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At least 433 records · Page 24Linked to original sources

USGS2024

Identifying indicators of polar bear population status

Monitoring trends in large mammal populations is a fundamental component of wildlife management and conservation. However, direct estimates of population size and vital rates of large mammals can be logistically challenging and expensive. Indicators that reflect trends in abundance, therefore, can be valuable tools for supporting population monitoring. Polar bears have a relatively simple life history such that a few key variables may be effective indicators for tracking changes in body condition and recruitment that affect abundance. Direct estimates of polar bear abundance are difficult to obtain due to their large home ranges in remote Arctic habitats. Changes in abundance associated with environmental conditions appear to affect polar bears largely via effects on female body condition which influence reproduction and cub survival (i.e., recruitment). Loss of sea ice habitat is further limiting researcher access for population monitoring creating a need for alternative approaches. Here we used relationships established from eight years (2008–2017) of data collected on 439 polar bears in the Chukchi Sea, to transform previously published individual-based relationships with annually available sea ice, atmospheric circulation, and prey body condition variables to predict annual mean body condition and recruitment during 2018–2022. Although annual sample sizes were limited for verifying predicted body condition and recruitment via techniques such as cross-validation, in most cases predicted annual means were closely correlated with observed means for 2008–2017. Summer sea ice and prey body condition remained within or increased relative to levels observed during 2008–2017 and predicted polar bear body condition and recruitment during 2018–2022 were largely within or above observed annual means during 2008–2017. A lack of trend in environmental and ecological variables or polar bear body condition and recruitment metrics during 2008–2022 is suggestive that the Chukchi Sea polar bear population was likely stable during this time. Our results provide support for developing models that predict important population parameters of large mammals based on environmental and ecological indicators. Given that trend information is lacking for 10 of the 19 recognized polar bear populations and is outdated for others, the use of environmental and ecological indicators may be particularly useful for augmenting direct estimates of polar bear vital rates in between periods of data collection. Although demographic assessments for polar bears have primarily focused on correlations with sea ice availability, our study and others highlight that prey health is also an important indicator of polar bear population status.

Ecological Indicators↗

USGS2014

Minimal role of eastern fence lizards in Borrelia burgdorferi transmission in central New Jersey oak/pine woodlands

The Eastern fence lizard, Sceloporus undulatus , is widely distributed in eastern and central North America, ranging through areas with high levels of Lyme disease, as well as areas where Lyme disease is rare or absent. We studied the potential role of S. undulatus in transmission dynamics of Lyme spirochetes by sampling ticks from a variety of natural hosts at field sites in central New Jersey, and by testing the reservoir competence of S. undulatus for Borrelia burgdorferi in the laboratory. The infestation rate of ticks on fence lizards was extremely low (proportion infested = 0.087, n = 23) compared to that on white footed mice and other small mammals (proportion infested = 0.53, n = 140). Of 159 nymphs that had fed as larvae on lizards that had previously been exposed to infected nymphs, none was infected with B. burgdorferi , compared with 79.9% of 209 nymphs that had fed as larvae on infected control mice. Simulations suggest that changes in the numbers of fence lizards in a natural habitat would have little effect on the infection rate of nymphal ticks with Lyme spirochetes. We conclude that in central New Jersey S. undulatus plays a minimal role in the enzootic transmission cycle of Lyme spirochetes.

