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At least 433 records · Page 24Linked to original sources
USGS2002

Incidence of Ichthyophonus hoferi in Puget Sound fishes and its increase with age of Pacific herring

A recent decrease in the mean age of adult Pacific herring Clupea pallasi in Puget Sound was associated with a high prevalence of Ichthyophonus hoferi , a protistan parasite that can be highly pathogenic to Pacific herring. In Puget Sound, high intensities of I. hoferi infection may be maintained in older cohorts of Pacific herring because the prevalence of I. hoferi increased with age from 12% among juveniles to 58% among the oldest, age-6 and older cohorts. Low intensities of I. hoferi infection in the region may be maintained in alternative fish hosts, such as surf smelt Hypomesus pretiosus , Puget Sound rockfish Sebastes emphaeus , Pacific tomcod Microgadus proximus , and speckled sanddab Cithanichthys stigmaeus .

Washington↗
USGS2002

Optimization of nested polymerase chain reaction assays for identification of Aeromonas salmonicida, Yersinia ruckeri and Flavobacterium psychrophilum

Nested polymerase chain reaction (PCR) assays were developed using first-round primers complementary to highly conserved regions within the bacterial 16S ribosomal RNA (rRNA) gene (universal eubacterial primers) and second-round primers specific for sequences within the 16S rRNA genes of Aeromonas salmonicida , Yersinia ruckeri , and Flavobacterium psychrophilum . Following optimization of the MgCl 2 concentration and primer annealing temperature, PCR employing the universal eubacterial primers was used to amplify a 1,500-base-pair (bp) product visible in agarose gels stained with ethidium bromide. The calculated detection limit of this single-round assay was less than 1.4 × 10 4 colony-forming units (CFU) per reaction for all bacterial species tested. Single-round PCR using primer sets specific for A. salmonicida , Y. ruckeri , and F. psychrophilum amplified bands of 271, 575, and 1,100 bp, respectively, with detection limits of less than 1.4 × 10 4 , 1.4 × 10 5 , and 1.4 × 10 5 CFU per reaction. Using the universal eubacterial primers in the first round and the species-specific primer sets in the second round of nested PCR assays improved the detection ability by approximately four orders of magnitude to fewer than 14 CFU per sample for each of the three bacterial species. Such nested assays could be adapted to a wide variety of bacterial fish pathogens for which 16S sequences are available.

Journal of Aquatic Animal Health↗
USGS2004

Immunomodulation and disease resistance in postyearling rainbow trout infected with Myxobolus cerebralis, the causative agent of whirling disease

Myxobolus cerebralis , the myxosporean parasite that causes whirling disease, has a number of deleterious effects on its salmonid host. Although it is well established that juvenile salmonids in the active stages of whirling disease mount an immune response to the pathogen, the occurrence and longevity of any related immunomodulatory effects are unknown. In this study, postyearling rainbow trout Oncorhynchus mykiss infected with M. cerebralis were examined for leukocyte functions and for resistance to Yersinia ruckeri , a bacterial pathogen of salmonids. Compared with uninfected controls, M. cerebralis -infected fish showed lower proliferative lymphocyte responses to four mitogens (concanavalin A, pokeweed mitogen, phytohemagglutinin, and lipopolysaccharide). Conversely, M. cerebralis -infected fish displayed greater bactericidal activity of anterior kidney macrophages than did uninfected fish. After bath challenges with Y. ruckeri , M. cerebralis -infected fish had slightly lower survival and a more rapid onset of mortality than did the control fish. Renal tissue and fecal samples from M. cerebralis -infected and uninfected survivors were cultured for the presence of Y. ruckeri , and no difference in prevalence was noted between the two groups. Because immunomodulatory changes in the M. cerebralis -infected fish involved functional enhancement and suppression of different leukocyte populations, disease resistance among M. cerebralis -infected fish in the later stages of whirling disease will probably vary with the secondary pathogen and the nature of immune response the pathogen evokes.

