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At least 397 records · Page 22Linked to original sources

USGS2017

Status of scientific knowledge, recovery progress, and future research directions for the Gulf Sturgeon, Acipenser oxyrinchus desotoi Vladykov, 1955

The Gulf Sturgeon, Acipenser oxyrinchus desotoi , is an anadromous species of Acipenseridae and native to North America. It currently inhabits and spawns in the upper reaches of seven natal rivers along the northern coast of the Gulf of Mexico from the Suwannee River, Florida, to the Pearl River, Louisiana, during spring to autumn. Next to the Alligator Gar (Atractosteus spatula) , the Gulf Sturgeon is currently the largest fish species occurring in U.S. Gulf Coast rivers, attaining a length of 2.35 m and weights exceeding 135 kg, but historically attained a substantially larger size. Historically, the spawning populations existed in additional rivers from which the species has been wholly or nearly extirpated, such as the Mobile and Ochlockonee rivers, and possibly the Rio Grande River. Most Gulf Sturgeon populations were decimated by unrestricted commercial fishing between 1895–1910. Subsequently most populations remained unrecovered or extirpated due to continued harvest until the 1970s–1980s, and the construction of dams blocking access to ancestral upriver spawning grounds. Late 20th Century harvest bans and net bans enacted by the several Gulf Coast states have stabilized several populations and enabled the Suwannee River population to rebound substantially and naturally. Hatchery supplementation has not been necessary in this regard to date. Sturgeon are resilient and adaptable fishes with a geological history of 150 million years. Research undertaken since the 1970s has addressed many aspects of Gulf Sturgeon life history, reproduction, migration, population biology, habitat requirements, and other aspects of species biology. However, many knowledge gaps remain, prominently including the life history of early developmental stages in the first year of life. Natural population recovery is evident for the Suwannee River population, but seems promising as well for at least four other populations. The Pascagoula and Pearl River populations face a challenging future due a combination of natural and anthropogenic factors. These two populations, and perhaps the Escambia River population, are particularly vulnerable to periodic mass mortality due to major stochastic events including hurricanes, flooding, hypoxia, and toxic spills. The present manuscript provides a comprehensive synthesis of knowledge regarding the Gulf Sturgeon at the organismal and population levels, identifying knowledge gaps as priorities for future research. Topics not treated in the present synthesis include morphology, internal biology, physiology, and endocrinology. Topics only briefly treated include parasites and diseases, contaminants, and sturgeon aquaculture.

Journal of Applied Ichthyology↗

USGS2021

Advances in the use of lampricides to control sea lampreys in the Laurentian Great Lakes, 2000–2019

The periodic application of chemical lampricides that selectively kill larval sea lampreys ( Petromyzon marinus ) in their nursery habitats remains a primary component of the Great Lakes Fishery Commission’s (GLFC) Sea Lamprey Control Program in the Laurentian Great Lakes. Lampricides include 3-trifluoromethyl-4-nitrophenol (TFM) and niclosamide, the 2-aminoethanol salt of 2′, 5-dichloro-4′-nitrosalicylanilide, which may be used as an additive to TFM during stream treatments, or alone in a granular, bottom-release formulation to target sea lamprey larvae in deepwater environments where dilution would render TFM ineffective. During the early 1990s, the GLFC identified lampricide reduction targets in response to societal concerns with pesticide use, rising lampricide costs, and promising research into alternative controls. By 1999, the GLFC’s control agents, Fisheries and Oceans Canada (DFO) and the U.S. Fish and Wildlife Service (USFWS), had reduced TFM use by 36%. However, without effective alternative methods to compensate for increasing larval and juvenile production, sea lamprey abundance and lake trout ( Salvelinus namaycush ) marking rates rose throughout the Great Lakes. Beginning in the early 2000s, the GLFC and its control agents responded to burgeoning sea lamprey populations by implementing measures to advance the use of lampricides, which included: 1) assessing and controlling sea lamprey larvae that survived treatment; 2) enhancing treatment efficacy; 3) developing new technology to effectively treat larval populations that inhabit deepwater environments; 4) increasing operational capacity to treat more tributaries and lentic areas at shorter intervals; and, 5) conducting large-scale and targeted treatment strategies. When comparing lampricide use between the decades of 1990–1999 and 2010–2019, significant increases occurred in the mean number of treatments and amounts of TFM and niclosamide applied annually. Concurrent with these actions, researchers undertook studies to identify factors that erode lampricide treatment efficiency, elucidate physiological mode of action, and investigate lethal and sub-lethal impacts of lampricide exposure on aquatic organisms. By integrating new operational tactics and strategies with advances in science and technology, the GLFC, DFO, and USFWS, with support from the U.S. Geological Survey and the U.S. Army Corps of Engineers, have achieved unprecedented suppression of sea lampreys and reduction in lake trout marking in the Great Lakes. However, emerging challenges potentially threaten the future use of lampricides.