New Jersey↗

USGS2002

French Frigate Shoals reef health survey

French Frigate Shoals (FFS) is one of the refugia comprising the Northwest Hawaiian Islands National Wildlife Refuge (NWHINWR). French Frigate Shoals was discovered by La Perouse in the late 18th century; however, the atoll was most notable as a naval air station during World War II when the US Navy dredged Tern Island into an airstrip, and the US Coast guard established a LORAN station on East Island. After the war, the LORAN station was moved to Tern Island where it remained until the Coast Guard vacated in 1979. Since then, the US Fish and Wildlife Service (USFWS) has managed Tern Island-FFS as a wildlife refuge with a full time staff presence (USFWS, 2001). French Frigate Shoals consists of a large (31 nm) fringing reef partially enclosing a lagoon. A basalt pinnacle (La Perouse Pinnacle) arises approximately halfway between the two ends of the arcs of the fringing reefs. Tern Island is situated at the northern end of the lagoon and is surrounded by a dredged ship channel. The lagoon becomes progressively shallower from west to east and harbors a variety of marine life including corals, fish, marine mammals, and sea turtles (Amerson 1971). In 2000, an interagency survey of the northwestern Hawaiian Islands was done to document the fauna and flora in FFS (Maragos and Gulko, 2002). During that survey, 38 stations were examined, and 41 species of stony corals were documented, the most of any of the NW Hawaiian islands (Maragos and Gulko 2002). In some of these stations, corals with abnormalities were observed. The present study aimed to expand on the 2000 survey to evaluate the lesions in areas where they were documented.

Report↗

USGS2012

Anticipated effects of development on habitat fragmentation and movement of mammals into and out of the Schoodic District, Acadia National Park, Maine

Most national parks interact with adjacent lands because their boundaries fail to encompass all regional habitats, species pools, and migration routes. Activities planned for adjacent lands can have adverse effects on park resources and visitor experiences. For example, fragmentation of adjacent habitat into smaller and more isolated remnants may influence the suitability of park habitat for a wide range of species and limit animal dispersal pathways, which may influence visitor experiences and park resources as well as the energy balance and population dynamics of the animals themselves. In this study, we examined habitat fragmentation consequences owing to a planned 1,295 hectare development by Winter Harbor Holding Company (WHHC) adjacent to the Schoodic District of Acadia National Park (ANP), Maine. Specifically, we examined the effects of development on (a) core natural habitat area (a cross-habitat indicator of fragmentation), (b) the suitability of habitat for bobcat, fisher, mink, and moose, and (c) the movement of these four species between ANP and other nearby protected areas (species specific indicators of fragmentation). Our intention was to assist ANP staff in forecasting both the general and specific effects of development on natural habitat area, habitat suitability, and animal movement, which would allow them to develop suitable management alternatives.

Maine↗

USGS2021

Exposure to domoic acid is an ecological driver of cardiac disease in southern sea otters

Harmful algal blooms produce toxins that bioaccumulate in the food web and adversely affect humans, animals, and entire marine ecosystems. Blooms of the diatom Pseudo-nitzschia can produce domoic acid (DA), a toxin that most commonly causes neurological disease in endothermic animals, with cardiovascular effects that were first recognized in southern sea otters. Over the last 20 years, DA toxicosis has caused significant morbidity and mortality in marine mammals and seabirds along the west coast of the USA. Identifying DA exposure has been limited to toxin detection in biological fluids using biochemical assays, yet measurement of systemic toxin levels is an unreliable indicator of exposure dose or timing. Furthermore, there is little information regarding repeated DA exposure in marine wildlife. Here, the association between long-term environmental DA exposure and fatal cardiac disease was investigated in a longitudinal study of 186 free-ranging sea otters in California from 2001 – 2017, highlighting the chronic health effects of a marine toxin. A novel Bayesian spatiotemporal approach was used to characterize environmental DA exposure by combining several DA surveillance datasets and integrating this with life history data from radio-tagged otters in a time-dependent survival model. In this study, a sea otter with high DA exposure had a 1.7-fold increased hazard of fatal cardiomyopathy compared to an otter with low exposure. Otters that consumed a high proportion of crab and clam had a 2.5- and 1.2-times greater hazard of death due to cardiomyopathy than otters that consumed low proportions. Increasing age is a well-established predictor of cardiac disease, but this study is the first to identify that DA exposure affects the risk of cardiomyopathy more substantially in prime-age adults than aged adults. A 4-year-old otter with high DA exposure had 2.3 times greater risk of fatal cardiomyopathy than an otter with low exposure, while a 10-year old otter with high DA exposure had just 1.2 times greater risk. High Toxoplasma gondii titers also increased the hazard of death due to heart disease 2.4-fold. Domoic acid exposure was most detrimental for prime-age adults, whose survival and reproduction are vital for population growth, suggesting that persistent DA exposure will likely impact long-term viability of this threatened species. These results offer insight into the pervasiveness of DA in the food web and raise awareness of under-recognized chronic health effects of DA for wildlife at a time when toxic blooms are on the rise.