Journal of Aquatic Animal Health↗
USGS2004

Exposure to perchlorate induces the formation of macrophage aggregates in the trunk kidney of zebrafish and mosquitofish

Environmental contamination of ground and surface waters by perchlorate, derived from ammonium perchlorate (AP) and other perchlorate salts, is of increasing concern. Exposure to perchlorate can impair the thyroid endocrine system, which is thought to modulate renal and immune function in vertebrates. This study with zebrafish Danio rerio and eastern mosquitofish Gambusia holbrooki examined the histological effects of perchlorate on the trunk kidney, which in teleosts serves excretory and hemopoietic functions and therefore may be a target of perchlorate effects. Adult zebrafish of both sexes were exposed in the laboratory to waterborne, AP-derived perchlorate at measured concentrations of 18 mg/L for 8 weeks. Adult male mosquitofish were exposed to waterborne sodium perchlorate at measured perchlorate concentrations of 1-92 mg/L for 8 weeks. Control fish were kept in untreated water. The region of the body cavity containing the trunk kidney was processed from each fish for histological analysis. Macrophage aggregates (MAs), possible markers of contaminant exposure or immunotoxic effect, were present in the hemopoietic region of the kidney in both species exposed to perchlorate. The estimated percent area of kidney sections occupied by MAs was greater in zebrafish exposed to perchlorate at 18 mg/L (P < 0.05) than in controls. In male mosquitofish, the incidence of renal MAs increased proportionally with sodium perchlorate concentration and was significantly different from that of controls at 92 mg/L (P < 0.05). These observations confirm that in fish the kidney is affected by exposure to perchlorate. The concentrations of perchlorate at which the effects were noted are relatively high but within the range reported in some contaminated habitats.

Journal of Aquatic Animal Health↗
USGS2005

Ichthyophonus in Puget Sound rockfish from the San Juan Islands archipelago and Puget Sound, Washington, USA

In vitro explant cultures identified Ichthyophonus in 10.9% of 302 Puget Sound rockfish Sebastes emphaeus sampled from five sites in the San Juan Islands archipelago and Puget Sound, Washington, in 2003. None of the infected fish exhibited visible lesions and only a single fish was histologically positive. Significantly more females were infected (12.4%) than males (6.8%), and while infected males were only detected at two of the five sites, infected females were identified at all sites, with no significant differences in infection prevalence. Genomic sequences of Ichthyophonus isolates obtained from Puget Sound rockfish, Pacific herring Clupea pallasii, and Yukon River Chinook salmon Oncorhynchus tshawytscha were identical in both the A and B regions of the small subunit 18S ribosomal DNA but were different from Ichthyophonus sequences previously isolated from four different species of rockfish from the northeastern Pacific Ocean. Ichthyophonus in Puget Sound rockfish may not have been previously detected because the infection is subclinical in this species and earlier investigators did not utilize in vitro techniques for diagnosis of ichthyophoniasis. However, since clinical ichthyophoniasis has recently been identified in several other species of northeast Pacific rockfishes, it is hypothesized that this either is an emerging disease resulting from changing marine conditions or the result of introduction by infected southern species that appear during periodic El Nin??o events. ?? Copyright by the American Fisheries Society 2005.

Washiginton↗
USGS2008

Genetic analysis of paramyxovirus isolates from pacific salmon reveals two independently co-circulating lineages

Viruses with the morphological and biochemical characteristics of the family Paramyxoviridae (paramyxoviruses) have been isolated from adult salmon returning to rivers along the Pacific coast of North America since 1982. These Pacific salmon paramyxoviruses (PSPV), which have mainly been isolated from Chinook salmon Oncorhynchus tshawytscha, grow slowly in established fish cell lines and have not been associated with disease. Genetic analysis of a 505-base-pair region of the polymerase gene from 47 PsPV isolates produced 17 nucleotide sequence types that could be grouped into two major sublineages, designated A and B. The two independently co-circulating sublineages differed by 12.1-13.9% at the nucleotide level but by only 1.2% at the amino acid level. Isolates of PSPV from adult Pacific salmon returning to rivers from Alaska to California over a 25-year period showed little evidence of geographic or temporal grouping. Phylogenetic analyses revealed that these paramyxoviruses of Pacific salmon were most closely related to the Atlantic salmon paramyxovirus (ASPV) from Norway, having a maximum nucleotide diversity of 26.1 % and an amino acid diversity of 19.0%. When compared with homologous sequences of other paramyxoviruses, PSPV and ASPV were sufficiently distinct to suggest that they are not clearly members of any of the established genera in the family Paramyxoviridae. in the course of this study, a polymerase chain reaction assay was developed that can be used for confirmatory identification of PSPV. ?? Copyright by the American Fisheries Society 2008.

