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At least 1,693 records · Page 94Linked to original sources

USGS2014

Influence of sediment presence on freshwater mussel thermal tolerance

Median lethal temperature (LT50) data from water-only exposures with the early life stages of freshwater mussels suggest that some species may be living near their upper thermal tolerances. However, evaluation of thermal sensitivity has never been conducted in sediment. Mussels live most of their lives burrowed in sediment, so understanding the effect of sediment on thermal sensitivity is a necessary step in evaluating the effectiveness of the water-only standard method, on which the regulatory framework for potential thermal criteria currently is based, as a test of thermal sensitivity. We developed a method for testing thermal sensitivity of juvenile mussels in sediment and used the method to assess thermal tolerance of 4 species across a range of temperatures common during summer. Stream beds may provide a thermal refuge in the wild, but we hypothesized that the presence of sediment alone does not alter thermal sensitivity. We also evaluated the effects of 2 temperature acclimation levels (22 and 27°C) and 2 water levels (watered and dewatered treatments). We then compared results from the sediment tests to those conducted using the water-only standard methods. We also conducted water-only LT tests with mussel larvae (glochidia) for comparison with the juvenile life stage. We found few consistent differences in thermal tolerance between sediment and water-only treatments, between acclimation temperatures, between waterlevel treatments, among species, or between juvenile and glochidial life stages (LT50 range = 33.3-37.2°C; mean = 35.6°C), supporting our hypothesis that the presence of sediment alone does not alter thermal sensitivity. The method we developed has potential for evaluating the role of other stressors (e.g., contaminants) in a more natural and complex environment.

Freshwater Science↗

USGS2008

Cloned embryos from semen. Part 2: Intergeneric nuclear transfer of semen-derived eland (Taurotragus oryx) epithelial cells into bovine oocytes

The production of cloned offspring by nuclear transfer (NT) of semen-derived somatic cells holds considerable potential for the incorporation of novel genes into endangered species populations. Because oocytes from endangered species are scarce, domestic species oocytes are often used as cytoplasts for interspecies NT. In the present study, epithelial cells isolated from eland semen were used for intergeneric transfer (IgNT) into enucleated bovine oocytes and compared with bovine NT embryos. Cleavage rates of bovine NT and eland IgNT embryos were similar (80 vs. 83%, respectively; p > 0.05); however, development to the morula and blastocyst stage was higher for bovine NT embryos (38 and 21%, respectively; p < 0.0001), than for eland IgNT embryos (0.5 and 0%, respectively). DNA synthesis was not observed in either bovine NT or eland IgNT cybrids before activation, but in 75 and 70% of bovine NT and eland igNT embryos, respectively, cell-cycle resumption was observed at 16 h postactivation (hpa). For eland IgNT embryos, 13% had ???8 cells at 84 hpa, while 32% of the bovine NT embryos had ???8 cells at the same interval. However, 100 and 66% of bovine NT and eland IgNT embryos, respectively, that had ???8 cells synthesized DNA. From these results we concluded that (1) semen-derived epithelial cell nuclei can interact and be transcriptionally controlled by bovine cytoplast, (2) the first cell-cycle occurred in IgNT embryos, (3) a high frequency of developmental arrest occurs before the eight-cell stage in IgNT embryos, and (4) IgNT embryos that progress through the early cleavage stage arrest can (a) synthesize DNA, (b) progress through subsequent cell cycles, and (c) may have the potential to develop further. ?? 2008 Mary Ann Liebert, Inc.

