Diseases In Aquatic Organisms Research Articles

The use of oral boosters as an alternative to control Piscirickettsia salmonis in farmed salmon in Chile

The use of oral boosters as an alternative to control Piscirickettsia salmonis in farmed salmon in Chile

Climate change effects in the Bay of Bengal Large Marine Ecosystem

Evidences are accumulating on the long-term changes in seawater temperature, acidity, deoxygenation, cyclones and sea level in the Bay of Bengal Large Marine Ecosystem. These changes have impacts on ocean productivity, habitats and biological processes. Distributional and phenological changes in fish species, and increase in frequency and intensity of coral bleaching are becoming evident. Fisheries, particularly traditional fisheries, will be the most vulnerable to climate change. Climate warming will also affect the inland and coastal aquaculture sectors of the Bay of Bengal LME countries. Impacts will include changes in hydrology and therefore availability of water, physical threats to aquaculture facilities, and prevalence or spread of known and new diseases of aquatic organisms. The most important and critical adaptation measures will be to develop human resources capacity to increase understanding of the marine resources, and implement measures to sustainably manage fisheries. Bay of Bengal Large Marine Ecosystem project's two main directions taken for climate change response are contribution to the understanding of large-scale processes and climate change effects on one hand, and contributions to adaptation by addressing habitat degradation, pollution and fisheries management, as well as developing capacity and resilience of coastal populations on the other. Recognizing that current problems in weak fisheries management make the sector vulnerable to climate change, BOBLME supports adaptation and increases resilience by strengthening fisheries management and providing assistance to improve fisheries assessments. By strengthening governance, BOBLME also contributes to the integration of climate change adaptation into decision-making and response initiatives, e.g. disaster risk management plans.

양식 넙치 폐사피해 및 수산생물용 의약품 사용량 모니터링

The monitoring was performed to survey the mortalities and medications occurred in the inland aquaculture farms of olive flounder in South Korea from May to October, 2012. Both of the indirect inquiry for entire inland farms and the sample survey for selected farms were carried out. The aquatic organism disease inspectors, who have the national licenses for the diagnosis and prevention of aquatic organism diseases and have close relationship with the farms, investigated the rates and causes of mortalities according to the standard manual. The cumulative mortalities rate by the indirect inquiry on 565 farms, was calculated to 27.18%, and the mortalities rate by infectious diseases was 22.64%. Otherwise, the mortalities rate by sample survey on 60 farms was 25.50%, 19.33% of them were caused by infectious diseases. The high mortality rates were recorded by scuticociliatosis, non-infectious loss, streptococcosis, VHS, artificial eliminations, vibriosis and gliding bacterial disease. Streptococcosis and non-infectious mortality caused to serious loss in productivity and economy of the farms, because of their outbreaks in the flounder groups over 600 g. The monitoring of medications in the selected farms revealed that formalin for the treatment of external parasites, such as scuticociliates, was the most commonly used drugs in the farms. As the antibiotic medications, amoxicillin and florfenicol for streptococcosis, and oxytetracycline and neomycin expecting wide antibacterial spectrum, were frequently prescribed.

한국표준직업분류에 있어서 수산질병관리사의 직업분류에 관한 연구

Abstract The aquatic disease inspector is not classified as an occupation in the current Korean Standard Classification of Occupations(KSCO). Therefore, the roll of the aquatic disease inspector in the medical treatment and the prevention against the aquatic organism disease is underestimated. The aquatic disease inspector is in a more disadvantageous position than the pharmacist and the veterinarian. The purpose of this study is to approve the aquatic disease inspector as an occupation in KSCO. The important contents of this study are as follows.In the first place, this study looks around the general requirements of classifying the occupations in KSCO. The aquatic disease inspector satisfies the most general requirements. But, because of the similarities of job between the aquatic disease inspector and the veterinarian, the aquatic disease inspector do not satisfy the requirement for ‘the principle of exclusiveness'. In the second place, this study looks around the classification system of KSCO. The classification system of KSCO is consists of multi steps. This study makes the plan for the appropriate occupation classification of the aquatic disease inspector. In the third place, this study looks for the legal methods to classify the aquatic disease inspector as an occupation in KSCO. In order to classify the aquatic disease inspector as an occupation in KSCO, many regulations of the laws about the aquatic disease inspector and the veterinarian are to be amended and the number of the aquatic disease inspectors is to be increased by the innovative measures.Key words : Aquatic disease inspector, Occupation classification, KSCO