Journal of Great Lakes Research↗

USGS2024

Dopaminergic and anti-estrogenic responses in juvenile steelhead (Oncorhynchus mykiss) exposed to bifenthrin

The frequency of detection and concentrations of bifenthrin, a pyrethroid insecticide, in the waterways inhabited by the endangered species, steelhead trout ( Oncorhynchus mykiss ), has become a significant concern for regulatory agencies. Endocrine disruption has been observed with estrogenic and anti-estrogenic responses in fish species at different life stages. Since several studies have indicated alterations in dopaminergic signaling associated with endocrine responses, juvenile steelhead were exposed to environmentally relevant concentrations of 60 or 120 ng/L bifenthrin for two weeks. Fish brains were assessed for dopamine levels and the expression of genes involved in dopaminergic and estrogenic processes, such as catechol- o -methyltransferase ( comt ) and monoamine oxidase ( mao ). Vitellogenin ( vtg ) and estrogenic receptors ( ERα1 , ERβ1 , and ERβ2 ) were also evaluated in livers of the animals. Dopamine concentrations were significantly higher in fish brains following bifenthrin exposure. Consistent with a reduction in dopamine clearance, there was a significant decrease in the mRNA expression of comt with increased bifenthrin concentration. Hepatic expression of ERα1 and ERβ2 mRNA was significantly decreased with increased bifenthrin concentration. These data support the possible mechanism of bifenthrin altering the dopaminergic pathway at low ng/L concentrations, in juvenile steelhead, which could interfere with endocrine feedback loops. These findings support the need for and importance of identifying species and life stage differences in pesticide modes of action to reduce uncertainties in risk assessments.

Comparative Biochemistry and Physiology Part C: To↗

USGS2004

Intra-strain dioxin sensitivity and morphometric effects in swim-up rainbow trout ( Oncorhynchus mykiss )

Inter and intra-specific differences in sensitivity of early life stage salmonids to 2,3,7,8-TCDD exposure have been reported, but intra-strain differences have not been found in the literature. Our results indicate that intra-strain variability in terms of embryo mortality (LD50) is small in Eagle Lake strain of rainbow trout, LD50 values ranging from 285 to 457 pg TCDD egg g −1 . These results confirm Eagle Lake as a less sensitive strain within rainbow trout, and do not indicate overlap with reported LD50 values for brook or lake trout. Our results also demonstrate that although generalized edema in regions including the yolk-sac are frequently associated with mortality following dioxin exposure, not all edematous fish die. We detected dose-dependent decreases in cranial length, eye diameter, mass, and total length ( P <0.05) in viable swim-up rainbow trout. These effects are presumed to indicate more subtle dose-dependent disruptions of the viteline vein vasculature and, therefore, in access to energy sources. A tendency for dose-dependent decrease in liver glycogen reserves concurred with previous results on salmonids and with the well described TCDD-induced alterations in intermediate metabolism of rats and chicken embryos (wasting syndrome). This syndrome could be contributing to the reduced growth that we observed.

Comparative Biochemistry and Physiology, Part C: T↗

USGS1970

The effect of anesthetization and urinary bladder catheterization on renal function of rainbow trout

1. Rainbow trout were anesthetized with MS-222 (Sandoz) or methylpentynol and catheterized. Urine was collected at selected intervals up to 48 hr. 2. Effects of MS-222 anesthesia on urine flow and composition were isolated from the stress of catheterization by re-anesthetizing the fish 18 to 20 hr post catheterization. 3. Urine output patterns were similar following MS-222 or methylpentynol anesthesia and catheterization. Highest urine flows were measured 4 to 8 hr post treatment. The highest urine output after re-anesthetization with MS-222 was observed 2 to 4 hr post-anesthesia. 4. Highest concentrations of Na 2+ , K + , Ca 2+ , Cl - and inorganic PO 4 in the urine were measured in the first 2 hr after anesthesia and catheterization. 5. Flow rates and chemical composition of urine indicate that "normal" renal function is re-established 12 to 24 hr post-treatment.

