Comprehensive broad-scale observations by weather surveillance radars of animals as they leave terrestrial habitats for migration or feeding flights can be used to map their terrestrial distributions either as point locations (e.g., communal roosts) or as continuous surface layers (e.g., animal densities in habitats across a landscape). We discuss some of the technical challenges to reducing measurement biases related to how radars sample the aerosphere and the flight behavior of animals. We highlight a recently developed methodological approach that precisely and quantitatively links the horizontal spatial structure of birds aloft to their terrestrial distributions and provides novel insights into avian ecology and conservation across broad landscapes. Specifically, we present case studies that (1) elucidate how migrating birds contend with crossing ecological barriers and extreme weather events, (2) identify important stopover areas and habitat use patterns of birds along their migration routes, and (3) assess waterfowl response to wetland habitat management and restoration. These studies aid our understanding of how anthropogenic modification of the terrestrial landscape (e.g., urbanization, habitat management), natural geographic features, and weather (e.g., hurricanes) can affect the terrestrial distributions of flying animals.

Book chapter↗
USGS1991

The Detroit River: Effects of contaminants and human activities on aquatic plants and animals and their habitats

Despite the extensive urbanization of its watershed, the Detroit River still supports diverse fish and wildlife populations. Conflicting uses of the river for waste disposal, water withdrawals, shipping, recreation, and fishing require innovative management. Chemicals added by man to the Detroit River have adversely affected the health and habitats of the river's plants and animals. In 1985, as part of an Upper Great Lakes Connecting Channels Study sponsored by Environment Canada and the U.S. Environmental Protection Agency, researchers exposed healthy bacteria, plankton, benthic macroinvertebrates, fish, and birds to Detroit River sediments and sediment porewater. Negative impacts included genetic mutations in bacteria; death of macroinvertebrates; accumulation of contaminants in insects, clams, fish, and ducks; and tumor formation in fish. Field surveys showed areas of the river bottom that were otherwise suitable for habitation by a variety of plants and animals were contaminated with chlorinated hydrocarbons and heavy metals and occupied only by pollution-tolerant worms. Destruction of shoreline wetlands and disposal of sewage and toxic substances in the Detroit River have reduced habitat and conflict with basic biological processes, including the sustained production of fish and wildlife. Current regulations do not adequately control pollution loadings. However, remedial actions are being formulated by the U.S. and Canada to restore degraded benthic habitats and eliminate discharges of toxic contaminants into the Detroit River.

Hydrobiologia↗
USGS1996

Toxicity and oxidative stress of different forms of organic selenium and dietary protein in mallard ducklings

Concentrations of over 100 ppm (mg/kg) selenium (Se) have been found in aquatic plants and insects associated with irrigation drainwater and toxicity to fish and wildlife. Composition of diet for wild ducklings can vary in selenium-contaminated environments. Earlier studies have compared toxicities and oxidative stress of Se as selenite to those of seleno-DL-methionine (DL) in mallards ( Anas platyrhynchos ). This study compares DL, seleno-L-methionine (L), selenized yeast (Y) and selenized wheat (W). Day-old mallard ducklings received an untreated diet (controls) containing 75% wheat (22% protein) or the same diet containing 15 or 30 ppm Se in the above forms except for 30 ppm Se as W. After 2 weeks, blood and liver samples were collected for biochemical assays and Se analysis. All forms of selenium caused significant increases in plasma and hepatic glutathione peroxidase activities. Se as L at 30 ppm in the diet was the most toxic form, resulting in high mortality (64%) and impaired growth (>50%) in survivors and the greatest increase in ratio of oxidized to reduced hepatic glutathione (GSH). Se as both L and DL decreased the concentrations of hepatic GSH and total thiols. Se as Y accumulated the least in liver (approximately 50% of other forms) and had less effect on GSH and total thiols. In a second experiment, in which the basal diet was a commercial duck feed (22% protein), survival was not affected by 30 ppm Se as DL, L, or Y and oxidative effects on GSH metabolism were less pronounced than with the wheat diet.

Archives of Environmental Contamination and Toxico↗
USGS1989

Pesticide contamination of endangered gray bats and their food base in Boone County, Missouri, 1982

Gray bat guano from Devil's Icebox and Hunters Caves contained dieldrin at levels previously associated with gray bat mortality. Two of four gray bats found dead in Holton Cave had lethal brain concentrations of dieldrin. Twenty-five of 28 (86%) insect samples from bat foraging areas contained measurable dieldrin, heptachlor epoxide or both. Beetle samples were most heavily contaminated containing up to 2.2 ppm and 1.1 ppm heptachlor epoxide. The addition of Holton Cave brings to five the number of Missouri caves where gray bats have died of food chain pesticide poisoning.