Journal of Aquatic Animal Health↗
USGS2011

Coelomic implantation of satellite transmitters in the bar-tailed godwit ( Limosa lapponica ) and the bristle-thighed curlew ( Numenius tahitiensis ) using propofol, bupivacaine, and lidocaine

Intravenous propofol was used as a general anesthetic with a 2∶1 (mg∶mg) adjunctive mixture of lidocaine and bupivacaine as local anesthetics infiltrated into the surgical sites for implantation of satellite transmitters into the right abdominal air sac of 39 female and 4 male bar-tailed godwits ( Limosa lapponica baueri and Limosa lapponica menzbeiri ) and 11 female and 12 male bristle-thighed curlews ( Numenius tahitiensis ). The birds were captured on nesting grounds in Alaska, USA, and on overwintering areas in New Zealand and Australia from 2005 through 2008. As it was developed, the mass of the transmitter used changed yearly from a low of 22.4 ± 0.2 g to a high of 27.1 ± 0.2 g and weighed 25.1 ± 0.2 g in the final year. The mean load ratios ranged from 5.2% to 7.7% for godwits and from 5.7% to 7.5% for curlews and exceeded 5% for all years, locations, and genders of both species. The maximum load ratio was 8.3% for a female bar-tailed godwit implanted in Australia in 2008. Three godwits and no curlews died during surgery. Most birds were hyperthermic upon induction but improved during surgery. Two godwits (one in New Zealand and one in Australia) could not stand upon release, likely due to capture myopathy. These birds failed to respond to treatment and were euthanized. The implanted transmitters were used to follow godwits through their southern and northern migrations, and curlews were followed on their southern migration.

Alaska↗
USGS2011

Adult survival and population growth rate in Colorado big brown bats (Eptesicus fuscus)

We studied adult survival and population growth at multiple maternity colonies of big brown bats ( Eptesicus fuscus ) in Fort Collins, Colorado. We investigated hypotheses about survival using information-theoretic methods and mark–recapture analyses based on passive detection of adult females tagged with passive integrated transponders. We constructed a 3-stage life-history matrix model to estimate population growth rate (λ) and assessed the relative importance of adult survival and other life-history parameters to population growth through elasticity and sensitivity analysis. Annual adult survival at 5 maternity colonies monitored from 2001 to 2005 was estimated at 0.79 (95% confidence interval [95% CI ] = 0.77–0.82). Adult survival varied by year and roost, with low survival during an extreme drought year, a finding with negative implications for bat populations because of the likelihood of increasing drought in western North America due to global climate change. Adult survival during winter was higher than in summer, and mean life expectancies calculated from survival estimates were lower than maximum longevity records. We modeled adult survival with recruitment parameter estimates from the same population. The study population was growing (λ = 1.096; 95% CI = 1.057–1.135). Adult survival was the most important demographic parameter for population growth. Growth clearly had the highest elasticity to adult survival, followed by juvenile survival and adult fecundity (approximately equivalent in rank). Elasticity was lowest for fecundity of yearlings. The relative importances of the various life-history parameters for population growth rate are similar to those of large mammals.