Comparative Biochemistry and Physiology↗

USGS2005

Preliminary results from a shallow water benthic grazing study

The nutrient-rich, shallow waters of San Francisco Bay support high rates of primary production, limited not by nutrients but by light availability and benthic grazing (Alpine and others 1992; Cloern 1982). Phytoplankton blooms are an important food source for upper trophic levels. Consequently animal populations, such as fish, may suffer under conditions of high benthic bivalve grazing. It has been hypothesized that several species of fish are suffering as a result of severe decreases in available phytoplankton since the introduction of Potamocorbula amurensis into San Francisco Bay (Feyrer 2003). The extent of reduction in phytoplankton biomass by benthic bivalves is dependent on both physical and biological factors in addition to their spatial and temporal variability. Physical factors identified as important include: (1) vertical mixing rates, which are a function of wind velocity, currents, and bottom roughness; (2) suspended sediment concentrations; and (3) phytoplankton settling rates. The biological factors controlling the extent of phytoplankton grazing include animal density and organism size, pumping rate, food type and concentration, metabolic demands, assimilation efficiency, and behaviour (Wildish and Kristmanson 1997). Several laboratory studies involving model and live clams have shown that benthic grazers can deplete phytoplankton in the water column (for example, Cole and others 1992). Initially, these studies assumed that the water column remained well mixed above benthic suspension feeders; therefore, parameters measured in the bulk water column were believed to be representative of available particle concentration. For this reason many relationships describing the influence of the bulk flow and bulk seston concentration on benthic grazers physiological processes exist (for example, Levinton 1991). Laboratory measurements using live animals have shown that filtration rates vary with free stream velocity (for example, Levinton 1991). Increases in current speed lead to an increase in filtration rate; however, several studies have shown that filtration may cease at some critical current speed. It has been suggested that resuspension, occurring as a result of high current speeds, may be a factor that negatively affects uptake (Cloern 1987; Levinton 1991). Several mechanisms have been invoked to explain the effects of low speed on growth rates of active suspension feeders. These mechanisms include the formation of a concentration boundary layer and the limiting horizontal flux of seston. It is now accepted that a combination of these factors dictates the growth success of benthic grazers in a particular area. Several field studies have shown that concentration boundary layers can form over benthic ecosystems (for example, Frechette and others 1989, Dolmer 2000); however, many of these studies have failed to measure the hydrodynamics needed to calculate benthic grazing rates. Furthermore, calculating benthic grazing rates with vertical measurements at a single point is problematic due to lack of knowledge of the horizontal gradients in seston (Thompson and others, forthcoming). Despite great improvements in our knowledge on the effects of benthic grazers on seston concentrations in water columns, the effects of different hydrodynamic conditions on grazing rates has not been formulated. This makes it difficult to assess the system-wide effect of the benthic ecosystem on phytoplankton concentrations. Furthermore, it affects our ability to predict the potential success of a benthic species, such as the invasive clams Corbicula fluminea and Potamocorbula amurensis. This paper presents the preliminary results of a control volume approach to elucidate the effect of different hydrodynamic conditions on the grazing rates of Corbicula fluminea.

California↗

USGS2018

Refining aging criteria for northern sea otters in Washington State

Measurement of skull ossification patterns is a standard method for aging various mammalian species and has been used to age sea otters Enhydra lutris from Russia, California, and Alaska. Cementum annuli counts have also been verified as an accurate aging method for sea otters in Alaska. In this study, we compared cementum annuli count results and skull ossification patterns as methods for aging the northern sea otter, E. l. kenyoni, in Washington State. We found significant agreement between the two methods, suggesting that either method could be used to age sea otters in Washington. We found that ossification of the squamosal–jugal suture at the ventral glenoid fossa can be used to differentiate male subadults from adults. To assist field biologists or others without access to cementum annuli or skull ossification analysis techniques, we analyzed a suite of morphologic, physiologic, and developmental characteristics to assess whether a set of these more easily accessible parameters could also predict age class. We identified tooth condition score, evidence of reproductive activity in females, and tooth eruption pattern as the most useful criteria for classifying sea otters in Washington. We created a simple decision tree based on characteristics accessible in the field or at necropsy, which can be used to reliably predict age class of Washington sea otters as determined by cementum annuli. These techniques offer field biologists and marine mammal stranding networks a replicable, cost-conscious methodology to gather useful biological information from sea otters.