Missouri↗
USGS2005

Residues of toxaphene in insectivorous birds ( Petrochelidon spp.) from the Rio Grande, Texas

Although it has been documented that wildlife in the Rio Grande Valley (RGV) contain increased concentrations of organochlorine (OC) contaminants, particularly DDE, little has been published on residues of toxaphene throughout this major North American watershed. In this study, 28 liver composites from adult swallows ( Petrochelidon spp.) collected along the Rio Grande from 1999 through 2000 were analyzed for toxaphene residues using congener-specific gas chromatography–electron-capture negative ionization–mass spectrometry. Estimated total toxaphene concentrations ranged from 12 to 260 ng/g wet wt and were highest in samples from the lower RGV near Llano Grande Lake in Hidalgo and Cameron counties (Texas). Toxaphene congener profiles were relatively invariant throughout the watershed and were dominated by 2,2,5-endo,6-exo,8,8,9,10-octachlorobornane (P-42a or B8-806) with lesser amounts of several other Cl 7 -Cl 9 compounds, many of which remain unidentified. Petrochelidon spp. liver profiles appear to be intermediate in complexity between those in invertebrates and fish (more complex) and mammals (less complex) and differs somewhat from those reported for other avian species. In addition to other legacy OC contaminants, toxaphene residues were most concentrated in the lower RGV and accumulated at up to hundreds of parts per billion in these insect-eating birds, underscoring their utility as avian bioindicators of persistent organic pollutants.

Archives of Environmental Contamination and Toxico↗
USGS2019

Contaminant concentrations in sediments, aquatic invertebrates, and fish in proximity to rail tracks used for coal transport in the Pacific Northwest: A baseline assessment

Railway transport of coal poses an environmental risk because coal dust contains polycyclic aromatic hydrocarbons (PAHs), mercury (Hg), and other trace metals. In the Pacific Northwest, proposed infrastructure projects could result in an increase in coal transport by train through the Columbia River corridor. Baseline information is needed on current distributions, levels, and spatial patterns of coal dust-derived contaminants in habitats and organisms adjacent to existing coal transport lines. To that end, we collected aquatic surface sediments, aquatic insects, and juvenile fish in 2014 and 2015 from Horsethief Lake State Park and Steigerwald National Wildlife Refuge (NWR), both located close to the rail line and within the Columbia River Gorge National Scenic Area. Two subsites in each area were selected: one close to the rail line and one far from the rail line. Detected PAH concentrations were relatively low compared to those measured at more urbanized areas. Some contaminants were measured at higher concentrations at the subsites close to the rail line, but it was not possible to link the contaminants to a definitive source. Trace metal concentrations were only slightly higher than background concentrations, but a few of the more sensitive benchmarks were exceeded, including those for As, Pb, and Se in fish tissue and fluoranthene, Cd, Cu, Mn, Ni, Zn, Fe, and As in sediments. At Horsethief Lake, Chinook salmon and yellow perch showed lower total mercury body burdens than other species, but PAH body burdens did not differ significantly among species. Differences in the species caught among subsites and the low number of invertebrate samples rendered food web comparisons difficult, but these data show that the PAHs and trace metals, including mercury, are accumulating in these wetland sites and in some resident organisms.

Washington↗
USGS2023

Adult mosquito and butterfly exposure to permethrin and relative risk following ULV sprays from a truck-mounted sprayer

Ground applications of adulticides via a specialized truck-mounted sprayer are one of the most common practices for control of flying adult mosquitoes. Aerosols released to drift through a targeted area persist in the air column to contact and kill flying mosquitoes, but may also drift into adjacent areas not targeted by the applications where it may affect nontarget insects such as imperiled butterflies. This study compared the risk of permethrin to adult mosquitoes and adult butterflies to assess the likelihood that the butterflies would be affected following such sprays. Permethrin toxicity values were determined for Aedes aegypti and Culex quinquefasciatus (LD50s of 81.1 and 166.3 ng/g dw, respectively) and then combined with published toxicity data in a species sensitivity distribution for comparison with published permethrin toxicity data for adult butterflies. The sensitivity distributions indicated adult butterflies and mosquitoes are similarly sensitive, meaning relative risk would be a function of exposure. Exposure of adult butterflies and adult mosquitoes to permethrin was measured following their exposure to ULV sprays in an open field. Average permethrin concentrations on adult mosquitoes (912–38,061 ng/g dw) were typically an order of magnitude greater than on adult butterflies (110–11,004 ng/g dw) following each spray, indicating lower risk for butterflies relative to mosquitoes. Despite lower estimated risk, 100% mortality of adult butterflies occurred following some of the sprays. Additional studies could help understand exposure and risk for butterflies in densely vegetated habitats typical near areas treated by ULV sprays.