Cloning and Stem Cells↗

USGS2025

Context matters: Intrinsic and extrinsic factors modulate habitat choices in an endangered forest bat

Effective management of declining species depends upon fundamental understanding of habitat preferences during key life stages such as reproduction. Peripheral populations of wildlife are often poorly understood and rarely the focus of study, despite their contribution to genetic diversity and their potential to aid in recolonization if a species becomes endangered. We assessed the maternal roost-site preferences of the endangered northern long-eared bat ( Myotis septentrionalis ) within a managed forest near the western edge of their range in the Black Hills region of Wyoming, USA. We further examined whether habitat preferences and roost-switching varied by reproductive state (pregnant or lactating) or proximate weather conditions. Bats were more likely to roost in quaking aspens during pregnancy, and when weather was cooler and wetter. Conversely, bats roosted more in ponderosa pines ( Pinus ponderosa) post-parturition, and when temperatures were warmer. Bats also were more likely to switch to a new roost after periods of warmer temperature and reduced solar radiation. Our results support growing evidence that habitat choices can be modulated proximately by intrinsic and extrinsic factors. Northern long-eared bats in the Black Hills relied on a variety of roost types, from healthy live trees to snags at different decay stages depending on reproductive stage and ambient weather. Our study highlights the importance of considering diverse contexts when characterizing habitat preferences, particularly for endangered species in a rapidly changing world.

Wyoming↗

USGS2017

Acquisition of Borrelia burgdorferi infection by larval Ixodes scapularis (Acari: Ixodidae) associated with engorgement measures

Measuring rates of acquisition of the Lyme disease pathogen, Borrelia burgdorferi sensu lato Johnson, Schmid, Hyde, Steigerwalt & Brenner, by the larval stage of Ixodes scapularis Say is a useful tool for xenodiagnoses of B. burgdorferi in vertebrate hosts. In the nymphal and adult stages of I. scapularis , the duration of attachment to hosts has been shown to predict both body engorgement during blood feeding and the timing of infection with B. burgdorferi . However, these relationships have not been established for the larval stage of I. scapularis . We sought to establish the relationship between body size during engorgement of larval I. scapularis placed on B. burgdorferi- infected, white-footed mice ( Peromyscus leucopus Rafinesque) and the presence or absence of infection in larvae sampled from hosts over time. Body size, time, and their interaction were the best predictors of larval infection with B. burgdorferi . We found that infected larvae showed significantly greater engorgement than uninfected larvae as early as 24 h after placement on a host. These findings may suggest that infection with B. burgdorferi affects the larval feeding process. Alternatively, larvae that engorge more rapidly on hosts may acquire infections faster. Knowledge of these relationships can be applied to improve effective xenodiagnosis of B. burgdorferi in white-footed mice. Further, these findings shed light on vector–pathogen–host interactions during an understudied part of the Lyme disease transmission cycle.

Journal of Medical Entomology↗

USGS2013

Shifts in stable-isotope signatures confirm parasitic relationship of freshwater mussel glochidia attached to host fish

The parasitic nature of the association between glochidia of unionoidean bivalves and their host fish (i.e. the role of fish hosts in providing nutritional resources to the developing glochidia) is still uncertain. While previous work has provided descriptions of development of glochidia on fish hosts, earlier studies have not explicitly documented the flow of nutrition from the host fish to the juvenile mussel. Therefore, our objective was to use stable isotope analysis to quantitatively document nutrient flow between fish and glochidia. Glochidia were collected from nine adult Lampsilis cardium and used to inoculate Micropterus salmoides ( n = 27; three fish per maternal mussel) that produced juvenile mussels for the experiment. Adult mussel tissue samples, glochidia, transformed juvenile mussels and fish gill tissues were analysed for δ 15 N and δ 13 C isotope ratios. We used a linear mixing model to estimate the fraction of juvenile mussel tissue derived from the host fish's tissue during attachment. Our analyses indicate a distinct shift in both C and N isotopic ratios from the glochidial stage to the juvenile stage during mussel attachment and development. Linear mixing model analysis indicated that 57.4% of the δ 15 N in juvenile tissues were obtained from the host fish. This work provides novel evidence that larval unionoideans are true parasites that derive nutrition from host fish during their metamorphosis into the juvenile stage.

