I. Paperna

Diseases caused by parasites in the aquaculture of warm water fish.

Abstract Parasitic infections of fish cultured in fresh and marine waters of subtropical and tropical geographic regions are reviewed. The following parasites are discussed: Ectoparasitic protozoa, Coccidia, Myxosporea, Monogenea, Metacercariae of trematodes, the Asian tapeworm, nematodes, ergasilids, lernaeids, and argulids. Criteria for selection were their impact on farmed fish and the availability of data beyond case reports and surveys. Epizootic ectoparasitic infections are usually the outcome of adverse growth conditions, either climatic or resulting from management practices. Epizootiology of infections by internal parasites, heteroxenous in particular, is more complex, particularly in man-made systems, as it is determined by a wider range of interacting ecological parameters. Exotic species, particularly cyprinids, comprise the bulk of freshwater fish farmed in warm water systems. Most important diseases affecting fishes in such systems are caused by introduced pathogens. Only a few of the autochthonous parasites become involved in epizootic infections, also where indigenous species are farmed. Marine farming is usually based on indigenous species. The relatively short history of piscine mariculture has already recorded epizootic infections and mortalities both by parasites contracted from the local environment and by specific parasites associated with the cultured species. As in freshwater systems, culture practices often create an environment favorable to epizootic infection.

Desiccation stress of entomopathogenic nematodes induces the accumulation of a novel heat-stable protein

The present study describes a novel heat-stable, water-stress-related protein with a molecular mass of 47 kDa (designated Desc47) in the entomopathogenic nematode Steinernemafeltiae (IS-6). The protein was accumulated about 10-fold (from 7.84 +/- 1.85 to 74.09 +/- 4.35 % relative content level [RCL]) in dehydrated clumps of infective juveniles (IJs), which had lost 344.% of their initial water content (from 65.1 +/- 1.7% to 427 +/- 0.72%) in a desiccation-tolerance-inducing treatment (97% relative humidity [RH] for 3 days). The appearance of Desc47 was accompanied by trehalose accumulation (from 300 to 600 mg trehalose/g protein) during the process of inducing the IJs into a quiescent anhydrobiotic state. A second cycle of IJ dehydration did not alter the RCL of Desc47 (79.3% for the first cycle and 73.3% for the second cycle). Desc47 retained its high RCL (69.7%) in rehydrated active IJs for 3 days, reaching 51.2% of its initial RCL only after a week. No homology to other known proteins was found by mass-spectrometry electrospray-ion-trap analysis. However, of the 5 sequences obtained from the 11protein(ranging from to 21 amino acids), the 21-amino-acid peptide N V A S D A V E T V G N A A G Q A G (D/T) A V showed excellent homology (74% identity in 19 amino acids) to the cold-responsive protein COR14b (g6564861) from Triticum aestivum. In the Caenorhabditis elegans predicted proteome database search, the N21 yielded the first-best identity score (59 % identity in 17 amino acids) to the CE-LEA homologue protein (g2353333). In plants, COR and LEA are related proteins, heat-stable, which are expressed in response to both dehydration and cold acclimation. The implication of the involvement of Desc47 and the osmoprotectant trehalose in the desiccation-tolerance mechanisms of S. feltiae is discussed.

Morphological versus molecular identification of avian Haemosporidia: an exploration of three species concepts

More than 200 species of avian Haemosporidia (genera Plasmodium, Haemoproteus, and Leucocytozoon) have been described based primarily on morphological characters seen in blood smears. Recent molecular studies, however, suggest that such methods may mask a substantial cryptic diversity of avian haemosporidians. We surveyed the haemosporidians of birds sampled at 1 site in Israel. Parasites were identified to species based on morphology, and a segment of the parasites cytochrome b gene was sequenced. We compared 3 species concepts: morphological, genetic, and phylogenetic. Fifteen morphological species were present. Morphological species that occurred once within our dataset were associated with a unique gene sequence, displayed large genetic divergence from other morphological species, and were not contained within clades of morphological species that occurred more than once. With only 1 exception, morphological species that were identified from multiple bird hosts presented identical sequences for all infections, or differed by few synonymous substitutions, and were monophyletic for all phylogenetic analyses. Only the morphological species Haemoproteus belopolskyi did not follow this trend, falling instead into at least 2 genetically distant clades. Thus, except for H. belopolskyi, parasites identified to species by morphology were supported by both the genetic and phylogenetic species concepts.

Trichodinid ectoparasites of cichlid and cyprinid fishes in South Africa and Israel

SummaryThree new and seven known species of trichodinid ectoparasites (Ciliophora: Peritricha) were identified from cichlid and cyprinid fishes collected from fish ponds, natural and man-made lakes, rivers and streams in South Africa and Israel. The new species described are: Trichodina centrostrigata n.sp., T. minuta n.sp. and Tripartiella cichlidarum n.sp. The known species, of which comparative descriptions are given and intraspecific variability discussed, are: Trichodina acuta Lom, 1961, T. heterodentata Duncan, 1977, T. mutabilis Kazubski & Migala, 1968, T. nigra Lom, 1960, T. pediculus Ehrenberg, 1838, T. reticulata Hirschmann & Partsch, 1955 and Trichodinella epizootica (Raabe, 1950). ac]19820916

Bacterial infections in gilt-head sea bream Sparus aurata cultured at Elat

Abstract Acute septicemia following handling operations was a frequent cause of mortality among Sparus aurata reared in the facilities of the I.O.L.R. Mariculture Laboratory at Elat (on the Red Sea). 116 bacterial strains were isolated from the blood of 88 dying Sparus aurata. Vibrio alginolyticus was the most frequently isolated species. Biochemical dissimilarities justified its further subdivision into at least six distinct strains. Healthy fish challenged with three of these strains failed, however, to develop any clinical signs. The opportunistic nature of the bacteria involved in acute septicemia is discussed. Commercial miniaturized kits for biochemical tests (Pathotec and Minitek) were found to be inadequate for their identification. All the isolated strains were tested for their sensitivity to antibacterial drugs. None was found resistant to nitrofurazone, furaltadone tartrate and chloramphenicol. Treatment methods with such agents are described and discussed.