California↗

USGS1983

Effects on birds of fenthion aerial application for mosquito control

Effects on birds of an aerial application of fenthion, a potent organophosphorus cholinesterase (ChE)-inhibiting insecticide, were assessed on four study sites 1.8 to 3.6 km 2 in size. These sites were located within 121.5 km 2 of wet meadows treated with 47 g of fenthion (AI) per ha in ultra-low-volume formulation. Assessment methods were searches for sick or dead birds, measurements of brain ChE activity in specimens found dead or collected alive at different time intervals, and counts of bird populations. After treatment, 99 birds and 15 mammals were found sick or dead; 106 of these were on one site. Brain ChE activity in dead birds was depressed sufficiently to indicate that death was caused by an anti-ChE substance. Brain ChE activity in three common bird species collected alive showed the greatest reduction 2 days postspray. Two of these species had ChE activity that was still significantly ( P <0.05) depressed 15 days postspray. Bird populations declined most where mortality was heaviest. Fenthion sprayed for mosquito control was life threatening to many birds inhabiting treated meadows.

Journal of Economic Entomology↗

USGS2024

Prion seeding activity in plant tissues detected by RT-QuIC

Prion diseases such as scrapie, bovine spongiform encephalopathy (BSE), and chronic wasting disease (CWD) affect domesticated and wild herbivorous mammals. Animals afflicted with CWD, the transmissible spongiform encephalopathy of cervids (deer, elk, and moose), shed prions into the environment, where they may persist and remain infectious for years. These environmental prions may remain in soil, be transported in surface waters, or assimilated into plants. Environmental sampling is an emerging area of TSE research and can provide more information about prion fate and transport once shed by infected animals. In this study, we have developed the first published method for the extraction and detection of prions in plant tissue using the real-time quaking-induced conversion (RT-QuIC) assay. Incubation with a zwitterionic surfactant followed by precipitation with sodium phosphotungstate concentrates the prions within samples and allows for sensitive detection of prion seeding activity. Using this protocol, we demonstrate that prions can be detected within plant tissues and on plant surfaces using the RT-QuIC assay.