Washington↗

USGS2006

The chlorinated AHR ligand 3,3′,4,4′,5-pentachlorobiphenyl (PCB126) promotes reactive oxygen species (ROS) production during embryonic development in the killifish ( Fundulus heteroclitus )

Exposure to dioxin-like chemicals that activate the aryl hydrocarbon receptor (AHR) can result in increased cellular and tissue production of reactive oxygen species (ROS). Little is known of these effects during early fish development. We used the fish model, Fundulus heteroclitus , to determine if the AHR ligand and pro-oxidant 3,3′,4,4′,5-pentachlorobiphenyl (PCB126) can increase ROS production during killifish development, and to test a novel method for measuring ROS non-invasively in a living organism. The superoxide-sensitive fluorescent dye, dihydroethidium (DHE), was used to detect in ovo ROS production microscopically in developing killifish exposed to PCB126 or vehicle. Both in ovo CYP1A activity (ethoxyresorufin- o -deethylase, EROD) and in ovo ROS were induced by PCB126. In ovo CYP1A activity was inducible by PCB126 concentrations as low as 0.003 nM, with maximal induction occurring at 0.3 nM PCB126. These PCB126 concentrations also significantly increased in ovo ROS production in embryonic liver, ROS being detectable as early as 5 days post-fertilization. These data demonstrate that the pro-oxidant and CYP1A inducer, PCB126, increases both CYP1A activity and ROS production in developing killifish embryos. The superoxide detection assay (SoDA) described in this paper provides a semi-quantitative, easily measured, early indicator of altered ROS production that can be used in conjunction with simultaneous in ovo measurements of CYP1A activity and embryo development to explore functional relationships among biochemical, physiological and developmental responses to AHR ligands.

Aquatic Toxicology↗

USGS2016

Gut content analysis of Lake Michigan waterbirds in years with avian botulism type E mortality, 2010–2012

Waterbird die-offs caused by Clostridium botulinum neurotoxin type E (BoNT/E) have occurred sporadically in the Great Lakes since the late 1960s, with a recent pulse starting in the late 1990s. In recent die-offs, round gobies ( Neogobius melanostomus ) have been implicated as vectors for the transfer of BoNT/E to fish-eating birds due to the round goby invasion history and their importance as prey. Dreissenid mussels ( Dreissena spp.) are also potentially involved in BoNT/E transmission to birds and round gobies. We examined gut contents of waterbirds collected in Lake Michigan during die-offs in 2010–2012, and the gut contents of culled, presumably BoNT/E-free double-crested cormorants ( Phalacrocorax auritus ). Round gobies were found in 86% of the BoNT/E-positive individuals, 84% of the BoNT/E-negative birds, and 94% of the BoNT/E-free cormorants examined. Double-crested cormorants, ring-billed gulls ( Larus delewarensis ), and common loons ( Gavia immer ) consumed larger-sized round gobies than horned and red-necked grebes ( Podiceps auritus and Podiceps grisegena ), white-winged scoters ( Melanitta deglandi ), and long-tailed ducks ( Clangula hymealis ). Other common prey included dreissenid mussels, terrestrial insects, and alewives ( Alosa pseudoharengus ). Our data emphasize the importance of round gobies and mussels in diets of Lake Michigan waterbirds and suggest they may play a role in the transfer of BoNT/E to waterbirds; however, round gobies and mussels were found in BoNT/E-positive, -negative, and -free individuals, suggesting that other factors, such as alternative trophic pathways for toxin transfer, bird migratory timing and feeding locations, prey behavior, and individual physiological differences across birds may affect the likelihood that a bird will succumb to BoNT/E intoxication.

