SEARCH · Search USGS

Results for “Plant Disease”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5Linked to original sources

USGS1984

Annual variation in the distribution, abundance, and habitat response of the palila ( Loxioides bailleui )

We studied the distribution, population size, and habitat response of the Palila ( Loxioides bailleui ) during the 1980-1984 nonbreeding seasons to infer factors that limit the population and to develop management strategies. Distribution was fairly constant from year to year. Palila were confined to the subalpine woodland on Mauna Kea on the island of Hawaii, occurred between 2,000 and 2,850 m elevation, and reached highest densities on the southwest slopes. The population showed large annual fluctuations, from 6,400 birds in 1981 to 2,000 in 1984. The width of woodland was the most important variable in determining habitat response. Palila were more common in areas with greater crown cover, taller trees, and a higher proportion of native plants in the understory. Annual variation in Palila density within a habitat reflected variation in levels of their staple food, mamane pods. The main limiting factors of the population appeared to be the availability of good habitat and levels of their staple food. Palila had strongly depressed densities in the Pohakuloa flats area. This low density could not be explained by gross habitat features or food levels. Site tenacity, thermal stress, disturbance, and disease were hypothesized explanations. Our study indicated that the most effective management strategies would be the removal of feral ungulates and certain noxious plants from Palila habitat and the extension of the woodland zone to areas now intensively grazed.

The Auk↗

USGS2015

Wyoming Basin Rapid Ecoregional Assessment

The Wyoming Basin Rapid Ecoregional Assessment was conducted in partnership with the Bureau of Land Management (BLM). The overall goals of the BLM Rapid Ecoregional Assessments (REAs) are to identify important ecosystems and wildlife habitats at broad spatial scales; identify where these resources are at risk from Change Agents, including development, wildfire, invasive species, disease and climate change; quantify cumulative effects of anthropogenic stressors; and assess current levels of risk to ecological resources across a range of spatial scales and jurisdictional boundaries by assessing all lands within an ecoregion. There are several components of the REAs. Management Questions, developed by the BLM and stakeholders for the ecoregion, identify the regionally significant information needed for addressing land-management responsibilities. Conservation Elements represent regionally significant species and ecological communities that are of management concern. Change Agents that currently affect or are likely to affect the condition of species and communities in the future are identified and assessed. REAs also identify areas that have high conservation potential that are referred to as “large intact areas.” At the ecoregion level, the ecological value of large intact areas is based on the assumption that because these areas have not been greatly altered by human activities (such as development), they are more likely to contain a variety of plant and animal communities and to be resilient and resistant to changes resulting from natural disturbances such as fire, insect outbreaks, and disease. The Wyoming Basin Ecoregion encompasses approximately 133,656 square kilometers (51,604.87 square miles), including portions of Wyoming, Colorado, Utah, Idaho, and Montana. The Wyoming Basin has some of the highest quality wildlife habitats remaining in the Intermountain West. The wide variety of habitats includes intermountain basins dominated by sagebrush shrublands interspersed with deciduous and conifer woodlands and montane or subalpine forests at higher elevations. The Wyoming Basin also supports ranching and agricultural operations that are important to the region’s economy and vital to conserving habitats for wildlife. The region also contains abundant energy resources, including large natural gas reserves and areas of high wind-energy potential. Combined with increased residential and industrial development, fast-paced energy development is resulting in notable land-use changes, including habitat loss and fragmentation. In the Wyoming Basin REA, we evaluated the following seven communities as Conservation Elements: streams and rivers, wetlands, riparian forests and shrublands, sagebrush steppe, desert shrublands, foothill shrublands and woodlands, and mountain forests and alpine zones. We evaluated a total of 14 species and species assemblages as Conservation Elements: aspen forests and woodlands, five-needle pine forests and woodlands, juniper woodlands, cutthroat trout, three-species fish assemblage, northern leatherside chub, sauger, spadefoot assemblage, greater sage-grouse, golden eagle, ferruginous hawk, sagebrush-obligate birds, pygmy rabbit, and mule deer. We evaluated Management Questions (Core and Integrated) for each species and community for the Wyoming Basin REA. Core Management Questions address primary management issues, including (1) where is the Conservation Element, and what are its key ecological attributes (characteristics of species and communities that may affect their long-term persistence or viability); (2) what and where are the Change Agents; and (3) how do the Change Agents affect the key ecological attributes? Integrated Management Questions synthesize the Core Management Questions as follows: (1) where are the areas with high landscape-level ecological values; (2) where are the areas with high landscape-level risks; and (3) where are the potential areas for conservation, restoration, and development? The associated maps and key findings for each Management Question are summarized for each Conservation Element in individual chapters. Additional chapters on landscape intactness and an REA synthesis are included.