Pathogens↗

USGS1973

Pesticide residues in birds and mammals

SUMMARY: Residues of organochlorine pesticides and their breakdown products are present in the tissues of essentially all wild birds throughout the world. These chemicals accumulate in fat from a relatively small environmental exposure. DDE and dieldrin are most prevalent. Others, such as heptachlor epoxide, chlordane, endrin, and benzene hexachloride also occur, the quantities and kinds generally reflecting local or regional use. Accumulation may be sufficient to kill animals following applications for pest control. This has occurred in several large-scale programmes in the United States. Mortality has also resulted from unintentional leakage of chemical from commercial establishments. Residues may persist in the environment for many years, exposing successive generations of animals. In general, birds that eat other birds, or fish, have higher residues than those that eat seeds and vegetation. The kinetic processes of absorption, metabolism, storage, and output differ according to both kind of chemical and species of animal. When exposure is low and continuous, a balance between intake and excretion may be achieved. Residues reach a balance at an approximate animal body equilibrium or plateau; the storage is generally proportional to dose. Experiments with chickens show that dieldrin and heptachlor epoxide have the greatest propensity for storage, endrin next, then DDT, then lindane. The storage of DDT was complicated by its metabolism to DDE and DDD, but other studies show that DDE has a much greater propensity for storage than either DDD or DDT. Methoxychlor has little cumulative capacity in birds. Residues in eggs reflect and parallel those in the parent bird during accumulation, equilibrium, and decline when dosage is discontinued. Residues with the greatest propensity for storage are also lost most slowly. Rate of loss of residues can be modified by dietary components and is speeded by weight loss of the animal. Under sublethal conditions of continuous exposure to an organochlorine pesticide, the concentrations of residues in the different tissues are ordinarily directly correlated with each other. When the dosage is at lethal levels, or when stored residues are mobilised to lethal levels, the balanced relationship is disrupted. The concentrations of residues in the brain provide the most rigorous criteria for diagnosis of death due to these chemicals, and levels are generally similar across a wide range of species of birds and mammals. Residues in liver are closely correlated with recent dose, either from direct intake or from mobilisation from storage, and so reflect hazardous exposure. Residues in the whole carcass show the storage reserve, and so indicate the potential for adverse effects from lethal mobilisation or from the continuous slow mobilisation that occurs during the normal processes of metabolism and excretion. A synchronous, rapid, and widespread decline in weight and thickness of shells of eggs laid by many species of wild birds occurred in the late 1940's and has persisted. Birds of prey were primarily affected; exceptions apparently are the result of lesser exposure because of different food habits. Many species of fish-eating birds are also affected. Others, however, appear to be more resistant and to accumulate much higher residues before shell-thinning occurs. Seed-eating birds do not appear to have been generally affected; their exposure is ordinarily lower, but physiological factors also seem to be involved. A relationship between shell-thinning and population decline has been established for many species. In exceptional cases, such as the herring gull, persistent re-nesting and other population reactions have overcome adverse effects at the population level. The discovery of shell-thinning among natural populations, and the hypothesis that this thinning was related to the occurrence of organochlorine pesticides, stimulated experimental studies to determine wheth

Book chapter↗

USGS1960

Bureau of Sport Fisheries and Wildlife Pesticide-Wildlife Review: 1959

Research findings of the Bureau of Sport Fisheries and Wildlife, State agencies and independent research workers in Ala., Ark., Fla., Ga., La., Mass., Mich., Mont., N. Dak., Tex., and Wis. are summarized in this report together with recommendations for reducing damage from pest control operations. Major topics discussed are: Scope of Pesticide-Wildlife Problem; Effects on Wildlife-General; Laboratory Studies and Toxicology; Direct and Indirect Effects of Pesticides on Wildlife; Recent Pesticide Legislation; Value of Wildlife; and Recommendations for Safeguarding Wildlife Values during Pest Control. To avoid undue hazards to wildlife, applications must not exceed the toxicity equivalent of the following concentrations of DDT to the respective forms of wildlife: 0.1 pounds of DDT/acre for crustaceans; 0.2 for fish; 1.0 for amphibians; 2.0 for reptiles and birds; and 5.0 for most mammals. Other suggestions are: 1) Chemical treatment should be used only when entomological research has proved it to be necessary; 2) Before pesticides are used, the effects on different kinds of animals and on animals living in different habitats should be known and carefully considered; 3) Only minimum quantities of chemicals necessary to achieve adequate control of pests should be applied; 4) Pesticides should not be applied to areas that are any larger than is necessary and the chemicals that are used should be the ones whose effects are no more long-lasting than necessary; 5) Whenever possible, chemicals should be applied at the seasons of the year when wildlife damage will be least; 6) Conscientious effort should be made to be sure that pesticides are applied at no more than the intended rates and that no areas receive double doses. Alternates to chemical control are suggested. Among these are biological control, modified agricultural practices, destruction of insect wintering quarters, and the manipulation of water levels.