Journal of Great Lakes Research↗

USGS2014

Photoperiod control of downstream movements of Atlantic salmon Salmo salar smolts

This study provides the first direct observations that photoperiod controls the initiation of downstream movement in Atlantic salmon Salmo salar smolts. Under simulated natural day length (LDN) conditions and seasonal increases in temperature, smolts increased their downstream movements five-fold for a period of 1 month in late spring. Under the same conditions, parr did not show changes in downstream movement behaviour. When given a shortened day length (10L:14D) beginning in late winter, smolts did not increase the number of downstream movements. An early increase in day length (16L:8D) in late winter resulted in earlier initiation and termination of downstream movements compared to the LDN group. Physiological status and behaviour were related but not completely coincident: gill Na + /K + -ATPase activity increased in all treatments and thyroid hormone was elevated prior to movement in 16L:8D treatment. The most parsimonious model describing downstream movement of smolts included synergistic effects of photoperiod treatment and temperature, indicating that peak movements occurred at colder temperatures in the 16L:8D treatment than in LDN, and temperature did not influence movement of smolts in the 10L:14D treatment. The complicated interactions of photoperiod and temperature are not surprising since many organisms have evolved to rely on correlations among environmental cues and windows of opportunity to time behaviours associated with life-history transitions. These complicated interactions, however, have serious implications for phenological adjustments and persistence of S . salar populations in response to climate change.

Journal of Fish Biology↗

USGS2021

Disruption of the Francisella noatunensis orientalis pdpA gene results in virulence attenuation and protection in zebrafish

Several Francisella spp. including F. noatunensis are regarded as important emerging pathogens of wild and farmed fish. However, very few studies have investigated the virulence factors that allow these bacterial species to be pathogenic in fish. The Francisella Pathogenicity Island (FPI) is a well-described, gene-dense region encoding major virulence factors for the genus Francisella. PdpA is a member of the pathogenicity determining protein genes encoded by the FPI that are implicated in the ability of the mammalian pathogen, F. tularensis , to escape and replicate in infected host cells. Using a sacB suicide approach, we generated pdpA knockouts to address the role of PdpA as a virulence factor for F. noatunensis . Because polarity can be an issue in gene-dense regions, we generated two different marker-based mutants in opposing polarity ( Fno Δ pdpA1 and Δ pdpA2 ). Both mutants were attenuated (p<0.0001) in zebrafish challenges and displayed impaired intracellular replication (p<0.05) and cytotoxicity (p<0.05), all of which could be restored to wild-type (WT) levels by complementation for Fno Δ pdpA 1. Importantly, differences were found for bacterial burden and induction of acute phase and pro-inflammatory genes for Fno Δ pdpA 1 and Δ pdpA 2 compared to WT during acute infection. In addition, neither mutant resulted in significant histopathological changes. Finally, immunization with Fno Δ pdpA1 led to protection (p<0.012) against an acute lethal-dose 40 challenge with WT Fno in the zebrafish model of infection. Taken together, this study further demonstrates physiological similarities within the genus Francisella relative to their phylogenetic relationships and the utility of zebrafish for addressing virulence factors for the genus.

Infection and Immunity↗

USGS2009

Egg fatty acid composition from lake trout fed two Lake Michigan prey fish species.

We previously demonstrated that there were significant differences in the egg thiamine content in lake trout Salvelinus namaycush fed two Lake Michigan prey fish (alewife Alosa pseudoharengus and bloater Coregonus hoyi). Lake trout fed alewives produced eggs low in thiamine, but it was unknown whether the consumption of alewives affected other nutritionally important components. In this study we investigated the fatty acid composition of lake trout eggs when females were fed diets that resulted in different egg thiamine concentrations. For 2 years, adult lake trout were fed diets consisting of four combinations of captured alewives and bloaters (100% alewives; 65% alewives, 35% bloaters; 35% alewives, 65% bloaters; and 100% bloaters). The alewife fatty acid profile had higher concentrations of arachidonic acid and total omega-6 fatty acids than the bloater profile. The concentrations of four fatty acids (cis-13, 16-docosadienoic, eicosapentaenoic, docosapentaenoic, and docosahexaenoic acids) were higher in bloaters than in alewives. Although six fatty acid components were higher in lake trout eggs in 2001 than in 2000 and eight fatty acids were lower, diet had no effect on any fatty acid concentration measured in lake trout eggs in this study. Based on these results, it appears that egg fatty acid concentrations differ between years but that the egg fatty acid profile does not reflect the alewife-bloater mix in the diet of adults. The essential fatty acid content of lake trout eggs from females fed alewives and bloaters appears to be physiologically regulated and adequate to meet the requirements of developing embryos.