Colorado, Idaho, Montana, Utah, Wyoming↗

USGS2019

The evolving threat of rapid Ohia death (ROD) to Hawaii’s native ecosystems and rare plant species

Hawai‘i’s most widespread native tree, ‘ōhi‘a lehua ( Metrosideros polymorpha ), has been dying across large areas of Hawai‘i Island mainly due to two fungal pathogens ( Ceratocystis lukuohia and Ceratocystis huliohia ) that cause a disease collectively known as Rapid ‘Ōhi‘a Death (ROD). Here we examine patterns of positive detections of C. lukuohia as it has been linked to the larger mortality events across Hawai‘i Island. Our analysis compares the environmental range of C. lukuohia and its spread over time through the known climatic range and distribution of ‘ōhi‘a. Analyses show this fungal pathogen generally encompassed the core, but not the extremes of the climatic range of ‘ōhi‘a. We further modeled the potential distribution of C. lukuohia across the Hawaiian Archipelago to estimate the risk of ROD to other islands. Given the potential for C. lukuohia to alter the structure of ‘ōhi‘a dominated forests, we used our projected potential distribution of C. lukuohia to assess the risk of ROD to threatened and endangered plant species across Hawai‘i. Many native plants are likely vulnerable to these types of large ‘ōhi‘a mortality events: of 234 endangered native plant species considered, 147 (62.8%) have more than half of their range within current and expanding C. lukuohia suitable areas. We also found evidence that protecting habitat by fencing out introduced feral ungulates reduces the prevalence of the disease likely by reducing physical damage caused by these animals to ‘ōhi‘a trees, a precondition for Ceratocystis infection. Given the ongoing spread of C. lukuohia , we developed a dynamic web portal to host our results online, where models and analyses are updated with new lab-confirmed detections to provide managers with a useful tool to help monitor and assess the risk of C. lukuohia as it continues to spread.

Hawaii↗

USGS2010

Bat guano virome: Predominance of dietary viruses from insects and plants plus novel mammalian viruses

Bats are hosts to a variety of viruses capable of zoonotic transmissions. Because of increased contact between bats, humans, and other animal species, the possibility exists for further cross-species transmissions and ensuing disease outbreaks. We describe here full and partial viral genomes identified using metagenomics in the guano of bats from California and Texas. A total of 34% and 58% of 390,000 sequence reads from bat guano in California and Texas, respectively, were related to eukaryotic viruses , and the largest proportion of those infect insects , reflecting the diet of these insectivorous bats, including members of the viral families Dicistroviridae, Iflaviridae, Tetraviridae, and Nodaviridae and the subfamily Densovirinae. The second largest proportion of virus -related sequences infects plants and fungi, likely reflecting the diet of ingested insects , including members of the viral families Luteoviridae, Secoviridae, Tymoviridae, and Partitiviridae and the genus Sobemovirus. Bat guano viruses related to those infecting mammals comprised the third largest group, including members of the viral families Parvoviridae, Circoviridae, Picornaviridae, Adenoviridae, Poxviridae, Astroviridae, and Coronaviridae. No close relative of known human viral pathogens was identified in these bat populations. Phylogenetic analysis was used to clarify the relationship to known viral taxa of novel sequences detected in bat guano samples, showing that some guano viral sequences fall outside existing taxonomic groups. This initial characterization of the bat guano virome , the first metagenomic analysis of viruses in wild mammals using second-generation sequencing, therefore showed the presence of previously unidentified viral species, genera, and possibly families. Viral metagenomics is a useful tool for genetically characterizing viruses present in animals with the known capability of direct or indirect viral zoonosis to humans.