Colorado↗
USGS2013

Roost selection by western long-eared myotis (Myotis evotis) in burned and unburned piñon–juniper woodlands of southwestern Colorado

All 16 species of bats known to occur in western Colorado are found at Mesa Verde National Park (MVNP) in the southwestern United States. Since 1996, wildfires have burned more than 70% of MVNP (> 15,000 ha), potentially altering food and roosting resources for bats. During the summers of 2006–2007, we investigated roost use by reproductive female western long-eared myotis ( Myotis evotis ). We located 33 bat roosts in rock crevices and 1 in a juniper snag. All but 2 of the roosts were in unburned habitat. Bats roosted alone or in small groups (≤3 individuals) and switched roosts frequently (1–7 roosts per bat, median = 1.5 roosts per bat, SE = 0.5 roosts per bat). We compared occupied roosts with randomly selected unoccupied crevices and used an information theoretic approach to determine which variables were most important in determining roost use at microhabitat and landscape scales. At the microhabitat scale, maternity roosts were higher above the ground and deeper than random, unoccupied rock crevices. At the landscape scale, roosts were closer to water and farther from burned habitat than random crevices, providing reproductive female M. evotis with the best opportunities to drink and forage for insects. Tree roosts are apparently not a vital resource for reproductive female M. evotis during the summer months at our study site, presumably because of the extensive availability of rock crevices. Understanding site-specific roosting behavior is important for proper management of bat populations because differences can exist between geographic regions, even among areas with similar plant communities.

Colorado↗
USGS2001

Estimated areal extent of colonies of black-tailed prairie dogs in the northern Great Plains

During 1997–1998, we undertook an aerial survey, with an aerial line-intercept technique, to estimate the extent of colonies of black-tailed prairie dogs ( Cynomys ludovicianus ) in the northern Great Plains states of Nebraska, North Dakota, South Dakota, and Wyoming. We stratified the survey based on knowledge of colony locations, computed 2 types of estimates for each stratum, and combined ratio estimates for high-density strata with average density estimates for low-density strata. Estimates of colony areas for black-tailed prairie dogs were derived from the average percentages of lines intercepting prairie dog colonies and ratio estimators. We selected the best estimator based on the correlation between length of transect line and length of intercepted colonies. Active colonies of black-tailed prairie dogs occupied 2,377.8 km 2 ± 186.4 SE, whereas inactive colonies occupied 560.4 ± 89.2 km 2 . These data represent the 1st quantitative assessment of black-tailed prairie dog colonies in the northern Great Plains. The survey dispels popular notions that millions of hectares of colonies of black-tailed prairie dogs exist in the northern Great Plains and can form the basis for future survey efforts.

Journal of Mammalogy↗
USGS2004

Analysis of predator movement in prairie landscapes with contrasting grassland composition

Mammalian predation influences waterfowl breeding success in the U.S. northern Great Plains, yet little is known about the influence of the landscape on the ability of predators to find waterfowl nests. We used radiotelemetry to record nightly movements of red foxes ( Vulpes vulpes ) and striped skunks ( Mephitis mephitis ) in two 41.4-km 2 study areas in North Dakota. Study areas contained either 15–20% grassland (low grassland composition) or 45–55% grassland (high grassland composition). Grasslands included planted cover, pastureland, and hayland. We predicted that the type and composition of cover types in the landscape would influence both predator movement across the landscape (as measured by the fractal dimension and displacement ratio) as well as localized movement (as measured by the rate of movement and turning angle between locations) within patches of different cover types. Red fox movements were straighter (lower fractal dimensions and higher displacements) across landscapes with a low grassland composition, indicating directed movement between the more isolated patches of planted cover. Striped skunk movements did not differ between landscape types, illustrating their movement along wetland edges, which had similar compositions in both landscape types. The high variability in turning angles by red fox in planted cover and pastureland in both landscape types is consistent with restricted-area foraging. The high rate of movement by red foxes in planted cover and by striped skunks in wetland edges suggests that spatial memory may influence movement patterns. Understanding the behavior of predators in fragmented prairie landscape is essential for managing breeding habitat for grassland birds and for predicting the spatial and temporal dynamics of predators and their prey.