Journal of Aquatic Animal Health↗

USGS2016

Transcriptome discovery in non-model wild fish species for the development of quantitative transcript abundance assays

Environmental studies increasingly identify the presence of both contaminants of emerging concern (CECs) and legacy contaminants in aquatic environments; however, the biological effects of these compounds on resident fishes remain largely unknown. High throughput methodologies were employed to establish partial transcriptomes for three wild-caught, non-model fish species; smallmouth bass ( Micropterus dolomieu ), white sucker ( Catostomus commersonii ) and brown bullhead ( Ameiurus nebulosus ). Sequences from these transcriptome databases were utilized in the development of a custom nCounter CodeSet that allowed for direct multiplexed measurement of 50 transcript abundance endpoints in liver tissue. Sequence information was also utilized in the development of quantitative real-time PCR (qPCR) primers. Cross-species hybridization allowed the smallmouth bass nCounter CodeSet to be used for quantitative transcript abundance analysis of an additional non-model species, largemouth bass ( Micropterus salmoides ). We validated the nCounter analysis data system with qPCR for a subset of genes and confirmed concordant results. Changes in transcript abundance biomarkers between sexes and seasons were evaluated to provide baseline data on transcript modulation for each species of interest.

Comparative Biochemistry and Physiology, Part D: G↗

USGS2004

Interaction of xenobiotics with estrogen receptors α and β and a putative plasma sex hormone-binding globulin from channel catfish ( Ictalurus punctatus )

Estrogens are important regulators of physiological functions. Although environmental contaminants (xenoestrogens) which interfere with estrogen signaling are of increasing concern, there is only limited information about their ability to interact with estrogen-binding proteins (SHBG) or receptors (ER). Recombinant ER?? and ?? were obtained after transient transfection of COS-7 cells with channel catfish ER cDNA. Plasma from adult female channel catfish was the source of SHBG. Tritiated estradiol ( 3H-E2) was used in standard radioligand-binding assays to characterize the binding properties of channel catfish SHBG (ccfSHBG) and to estimate the inhibition constants for various estrogenic compounds. Binding of 3H-E2 to ccfSHBG was saturable and of high affinity with a Kd (??SE) of 1.9??0.14nM and a Bmax of 14.3??2.4pmol/mg protein (n=3 assays). Additionally, ccfSHBG displayed binding specificity for androgens and estrogens. Endosulfan, 4-nonylphenol, and 4-octylphenol displaced 3H-E2 binding to ccfSHBG albeit only at very high concentrations, whereas dieldrin and atrazine showed little displacement activity even at the highest concentrations used. The synthetic estrogen ethynylestradiol had higher affinity than E2 for ccfSHBG. This finding differs from results with human and rainbow trout SHBG. The alkylphenolic compounds (4-octylphenol and 4-nonylphenol) displayed some ability to displace 3H-E2 binding from ER?? and ?? at high concentrations, but dieldrin and atrazine had little binding activity for both ER subtypes and endosulfan for ER??. The xenobiotics tested generally showed equivalent or greater affinity for ER?? than ER??, whereas natural estrogens had much greater affinity for ER?? than ER??. These observations suggest that results of studies using fish tissue ER extracts must be interpreted with caution, since both ER subtypes may be present, and that the binding of xenoestrogens to SHBG must be taken into account for proper assessment of endocrine disruption caused by environmental contaminants.