Circular↗

USGS1992

Waterfowl production on the Woodworth Station in south-central North Dakota, 1965-1981

During 17 years of study at the Woodworth, North Dakota study area, the percent of 548 wetland basin with water during 1-15 May ranged from 8 to 87 and averaged 56; waterfowl pair densities varied from 19 to 56/km2 and averaged 40/km2. Pond occupancy by duck pairs averaged 37% during mid-May counts and 48% for late May and early June counts. A positive linear relation occurred between the estimated number of duck pairs and the percent of basins with water during 1-15 May.There were 3,339 duck nests found in grassland habitats from 1966 through 1981. Approximately 66% (85% Mayfield) of these were depredated or abandoned. Mammals caused 88% of nest failures. Half or more of the eventually successful clutches were unhatched by 10 July in 9 of 16 years. Haying would have disturbed or destroyed an average of 43%, 33%, 22%, 15%, and 9% of the duck nests if initiated on 10 July, 15 July, 20 July, 25 July, and 1 August, respectively.The total average size of completed clutch for all species was 29% smaller at the end of the nesting season than at the beginning, underscoring the importance of protecting early clutches.Production averaged 30 broods per 100 pairs of ducks and ranged from 15 to 61 broods per 100 pairs. Brood densities ranged from 10 to 63/km2 and averaged 12/km2. Mean brood size averaged 6.4 for all species. July broods averaged 7.2 ducklings and August broods 5.7 ducklings. Duckling loss averaged 2.6 per brood and 85% (2.2 ducklings) of this loss was estimated to occur during the first 14 days after hatch.Wetlands of all sizes and classes were important at some time to one species of duck or another. With the exception of some diving ducks, all species used a complex of sizes and classes of wetlands for space, food, and shelter necessary for nesting and brooding. Pair counts during 20 May-7 June were most indicative of the breeding population. A combination of two brood counts resulted in the best estimate of annual production. An average of only 50% of the total duck broods per year was counted during the 1-15 July surveys, which approximated the average time of the Service's July aerial surveys. During this study the area produced an average of 1 duck per 4 ha of upland and had a nest density of approximately 1 nest per 14 ha. Nest success rates averaged 35.1% (16.3% Mayfield). Predation was significantly reduced by good vegetative cover at nest sites. Seeded grasslands (dense nesting cover) yielded better production than native prairie or croplands. Seeded grasslands also produced 3 times more ducklings per unit area than adjacent native prairie and more than 14 times as many as adjacent, annually tilled croplands.Ducks generally showed higher nest densities and better nesting success when using growing grain crops than when nesting in standing or mulched stubble fields. Among native mixed-grass prairie and seeded grassland, production was enhanced by leaving fields idle or by treating them with periodic burning. Duck production was generally lowered by grazing field of native prairie but duck production on grazing lands was higher than in annually tilled croplands.

Resource Publication↗

USGS2023

High winds and melting sea ice trigger landward movement in a polar bear population of concern

Some animal species are responding to climate change by altering the timing of events like mating and migration. Such behavioral plasticity can be adaptive, but it is not always. Polar bears ( Ursus maritimus ) from the southern Beaufort Sea subpopulation have mostly remained on ice year-round, but as the climate warms and summer sea ice declines, a growing proportion of the subpopulation is summering ashore. The triggers of this novel behavior are not well understood. Our study uses a parametric time-to-event model to test whether biological and/or time-varying environmental variables thought to influence polar bear movement and habitat selection also drive decisions to swim ashore. We quantified the time polar bears spent occupying offshore sea ice of varying ice concentrations. We evaluated variations in the ordinal date bears moved to land with respect to local environmental conditions such as sea ice concentration and wind across 10 years (2005–2015). Results from our study suggest that storm events (i.e., sustained high wind speeds) may force polar bears from severely degraded ice habitat and catalyze seasonal movements to land. Unlike polar bears long adapted to complete summer ice melt, southern Beaufort Sea bears that summer ashore appear more tolerant of poor-quality sea ice habitat and are less willing to abandon it. Our findings provide a window into emergent, climatically mediated behavior in an Arctic marine mammal vulnerable to rapid habitat decline.

