Diseases of aquatic organisms最新文献

Considerable attention has been directed to studying the infection dynamics of the fungal pathogen Batrachochytrium dendrobatidis (Bd) affecting amphibians in the high elevations of the Neotropics. However, lowland forests of the same realm remain comparatively understudied in this context. Herein, we attempt to bridge this gap by measuring the prevalence of Bd via quantitative polymerase chain reaction (qPCR) in several anuran taxa inhabiting the Amazonian lowlands in the northeast of Ecuador. To this end, we sampled 207 anurans from 10 different families, 25 different genera, and 55 distinct host species originally collected in 2008. Taxonomy (at the family level), morphology (i.e. weight and snout-vent length), and life-long aquatic dependency of hosts (i.e. aquatic index) were also compiled to serve as potential predictors of Bd infection status. Our findings revealed a relatively high Bd prevalence of 58%, with 88% of sampled anuran families testing positive for the fungus at varying proportions. Model selection involving fitting and testing several different linear models, including mixed linear models, revealed a significant negative relationship between host weight and Bd infection status (p < 0.01). However, no significant associations were observed between taxonomy, aquatic dependency, snout-vent length, and Bd infections. In addition, we only detected the global panzootic lineage of Bd (Bd-GPL) and not the Bd-Asia-2/Bd-Brazil lineage via qPCR single nucleotide polymorphism (SNP) genotyping. Our findings contribute to the understanding of Bd dynamics in the Neotropical lowlands and emphasize the need for future research on the ecological factors influencing Bd in the Amazon and their implications for amphibian conservation.

Intentional harm to marine mammals refers to deliberate human actions that cause injury, suffering, or death, and it is illegal in many countries. These actions often result from direct human attacks and are motivated by various reasons, with retaliation by fishermen being the most common. Such attacks cause severe tissue damage, frequently leading to the debilitation or death of the targeted animal. In this report, we document 13 cases of intentionally harmed marine mammals: 12 bottlenose dolphins Tursiops truncatus and 1 Mediterranean monk seal Monachus monachus found in the Croatian part of the Adriatic Sea between 1990 and 2023. Our analysis includes the life history data of the attacked specimens, post-mortem findings, and the weaponry involved. Among 311 post-mortem examinations conducted, 4.2% revealed intentional harm. Adult male bottlenose dolphins were most frequently targeted (46.2%), with a majority (53.8%) succumbing immediately due to exsanguination. Shotgun pellets, bullets, and underwater speargun spearheads were recovered from their carcasses. The attacks occurred with no discernible seasonal pattern; however, 61.5% of the cases were recorded from Istria County. Our findings underscore the inadequacy of current surveillance and enforcement in protecting marine mammals from deliberate harm. We advocate for the implementation of educational initiatives targeting relevant groups, intensive sea patrols, and routine inspection of weapons with high penalties for illegal possession and misuse, all reinforced by media campaigns to combat this malicious human behaviour.

Gas-bubble disease (GBD)-a non-infectious disease in aquatic organisms caused by supersaturated levels of total dissolved gases (oxygen and nitrogen) in water-is well known in various species, including fish and amphibians, but has not previously been reported in giant salamanders. In the present study, macroscopic and histopathological examinations of 2 mature Andrias spp. (kept with 293 fish in an aquarium) were performed to characterize GBD pathology. Bubbles developed on the body surfaces of the salamanders and fish, with erythema specifically noted in the salamanders. Within 3 d of the bubbles appearing, both salamanders and more than 270 fish had died. On Days 1 and 2, dissolved oxygen levels were 75.5 and 86.9%, respectively, while dissolved nitrogen gas levels were 90.6 and 103.1%, respectively. The 2 salamanders exhibited identical lesions characterized by erythema, congestion, and numerous bubbles in the major veins of the body cavity. Histopathologically, congestion and gas embolism-like dilatations were observed in the small vessels and capillaries. These lesions were found in the parenchymal and gastrointestinal organs, skin, eyeballs, and surrounding stromal tissue. Based on these findings and that GBD occurs at dissolved nitrogen gas and oxygen levels above 120 and 200%, respectively, the salamanders were diagnosed with nitrogen GBD. The exact etiology of this disease remains unconfirmed but likely involves circulatory system dysfunction within the aquarium environment, highlighting the importance of routine inspections and maintenance of equipment.

