Geology topics

Yasu Kiryu

Publications and source records attributed to Yasu Kiryu.

6 recordsLinked to original sources

USGS2024

Stony coral tissue loss disease (SCTLD) case definition for wildlife

Diagnostic laboratories receive carcasses and samples for diagnostic evaluation and pathogen/toxin detection. Case definitions bring clarity and consistency to the evaluation process. Their use within and between organizations allows more uniform reporting of diseases and etiologic agents. The intent of a case definition is to provide scientifically based criteria for determining (a) if an individual carcass has a specific disease and degree of confidence in that diagnosis and (b) if there is evidence of a pathogen or toxin in a carcass or sample (for example, swab, tissue sample, skin scraping, blood/serum sample, environmental sample, or other). This case definition is specific to Stony Coral Tissue Loss Disease (SCTLC) and applies to several species of scleractinian corals across seven families: Faviidae, Meandrinidae, Merulinidae, Montastraeidae, Astrocoeniidae, Scleractinia, and Siderastreidae. Other species presumed to be susceptible are in Families Agaridiidae, Faviidae, and Pocilloporidae.

Florida↗

USGS2023

Rapid prototyping for quantifying belief weights of competing hypotheses about emergent diseases

Emerging diseases can have devastating consequences for wildlife and require a rapid response. A critical first step towards developing appropriate management is identifying the etiology of the disease, which can be difficult to determine, particularly early in emergence. Gathering and synthesizing existing information about potential disease causes, by leveraging expert knowledge or relevant existing studies, provides a principled approach to quickly inform decision-making and management efforts. Additionally, updating the current state of knowledge as more information becomes available over time can reduce scientific uncertainty and lead to substantial improvement in the decision-making process and the application of management actions that incorporate and adapt to newly acquired scientific understanding. Here we present a rapid prototyping method for quantifying belief weights for competing hypotheses about the etiology of disease using a combination of formal expert elicitation and Bayesian hierarchical modeling. We illustrate the application of this approach for investigating the etiology of stony coral tissue loss disease (SCTLD) and discuss the opportunities and challenges of this approach for addressing emergent diseases. Lastly, we detail how our work may apply to other pressing management or conservation problems that require quick responses. We found the rapid prototyping methods to be an efficient and rapid means to narrow down the number of potential hypotheses, synthesize current understanding, and help prioritize future studies and experiments. This approach is rapid by providing a snapshot assessment of the current state of knowledge. It can also be updated periodically (e.g., annually) to assess changes in belief weights over time as scientific understanding increases. Synthesis and applications: The rapid prototyping approaches demonstrated here can be used to combine knowledge from multiple experts and/or studies to help with fast decision-making needed for urgent conservation issues including emerging diseases and other management problems that require rapid responses. These approaches can also be used to adjust belief weights over time as studies and expert knowledge accumulate and can be a helpful tool for adapting management decisions.

Journal of Environmental Management↗

USGS2023

A scuticociliate causes mass mortality of Diadema antillarum in the Caribbean Sea

Echinoderm mass mortality events shape marine ecosystems by altering the dynamics among major benthic groups. The sea urchin Diadema antillarum , virtually extirpated in the Caribbean in the early 1980s by an unknown cause, recently experienced another mass mortality beginning in January 2022. We investigated the cause of this mass mortality event through combined molecular biological and veterinary pathologic approaches comparing grossly normal and abnormal animals collected from 23 sites, representing locations that were either affected or unaffected at the time of sampling. Here, we report that a scuticociliate most similar to Philaster apodigitiformis was consistently associated with abnormal urchins at affected sites but was absent from unaffected sites. Experimentally challenging naïve urchins with a Philaster culture isolated from an abnormal, field-collected specimen resulted in gross signs consistent with those of the mortality event. The same ciliate was recovered from treated specimens postmortem, thus fulfilling Koch’s postulates for this microorganism. We term this condition D. antillarum scuticociliatosis.

Science Advances↗

USGS2020

Stony coral tissue loss disease in Florida is associated with disruption of host–zooxanthellae physiology

Samples from eight species of corals ( Colpophyllia natans , Dendrogyra cylindrus , Diploria labyrinthiformis , Meandrina meandrites , Montastraea cavernosa , Orbicella faveolata, Pseudodiploria strigosa , and Siderastrea siderea ) that exhibited gross clinical signs of acute, subacute, or chronic tissue loss attributed to stony coral tissue loss disease (SCTLD) were collected from the Florida Reef Tract during 2016–2018 and examined histopathologically. The hallmark microscopic lesion seen in all eight species was focal to multifocal lytic necrosis (LN) originating in the gastrodermis of the basal body wall (BBW) and extending to the calicodermis, with more advanced lesions involving the surface body wall. This was accompanied by other degenerative changes in host cells such as mucocyte hypertrophy, degradation and fragmentation of gastrodermal architecture, and disintegration of the mesoglea. Zooxanthellae manifested various changes including necrosis (cytoplasmic hypereosinophilia, pyknosis); peripheral nuclear chromatin condensation; cytoplasmic vacuolation accompanied by deformation, swelling, or atrophy; swollen accumulation bodies; prominent pyrenoids; and degraded chloroplasts. Polyhedral intracytoplasmic eosinophilic periodic acid–Schiff-positive crystalline inclusion bodies (∼1–10 μm in length) were seen only in M. cavernosa and P. strigosa BBW gastrodermis in or adjacent to active lesions and some unaffected areas (without surface lesions) of diseased colonies. Coccoidlike or coccobacilloidlike structures (Gram-neutral) reminiscent of microorganisms were occasionally associated with LN lesions or seen in apparently healthy tissue of diseased colonies along with various parasites and other bacteria all considered likely secondary colonizers. Of the 82 samples showing gross lesions of SCTLD, 71 (87%) were confirmed histologically to have LN. Collectively, pathology indicates that SCTLD is the result of a disruption of host–symbiont physiology with lesions originating in the BBW leading to detachment and sloughing of tissues from the skeleton. Future investigations could focus on identifying the cause and pathogenesis of this process.