양식산 넙치에서 Enrofloxacin의 잔류

Enrofloxacin is one of the normally used flouroquinolones in mammalian and fish but its withdrawal time and studies were remain obscure. The residual contents of enrofloxacin in fish muscle were analyzed by using HPLC-FLD. More than 0.1 mg/kg of ENR was detected in muscle tissues and the residues were found over 1 year after treatment. The concentration of ENR in Paralichthys olivaceus was not affected by water temperature and lasted for an extended amount of time. The spike recoveries of ENR in the muscle tissue ranged from 78% to 85%. From this results, we need the prescription by veterinarian or aquatic organism disease inspector in ENR usage to assure safety of fish. Future research is required to determine the recommendation dose of ENR for side effects and safety.

Vibriostatic effects of probiotic Bacillus licheniformis Dahb1 and its molecular phylogeny resolved through RAPD markers

The in vitro vibriostatic effects of probiotic Bacillus licheniformis strains (Dahb1 to Dahb7) from both wild and commercial sources were evaluated against pathogenic Vibrios isolated from shrimp hatcheries and farms. Agar antagonism assay results showed that, out of seven B. licheniformis strains, strain Dahb1 showed the biggest inhibitory zone (6–12 mm) tested against 162 isolates of Vibrio spp. viz., V. harveyi (53 isolates), V. anguillarum (42 isolates), V. vulnificus (31 isolates) and Photobacterium damselae ssp. damselae (36 isolates) obtained from Penaeus monodon culture hatcheries and ponds. The genetic status of these seven strains were analyzed through randomly amplified polymorphic DNA analysis using 18 random primers. Of the 18 primers studied, only 6 generated repeatable polymorphic DNA bands with sizes ranging from 250 to 1,000 bp in seven isolates of B. licheniformis. The dendrogram generated from resolved gel profiles showed two major branches with three clusters. The results of the present study allow us to conclude that B. licheniformis Dahb1 can be used as an effective probiotic to control Vibrios. Field studies are needed to evaluate probiotic efficiency to control diseases in aquatic organisms.