Cold stress is the leading cause of mortality in West Indian manatees Trichechus manatus in the northcentral Gulf of Mexico. This report describes an adult male manatee that stranded alive with signs of cold stress in Alabama (USA) waters in January 2022 and died during the rescue intervention. Postmortem examination and histopathologic review revealed multiple contributors to death. While the animal had evidence of cold stress syndrome, there was aortic stenosis and concentric left ventricular hypertrophy as well as an esophageal foreign body (plastic bag). Main findings from blood analysis indicated systemic inflammation and possible disseminated intravascular coagulation. Histopathologic findings from the cardiovascular system included aortic fibromuscular dysplasia, mitral and tricuspid valve endocardiosis, left ventricular myocardial hypertrophy, and right myocardial atrophy. A cause of the cardiovascular findings was not determined. This report is the first to document a case of cold stress syndrome complicated by aortic stenosis and esophageal occlusion in this species.

Between September and December 2023, Uruguay experienced unusually high pinniped mortality due to an HPAI-H5N1 virus outbreak. We examined and compared the temporal distribution of strandings and swab results. Data on pinniped strandings was compiled from the Stranding Network project and governmental institutions, and the number of positive and total swabs conducted was obtained through government public information requests. A total of 2713 stranded pinnipeds were recorded; 92.4% were dead, including 80 aborted fetuses. Live stranded animals showed clinical signs such as tremors, convulsions, and extreme weakness. Strandings peaked from mid-September to early November. Species was identified in 1121 cases: 56.1% were South American sea lions (SASL), and 42.6% were South American fur seals (SAFS). Out of 159 swabs, 22.6% tested positive for HPAI-H5N1. Most positive cases were unidentified pinnipeds, 33% in SASL and 22% in SAFS. The estimated mortality reached 1465 SASL, about 15% of the population, significantly affecting the declining population and its reproductive stock. The outbreak response revealed weaknesses in disease surveillance, poor institutional coordination, and delayed swabbing efforts. Improved management strategies are necessary to protect vulnerable species from emerging diseases and catastrophic events.

Coral diseases are an increasing threat to continuously degrading reefs as disease abundance and virulence are expected to increase in the future. Active conservation measures, specifically coral restoration projects, are increasingly being implemented worldwide. Yet little is known about the implications of disease occurrence in a restoration context. This study describes white syndrome pathogenesis in 2 coral genera, farmed in 2 mid-water rope nurseries located in a reef and a lagoon habitat in the Maldives. Over a 112 d monitoring period, disease metrics were obtained from 336 Pocillopora and 96 Acropora fragments to assess the impacts of unmitigated disease progression in coral nurseries. Disease had low prevalence (2.2%) and incidence (0.007) in reef-farmed Pocillopora, but survival (91%) was significantly reduced in comparison with the unaffected lagoon-farmed Pocillopora (99%). In contrast, lagoon-farmed Acropora showed high disease prevalence (78.5%) and incidence (0.064), and a lower survival (79%) than disease-unaffected reef-farmed Acropora (98%). These findings had distinct implications for coral gardening success. While Pocillopora was considered suitable for outplanting, especially since subsequent mitigation interventions were successful, the diseased, lagoon-reared Acropora posed a potential risk to the restoration site and was unsuitable for outplanting following 1 yr of farming effort. Our findings demonstrate that unmitigated diseases can cause major setbacks to restoration success. Coral gardening projects are likely to be particularly susceptible; therefore, disease monitoring and risk management are imperative. Since there is currently a lack of available diagnostic and mitigative tools, this study aims to provide case study data for restoration practitioners.