Alaska↗

USGS2011

Host and viral ecology determine bat rabies seasonality and maintenance

Rabies is an acute viral infection that is typically fatal. Most rabies modeling has focused on disease dynamics and control within terrestrial mammals (e.g., raccoons and foxes). As such, rabies in bats has been largely neglected until recently. Because bats have been implicated as natural reservoirs for several emerging zoonotic viruses, including SARS-like corona viruses, henipaviruses, and lyssaviruses, understanding how pathogens are maintained within a population becomes vital. Unfortunately, little is known about maintenance mechanisms for any pathogen in bat populations. We present a mathematical model parameterized with unique data from an extensive study of rabies in a Colorado population of big brown bats (Eptesicus fuscus) to elucidate general maintenance mechanisms. We propose that life history patterns of many species of temperate-zone bats, coupled with sufficiently long incubation periods, allows for rabies virus maintenance. Seasonal variability in bat mortality rates, specifically low mortality during hibernation, allows long-term bat population viability. Within viable bat populations, sufficiently long incubation periods allow enough infected individuals to enter hibernation and survive until the following year, and hence avoid an epizootic fadeout of rabies virus. We hypothesize that the slowing effects of hibernation on metabolic and viral activity maintains infected individuals and their pathogens until susceptibles from the annual birth pulse become infected and continue the cycle. This research provides a context to explore similar host ecology and viral dynamics that may explain seasonal patterns and maintenance of other bat-borne diseases.

Proceedings of the National Academy of Sciences of↗

USGS1981

Population dynamics and bioenergetics of a fossorial herbivore, Thomomys talpoides (Rodentia: Geomyidae), in a spruce-fir sere

Studies of the bioenergetics of the northern pocket gopher, Thomomys talpoides , are coupled with data on demography, activity budgets, and microclimates to model the energy requirements of individuals and populations in the Wasatch Mountains of Utah during 1976-1979. Metabolic rates during rest increased linearly with decreasing ambient temperature, but burrowing metabolic rates (16.3 mL O 2 • h -1 • g -9.75 ) were independent of both temperature and physical properties of the soil. Radio-telemetry studies indicated that free-ranging gophers are active =50% of each day. Conservative estimates of true energy consumption were calculated using estimates of habitat-specific minimum daily burrowing requirements. Rates of burrowing measured in the laboratory were either ∞ 0.0 or ∞ 2.0 cm/min. The low burrowing rate was observed when the soil was frozen or saturated with water, as would occur in the field in early winter and in spring, respectively. Gophers burrowed through soil at the study site at an average rate of ∞ 1.5 cm/min. Belowground food energy densities at gopher foraging depth declined from 24.6 to 3.2 J/cm 3 along a successional gradient (subalpine forb meadow to Engelmann spruce dominated forest). We conclude that individual gophers are food limited within the climax spruce seral stage. Further, daily energy costs associated with reproduction in females may exceed the belowground energy supply available in intermediate seral stages (aspen and subalpine fir). Reduction of burrowing rates for any reason will affect gophers in the late seral stages proportionately more than those resident in the meadow. The peak gopher densities recorded (from 62 individuals/ha in the meadow to 2 individuals/ha in spruce forest) support these inferences. Detailed demographic information was obtained only in the meadow seral stage. Adult survivorship was lower in winter than in summer and varied greatly between years (0.18-0.70 yr -1 ). Juvenile survivorship from weaning through the first year was comparable to adult annual rates. The fertility rate was 3.75 young • female -1 • yr -1 . The energy supply and demand analyses indicate that the growth of Thomomys talpoides populations in the early seral stages is seldom directly limited by the amount of food present. From our demographic, environmental, and autecological studies we conclude that stochastic events associated with weather affect energy acquisition (burrowing) rates, and thus survivorship. In montane environments, such events may prevent populations from attaining sizes at which territorial behavior would hypothetically limit further increases. The energy flow through the meadow population at moderate to high )1976-1977) densities (at least 1100 MJ • ha -1 • yr -1 ) indicates that pocket gophers are proficient energy movers relative to non-fossorial small mammals. Subalpine T. talpoides populations appear commonly to attain such densities. More than 30% of the annual primary productivity allocated to belowground parts of meadow forbs may be consumed by gophers.