한국 주요 양식종의 수산동물 폐사피해 모니터링

2012년 5월에서 11월 사이에 우리나라 넙치, 조피볼락, 무지개송어, 뱀장어, 흰다리새우, 전복 양식장에서 발생하는 폐사피해를 표본조사를 통해 모니터링하였다. 조사의 방식은 해당 양식장과 거래하고 있거나 관계를 맺고 있는 전국의 수산질병관리사 조사요원의 직접 현장 방문을 통한 면접과 표준 매뉴얼을 통한 진단을 통하여 실시하였다. 조사기간 중 넙치 양식장에서는 총 27.9%의 누적 피해율을 보여주었고, 이중 스쿠티카병, 연쇄구균병, VHS, 비감염성 원인에 의한 폐사, 비브리오병, 활주세균병의 순으로 폐사피해가 높은 것으로 나타났다. 조피볼락 양식장에서는 13.6%의 누적 피해율을 보여주었고, 아가미 흡충병, 연쇄구균병, 비브리오병, 활주세균병, 비감염성 원인에 의한 폐사 순의 폐사피해가 나타났다. 무지개송어의 경우 총 17.1%의 피해율을 기록하였고, 비감염성 원인에 의한 폐사와 백점병이 주된 폐사 원인으로 집계되었다. 뱀장어의 경우 비교적 낮은 0.6%의 피해율을 기록하였으며, 에드워드병, 백점병, 아가미흡충병이 주된 피해요인이었다. 흰다리새우는 71.2%의 피해율을 보였으며, 대부분 비감염성 원인에 의한 폐사으로 집계되었고, 바이러스성 흰반점병도 12.5%의 피해를 준 것으로 나타났다. 전복의 경우 10.7%의 피해율 모두가 비감염성 원인에 의한 폐사 피해인 것으로 조사되었다. The practical monitoring was performed to survey the mortalities in aquaculture farms of olive flounder, rockfish, rainbow trout, Japanese eel, white shrimp and abalone in South Korea from May to November, 2011. The aquatic organism disease inspectors, who have the national licenses for the diagnosis and prevention of aquatic disease and have close relationship with the farms, investigated the rates and causes of mortalities according to the standard manual. In 70 flounder farms, the cumulative mortalities rate was 27.9%, and the mortalities were caused by scuticociliatosis, streptococcosis, VHS, non-infectious loss, vibriosis and gliding bacterial disease. The moralities rate of 30 rockfish farms was 13.6%, and those were mainly contributed by gill flukes and streptococcosis. Most of mortalities of rainbow trout were caused by non-infectious loss and protozoan white spot disease. The mortalities rate of Japanese eel was 0.6% by edwardsiellosis, protozoan white spot disease and gill flukes. The loss rate of white shrimp was 71.2%, and most of them was related with non-infectious ones, such as carnivalization, transportation loss, and the rest was caused by viral white spot disease. The mortalities rate in the abalone farms was 10.7% and all of them were related with non-infectious loss.

100 volumes of Diseases of Aquatic Organisms

100 volumes of Diseases of Aquatic Organisms

Land Use, Macroalgae, and a Tumor-Forming Disease in Marine Turtles

Wildlife diseases are an increasing concern for endangered species conservation, but their occurrence, causes, and human influences are often unknown. We analyzed 3,939 records of stranded Hawaiian green sea turtles (Chelonia mydas) over 28 years to understand fibropapillomatosis, a tumor-forming disease linked to a herpesvirus. Turtle size is a consistent risk factor and size-standardized models revealed considerable spatial and temporal variability. The disease peaked in some areas in the 1990s, in some regions rates remained constant, and elsewhere rates increased. Land use, onshore of where the turtles feed, may play a role. Elevated disease rates were clustered in watersheds with high nitrogen-footprints; an index of natural and anthropogenic factors that affect coastal eutrophication. Further analysis shows strong epidemiological links between disease rates, nitrogen-footprints, and invasive macroalgae and points to foraging ecology. These turtles now forage on invasive macroalgae, which can dominate nutrient rich waters and sequester environmental N in the amino acid arginine. Arginine is known to regulate immune activity, promote herpesviruses, and contribute to tumor formation. Our results have implications for understanding diseases in aquatic organisms, eutrophication, herpesviruses, and tumor formation.

Defining environmental risk assessment criteria for genetically modified fishes to be placed on the EU market

Defining environmental risk assessment criteria for genetically modified fishes to be placed on the EU market