Journal of Molluscan Studies↗

USGS2026

Tringa flavipes (Lesser Yellowlegs) from separate breeding sites subdivides the Prairie Pothole Region in space and time during southbound migration

Some staging regions support multiple groups of the same migratory species, each of which may use the region differently. Characterizing the ways, in which separate groups use such regions can therefore help to identify vulnerabilities during this sensitive period of the annual cycle. The Prairie Pothole Region (PPR) is a massive wetland complex in the northern Great Plains of North America used by ∼11 million shorebirds during migration. The PPR has been heavily modified by agriculture and is experiencing varied effects of global climate change, threatening the health of the shorebirds that rely on it. Here, we used 6 seasons of southbound tracking data of Tringa flavipes (Lesser Yellowlegs)—a long-distance migratory shorebird species with an estimated population decline of 63% over the last 4 decades—from 9 sites across their breeding range to explore differences in migratory behavior within this important staging region. We found that 75% of tracked individuals used the region during southbound migration, and T. flavipes from different breeding sites detoured 110–875 km from their most direct migratory route to access the PPR. Individuals that arrived later stayed longer and made more stops within the region than those that arrived early. Individuals originating from different breeding sites also displayed spatial and temporal segregation within the region: T. flavipes from southwest and central Alaska relied heavily on the northwestern PPR, while those from Canada used the central and southeastern portions of the PPR. Finally, timing of use varied among groups, but the southeastern PPR became increasingly important over the course of the southbound migratory window, as other wetlands likely dried out. Our study highlights the portions of the PPR of critical importance to migrating T. flavipes and the diversity of ways, in which different groups from within the same species can use a single staging region.

Alaska, Manitoba, Northwest Territories, Ontario, ↗

USGS2023

Faster growth and larger size at crèche onset are associated with higher offspring survival in Adélie Penguins

We conducted the first assessment of Adélie Penguin ( Pygoscelis adeliae ) chick survival that accounts for imperfect resighting. We found that when chicks are larger in size when they enter the crèche stage (the period when both parents forage at the same time and chicks are left relatively unprotected), they have a higher probability of survival to fledging. We investigated the relationships between growth, crèche timing, and chick survival during one typical year and one year of reduced food availability. Chicks that hatched earlier in the season entered the crèche stage older, and chicks that both grew faster and crèched older entered the crèche at a larger size. These relationships were stronger in the year of reduced food availability. Thus, parents increased their chicks’ chance of fledging if they provided sufficient food for faster growth rates and/or extended the length of the brood-guarding period. Early nest initiation (i.e., early hatching) provided parents with the opportunity to extend the guard period and increase chick survival. However, to extend the guard stage successfully, they must provide larger meals and maintain higher chick growth rates, even if just one parent at a time is foraging, which previous work has shown is not possible for all individuals. We show that the factors governing tradeoffs in chick-rearing behavior of Adélie Penguin parents may vary in accord with environmental conditions, a result from which we can better understand species’ adaptations to environmental changes.

Ornithology↗

USGS1992

Petrology of the Caribou Mountain Pluton, Klamath Mountains, California

The Caribou Mountain pluton is a small trondhjemitic body that intruded semipelitic schist of the Stuart Fork terrane in late Middle Jurassic to Early Cretaceous time. Its emplacement followed the intrusion of an adjoining body of hornblende quartz diorite called the Middle Fork pluton and the mode of its emplacement was as an asymmetric ballooning diapir (Davis, 1963), as shown by concentric foliation, radial late-stage dikes, foliated enclaves, and folded blocks of schlieren-banded tonalite. Coarse-grained hornblende-bearing trondhjemite is the dominant rock type in the Caribou Mountain pluton, and it is called the ‘main trondhjemite’. It was followed by medium-grained ‘late trondhjemite’ and by late-stage trondhjemitic and granodioritic dikes. All the trondhjemitic rock types are characterized by low alkali contents, high light rare earth elements, low initial 87 Sr/ 86 Sr, and low δ 18 O. However, the late trondhjemite has higher Na 2 O and a higher initial 87 Sr/ 86 Sr value than the main trondhjemite, and the two units cannot be related by fractional crystallization. The late granodioritic dikes are richer in Ba, Rb, Y, and Sc than the late trondhjemite and probably reflect assimilation of Stuart Fork metasedimentary rocks by late-stage trondhjemitic magma. Mafic enclaves in the main trondhjemite contain xenocrysts of quartz and plagioclase derived from the host by magma mixing. The enclaves have K 2 O, Ba, and Rb contents similar to, or higher than those of the host rocks. Their rare earth element (REE) patterns display strong middle REE enrichment caused by accumulation of hornblende, probably as the result of filter pressing. The main trondhjemite cannot be derived from Middle Fork magma because the initial 87 Sr/ 86 Sr of the Middle Fork pluton is lower than that of the trondhjemite. The absence of parental mafic magmas of appropriate composition suggests that the Caribou Mountain trondhjemitic magmas formed by partial melting of an amphibolitic source rock compositionally similar to low-K tholeiite.