Journal of Virology↗

USGS2022

Host plant associations of Lepidoptera and implications for forest bird management at Hakalau Forest National Wildlife Refuge

Forests dominated or co-dominated by ‘ōhi‘a ( Metrosideros polymorpha ) are critical to most Hawaiian forest birds, but fungal diseases causing Rapid ‘Ōhi‘a Death (ROD) threaten ‘ōhi‘a-based food webs that support native bird communities on Hawai‘i Island. Caterpillars are the most frequently consumed arthropod prey of native birds and their young and are especially frequent in the diets of one threatened (T) and three endangered (E) species (“listed” species) at Hakalau Forest National Wildlife Refuge (Hakalau): ‘akiapōlā‘au ( Hemignathus wilsoni , E), ‘alawī (Hawai‘i creeper; Loxops mana , E), Hawai‘i ‘ākepa ( L. coccineus , E), and ‘i‘iwi ( Drepanis coccinea , T). Hakalau harbors the largest and most stable populations of listed forest birds in Hawai‘i, presumably due to the availability of food resources and the extent of suitable, managed habitat above the range of mosquito-borne avian malaria. Because a previous study indicated that only a few caterpillar species were important in the diets of listed birds at Hakalau, we investigated the distribution of caterpillars on common host plants available to foraging birds. Eleven native plant species hosted two or more taxa identified to genus or species, with at least seven from ‘ōhi‘a, six from koa ( Acacia koa ), and five from ‘ākala ( Rubus hawaiensis ). We identified 16 taxa to genus or species from 9 families, assigning 11 to species. Leaves, which were the focus of our sampling effort, were the substrate used by 20 caterpillar taxa, and dead wood or bark was used by 7 taxa. In a previous study, we classified 19 morphotypes of caterpillar mandibles in the diets of native and alien birds at Hakalau, and in the present study we dissected mandibles from caterpillars that likely matched 10 of those morphotypes. These 10 morphotypes potentially represented >95% of caterpillar prey found in the earlier diet study and were collected from 11 host plant species, with ‘ōhi‘a hosting 8 morphotypes, 4 of which were exclusive to ‘ōhi‘a. The most widely hosted morphotype was found on all 11 plant species that we sampled, including ‘ōhi‘a, but the other 9 morphotypes were found on 1–7 hosts. As shown by the previous diet study, each of the listed bird species consumed caterpillar prey consisting mostly of combinations of two morphotypes drawn from a pool of only five, indicating a high degree of specialization. In the present study, we collected three of the five key morphotypes only on ‘ōhi‘a, highlighting the importance of this tree to listed bird species. Because ‘ōhi‘a forests in Hakalau remain vulnerable to ROD, measures to mitigate the impacts of reduced ‘ōhi‘a cover are important to consider from the perspective of forest bird food webs and diet. Ongoing reforestation of former pasturelands with koa and common understory species should provide alternative caterpillar prey for forest birds. Our results and information from the literature indicate that koa supports, to varying degrees, nearly all forest birds at Hakalau, while ‘ākala, ‘ōhelo ( Vaccinium calycinum ), kōlea ( Myrsine lessertiana ), ‘ōlapa ( Cheirodendron trigynum ), pūkiawe ( Leptecophylla tameiameiae ), and māmaki ( Pipturus albidus ) could benefit bird populations by increasing prey availability and structural complexity in koa-dominated stands. Foraging studies and additional research to identify species and host plant associations of important forest bird prey, including caterpillars and other arthropods, can help managers evaluate the complex interactions between native forest birds and their food webs and habitats.