Fast detection of Vibrio species potentially pathogenic for mollusc

Vibrio tasmaniensis, Vibrio splendidus and Vibrio neptunius species were distributed worldwide and associated with aquaculture and have been reported as the cause of diseases in aquatic organisms. Polyphasic analyses for bacterial identification are not feasible for routine diagnostic because of the time involved. The aim of this study is to design three PCR primer sets that can assist with fast detection of these species. They were designed from the 16S ribosomal RNA gene, and PCR conditions were found. Each PCR test successfully identified all the tested strains of each target species. The combined specificity of V. tasmaniensis and V. splendidus primer sets offered the best coverage (86%) in terms of separating target organisms from other related species. The primer set of V. tasmaniensis showed a lower sensitivity limit (500fg of DNA) than the V. splendidus set (1pg) and both sets gave positive amplification using homogenized tissues from inoculated clams, with 102 and 104cfu/g of clam, respectively. The primer set of V. neptunius was highly specific, showing only cross-reaction with V. parahaemolyticus species from 44 tested species. Its sensitivity limit was 100pg of DNA. A small number of biochemical tests were proposed concurrently with the PCR to differentiate the cross-reacting bacteria. The time of detection of the three tested species was reduced and the further affected animals can be diagnosed in a rapid fraction of time. The detection of virulent strains of V. tasmaniensis pointed to the risk of mollusc culture outbreaks.

Ranavirus detection by PCR in cultured tadpoles (Rana catesbeiana Shaw, 1802) from South America

Diseases in farmed tadpoles (Rana catesbeiana) are a common event, being an economically important threat for Uruguayan and Brazilian farms. Based on clinical signs and epizootiology, pathogens belonging to the Family Iridoviridae were suspected as the possible etiology. Although these viruses have already been widely incriminated affecting aquatic organisms including frogs, their presence in Brazil and Uruguay was never mentioned so far. The objective of this work was to detect the presence of ranaviral agents in affected tadpoles using Polymerase Chain Reaction (PCR) technique as a primary approach to the study of the disease. Primers were designed based on highly conserved iridoviral sequences. Major Capsid Protein (MCP) and Immediate Early Protein (IE) genes were the selected targets. A positive PCR result was obtained for both genes when sick tadpoles from Brazil and Uruguay were analyzed. To confirm the amplification of an Iridoviridae, PCR products were purified and sequenced. Amplified products showed high degree of homology with several members of the Iridoviridae, mostly with those belonging to the genus Ranavirus. Obtained sequences were registered in the GenBank with accession nos. AY585203, AY585204 and AY744387. This report indicates that Ranavirus should be considered into the aquatic organism disease etiologies throughout this geographical region.

Isolation and identification of pathogenic Acanthamoeba strains in Tenerife, Canary Islands, Spain from water sources

A comprehensive survey to document the presence of free-living amoebae of the genus Acanthamoeba was conducted in tap water and sea water sources related to human environments in Tenerife, Canary Islands, Spain. Acanthamoeba identification was based on the morphology of cyst and trophozoite forms and PCR amplification with a genus-specific primer pair. The pathogenic potential of Acanthamoeba isolates was characterized by temperature and osmotolerance assays and PCR reactions with two primer pairs related to Acanthamoeba pathogenesis. The results demonstrate the presence of potentially pathogenic strains in both sources. Thus, some of the amoebae in these aquatic habitats can act as opportunistic pathogens, could play a role in the diseases of aquatic organisms, and may present a risk to human health.

Are Ichthyosporea animals or fungi? Bayesian phylogenetic analysis of elongation factor 1α of Ichthyophonus irregularis

Ichthyosporea is a recently recognized group of morphologically simple eukaryotes, many of which cause disease in aquatic organisms. Ribosomal RNA sequence analyses place Ichthyosporea near the divergence of the animal and fungal lineages, but do not allow resolution of its exact phylogenetic position. Some of the best evidence for a specific grouping of animals and fungi (Opisthokonta) has come from elongation factor 1α, not only phylogenetic analysis of sequences but also the presence or absence of short insertions and deletions. We sequenced the EF-1α gene from the ichthyosporean parasite Ichthyophonus irregularis and determined its phylogenetic position using neighbor-joining, parsimony and Bayesian methods. We also sequenced EF-1α genes from four chytrids to provide broader representation within fungi. Sequence analyses and the presence of a characteristic 12 amino acid insertion strongly indicate that I. irregularis is a member of Opisthokonta, but do not resolve whether I. irregularis is a specific relative of animals or of fungi. However, the EF-1α of I. irregularis exhibits a two amino acid deletion heretofore reported only among fungi.