California↗

USGS2019

The contribution of road-based citizen science to the conservation of pond-breeding amphibians

Roadside amphibian citizen science (CS) programmes bring together volunteers focused on collecting scientific data while working to mitigate population declines by reducing road mortality of pond‐breeding amphibians. Despite the international popularity of these movement‐based, roadside conservation efforts (i.e. “big nights,” “bucket brigades” and “toad patrols”), direct benefits to conservation have rarely been quantified or evaluated. As a case study, we used a population simulation approach to evaluate how volunteer intensity, frequency and distribution influence three conservation outcomes (minimum population size, population growth rate and years to extinction) of the spotted salamander ( Ambystoma maculatum ), often a focal pond‐breeding amphibian of CS and conservation programmes in the United States. Sensitivity analysis supported the expectation that spotted salamander populations were primarily recruitment‐driven. Thus, conservation outcomes were highest when volunteers focused on metamorph outmigration as opposed to adult in‐migration—contrary to the typical timing of such volunteer events. Almost every volunteer strategy resulted in increased conservation outcomes compared to a no‐volunteer strategy. Specifically, volunteer frequency during metamorph migration increased outcomes more than the same increases in volunteer effort during adult migration. Small population sizes resulted in a negligible effect of volunteer intensity. Volunteers during the first adult in‐migration had a relatively small effect compared to most other strategies. Synthesis and applications . Although citizen science (CS)‐focused conservation actions could directly benefit declining populations, additional conservation measures are needed to halt or reverse local amphibian declines. This study demonstrates a need to evaluate the effectiveness of focusing CS mitigation efforts on the metamorph stage, as opposed to the adult stage. This may be challenging, compared to other management actions such as road‐crossing infrastructure. Current amphibian CS programmes will be challenged to balance implementing evidence‐based conservation measures on the most limiting life stage, while retaining social and community benefits for volunteers.

Journal of Applied Ecology↗

USGS2016

Estimating abundance in the presence of species uncertainty

1.N-mixture models have become a popular method for estimating abundance of free-ranging animals that are not marked or identified individually. These models have been used on count data for single species that can be identified with certainty. However, co-occurring species often look similar during one or more life stages, making it difficult to assign species for all recorded captures. This uncertainty creates problems for estimating species-specific abundance and it can often limit life stages to which we can make inference. 2.We present a new extension of N-mixture models that accounts for species uncertainty. In addition to estimating site-specific abundances and detection probabilities, this model allows estimating probability of correct assignment of species identity. We implement this hierarchical model in a Bayesian framework and provide all code for running the model in BUGS-language programs. 3.We present an application of the model on count data from two sympatric freshwater fishes, the brook stickleback ( Culaea inconstans ) and the ninespine stickleback ( Pungitius pungitius ), ad illustrate implementation of covariate effects (habitat characteristics). In addition, we used a simulation study to validate the model and illustrate potential sample size issues. We also compared, for both real and simulated data, estimates provided by our model to those obtained by a simple N-mixture model when captures of unknown species identification were discarded. In the latter case, abundance estimates appeared highly biased and very imprecise, while our new model provided unbiased estimates with higher precision. 4.This extension of the N-mixture model should be useful for a wide variety of studies and taxa, as species uncertainty is a common issue. It should notably help improve investigation of abundance and vital rate characteristics of organisms’ early life stages, which are sometimes more difficult to identify than adults.