North Dakota↗
USGS2004

Landscape responses of bats to habitat fragmentation in Atlantic forest of paraguay

Understanding effects of habitat loss and fragmentation on populations or communities is critical to effective conservation and restoration. This is particularly important for bats because they provide vital services to ecosystems via pollination and seed dispersal, especially in tropical and subtropical habitats. Based on more than 1,000 h of survey during a 15-month period, we quantified species abundances and community structure of phyllostomid bats at 14 sites in a 3,000-km2 region of eastern Paraguay. Abundance was highest for Artibeus lituratus in deforested landscapes and for Chrotopterus auritus in forested habitats. In contrast, Artibeus fimbriatus, Carollia perspicillata, Glossophaga soricina, Platyrrhinus lineatus, Pygoderma bilabiatum, and Sturnira lilium attained highest abundance in moderately fragmented forest landscapes. Forest cover, patch size, and patch density frequently were associated with abundance of species. At the community level, species richness was highest in partly deforested landscapes, whereas evenness was greatest in forested habitat. In general, the highest diversity of bats occurred in landscapes comprising moderately fragmented forest habitat. This underscores the importance of remnant habitat patches to conservation strategies.

Journal of Mammalogy↗
USGS2005

Prevalence and spatial distribution of intraerythrocytic parasite(s) in Puget Sound rockfish (Sebastes emphaeus) from the San Juan Archipelago, Washington (USA)

Two morphologically distinct forms of an intraerythrocytic parasite(s) were detected by microscopic observation of Giemsa-stained blood films in 45.7% of 119 rockfish (Sebastes emphaeus) from the San Juan Archipelago (Washington State, U.S.A.). Infection prevalence for both forms was 53% in males, 44% in females, and 33% in fish of undetermined gender. A binucleate "ring-stage" was present at all 4 geographic sites, with a mean prevalence of 45.7%, while mean prevalence of a larger gamont-like form from the same sites was 5.1%. The relationship of the 2 forms to each other could not be determined. Neither schizogony nor binary fission was evident in any of the infected erythrocytes and the parasites contained no obvious pigment. The possibility of the 2 morphologic forms being 2 distinct species is supported by the observation that no difference in parasitemia was seen in the binucleate form among sites (1.6-1.9%), while parasitemia of the gamont-like form varied significantly among sites, ranging from a high of 4% to a low of 0.1%. Taxonomic status of either form could not be determined at this time based on limited existing morphologic data. ?? American Society of Parasitologists 2005.

Journal of Parasitology↗
USGS2004

Differential propagation of the metazoan parasite Myxobolus cerebralis by Limnodrilus hoffmeisteri, Ilyodrilus templetoni, and genetically distinct strains of Tubifex tubifex

Whirling disease, caused by the parasite Myxobolus cerebralis, has infected rainbow trout (Oncorhynchus mykiss) and other salmonid fish in the western United States, often with devastating results to native populations but without a discernible spatial pattern. The parasite develops in a complex 2-host system in which the aquatic oligochaete Tubifex tubifex is an obligate host. Because substantial differences in whirling disease severity in different areas of North America did not seem explainable by environmental factors or features of the parasite or its fish host, we sought to determine whether ecological or genetic variation within oligochaete host populations may be responsible. We found large differences in compatibility between the parasite and various laboratory strains of T. tubifex that were established from geographic regions with different whirling disease histories. Moreover, 2 closely related species of tubificids, Limnodrilus hqffmeisteri and Ilyodrilus templetoni, which occur naturally in mixed species assemblages with T. tubifex, were incompatible with M. cerebralis. Virulence of the parasite was directly correlated with the numbers of triactinomyxon spores that developed within each strain of T. tubifex. Thus, the level of virulence was directly related to the compatibility between the host strain and the parasite. Genetic analyses revealed relationships that were in agreement with the level of parasite production. Differences in compatibilities between oligochaetes and M. cerebralis may contribute to the spatial variance in the severity of the disease among salmonid populations. ?? American Society of Parasitologists 2004.