General and Comparative Endocrinology↗

USGS2012

White-nose syndrome in bats: U.S. Geological Survey updates

White-nose syndrome (WNS) is a devastating disease that has killed millions of hibernating bats since it first appeared in New York in 2007 and has spread at an alarming rate from the northeastern to the central United States and Canada. The disease is named for the white fungus Geomyces destructans that infects the skin of the muzzle, ears, and wings of hibernating bats. The U.S. Geological Survey (USGS) National Wildlife Health Center (NWHC), the USGS Fort Collins Science Center, the U.S. Fish and Wildlife Service, and other partners continue to play a primary role in WNS research. Studies conducted at the NWHC led to the discovery (Blehert and others, 2009), characterization, and naming (Gargas and others, 2009) of the cold-loving fungus G. destructans and to the development of standardized criteria for diagnosing the disease (Meteyer and others, 2009). Additionally, scientists at the NWHC have pioneered laboratory techniques for studying the effects of the fungus on hibernating bats (Lorch and others, 2011). To determine if bats are affected by white-nose syndrome, scientists look for a characteristic microscopic pattern of skin erosion caused by G. destructans (Meteyer and others, 2009). Field signs of WNS can include visible white fungal growth on the bat's muzzle, wings, or both, but these signs alone are not a reliable disease indicator - laboratory examination and testing are required for disease confirmation. Infected bats also arouse from hibernation more frequently than uninfected bats (Warnecke and others, 2012) and often display abnormal behaviors in their hibernation sites, such as congregating at or near cave openings and daytime flights during winter. These abnormal behaviors may contribute to the bat's accelerated consumption of stored fat reserves, causing emaciation, a characteristic documented in some of the bats that die with WNS. During hibernation, bats likely have lowered immunity (Bouma and others, 2010), which may facilitate the ability of G. destructans to colonize and damage large areas of wing membrane (fig. 2). A current hypothesis suggests that erosion or ulceration of wing membrane caused by the fungus has the potential to alter the physiology of hibernating bats, resulting in fatal disruption of hydration, electrolyte balance, circulation, and thermoregulation (Cryan and others, 2010). Current estimates of bat population declines in the northeastern United States since the emergence of WNS are over 80 percent (Turner and others, 2011). This sudden and widespread mortality associated with WNS is unprecedented in hibernating bats, among which large-scale disease outbreaks have not been previously documented. It is unlikely that species of bats affected by WNS will recover quickly because most are long-lived and have only a single pup per year. Consequently, repopulation after widespread mortality of breeding adults will be a slow process. Worldwide, bats play essential roles as pollinators, seed dispersers, and as primary consumers of insects. The true ecological consequences of the recent large-scale reductions in populations of hibernating bats are not yet known. However, farmers might feel the impact. A recent economic analysis indicated that insect control services (ecosystem services) provided by bats to U.S. agriculture is valued between 4 to 50 billion dollars nationwide per year (Boyles and others, 2011). The number of North American bats estimated to have died from WNS thus far had the capacity to consume up to 8,000 tons of insects per year (Boyles and others, 2011). The area of North America affected by WNS continues to expand. Within the last 2 years, the disease has been confirmed in several Central States, including Alabama, Indiana, Kentucky, Ohio, Tennessee, and Missouri. High mortality of bats has not yet been reported at these locations, and it remains to be seen if WNS will develop and manifest in other States with the same severity as that in the Northeast.

Alabama;Connecticut;Delaware;Illinois;Indiana;Iowa↗

USGS2001

Dietary restriction causes chronic elevation of corticosterone and enhances stress response in red-legged kittiwake chicks

Release of corticosterone in hungry kittiwake chicks facilitates begging and allows them to restore depleted energy reserves by increasing parental food provisioning. However, in order to avoid detrimental effects of chronic elevation of corticosterone, chicks might suppress adrenocortical activity in response to prolonged food shortages. In this study we examined temporal dynamics of corticosterone release in red-legged kittiwake (Rissa brevirostris) chicks exposed to prolonged restrictions in energy content and/or nutritional quality (low versus high lipid content) of their food. Starting at the age of 15 days, chicks were fed either high- or low-lipid fish at 40%, 65%, and 100% of ad libitum energy intake. Body mass measurements and baseline plasma samples were taken on a weekly basis after beginning of the treatment. After 3 weeks of treatment, chicks were exposed to a standardized acute handling and restraint stress protocol, where in addition to a baseline sample, three plasma samples were taken at intervals up to 50 min. We found that food-restricted chicks had lower body mass, chronically (during 2-3 weeks) elevated baseline and higher acute stress-induced levels of corticosterone compared to chicks fed ad libitum. Low lipid content of food further exacerbated these effects. An increase in baseline levels of corticosterone was observed within a week after energy requirements of food-restricted chicks exceeded their daily energy intake. A tendency for suppression of adrenocortical activity was observed in treatments fed low-lipid diets only at the end of the experiment. We suggest that nest-bound chicks, if food-stressed, might suffer deleterious effects of chronic elevation of corticosterone.