Methods in Ecology and Evolution↗

USGS2024

Facilitating comparable research in seedling functional ecology

Ecologists have worked to ascribe function to the variation found in plant populations, communities and ecosystems across environments for at least the past century. The vast body of research in functional ecology has drastically improved understanding of how individuals respond to their environment, communities are assembled and ecosystems function. However, with limited exceptions, few studies have quantified differences in plant function during the earliest stages of the plant life cycle, and fewer have tested how this early variability shapes populations, communities and ecosystems. Drawing from the literature and our collective experience, we describe the current state of knowledge in seedling functional ecology and provide examples of how this subdiscipline can enrich our fundamental understanding of plant function across levels of organisation. To inspire progressive work in this area, we also outline key considerations involved in seedling functional research (who, what, when, where and how to measure seedling traits) and identify remaining challenges and gaps in understanding around methodological approaches. Within this conceptual synthesis, we highlight three critical areas in seedling ecology for future research to target. First, given wide variation in the definition of a ‘seedling’, we provide a standard definition based on seed reserve dependence while emphasising the need to measure ontogenetic variation more clearly both within and following the seedling stage. Second, studies demonstrate that seedlings can be studied in multiple media (e.g. soil, agar, filter paper) and conditions (e.g. field, greenhouse, laboratory). We recommend that researchers select methods based on explicit goals, yet follow standard guidelines to reduce methodological noise across studies. Third, research is critically needed to assess the implications of different methodologies on trait measurement and compatibility across studies. By highlighting the importance of seedling functional ecology and suggesting pathways to address key challenges, we aim to inspire future research that generates useful and comparable data on seedling functional ecology. This work is critical to explain variation within and among populations, communities and ecosystems and integrate this most vulnerable stage of plant life into ecological frameworks.

Methods in Ecology & Evolution↗

USGS2022

Exploring metapopulation-scale suppression alternatives for a global invader in a river network experiencing climate change

Invasive species can dramatically alter ecosystems, but eradication is difficult, and suppression is expensive once they are established. Uncertainties in the potential for expansion and impacts by an invader can lead to delayed and inadequate suppression, allowing for establishment. Metapopulation viability models can aid in planning strategies to improve responses to invaders and lessen invasive species’ impacts, which may be particularly important under climate change. We used a spatially explicit metapopulation viability model to explore suppression strategies for ecologically damaging invasive brown trout ( Salmo trutta ), established in the Colorado River and a tributary in Grand Canyon National Park. Our goals were to estimate the effectiveness of strategies targeting different life stages and subpopulations within a metapopulation; quantify the effectiveness of a rapid response to a new invasion relative to delaying action until establishment; and estimate whether future hydrology and temperature regimes related to climate change and reservoir management affect metapopulation viability and alter the optimal management response. Our models included scenarios targeting different life stages with spatially varying intensities of electrofishing, redd destruction, incentivized angler harvest, piscicides, and a weir. Quasi-extinction (QE) was obtainable only with metapopulation-wide suppression targeting multiple life stages. Brown trout population growth rates were most sensitive to changes in age 0 and large adult mortality. The duration of suppression needed to reach QE for a large established subpopulation was 12 years compared with 4 with a rapid response to a new invasion. Isolated subpopulations were vulnerable to suppression; however, connected tributary subpopulations enhanced metapopulation persistence by serving as climate refuges. Water shortages driving changes in reservoir storage and subsequent warming would cause brown trout declines, but metapopulation QE was achieved only through refocusing and increasing suppression. Our modeling approach improves understanding of invasive brown trout metapopulation dynamics, which could lead to more focused and effective invasive species suppression strategies and, ultimately, maintenance of populations of endemic fishes.