Archives of Environmental Contamination and Toxico↗
USGS2001

Cyclodiene insecticide, DDE, DDT, arsenic, and mercury contamination of big brown bats (Eptesicus fuscus) foraging at a Colorado Superfund site

Rocky Mountain Arsenal (RMA) National Wildlife Area, near Denver, Colorado, is a Superfund site contaminated by past military and industrial uses, including pesticide manufacturing. From an ecosystem standpoint, the most critical contaminants at RMA are certain cyclodiene insecticides and metabolites, p,p ′-DDE, p,p ′-DDT, arsenic, and mercury. Bats are important ecosystem components that can be impacted by persistent contaminants because of their position in the food chain and their potential longevity and thus duration of exposure. Big brown bats ( Eptesicus fuscus ) were captured (n = 51) while foraging at RMA in the summers of 1997 and 1998 for determination of concentrations of contaminants of concern in carcasses, brains, and stomach contents. Adult females (n = 15) were also tracked by radiotelemetry to determine locations of nearest maternity roosts for sampling of guano for contaminant analysis and inspection for potential contaminant-induced mortality. Bats captured while foraging at RMA had measurable quantities of dieldrin and DDE in masticated insect samples from stomach contents and significantly higher concentrations of dieldrin, DDE, DDT, and mercury (juveniles) in carcasses than big brown bats (n = 26) sampled at a reference area 80 km to the north. Concentrations of dieldrin and DDE in brains of bats captured while foraging at RMA were also greater than in bats from the reference area, but not high enough to suggest mortality. Maximum concentrations of DDE, DDT, and cyclodienes in brains of big brown bats were found in adult males from RMA. Guano from the two closest known roosts had significantly higher concentrations of dieldrin, DDE, and mercury than guano from two roosts at the reference area. Dieldrin concentrations in carcasses of bats from RMA were highest in juveniles, followed by adult males and adult females. DDE concentrations in carcasses were lowest in adult females at both sites and highest in adult males at RMA. No contaminant-related mortality was obvious at the small maternity colonies near RMA. Big brown bats show higher contamination than most other mammals previously sampled at this site. Concentrations and proportions of samples with detectable residues of dieldrin in carcasses of big brown bats from RMA were similar to or exceeded reports for this species from elsewhere in the United States some 25 years ago, prior to or just following restrictions on use of this compound.

Archives of Environmental Contamination and Toxico↗
USGS2007

Using chemical and microbiological indicators to track the impacts from the land application of treated municipal wastewater and other sources on groundwater quality in a karstic springs basin

Multiple chemical constituents (nutrients; N, O, H, C stable isotopes; 64 organic wastewater compounds, 16 pharmaceutical compounds) and microbiological indicators were used to assess the impact on groundwater quality from the land application of approximately 9.5 million liters per day of treated municipal sewage effluent to a sprayfield in the 960-km2 Ichetucknee Springs basin, northern Florida. Enriched stable isotope signatures (?? 18O and ??2H) were found in water from the effluent reservoir and a sprayfield monitoring well (MW-7) due to evaporation; however, groundwater samples downgradient from the sprayfield have ??18O and ??2H concentrations that represented recharge of meteoric water. Boron and chloride concentrations also were elevated in water from the sprayfield effluent reservoir and MW-7, but concentrations in groundwater decreased substantially with distance downgradient to background levels in the springs (about 12 km) and indicated at least a tenfold dilution factor. Nitrate-nitrogen isotope (??15N-NO3) values above 10 ??? in most water samples were indicative of organic nitrogen sources except Blue Hole Spring (??15N-NO3 = 4.6-4.9 ???), which indicated an inorganic source of nitrogen (fertilizers). The detection of low concentrations the insect repellent N,N-diethyl-metatoluamide (DEET), and other organic compounds associated with domestic wastewater in Devil's Eye Spring indicated that leakage from a nearby septic tank drainfield likely has occurred. Elevated levels of fecal coliforms and enterococci were found in Blue Hole Spring during higher flow conditions, which likely resulted from hydraulic connections to upgradient sinkholes and are consistent with previoius dye-trace studies. Enteroviruses were not detected in the sprayfield effluent reservoir, but were found in low concentrations in water samples from a downgradient well and Blue Hole Spring during high-flow conditions indicating a human wastewater source. The Upper Floridan aquifer in the Ichetucknee Springs basin is highly vulnerable to contamination from multiple anthropogenic sources throughout the springs basin. ?? 2007 Springer-Verlag.