Hawaii↗

USGS2010

U.S. Geological Survey activities related to American Indians and Alaska Natives: Fiscal years 2007 and 2008

In the late 1800s, John Wesley Powell, the second director of the U.S. Geological Survey (USGS), followed his interest in the tribes of the Great Basin and Colorado Plateau and studied their cultures, languages, and surroundings. From that early time, the USGS has recognized the importance of Native knowledge and living in harmony with nature as complements to the USGS mission to better understand the Earth. Combining traditional ecological knowledge with empirical studies allows the USGS and Native American governments, organizations, and people to increase their mutual understanding and respect for this land. The USGS is the earth and natural science bureau within the U.S. Department of the Interior (DOI) and is not responsible for regulations or land management. Climate change is a major current issue affecting Native lives and traditions throughout the United States. Climate projections for the coming century indicate an increasing probability for more frequent and more severe droughts in the Southwest, including the Navajo Nation. Erosion has claimed Native homes in Alaska. Fish have become inedible due to diseases that turn their flesh mushy. Native people who rely on or who are culturally sustained by hunting, fishing, and using local plants are living with climate change now. The traditional knowledge of Native peoples enriches and confirms the work of USGS scientists. The results are truly synergistic-greater than the sum of their parts. Traditional ecological knowledge is respected and increasingly used in USGS studies-when the holders of that knowledge choose to share it. The USGS respects the rights of Native people to maintain their patrimony of traditional ecological knowledge. The USGS studies can help Tribes, Native organizations, and natural resource professionals manage Native lands and resources with the best available unbiased data and information that can be added to their traditional knowledge. Wise Native leaders have noted that traditional ecological knowledge includes the connections between Earth and her denizens. From this perspective, it is the connections among these ?relatives? that needs to be nurtured. This perspective on nature is finding new adherents among Natives and non-Natives as understanding of climate change and other environmental conditions deepens. Although this report uses the term ?resources,? the USGS, through its interdisciplinary research, acknowledges the interconnectedness of the Earth and the things that live upon it.

Circular↗

USGS2006

A framework for spatial risk assessments: Potential impacts of nonindigenous invasive species on native species

Many populations of wild animals and plants are declining and face increasing threats from habitat fragmentation and loss as well as exposure to stressors ranging from toxicants to diseases to invasive nonindigenous species. We describe and demonstrate a spatially explicit ecological risk assessment that allows for the incorporation of a broad array of information that may influence the distribution of an invasive species, toxicants, or other stressors, and the incorporation of landscape variables that may influence the spread of a species or substances. The first step in our analyses is to develop species models and quantify spatial overlap between stressor and target organisms. Risk is assessed as the product of spatial overlap and a hazard index based on target species vulnerabilities to the stressor of interest. We illustrate our methods with an example in which the stressor is the ecologically destructive nonindigenous ant, Solenopsis invicta, and the targets are two declining vertebrate species in the state of South Carolina, USA. A risk approach that focuses on landscapes and that is explicitly spatial is of particular relevance as remaining undeveloped lands become increasingly uncommon and isolated and more important in the management and recovery of species and ecological systems. Effective ecosystem management includes the control of multiple stressors, including invasive species with large impacts, understanding where those impacts may be the most severe, and implementing management strategies to reduce impacts. Copyright ?? 2006 by the author(s).

Ecology and Society↗

USGS2024

Assessing the attractiveness of native wildflower species to bees (Hymenoptera: Anthophila) in the southeastern United States

Habitat loss, agricultural intensification, pesticide use, disease and climate change have contributed to the decline of numerous insect groups. Recent government initiatives have recognized the importance of supplementary wildflower plantings to support native bee populations, yet little information exists on the attractiveness of recommended plant species to bees. With the use of network analysis and generalized linear mixed models, we evaluated the attractiveness of 18 wildflower species belonging to 6 families (Apiaceae, Apocynaceae, Asteraceae, Fabaceae, Lamiaceae and Verbenaceae) planted in a randomized block design by conducting timed targeted sweep netting surveys. We also evaluated the floral preferences of four bee species ( Apis mellifera , Halictus poeyi/ligatus , Bombus griseocollis and Bombus impatiens ) to the planted wildflower species with the use of GLMs. We found that Asclepias tuberosa, Gaillardia pulchella and Verbena hastata attracted the greatest abundance, richness and diversity of native bees compared to the other wildflower species. Collectively, Asclepias tuberosa, Gaillardia pulchella and Verbena hastata attracted 89% of all bee taxa in the study, which exemplifies the importance of including them in a wildflower mixture to attract native bees. While several wildflower species attracted low abundance, richness and diversity of native bees such as Monarda fistulosa, Symphyotrichum pilosum and Eryngium yuccifolium , they are still ecologically important for attracting uncommon or specialist bee species and should be included in seed mixes for this reason. Solution . Our results highlight that each species of native wildflower varies in the abundance, richness and diversity of native bees they attract; this could be considered in the decision-making of landowners and land managers to promote wildflower plantings to reflect the needs of certain groups of bees of conservation interest.