Arizona↗

USGS2022

Riparian buffers provide refugia during secondary forest succession

Aim Secondary forests regenerating from human disturbance are increasingly becoming a predominant forest type in many regions, and they play a significant role in forest community dynamics. Understanding the factors that underlie the variation in species responses during secondary succession is important for understanding community assembly and biodiversity monitoring and management. Because species vary in ecology and behaviour, responses to ecosystem change should vary among species. Here, we show that habitat type (riparian, upland), phylogeny, and species traits mediate anuran and lizard probability of occurrence and species richness in pasture and secondary forest. Location Sarapiquí and Osa Peninsula, Costa Rica. Methods We used phylogenetic occupancy models to estimate assemblage-level and species-specific responses to forest succession in 30 chronosequence sites that include pasture, secondary forest regenerating from pasture, and mature forest sites. Results For the majority of species, we found increasing probability of occurrence in upland habitats as forest regenerated from pasture to secondary forest and similar probability of occurrence in riparian habitats across pasture, secondary forest, and mature forest sites. Species' responses to forest stage were phylogenetically correlated, and the trend was especially strong for anuran response to pasture sites. Anurans with lentic larval habitat had a positive occupancy response to pasture upland habitat, and anurans with lotic larval habitat had a variable response to different forest stages compared to mature forest. Main Conclusions Our study, which focuses on sites that are minimally isolated from mature forest reference sites, indicated that anuran and lizard occupancy rapidly recovered to a level similar to mature forest in a relatively short time span (approximately 20 years). Riparian habitats are key ecosystem features in our system and provide refugia for organisms in early successional stages. Maintenance of vegetation along streams shows that we can mitigate forest conversion by maintaining riparian buffers.

Osa Peninsula, Sarapiquí↗

USGS2015

Seasonal weather patterns drive population vital rates and persistence in a stream fish

Climate change affects seasonal weather patterns, but little is known about the relative importance of seasonal weather patterns on animal population vital rates. Even when such information exists, data are typically only available from intensive fieldwork (e.g., mark–recapture studies) at a limited spatial extent. Here, we investigated effects of seasonal air temperature and precipitation (fall, winter, and spring) on survival and recruitment of brook trout ( Salvelinus fontinalis ) at a broad spatial scale using a novel stage‐structured population model. The data were a 15‐year record of brook trout abundance from 72 sites distributed across a 170‐km‐long mountain range in Shenandoah National Park, Virginia, USA. Population vital rates responded differently to weather and site‐specific conditions. Specifically, young‐of‐year survival was most strongly affected by spring temperature, adult survival by elevation and per‐capita recruitment by winter precipitation. Low fall precipitation and high winter precipitation, the latter of which is predicted to increase under climate change for the study region, had the strongest negative effects on trout populations. Simulations show that trout abundance could be greatly reduced under constant high winter precipitation, consistent with the expected effects of gravel‐scouring flows on eggs and newly hatched individuals. However, high‐elevation sites would be less vulnerable to local extinction because they supported higher adult survival. Furthermore, the majority of brook trout populations are projected to persist if high winter precipitation occurs only intermittently (≤3 of 5 years) due to density‐dependent recruitment. Variable drivers of vital rates should be commonly found in animal populations characterized by ontogenetic changes in habitat, and such stage‐structured effects may increase population persistence to changing climate by not affecting all life stages simultaneously. Yet, our results also demonstrate that weather patterns during seemingly less consequential seasons (e.g., winter precipitation) can have major impacts on animal population dynamics.