Florida↗

USGS2008

Prevalence of tumors in brown bullhead from three lakes in southeastern Massachusetts, 2002

The Massachusetts Military Reservation (MMR) has been a military base on western Cape Cod since the early 1900s. Contaminated surface water and ground water from the MMR have discharged into several kettle lakes on or near the base. To discover whether the prevalences of tumors and other lesions in brown bullhead (Ameiurus nebulosus) in these lakes, particularly Ashumet Pond, were elevated above normal, the U.S. Geological Survey (USGS), assisted by the U.S. Environmental Protection Agency (USEPA) and the Massachusetts Division of Fisheries and Wildlife (MADFW), conducted a study in 2002 of brown bullhead in Ashumet Pond and in two reference lakes, Santuit Pond (on Cape Cod) and Great Herring Pond (on the mainland of Massachusetts). Brown bullhead from Great Herring Pond had few external raised lesions (2.8 percent), a low prevalence of liver neoplasms (5 percent), and little genetic damage to their red blood cell nuclei. Brown bullhead from Ashumet Pond had a high prevalence of raised lesions (62.1 percent), which included histopathologically verified papillomas and squamous carcinoma; an elevated incidence of liver neoplasms (16.7 percent); and an elevated level of genetic damage to their red blood cell nuclei. Because red blood cells in fish have a lifespan of about 100 days, these results indicate an ongoing exposure to genotoxins in Ashumet Pond. Brown bullhead from Santuit Pond also had elevated prevalences of raised lesions (48.3 percent) and liver neoplasms (15 percent), although the prevalences of large and multiple lesions were significantly lower than those in fish from Ashumet Pond. These differences may indicate differing causes of pathology in the two lakes. The high prevalence of melanistic lesions on brown bullhead from Ashumet Pond, combined with the tumor pathology and genetic damage, implicates chemical carcinogens as one of the causal factors in that lake.

Massachusetts↗

USGS2002

Induction of skin ulcers in Atlantic menhaden by injection and aqueous exposure to the zoospores of Aphanomyces invadans

The infectivity and role of Aphanomyces invadans in the etiology of skin ulcers in Atlantic menhaden Brevoortia tyrannus were investigated with two laboratory challenges. In the first experiment, Atlantic menhaden received subcutaneous injections with secondary zoospores from one of three cultures of Aphanomyces : WIC (an endemic isolate of A. invadans in Atlantic menhaden from the Wicomico River, Maryland), PA7 (an isolate of A. invadans from striped snakehead Channa striata (also known as chevron snakehead), infected with epizootic ulcerative syndrome from Thailand), and ATCC-62427 (an isolate from Atlantic menhaden from North Carolina). Fish were injected with 1.9 × 10 2 (WIC-low), 1.9 × 10 3 (WIC-high), 5.2 × 10 2 (PA7), or 6.0 × 10 2 (ATCC-62427) zoospores and held in static water at 23.5°C (6‰ salinity) for 21 d. Both low and high doses of WIC caused incipient, granulomatous lesions after 5 d. Fish injected with the high-dose WIC died within 7 d. All fish injected with the low-dose WIC were dead after 10 d. Fish injected with zoospores of PA7 developed lesions after 9 d. Fish injected with the ATCC-62427 isolate or those that received subcutaneous injections of sterile water (controls) did not develop lesions. In the second experiment, fish were bath-exposed with zoospores of the WIC isolate after various trauma-inducing treatments. These treatments consisted of handling fish with a net (net stress, exposed for 2 h to either 70 or 700 zoospores/mL), physically removing a few scales (trauma, exposed for 1 h to 700 zoospores/mL), or acclimating fish with less handling (acclimated, untraumatized, exposed for 5.5 h to 110 zoospores/mL). Unexposed fish served as controls. Mortality ranged from 94% to 100% for net-handled and traumatized fish, with the prevalence of ulcerous lesions ranging from 70% to 79% in net-handled fish. However, mortality was 24% for the “untraumatized” fish and the prevalence of lesions was 32%. Fish injected with or exposed to bath challenges of zoospores developed lesions that were grossly and histologically identical to those observed in naturally infected Atlantic menhaden from several estuaries and rivers along the mid-Atlantic coast of the USA. The deeply penetrating ulcers were characterized by dermatitis, myofibrillar degeneration, and deep, necrotizing granulomatous myositis. Experimentally induced lesions, however, exhibited invasiveness, often involving the kidney. Injected or bath-exposed fish developed incipient granulomas after 5 d, which progressed to overt lesions over 7–9 d. We have here demonstrated that ulcerative skin lesions can be experimentally induced in Atlantic menhaden after exposure to oomycete zoospores of an endemic strain of A. invadans .

Journal of Aquatic Animal Health↗