Alabama↗

USGS2012

Free tropospheric transport of microorganisms from Asia to North America

Microorganisms are abundant in the troposphere and can be transported vast distances on prevailing winds. This study measures the abundance and diversity of airborne bacteria and fungi sampled at the Mt. Bachelor Observatory (located 2.7 km above sea level in North America) where incoming free tropospheric air routinely arrives from distant sources across the Pacific Ocean, including Asia. Overall deoxyribonucleic acid (DNA) concentrations for microorganisms in the free troposphere, derived from quantitative polymerase chain reaction assays, averaged 4.94 × 10(-5) ng DNA m(-3) for bacteria and 4.77 × 10(-3) ng DNA m(-3) for fungi. Aerosols occasionally corresponded with microbial abundance, most often in the springtime. Viable cells were recovered from 27.4 % of bacterial and 47.6 % of fungal samples (N = 124), with 49 different species identified by ribosomal DNA gene sequencing. The number of microbial isolates rose significantly above baseline values on 22-23 April 2011 and 13-15 May 2011. Both events were analyzed in detail, revealing distinct free tropospheric chemistries (e.g., low water vapor, high aerosols, carbon monoxide, and ozone) useful for ruling out boundary layer contamination. Kinematic back trajectory modeling suggested air from these events probably originated near China or Japan. Even after traveling for 10 days across the Pacific Ocean in the free troposphere, diverse and viable microbial populations, including presumptive plant pathogens Alternaria infectoria and Chaetomium globosum, were detected in Asian air samples. Establishing a connection between the intercontinental transport of microorganisms and specific diseases in North America will require follow-up investigations on both sides of the Pacific Ocean.

Microbial Ecology↗

USGS2022

Exploring and mitigating plague for One Health purposes

Purpose of Review In 2020, the Appropriations Committee for the U.S. House of Representatives directed the CDC to develop a national One Health framework to combat zoonotic diseases, including sylvatic plague, which is caused by the flea-borne bacterium Yersinia pestis . This review builds upon that multisectoral objective. We aim to increase awareness of Y. pestis and to highlight examples of plague mitigation for One Health purposes (i.e., to achieve optimal health outcomes for people, animals, plants, and their shared environment). We draw primarily upon examples from the USA, but also discuss research from Madagascar and Uganda where relevant, as Y. pestis has emerged as a zoonotic threat in those foci. Recent Findings Historically, the bulk of plague research has been directed at the disease in humans. This is not surprising, given that Y. pestis is a scourge of human history. Nevertheless, the ecology of Y. pestis is inextricably linked to other mammals and fleas under natural conditions. Accumulating evidence demonstrates Y. pestis is an unrelenting threat to multiple ecosystems, where the bacterium is capable of significantly reducing native species abundance and diversity while altering competitive and trophic relationships, food web connections, and nutrient cycles. In doing so, Y. pestis transforms ecosystems, causing “shifting baselines syndrome” in humans, where there is a gradual shift in the accepted norms for the condition of the natural environment. Eradication of Y. pestis in nature is difficult to impossible, but effective mitigation is achievable; we discuss flea vector control and One Health implications in this context. Summary There is an acute need to rapidly expand research on Y. pestis , across multiple host and flea species and varied ecosystems of the Western US and abroad, for human and environmental health purposes. The fate of many wildlife species hangs in the balance, and the implications for humans are profound in some regions. Collaborative multisectoral research is needed to define the scope of the problem in each epidemiological context and to identify, refine, and implement appropriate and effective mitigation practices.