Ecological Monographs↗

USGS2014

Atrazine reduces reproduction in fathead minnow ( Pimephales promelas ): raw data report

The herbicide, atrazine, routinely is observed in surface and groundwaters, particularly in the “corn belt” region, a high-use area of the United States. Atrazine has demonstrated effects on reproduction in mammals and amphibians, but the characterization of endocrine-related effects in fish has received only limited attention. Peak concentrations of atrazine in surface water of streams from these agricultural areas coincide with annual spawning events of native fishes. Consequently, there was an unacceptable level of uncertainty in our understanding of the risks associated with the periods of greatest atrazine exposure and greatest vulnerability of certain species of fishes. For this reason, a study of the effects of atrazine on fathead minnow reproduction was undertaken (Tillitt and others, 2010). This report provides the raw data from that study.

Data Series↗

USGS2006

Assessment of gamete quality for the eastern oyster (Crassostrea virginica) by use of fluorescent dyes

Evaluation of sperm motility is the single most widely used parameter to determine semen quality in mammals and aquatic species. While a good indicator for fresh sperm viability, post-thaw motility is not always effective at predicting fertilizing ability. Techniques using fluorescent dyes can assess functionality of mammalian sperm, but have not been widely applied in aquatic organisms. The eastern oyster Crassostrea virginica is an important mollusk in the United States, and cryopreservation protocols have been developed to preserve sperm and larvae to assist research and hatchery production. In this study, protocols were developed to assess sperm cell membrane integrity and mitochondrial function by flow cytometry and to assess viability of eggs by fluorescence microscopy. The fluorescent dyes SYBR 14 and propidium iodide (PI) (to assess membrane integrity) and rhodamine 123 (R123) (to assess mitochondrial membrane potential) were used to evaluate the quality of thawed oyster sperm previously cryopreserved with different cryoprotectant and thawing treatments. Membrane integrity results were correlated with motility of thawed sperm and mitochondrial membrane potential with fertilizing ability. Fluorescein diacetate (FDA) was used to assess cytotoxicity of cryoprotectant solutions and post-thaw damage to oyster eggs. The results indicated that membrane integrity (P = 0.004) and thawing treatments (P = 0.04), and mitochondrial membrane potential (P = 0.0015) were correlated with motility. Fertilizing ability was correlated with cryoprotectant treatments (P = 0.0258) and with mitochondrial membrane potential (P = 0.001). The dye FDA was useful in indicating structural integrity of fresh and thawed eggs. Exposure of eggs, without freezing, to dimethyl sulfoxide yielded higher percentages of stained eggs and fertilization rate than did exposure to propylene glycol (P = 0.002). Thawed eggs were not stained with FDA (<1%) and larvae were not produced.

Cryobiology↗

USGS2017

A synthesis of thresholds for focal species along the U.S. Atlantic and Gulf Coasts: A review of research and applications