Distribution of free-living amoebae in James River, Virginia, USA.

A comprehensive survey to document the presence of free-living amoebae was conducted along 58 km of James River, near Richmond, Virginia, USA. Sites included tidal and non-tidal freshwater areas, near 40 combined sewer outflows, three municipal wastewater treatment plant release sites, and thermal discharge from a coal-fired power plant. Amoebae were present on all collection dates, spring through autumn, and at all sites ( n=330). Five genera, Naegleria, Vannella, Acanthamoeba, Vahlkampfia, and Hartmannella were present in both the water column and sediment. The most common isolates from the water column were Naegleria and Vannella. Water conditions conducive to the presence of large quantities of fecal coliform bacteria were correlated with the prevalence of free-living amoebae. Some of the amoebae in this complex ecosystem can act as opportunistic pathogens, may play a role in diseases of aquatic organisms in this heavily urbanized river, and may present a risk to human health.

Changing occurrence of epidermal lesions in wild bottlenose dolphins

There are increasing concerns that human activities promote the development of nat- ural diseases in aquatic organisms. Of these, diseases concerning small cetaceans have received increasing attention. Most studies have focused on dead animals and provided information on pathogens, contaminant exposure and probable causes of death. However, our understanding of dis- eases in living populations, particularly with respect to prevalence during the lives of individuals, and for whole populations in different years, remains limited. This study was designed to provide such information on epidermal lesions (abnormalities not directly attributable to physical trauma that may indicate disease) in a wild population of bottlenose dolphins Tursiops truncatus. An 8 yr time series of photographs of 82 free-ranging dolphins from NE Scotland was used to investigate the occurrence and dynamics of epidermal lesions in 7 age classes of young dolphins (from their 1st to their 7th sum- mer of life) and for an adult group. Lesions were found at high prevalence (90 to 100%) in both young and adult dolphins, with 1st-summer calves having the lowest levels. Lesions of different appearance showed 2 patterns of occurrence, either being restricted to young individuals or becoming more com- mon with age. When severity was compared between calves (in their 2nd summer of life) born in 8 different years, a significant decline over time was observed (p < 0.005). Comparison of this change with environmental and anthropogenic factors may help identify which factors may be promoting the ubiquitous epidermal lesions in these dolphins.

Spread of parasites and diseases of aquatic organisms by acclimatization: a short review

The influence of transportation and acclimatization of fishes and shellfishes on their parasites and pathogens is discussed. It has been shown that aquatic organisms lose most of their parasites during the period of establishment, but some species may remain. In most instances these are parasites with direct development (Myxosporea, Monogenea, Crustacea). Species with intermediate hosts, but which utilize many species of invertebrates, establish more easily than those which have specific invertebrate intermediate hosts. If there are closely related host species to those introduced into the water body, parasites brought to it can transfer to these related species. This may result in a high infection of the native species and significant mortality.

Parasite loads in parthenogenetic and sexual lizards (Heteronotia binoei) : support for the Red Queen hypothesis

One version of the Red Queen hypothesis suggests that sexual reproduction is maintained in populations because of the need to continually create genotypes that confer resistance against rapidly evolving pathogens and parasites. Here, we report that parthenogenetic individuals of the Heteronotia binoei species complex are much more prone to infection by mites than are their sexual relatives. This accords with a central prediction of the Red Queen hypothesis. The greater susceptibility of the parthenogens is consistent across localities with different combinations of parthenogenetic genotypes and sexual chromosome races and occurs despite the unusually high genetic diversity of the parthenogenetic form. These observations support the contention that clonal reproduction increases the susceptibility of hosts to infection by parasites.