Virginia↗

USGS2019

A seasonal population matrix model of the Caribbean Red-tailed Hawk Buteo jamaicensis jamaicensis in eastern Puerto Rico

Reliable estimates of life history parameters and their functional role in animal population trajectories are critical, yet often missing, components in conservation and management. We developed seasonal matrix population models of the Red-tailed Hawk Buteo jamaicensis jamaicensis in the upper and lower forests of the Luquillo Mountains, Puerto Rico, to describe the influence of early life stages (nestling and clutch survival) on population growth. Modelled populations exhibited positive discrete rates of growth in forests above 400 m ( λ highlands = 1.05) and in forests below 400 m ( λ lowlands = 1.27) of the Luquillo Mountains. Further, adult survival was the parameter with the highest proportional effect and direct contribution to growth of the population. Besides survival of adults, our results identified that nestling survival had the second greatest influence on λ , stressing the importance of this life stage for the population growth rate of Red-tailed Hawks in our study area. Seasonal matrices are not commonly used to describe population dynamics of birds. However, these may be a useful tool to analyse the influence of life stages in the annual cycle to better address conservation and management needs, especially for species inhabiting oceanic islands.

Puerto Rico↗

USGS2004

Multivariate control of plant species richness and community biomass in blackland prairie

Recent studies have shown that patterns of plant species richness and community biomass are best understood in a multivariate context. The objective of this study was to develop and evaluate a multivariate hypothesis about how herbaceous biomass and richness relate to gradients in soil conditions and woody plant cover in blackland prairies. Structural equation modeling was used to investigate how soil characteristics and shade by scattered Juniperus virginiana trees relate to standing biomass and species richness in 99 0.25 m2 quadrats collected in eastern Mississippi, USA. Analysis proceeded in two stages. In the first stage, we evaluated the hypothesis that correlations among soil parameters could be represented by two underlying (latent) soil factors, mineral content and organic content. In the second stage, we evaluated the hypothesis that richness and biomass were related to (1) soil properties, (2) tree canopy extent, and (3) each other (i.e. reciprocal effects between richness and biomass). With some modification to the details of the original model, it was found that soil properties could be represented as two latent variables. In the overall model, 51% and 53% of the observed variation in richness and biomass were explained. The order of importance for variables explaining variations in richness was (1) soil organic content, (2) soil mineral content, (3) community biomass, and (4) tree canopy extent. The order of importance for variables explaining biomass was (1) tree canopy and (2) soil organic content, with neither soil mineral content nor species richness explaining significant variation in biomass. Based on these findings, we conclude that variations in richness are uniquely related to both variations in soil conditions and variations in herbaceous biomass. We further conclude that there is no evidence in these data for effects of species richness on biomass.

Oikos↗

USGS2007

Fine structure of an unidentified protozoon in the epithelium of rainbow trout exposed to water with Myxosoma cerebralis

An intracellular protozoon was discovered in the epithelium of young rainbow trout ( Salmo gairdneri ) exposed for as short a time as 1 hr to water known to contain infective stages of Myxosoma cerebralis. Light- and electron-microscopic examination of this tissue revealed what appeared to be a proliferative stage (presumptive schizont) of a sporozoon; other possible stages in the life cycle were also observed. The relationship of this unidentified protozoon to M. cerebralis remains unresolved.

Journal of Protozoology↗

USGS1989

Development, characterization, and use of monoclonal and polyclonal antibodies against the myxosporean, Ceratomyxa shasta

Both monoclonal and polyclonal antisera were produced against Ceratomyxa shasta. Ascites containing trophozoites of the parasite was collected from infected fish and used as antigen for immunization of mice. The resulting monoclonal antibodies reacted specifically with trophozoite and sporoblast stages but did not react with C. shasta spores by either indirect fluorescent antibody techniques or in Western blots. This indicates that some C. shasta antigens are specific to certain life stages of the parasite. Polyclonal antiserum was produced in a rabbit by injecting a spore protein electro-eluted from an SDS-polyacrylamide gel. This antiserum reacted with both trophozoites and spores by indirect fluorescent antibody techniques and in Western blots. All antisera were tested for cross-reactivity to trout white blood cells, a contaminant of the ascites, and to other myxosporea. Two monoclonal antibodies reacted with white blood cells and myxosporea of the genera Sphaerospora and Myxobilatus. One hybridoma produced antibodies of high specificity for C. shasta pre-spore stages. This is the first report of a monoclonal antibody produced against a myxosporean parasite.

Journal of Eukaryotic Microbiology↗