Epitheliocystis infection in wild and cultured sea bream (Sparus aurata, Sparidae) and grey mullets (Liza ramada, Mugilidae)

Abstract Heavy infection with epitheliocystis on gills caused mortality in hatchery-born Sparus aurata . Histopathological findings showed extensive proliferation of the gill epithelium around the epitheliocystis capsule. Such proliferation was not observed in benign infections. Epizootic infections thus occurred only in hatchery-born S. aurata . In S. aurata and mullets reared from natural stocks, infection remained benign and sporadic. Epitheliocystis infections were also found in juvenile mullets from the east Mediterranean waters as well as from the Gulf of Elat, Red Sea.

Diseases of Sparus aurata in marine culture at Elat.

Abstract The predominant diseases occurring in Sparus aurata cultured in sea water at Elat were bacteria-contaminated skin lesions, gill rot and septicemia. These developed mainly in fish stressed and injured following handling. Bacteria involved were Gram-negative and myxobacteria which were controlled by application of Nitrofurazone. Ectoparasitic infections were generally sporadic and insignificant, however, on three occasions the ciliate Trichodina sp. and the monogenean Furnestia echeneis caused morbidity and mortality of epizootic proportion. Ectoparasites were successfully controlled by application of formalin. A diet-related disease, visceral granuloma, appeared in fish fed on certain artificial diets containing fish meal but not in fish fed on fresh mussels or fish meat. Pathological symptoms included extreme granuloma following hypertrophy of the kidneys and spleen and focal lesions in other organs. Hatchery-bred fish suffered from episodes of extreme infections of epitheliocystis, the monogenean F. echeneis, gill rot due to myxobacteria and skeletal deformations coupled with tumours of the swim bladder.

Development of Hepatozoon caimani (Carini, 1909) Pessôa, De Biasi & De Souza, 1972 in the Caiman Caiman c. crocodilus, the frog Rana catesbeiana and the mosquito Culex fatigans

The sporogony of Hepatozoon caimani has been studied, by light microscopy, in the mosquito Culex fatigans fed on specimens of the caiman Caiman c. crocodilus showing gametocytes in their peripheral blood. Sporonts iniciate development in the space between the epithelium of the insect gut and the elastic membrane covering the haemocoele surface of the stomach. Sporulating oocysts are clustered on the gut, still invested by the gut surface membrane. Fully mature oocysts were first seen 21 days after the blood-meal. No sporogonic stages were found in some unidentified leeches fed on an infected caiman, up to 30 days following the blood-meal. When mosquitoes containing mature oocysts were fed to frogs (Leptodactylus fuscus and Rana catesbeiana), cysts containing cystozoites developed in the internal organs, principally the liver. Feeding these frogs to farm-bred caimans resulted in the appearance of gametocytes in their peripheral blood at some time between 59 and 79 days later, and the development of tissue cysts in the liver, spleen, lungs and kidneys. Transmission of the parasite was also obtained by feeding young caimans with infected mosquitoes and it is suggested that both methods occur in nature. The finding of similar cysts containing cystozoites in the semi-aquatic lizard Neusticurus bicarinatus, experimentally fed with infected C. fatigans, suggests that other secondary hosts may be involved.

Parasitic infections of sea bass, Dicentrarchus labrax, and gilt head sea bream, Sparus aurata, in mariculture facilities in France

Abstract Parasitic infections occur in sea cultured Sparus aurata and Dicentrarchus labrax in France. Investigations indicate the presence of parasitic protozoans, monogeneans and copepods in these fish.

Chemical control of Amyloodinium ocellatum (Brown 1931) (Dinoflagellida) infections: In vitro tests and treatment trials with infected fishes

Abstract In vitro incubation of dividing tomonts of Amyloodinium ocellatum (Brown 1931) was used to evaluate efficacy and mode of action of potentially paraciticidal chemicals. Copper sulfate, in concentrations up to 10 ppm, did not interrupt division. However, concentrations as low as 0.5 ppm were lethal to sporulating tomonts and dinospores. None of the tested agents, formalin (25–200 ppm), Nitrofurazone (10–50 ppm), Furanace (1–5 ppm), malachite green (0.1–100 ppm) and Acriflavin (0.1–10 ppm) induced an immediate lethal effect. All of the agents induced a gradual inhibitory effect on the rate of division. Consequently sporulation was impaired or prevented. Inhibition was related to the duration of treatment and to concentration. Flush treatments of up to 9 h proved to be ineffective in preventing reinfestation. Effective eradication of A. ocellatum infection from Sparus aurata larvae and post-larvae in the hatchery was accomplished by continuous application of 0.75 ppm copper sulfate for up to 2 weeks.