Aquatic pollution problems, North Atlantic coast, including Chesapeake Bay

Pollutant effects on fishes and fisheries of the North Atlantic may be estimated from biological and biochemical responses to pollutant exposure and the incidence of pollution-related disease in aquatic organisms. Indirect and potential effects on ecosystems may be estimated from the accumulation of contaminants in biota. Based upon increases in pollutant-related disease and bioaccumulation of contaminants, marine biota in the North Atlantic region show evidence of deleterious, pollution-related effects. However, the plethora of contaminants discharged to the marine environment makes it impossible to determine which agents, or combinations of agents, have the greatest effect. Marine and estuarine sediments show a history of contaminant input. More than 300 aromatic hydrocarbons have been detected in the Chesapeake Bay, and polychlorinated biphenyls (PCBs) occur in sediments in parts of New Bedford Harbor at levels measured in percent. Major sites of marine contamination are Boston, New Bedford, Providence, New York, Baltimore Harbor, and the Elizabeth River, Virginia. Biota in these and other areas show increased burdens of many contaminants, including PCBs, pesticides, phthalates, metals and aromatic hydrocarbons. In general, the gradient of contaminant levels decreases offshore. Contaminant burdens result from discharges to rivers and ocean, marine dumping and atmospheric fallout. Health advisories have been posted in some regions regarding the consumption of striped bass, bluefish and lobster, and the effects of chlordecone (kepone) spills on fisheries in the James River are felt after more than 10 years. What the long-term biological effects of these contaminants will be is not fully known. Biological effects of pollutants include alterations in biochemical, respiratory, and immune functions, as well as changes in population structure and developmental or structural abnormalities. Fishes and invertebrates exposed to organic contaminants may be induced to produce higher levels of enzymes capable of transforming many contaminants to more polar, but occasionally more toxic, metabolites. The induction of biotransformation enzymes has been suggested as a link in the etiology of disease among marine and estuarine fishes in highly contaminated areas. Surveys show high incidences of diseases in fishes from New England, Long Island Sound, the Hudson River estuary/New York Bight and the Elizabeth River, Virginia. The most common diseases generally affect the liver, although cataracts and pollution-related disorders of the skin and gills occur. Neoplasia, including benign and malignant growths, has been documented for flatfish as well as for tomcod in the Hudson River estuary. Epidemiological studies and statistical analyses support the concept of an environmental etiology for disease in fishes from contaminated areas.

Pollution and parasitism in the aquatic environment

The studies of aquatic parasitology and of aquatic pollution effects both have experienced increasing interest during the recent fifteen years. Although considerable effort has been spent on studying the role of pollution as a cause or a trigger of anomalies, tumors and infectious diseases in aquatic organisms, the interactions between pollution and parasitism have been largely neglected by scientists. Pollution and other man-made alterations of the aquatic environment may affect a parasite community directly by acting on free-living parasite stages or on ectoparasites, or indirectly by acting on the intermediate or the definitive host population. Certain pollution conditions favour the propagation of parasites by excluding their natural predators, by reducing the resistance of their hosts or by providing improved living conditions for their intermediate hosts. In a number of experimental studies parasitized organisms have been shown to suffer from greater mortalities when exposed to high temperature, to low oxygen stress or to high levels of dissolved heavy metal salts, when compared to nonparasitized control animals. Unfortunately, field studies on synergistic effects of pollution and parasites on host populations are still scarce and seldom offer more than qualitative observations and theoretical evaluations. The complexity of the pollution-parasite-host system complicates the use of parasites as indicators of pollution effects. However, experience from aquaculture practice teaches that a number of (mostly ecto-) parasites are more susceptible to certain chemicals (used as parasiticides) and to artificial alterations of salinity, temperature or oxygen content of the water than their hosts. Accordingly, it is postulated that during future studies the composition of ectoparasitic faunas of aquatic organisms might turn out to become a useful and quickly reacting indicator for effects of certain pollution conditions, such as anthropogene oxygen deficiency, salt introduction from salines into freshwater ecosystems, and introduction of certain heavy metal salts.