Current Tropical Medicine Reports↗

USGS2024

A meta-analysis highlights the idiosyncratic nature of tradeoffs in laboratory models of virus evolution

Different theoretical frameworks have been invoked to guide the study of virus evolution. Three of the more prominent ones are (i) the evolution of virulence, (ii) life history theory, and (iii) the generalism–specialism dichotomy. All involve purported tradeoffs between traits that define the evolvability and constraint of virus-associated phenotypes. However, as popular as these frameworks are, there is a surprising paucity of direct laboratory tests of the frameworks that support their utility as broadly applicable theoretical pillars that can guide our understanding of disease evolution. In this study, we conduct a meta-analysis of direct experimental evidence for these three frameworks across several widely studied virus–host systems: plant viruses, fungal viruses, animal viruses, and bacteriophages. We extracted 60 datasets from 28 studies and found a range of relationships between traits in different analysis categories (e.g., frameworks, virus–host systems). Our work demonstrates that direct evidence for relationships between traits is highly idiosyncratic and specific to the host–virus system and theoretical framework. Consequently, scientists researching viral pathogens from different taxonomic groups might reconsider their allegiance to these canons as the basis for expectation, explanation, or prediction. Future efforts could benefit from consistent definitions, and from developing frameworks that are compatible with the evidence and apply to particular biological and ecological contexts.

Virus Evolution↗

USGS2021

Viral-like particles are associated with endosymbiont pathology in Florida corals affected by stony coral tissue loss disease

Stony coral tissue loss disease (SCTLD) was first documented in 2014 near the Port of Miami, Florida, and has since spread north and south along Florida’s Coral Reef, killing large numbers of more than 20 species of coral and leading to the functional extinction of at least one species, Dendrogyra cylindrus . SCTLD is assumed to be caused by bacteria based on presence of different molecular assemblages of bacteria in lesioned compared to apparently healthy tissues, its apparent spread among colonies, and cessation of spread of lesions in individual colonies treated with antibiotics. However, light microscopic examination of tissues of corals affected with SCTLD has not shown bacteria associated with tissue death. Rather, microscopy shows dead and dying coral cells and symbiotic dinoflagellates (endosymbionts) indicating a breakdown of host cell and endosymbiont symbiosis. It is unclear whether host cells die first leading to death of endosymbionts or vice versa. Based on microscopy, hypotheses as to possible causes of SCTLD include infectious agents not visible at the light microscopy level or toxicosis, perhaps originating from endosymbionts. To clarify this, we examined corals affected with SCTLD and apparently healthy corals using transmission electron microscopy. Endosymbionts in SCTLD-affected and apparently healthy corals consistently had varying degrees of pathology associated with elongated particles compatible in morphology with filamentous positive single-stranded RNA viruses of plants termed anisometric viral-like particles (AVLP). There was apparent progression from early to late replication of AVLP in the cytoplasm of endosymbionts adjacent to or at times within chloroplasts, with morphologic changes in chloroplasts consistent with those seen in plant cells infected by viruses. Coral host cell pathology appeared limited to massive proliferation and lysis of mucus cells. Based on these findings, we hypothesize that SCTLD is a viral disease of endosymbionts leading to coral host death. Efforts to confirm the presence of a virus associated with SCTLD through other means would be appropriate. These include showing the presence of a virus through molecular assays such as deep sequencing, attempts to grow this virus in the laboratory through culture of endosymbionts, localization of virus in tissue sections using immunohistochemistry or in situ hybridization, and experimental infection of known-virus-negative corals to replicate disease at the gross and microscopic level.