Environmental Geology↗
USGS2014

Effects of management legacies on stream fish and aquatic benthic macroinvertebrate assemblages

Fish and benthic macroinvertebrate assemblages often provide insight on ecological conditions for guiding management actions. Unfortunately, land use and management legacies can constrain the structure of biotic communities such that they fail to reflect habitat quality. The purpose of this study was to describe patterns in fish and benthic macroinvertebrate assemblage structure, and evaluate relationships between biota and habitat characteristics in the Chariton River system of south-central Iowa, a system likely influenced by various potential management legacies (e.g., dams, chemical removal of fishes). We sampled fishes, benthic macroinvertebrates, and physical habitat from a total of 38 stream reaches in the Chariton River watershed during 2002–2005. Fish and benthic macroinvertebrate assemblages were dominated by generalist species tolerant of poor habitat quality; assemblages failed to show any apparent patterns with regard to stream size or longitudinal location within the watershed. Metrics used to summarize fish assemblages and populations [e.g., presence–absence, relative abundance, Index of Biotic Integrity for fish (IBI F )] were not related to habitat characteristics, except that catch rates of piscivores were positively related to the depth and the amount of large wood. In contrast, family richness of benthic macroinvertebrates, richness of Ephemeroptera, Trichoptera, and Plecoptera taxa, and IBI values for benthic macroinvertebrates (IBI BM ) were positively correlated with the amount of overhanging vegetation and inversely related to the percentage of fine substrate. A long history of habitat alteration by row-crop agriculture and management legacies associated with reservoir construction has likely resulted in a fish assemblage dominated by tolerant species. Intolerant and sensitive fish species have not recolonized streams due to downstream movement barriers (i.e., dams). In contrast, aquatic insect assemblages reflected aquatic habitat, particularly the amount of overhanging vegetation and fine sediment. This research illustrates the importance of using multiple taxa for biological assessments and the need to consider management legacies when investigating responses to management and conservation actions.

Iowa↗
USGS2017

Effects of backpacker use, pack stock trail use, and pack stock grazing on water-quality indicators, including nutrients, E. coli, hormones, and pharmaceuticals, in Yosemite National Park, USA

We investigated how visitor-use affects water quality in wilderness in Yosemite National Park. During the summers of 2012–2014, we collected and analyzed surface-water samples for water-quality indicators, including fecal indicator bacteria Escherichia coli , nutrients (nitrogen, phosphorus, carbon), suspended sediment concentration, pharmaceuticals, and hormones. Samples were collected upstream and downstream from different types of visitor use at weekly to biweekly intervals and during summer storms. We conducted a park-wide synoptic sampling campaign during summer 2014, and sampled upstream and downstream from meadows to evaluate the mitigating effect of meadows on water quality. At pack stock stream crossings, Escherichia coli concentrations were greater downstream from crossings than upstream (median downstream increase in Escherichia coli of three colony forming units 100 mL −1 ), with the greatest increases occurring during storms (median downstream increase in Escherichia coli of 32 CFU 100 mL −1 ). At backpacker use sites, hormones, and pharmaceuticals (e.g., insect repellent) were detected at downstream sites, and Escherichia coli concentrations were greater at downstream sites (median downstream increase in Escherichia coli of 1 CFU 100 mL −1 ). Differences in water quality downstream vs. upstream from meadows grazed by pack stock were not detectable for most water-quality indicators, however, Escherichia coli concentrations decreased downstream, suggesting entrapment and die-off of fecal indicator bacteria in meadows. Our results indicate that under current-use levels pack stock trail use and backpacker use are associated with detectable, but relatively minor, effects on water quality, which are most pronounced during storms.

California↗
USGS2018

Energy allocation and feeding ecology of juvenile chum salmon (Oncorhynchus keta) during transition from freshwater to saltwater

Pacific salmon (Oncorhynchus spp.) populations near their northern range extent in the Arctic-Yukon-Kuskokwim region of Alaska have undergone major changes in population trajectory and illuminated the lack of basic information on juvenile ecology. This study fills information gaps on the early life history of chum salmon at northern latitudes. Energy allocation was examined in the context of distribution, feeding intensity, and diet during a critical life history period for a single cohort of juvenile chum salmon (O. keta) as they transition from freshwater to saltwater in Kuskokwim Bay from mid-May to early June. Juvenile chum salmon were primarily captured in the river mouth and plume. Energy density (kJ g−1 dry mass) was related to fork length, timing (day-of-year), and capture location in a general additive model. The smallest fish had slightly higher energy densities, but the change in energy density with fish size was minimal and consistent with allocating energy toward somatic growth rather than lipid storage. Fish captured earlier had higher energy density, likely reflecting the presence of residual yolk lipids during early migration. Fish captured in the river mouth and plume had higher energy densities. Feeding intensity was highest among small fish captured later within the river plume. Diet was dominated by surface prey (insects and calanoid copepods) rather than epibenthic harpacticoid copepods as commonly observed. These results provide the first data on energy allocation of juvenile chum salmon during a critical life history phase and suggest that somatic growth is prioritized over storing lipid at saltwater entry.

Alaska↗