Significant knowledge gaps remain in our understanding of the reproductive physiology and diseases of elasmobranchs. The objective of this work is to describe the clinical, imaging, and pathologic findings associated with polycystic ovaries in cownose rays housed in public aquariums. Ten adult female cownose rays Rhinoptera bonasus housed in 4 public aquariums presented with variable nonspecific (lethargy, anorexia, cutaneous discoloration) or no clinical signs. Clinical antemortem examination revealed a large, heterogeneously hyperechoic mass with many variably sized and shaped anechoic cavitations within the coelom on ultrasound in 2 animals. Necropsies of 10 animals revealed polycystic, fluid-filled ovarian masses filling approximately 65-75% of the coelomic cavity in severe cases along with substantial liver atrophy. Microscopically, the masses were composed of delicate connective tissue supporting a combination of cysts lined by attenuated squamous to foamy columnar epithelium, hemorrhage, embedded anovulatory follicles, and oocytes along the periphery. Polycystic ovarian disease is understudied in elasmobranchs and presumptively resulted from failure of follicular ovulation in these cases. Along with southern stingrays, cownose rays appear to be at heightened risk for developing polycystic ovaries under human care. Further study into disease prevalence, epidemiologic factors, etiopathogenesis, and treatment modalities are needed in order to prevent and medically manage this condition in cownose rays under human care.

The bopyrid Pseudione galacanthae is an ectoparasite of the squat lobster Grimothea gregaria (Munida gregaria). This study aimed to analyze the spatial variations in the prevalence of P. galacanthae in Argentine Patagonia and the potential drivers shaping this variability. To analyze this crustacean/crustacean parasitic relationship, bottom trawl net hauls, a CTD cast, and zooplankton samplings were performed in 10 locations between 43.6° and 47.7°S. Squat lobsters were assigned to 1 of 2 morphotypes (gregaria or subrugosa), sexed, and measured, and the branchial chambers were examined in search of bopyrids. Correlation analyses were performed to identify whether environmental variables (sea bottom salinity, SBS), sea bottom temperature, depth, and calanoid copepods abundance) or population traits (median of size distribution and density of squat lobsters) were related to P. galacanthae prevalence. The gregaria morphotype was dominant in the south of San Jorge Gulf (SJG), whereas the subrugosa morphotype was more abundant in the other locations. No significant differences were observed in P. galacanthae prevalence between sexes or morphotypes. Spatial variations in prevalence were observed, reaching 15.2% in the south of SJG. P. galacanthae prevalence was correlated only with SBS. We hypothesized that the highest prevalence of P. galacanthae could be related to the presence of a tidal frontal system in the south of SJG, which could favor parasite larval retention. The prevalence reported here is the highest for bopyrid parasites in squat lobster species and reveals that this interaction could have a detrimental impact on G. gregaria populations at local scale.

Piscinoodinium is a well-known parasitic dinoflagellate genus that causes epizootics in tropical freshwater fish. This study investigated the first outbreak of Piscinoodinium sp. in freshwater fish of the Andaman Islands, India. The infection was noticed in the non-native fish Betta splendens and Poecilia reticulata, and in the endemic killifish Aplocheilus andamanicus. The infection caused mass mortality in larval, sub-adult, and adult fish. The parasite was identified based on microscopy and molecular characterization. The prevalence, parasite density, and mortality percentage were recorded. Infected fish had numerous trophonts attached on the body surface, gills, fins, and eyes. Infected skin and gills showed degeneration of the epithelial cells and clubbed gills. Small subunit rDNA (955 bp) was amplified from the Piscinoodinium sp. infecting B. splendens, revealing genetic differences between it and Piscinoodinium spp. from the USA and from India.

We studied the population and reproductive characteristics of the stone crab Hapalogaster dentata (De Haan, 1849) (Anomura: Lithodidae) parasitized by Briarosaccus hoegi (Rhizocephala: Peltogastridae) from Peter the Great Bay (northwestern Sea of Japan) in 2023. The sex structure of the H. dentata population was female-biased and represented by 39.1% males and 60.9% females. The size-frequency distribution differed between males and females. The prevalence of parasitization of H. dentata by B. hoegi reached 6.7%. No relationship between crab sex and parasitization prevalence was found. Most of the parasitized specimens (94.8%) had only a single parasitic externa. The non-parasitized and parasitized crabs did not differ in main carapace length. The pleopods in most of the externa-bearing females were shortened or completely atrophied. H. dentata produced 1 clutch per year with ovigerous females occurring from October to May. An obvious delay in embryonic development was observed in winter. None of the parasitized H. dentata females were ovigerous. Externae with embryos of B. hoegi were found from May to July.