Journal of Comparative Physiology B: Biochemical, ↗

USGS2009

Lead in the environment

Anthropogenic uses of lead have probably altered its availability and environmental distribution more than any other toxic element. Consequently, lead concentrations in many living organisms may be approaching thresholds of toxicity for the adverse effects of lead. Such thresholds are difficult to define, as they vary with the chemical and physical form of lead, exposure regime, other elements present and also vary both within and between species. The technological capability to accurately quantify low lead concentrations has increased over the last decade, and physiological and behavioral effects have been measured in wildlife with tissue lead concentrations below those previously considered safe for humans.s.236 Consequently. lead criteria for the protection of wildlife and human health are frequently under review, and 'thresholds' of lead toxicity are being reconsidered. Proposed lead criteria for the protection of natural resources have been reviewed by Eisler. Uptake of lead by plants is limited by its generally low availability in soils and sediments, and toxicity may be limited by storage mechanisms and its apparently limited translocation within most plants. Lead does not generally accumulate within the foliar parts of plants, which limits its transfer to higher trophic levels. Although lead may concentrate in plant and animal tissues, no evidence of biomagnification exists. Acid deposition onto surface waters and soils with low buffering capacity may influence the availability of lead for uptake by plants and animals, and this may merit investigation at susceptible sites. The biological significance of chronic low-level lead exposure to wildlife is sometimes difficult to quantify. Animals living in urban environments or near point sources of lead emission are inevitably subject to greater exposure to lead and enhanced risk of lead poisoning. Increasingly strict controls on lead emissions in many countries have reduced exposure to lead from some sources. and the .reduction of lead in gasoline has resulted in lower tissue lead concentrations in humans and wildlife from many, particularly urban, locations. However, it has been suggested that increasing use of organic lead compounds as catalysts for the production of plastics and as wood preservatives and biocides could adversely affect wildlife. The most significant source of direct wildlife mortality from lead is spent gunshot and fishing sinkers. Elevated mortality from shot ingestion in avian species resulted in the introduction of nontoxic (steel) shot zones along certain flyways in the United States in the mid-1970s and a total ban on the use of lead for waterfowl and coot hunting nationwide by 1992. Several other countries are now following suit and have either banned or are in the process of restricting the use of lead shot for waterfowl hunting. In the United States it has been estimated that since the 1986 hunting season. when the use of nontoxic shot became widespread. over 6 million ducks have not been lost to lead poisoning. Raptors, especially eagles, have also apparently benefited. although lead poisoning from ingestion of bullet fragments remains a problem for the critically threatened California condor. Quantifying reductions in lead mortality rates would be difficult since eagle populations throughout North America are rapidly recovering from other anthropogenic perturbations, especially organochlorine pesticides.

Book chapter↗

USGS2022

Identification of supraoptimal temperatures in juvenile blueback herring (Alosa aestivalis) using survival, growth rate and scaled energy reserves

For young fishes, growth of somatic tissues and energy reserves are critical steps for survival and progressing to subsequent life stages. When thermal regimes become supraoptimal, routine metabolic rates increase and leave less energy for young fish to maintain fitness-based activities and, in the case of anadromous fishes, less energy to prepare for emigration to coastal habitats. Thus, understanding how energy allocation strategies are affected by thermal regimes in young anadromous fish will help to inform climate-ready management of vulnerable species and their habitat. Blueback herring ( Alosa aestivalis ) are an anadromous fish species that remain at historically low population levels and are undergoing southern edge-range contraction, possibly due to climate change. We examined the effects of temperature (21°C, 24°C, 27°C, 30°C, 33°C) on survival, growth rate and energy reserves of juveniles collected from the mid-geographic range of the species. We identified a strong negative relationship between temperature and growth rate, resulting in smaller juveniles at high temperatures. We observed reduced survival at both 21°C and 33°C, increased fat and lean mass-at-length at high temperatures, but no difference in energy density. Juveniles were both smaller and contained greater scaled energy reserves at higher temperatures, indicating growth in length is more sensitive to temperature than growth of energy reserves. Currently, mid-geographic range juvenile blueback herring populations may be well suited for local thermal regimes, but continued warming could decrease survival and growth rates. Blueback herring populations may benefit from mitigation actions that maximize juvenile energy resources by increasing the availability of cold refugia and food-rich habitats, as well as reducing other stressors such as hypoxic zones.

Conservation Physiology↗