Florida↗

USGS2016

Evolution of viral virulence: empirical studies

The concept of virulence as a pathogen trait that can evolve in response to selection has led to a large body of virulence evolution theory developed in the 1980-1990s. Various aspects of this theory predict increased or decreased virulence in response to a complex array of selection pressures including mode of transmission, changes in host, mixed infection, vector-borne transmission, environmental changes, host vaccination, host resistance, and co-evolution of virus and host. A fundamental concept is prediction of trade-offs between the costs and benefits associated with higher virulence, leading to selection of optimal virulence levels. Through a combination of observational and experimental studies, including experimental evolution of viruses during serial passage, many of these predictions have now been explored in systems ranging from bacteriophage to viruses of plants, invertebrates, and vertebrate hosts. This chapter summarizes empirical studies of viral virulence evolution in numerous diverse systems, including the classic models myxomavirus in rabbits, Marek's disease virus in chickens, and HIV in humans. Collectively these studies support some aspects of virulence evolution theory, suggest modifications for other aspects, and show that predictions may apply in some virus:host interactions but not in others. Finally, we consider how virulence evolution theory applies to disease management in the field.

Book chapter↗

USGS1993

Evaluation of invasions and declines of submersed aquatic macrophytes

During the past 60 yr, sightings of aquatic macrophyte species in geographic regions where they had previously not been found have occurred with increasing frequency, apparently due to both greater dispersal of the plants as a result of human activities as well as better documentation of plant distribution. Intercontinental invasions, such as Myriophyllum spicatum and Hydrilla into North America, Elodea canadensis into Europe and Elodea nuttallii, Egeria densa and Cabomba caroliniana into Japan, have generally been well documented. However, the spread of an exotic species across a continent after its initial introduction (e.g., Potamogeton crispus in North America) or the expansion of a species native to a continent into hitherto unexploited territory (e.g.,the expansion of the North American native Myriophyllum heterophyllum into New England) have received little attention. Natural declines in aquatic macrophyte communities have also received little scientific study although there are many accounts of macrophyte declines. The best-documented example comes from the marine literature where extensive declines of eelgrass (Zostera) occurred in the 1930s along the Atlantic coast due to a pathogenic marine slime mold (''wasting disease''). The aim of this workshop was to identify examples of invasions or natural declines of aquatic macrophyte species throughout the world and assess the importance of environmental factors in their control. Forty-five scientists and aquatic plant managers from ten countries participated in the workshop. Eleven of the participants contributed written evaluations of species invasions and declines in their geo-graphic region. These were distributed to registered participants prior to the meeting and served as the starting-point of workshop discussions. To address the topics raised in the working papers, the participants divided into four working groups to evaluate: 1. Environmental controls of species invasions. 2. Biotic controls of species declines. 3. Abiotic controls of species declines. 4. Impact of management practices on macrophyte invasions or declines. Each working group was asked to identify existing evidence, the need for additional evidence and management implications of their topics and then requested to discuss their findings with the entire workshop at the conclusion of discussions.

Journal of Aquatic Plant Management↗

USGS2024

Immunomodulation in adult largemouth bass (Micropterus salmoides) exposed to a model estrogen or mixture of endocrine disrupting contaminants during early gonadal recrudescence

Disease outbreaks, skin lesions, fish kill events, and reproductive abnormalities have been observed in wild populations of Centrarchids in watersheds throughout the United States. Occurrence of synthetic and natural hormones from wastewater treatment plants and livestock operations, pesticides from agricultural land use, and phytoestrogens have been implicated as potential causes of these adverse effects. Our objective was to investigate possible immunomodulation in adult largemouth bass ( Micropterus salmoides ) in response to a seasonal exposure to environmentally relevant contaminants in outdoor experimental ponds. Exposures included 17α-ethinylestradiol (EE2; 3.6 ng/L) or a binary mixture of endocrine-active substances commonly detected in surface waters, estrone (E1; 85.6 ng/L) and atrazine (ATR; 5.4 µg/L). The 4-month exposure was conducted from July to November. Functional immune responses of anterior kidney-derived leukocytes were evaluated in December in the week following the end of the dosing period, and in the following April, four months after dosing ended and just prior to spawning. Concentrations of EE2 and E1 in the ponds fell below detectable levels in December, but detectable concentrations of ATR (2.9 µg/L) persisted at least through May. For each sampling time, anterior kidney leukocytes were isolated and grown in primary culture for the assessment of zymosan-stimulated respiratory burst and lectin-stimulated mitogenic responses. We observed seasonal differences in respiratory burst stimulation over time and treatment with a significantly greater response in April relative to December. Respiratory burst activity was also significantly greater in April for fish exposed to the E1+ATR relative to control. In April, prior to spawning, we observed a significantly dampened mitogenic response to PHAP (a T cell mitogen) and LPS (a B cell mitogen) in the EE2 treatment relative to control fish. There were no significant differences in mitogenic responses or respiratory burst between sexes. However, there was significantly higher alternative complement pathway hemolytic activity in males compared to females in both the control and E1+ATR treatment groups. Our results demonstrate that environmentally relevant concentrations of contaminants can alter immune function in a socioeconomically important fish species.