The impacts from climate change are increasing the possibility of vulnerable coastal species and habitats crossing critical thresholds that could spur rapid and possibly irreversible changes. For species of high conservation concern, improved knowledge of quantitative thresholds could greatly improve management. To meet this need, we synthesized information pertaining to biological responses as tipping points to sea level rise (SLR) and coastal storms for 45 fish, wildlife, and plant species along the U.S. Atlantic and Gulf Coasts and Caribbean through a literature review and expert elicitation. Although these species were selected based on their ecological, economic, and cultural importance, just over half (56%, n = 25) have quantitative threshold data currently available that can be used to assess the effects of SLR and storms during some aspect of their life history. Birds, reptiles, and plants represent the best studied coastal species. Thirteen of the species (29%) are projected to lose at least 50% of their population or habitat (e.g., foraging, nesting, spawning, or resting habitat) in some areas with a 0.5 m or greater rise in sea levels by 2100. Two species (a bird and reptile) may gain habitat from projected SLR and be resilient to future impacts. Numeric thresholds were not available for the remaining 20 species we searched for. Coastal fishes, mammals, and amphibians were among the groups representing a major information gap in this field of research. In addition, quantitative threshold responses to coastal storms were scarce for all taxa. While vulnerability assessments and qualitative research related to the impacts of SLR and storms on coastal species and habitats are increasing, work that incorporates quantitative thresholds as response and impact metrics remains limited. Additional monitoring, modeling, and research that provides multiple quantitative thresholds across species' life stages and/or latitudinal gradients is ideal to support robust coastal management and decision-making across spatio-temporal scales in the face of climate change.

Ocean and Coastal Management↗

USGS1989

Persistent infections of fish cell lines by paramyxovirus isolates from Chinook salmon ( Oncorhynchus tschawytscha )

We have reported the isolation of a paramyxovirus from stocks of adult chinook salmon ( Oncorhynchus tshawytscha ) returning to coastal rivers of Oregon, USA (Winton et al 1985). The isolates were obtained from kidney and spleen tissues using the chinook salmon embryo cell line, CHSE-214. Initial cytopathic effect (CPE) was slow to develop, requiring 28 days incubation at 18°C. The virus replicated in CHSE-214, chum heart (CHH-1), kokanee ovary (K0-6), coho salmon embryo (CSE-119), and fathead minnow (FHM) cell lines where it produced a lytic type of CPE. The virus was stable at pH 3-11 and iodo-deoxyuridine did not inhibit wiral replication. Infectivity was lost after treatment with chloroform indicating the presence of essential lipids. The density of virions in CsCl was 1.2 g/ml. The virus hemagglutinated cells of 11 of 14 species of birds, mammals, and fish tested. Electron microscopy of infected cells revealed enveloped particles 125-250 nm in dia. containing coiled nucleocapsids and examination of freon-treated virions showed the nucleocapsid was a helix approximately 18 nm in dia. and > 1000 nm in length (Winton et al 1985). In addition to causing hemagglutination, members of the Paramyxoviridae are known for the ability to establish persistent infections of cell lines (Choppin and Compans 1975). The purpose of this study was to determine if the paramyxovirus isolates from salmon were able to establish persistent infections in fish cell lines and to study the nature of the infection.

Book chapter↗

USGS2000

Examining ecological consequences of feral horse grazing using exclosures

Although feral horses have inhabited western North America since the end of the 16th century, relatively little synecological research has been conducted to quantitatively characterize how they interact with ecosystem components. Because feral horses exhibit watering behavior markedly different from that of domestic cattle, it is particularly important to evaluate response of ecosystem elements near water sources to horse use. To assess this response, we performed live-trapping of small mammals and 2-tiered vegetative sampling in 2 mountain ranges in central Nevada in the interior Great Basin, USA. At low elevations, plots around horse-excluded springs exhibited notably greater plant species richness, percent cover, and abundance of grasses and shrubs, as well as more small mammal burrow entrances than plots at horse-grazed springs. At high elevations, meadows protected from grazing exhibited maximum vegetation heights 2.8 times greater than vegetation grazed by horses only and 4.5 times greater than vegetation grazed by horses and cattle. Species richness in quadrats was most different between the horse-and-cattle-grazed meadow and its ungrazed counterpart, suggesting the possibility of synergistic effects of horse and cattle grazing in the same location. This study, the first in the Great Basin to investigate quantitatively ecosystem consequences of feral horse use with exclosures, represents a preliminary step in identifying factors that determine the magnitude of horse grazing impacts.

Western North American Naturalist↗