Journal of Parasitology↗
USGS2001

Age and sex determination of the Maui Parrotbill

We determined the best plumage and morphometric variables for ageing and sexing the Maui Parrotbill ( Pseudonestor xanthophrys ), an endangered Hawaiian honeycreeper found only on east Maui, Hawaii, by examining and measuring 30 museum specimens and 71 live birds captured in mist nets. Juvenal plumage was identified by the presence of pale-tipped wing bars on the middle and greater coverts, grayish olive dorsal plumage, and dingy white underparts and superciliaries. Birds undergoing first prebasic molt retained the juvenal remiges, rectrices, and wing coverts. Birds in first basic plumage possessed juvenal wing bars and a dull juvenal-like plumage. Subsequent molts were complete, and adults lacked wing bars. Adult males had bright yellow plumage on the cheeks, throat, and superciliaries, as did 27% of adult females. All other adult females had less yellow in the underparts. The dorsal plumage of adult females was more variable than adult males and was either yellow-olive like the males or grayish olive. Adult males had longer wing, bill, tail, and tarsometatarsus and greater mass than adult females. Virtually all males and females could be distinguished by wing length. Morphometrics of immature birds were significantly smaller than for adult males. Only immature male wing chord was significantly larger than that of adult females. Although it was difficult to distinguish between immatures and some adult females based on plumage coloration or measurements, a cut-off point of 70.4 mm for wing chord separated 91% of females from 93% of males, regardless of age.

Hawaii↗
USGS2001

Effects of color bands on Semipalmated Sandpipers banded at hatch

Effects of color bands on adult birds have been investigated in many studies, but much less is known about the effects of bands on birds banded at hatch. We captured Semipalmated Sandpiper ( Calidris pusilla ) chicks at hatch on the Alaskan North Slope and attached 0–3 bands to them. The chicks were resighted and reweighed during the subsequent two weeks. The number of chicks banded varied from 18 to 21 among treatments; 6–9 were resighted, and 6–7 were reweighed, per treatment. The proportion resighted varied from 0.33 to 0.45. The estimated resighting probability, given that we encountered a brood, was 82%. We tested for effects of the bands on survival and mass gain by analyzing whether the proportion of chicks resighted, or their mass, varied with the number of bands. We found no evidence that bands affected the chicks and were able to rule out (with 95% confidence) a decline in survivorship of more than 13% and a loss of mass of more than 10%. Although bands had little if any effect on chicks in our study, we believe their effects should be evaluated whenever survivorship or mass gain are estimated using color-marked chicks.

Journal of Field Ornithology↗
USGS2002

Breeding habitat use by sympatric and allopatric populations of Wilson's Warblers and Yellow Warblers

We studied Wilson's Warbler ( Wilsonia pusilla ) and Yellow Warbler ( Dendroica petechia ) habitat use in allopatric and sympatric populations in the Rocky Mountains of northern Colorado and southeastern Wyoming in order to better understand the different habitat needs and interactions of these two species. Foraging Wilson's Warblers and Yellow Warblers used very similar habitat, both selecting larger, more open shrubs. In spite of similar foraging habitat, comparisons of habitat use by the two species at the sympatric sites yielded no evidence of foraging habitat partitioning or exclusion. There was evidence of nesting habitat partitioning. Wilson's Warblers nested on the ground, with some evidence that they used smaller, more densely stemmed shrubs under which to nest. Yellow Warblers are shrub nesters and selected larger, more open shrubs in which to nest. Results provide no evidence that Yellow Warblers can be blamed for population declines in Wilson's Warblers.

Colorado, Wyoming↗
USGS2003

Variation in plumage, molt, and morphology of the Whiskered Auklet ( Aethia pygmaea ) in Alaska

We studied molt and size variation in Whiskered Auklets collected at sea in August from the Aleutian Islands in 1992 and 1993. We evaluated size differences from external and skeletal measurements. Adults were molting extensively in August, indicating that molt began in July. Primaries 1-5 had been completely replaced, while primaries 6-8 were in various stages of replacement, and primaries 9 and 10 were old in most birds. We also found that juveniles were not molting. This pattern is similar to other species of small auklets where breeding and molt in adults overlap, but juveniles do not molt until the following summer. This suggests that Whiskered Auklets are subjected to similar ecological constraints as other auklets. We provide the first skeletal measurements of Whiskered Auklets and some new external measurements. Results of statistical analyses indicate that there is no sexual dimorphism in adults. A small sample of juveniles suggests that they are similar in size to adults.

Journal of Field Ornithology↗