Comparative Immunology Reports↗

USGS1987

Ecology, behavior, and conservation of the Maui parrotbill

The distribution, habitat response, sexual dimorphism, foraging, breeding, and flocking behavior of Maui Parrotbills (Pseudonestor xanthophrys ) were studied over a five year period. The species' present range is confined to montane rainforest on eastern Maui, but dry lowland habitats on Maui and Molokai were occupied before Polynesian contact. Birds occurred from 1,250 to 2,150 m elevation, becoming most abundant at 1,750 to 2,000 m. In Kipahulu Valley, birds moved to lower elevations in some seasons. Birds tended to forage in the subcanopy and understory, with 66% of the prey captured 1 to 5 m above ground. Plant species use deviated from expectations based on availability. The most frequent means of prey capture was excavation for timber-boring insects in dead branches on live plants. Foraging accounted for 39% of the diurnal time budget; an average prey item appeared to account for 1% of the daily energy intake. The principal limiting factors appeared to be habitat loss, avian disease, habitat degradation, predation, and competition from exotic species. Control of pig populations is a needed management action.

Condor↗

USGS2024

The skin I live in: Pathogenesis of white-nose syndrome of bats

The emergence of white-nose syndrome (WNS) in North America has resulted in mass mortalities of hibernating bats and total extirpation of local populations. The need to mitigate this disease has stirred a significant body of research to understand its pathogenesis. Pseudogymnoascus destructans , the causative agent of WNS, is a psychrophilic (cold-loving) fungus that resides within the class Leotiomycetes, which contains mainly plant pathogens and is unrelated to other consequential pathogens of animals. In this review, we revisit the unique biology of hibernating bats and P . destructans and provide an updated analysis of the stages and mechanisms of WNS progression. The extreme life history of hibernating bats, the psychrophilic nature of P . destructans , and its evolutionary distance from other well-characterized animal-infecting fungi translate into unique host–pathogen interactions, many of them yet to be discovered.

PLoS Pathogens↗

USGS2000

Stress resistance strategy in an arid land shrub: interactions between developmental instability and fractal dimention

This paper investigates allocation of energy to mechanisms that generate and preserve architectural forms (i.e. developmental stability, complexity of branching patterns) and productivity (growth and reproduction) in response to environmental disturbances (i.e. grazing and resource availability). The statistical error in translational symmetry was used to detect random intra-individual variability during development. This can be thought of as a measure of developmental instability caused by stress. Additionally, we use changes in fractal complexity and shoot distribution of branch structures as an alternate indicator of stress. These methods were applied to Anthyllis cytisoides L., a semi-arid environment shrub, to ascertain the effect of grazing and slope exposure on developmental traits in a 2×2 factorial design. The results show that A. cytisoides maintains developmental stability at the expense of productivity. Anthyllis cytisoides was developmentally more stable when grazed and when on south-facing, as opposed to north-facing slopes. On the contrary, shoot length, leaf area, fractal dimension and reproductive-to-vegetative allocation ratio were larger in north- than in south-facing slopes. As a consequence, under extreme xeric conditions, shrub mortality increased in north-facing slopes, especially when not grazed. The removal of transpiring area and the reduction of plant competition favoured developmental stability and survival in grazed plants. Differences between grazed and ungrazed plants were most evident in more mesic (north-facing) areas.

Journal of Fish Diseases↗