59 research outputs found
Occurrence of Neobenedenia girellae (Monogenea: Capsalidae) in Gilthead Seabream Sparus aurata (Actinopterygii: Sparidae) Cultured in Portugal
Monogenean capsalids of the genus Neobenedenia are widespread parasites of wild and
farmed marine fish, and represent a potential threat to mariculture due to their pathogenicity
and ability to cause mortality in fish maintained in controlled conditions. The identification of
Neobenedenia species and, consequently, the definition of their host specificity is often problematic
due to their highly conserved morphology; therefore, in order to establish their specific identity,
microscopic observation should be complemented with molecular analysis. The present work aims
at characterizing Neobenedenia specimens infecting the skin of cage reared gilthead seabream Sparus
aurata from Portugal. Parasite samples obtained from caged fish were processed for morphological
analysis, through observation in light and scanning electron microscopy, and for molecular analysis,
through amplification and sequencing of 28S rDNA and cytB, aimed at identifying them to the species
level. Our results showed that the collected parasites belonged to the species Neobenedenia girellae; the
susceptibility of S. aurata towards this pathogenic capsalid monogenean highlighted in the present
work represents an important risk in the farming of this valuable fish specie
Comparative Therapeutic Effects of Natural Compounds Against Saprolegnia spp. (Oomycota) and Amyloodinium ocellatum (Dinophyceae)
The fish parasites Saprolegnia spp. (Oomycota) and Amyloodinium ocellatum
(Dinophyceae) cause important losses in freshwater and marine aquaculture industry,
respectively. The possible adverse effects of compounds used to control these
parasites in aquaculture resulted in increased interest on the search for natural
products with antiparasitic activity. In this work, eighteen plant-derived compounds
(2\u2032,4\u2032-Dihydroxychalcone; 7-Hydroxyflavone; Artemisinin; Camphor (1R); Diallyl sulfide;
Esculetin; Eucalyptol; Garlicin 80%; Harmalol hydrochloride dihydrate; Palmatine
chloride; Piperine; Plumbagin; Resveratrol; Rosmarinic acid; Sclareolide; Tomatine,
Umbelliferone, and Usnic Acid) have been tested in vitro. Sixteen of these were
used to determine their effects on the gill cell line G1B (ATCC\uaeCRL-2536TM) and
on the motility of viable dinospores of Amyloodinium ocellatum, and thirteen were
screened for inhibitory activity against Saprolegnia spp. The cytotoxicity results on
G1B cells determined that only two compounds (2\u2032,4\u2032-Dihydroxychalcone and Tomatine)
exhibited dose-dependent toxic effects. The highest surveyed concentrations (0.1 and
0.01mM) reduced cell viability by 80%. Upon lowering the compound concentration
the percentage of dead cells was lower than 20%. The same two compounds
revealed to be potential antiparasitics by reducing in a dose-dependent manner the
motility of A. ocellatum dinospores up to 100%. With respect to Saprolegnia, a
Minimum Inhibitory Concentration was found for Tomatine (0.1mM), Piperine and
Plumbagin (0.25mM), while 2\u2032,4\u2032-Dihydroxychalcone considerably slowed downmycelial
growth for 24 h at a concentration of 0.1mM. Therefore, this research allowed to
identify two compounds, Tomatine and 2\u2032,4\u2032-Dihydroxychalcone, effective against both
parasites. These compounds could represent promising candidates for the treatment of
amyloodiniosis and saprolegniosis in aquaculture. Nevertheless, further in vitro and in
vivo tests are required in order to determine concentrations that are effective against the
considered pathogens but at the same time safe for hosts, environment and consumers
Anisakid and Raphidascaridid parasites in Trachurus trachurus: infection drivers and possible effects on the hostâs condition
This study investigated the distribution of nematode larvae of Anisakidae and Raphidascarididae (genera Anisakis and Hysterothylacium) in Trachurus trachurus (Linnaeus, 1758) in the Ligurian and central-northern Tyrrhenian Seas. The relationship between the number of parasites and the length and weight parameters of the fish was assessed, and the possible effect of the parasites on the condition factor was evaluated. A total of 190 T. trachurus specimens were collected in July 2019. Parasites were found in 70 individuals. A total of 161 visible larvae were collected in the viscera. Morphological analysis revealed the presence of Anisakis spp. in 55 fish and Hysterothylacium spp. in 15 fish, while 5 fish showed coinfection with both genera. The specimens subjected to PCR (nâ=â67) showed that 85% of the Anisakis larvae analyzed belonged to the species A. pegreffii, while the remaining 15% belonged to hybrids of A. pegreffii-A. simplex (s.s.). A total of 58% (nâ=â7) of the Hysterothylacium larvae analyzed belonged to the species H. fabri, while 42% belonged to the species H. aduncum. Our results support the hypothesis that infection with these parasites does not affect the condition of the fish host analyzed, and that body size and depth are major drivers in determining infection levels with Anisakid and Raphidascaridid nematodes
Evaluation of potential transfer of the pathogen Saprolegnia parasitica between farmed salmonids and wild fish
Funding: This project has received funding from the European Unionâs Horizon 2020 research and innovation programme under grant agreement No. 634429. This publication reflects the views only of the author, and the European Commission cannot be held responsible for any use, which may be made of the information contained therein. Data Availability Statement: The data presented in this study are available on request from the corresponding author. Acknowledgments: The authors would like to thank the fish farmers/staff, veterinarians, biologists and local authorities who collaborated in the sample collection.Peer reviewedPublisher PD
Morphological description and molecular characterization of Contracaecum larvae (Nematoda: Anisakidae) parasitizing market-size hybrid tilapia (Oreochromis aureus x Oreochromis niloticus) and red drum (Sciaenops ocellatus) farmed in Israel
Nematodes belonging to the genus Contracaecum (family: Anisakidae) are heteroxenous parasites with a complex life cycle. Contracaecum larvae infecting farmed fish and fishery products are economically important causing market rejection in massive infection and may have zoonotic potential. In Israel, Contracaecum larvae have been described morphologically in several fish species; however, none of these descriptions were supported by molecular tools. In 2019â2020, hybrid tilapia (Oreochromis aureus x Oreochromis niloticus) and red drum (Sciaenops ocellatus), farmed in polyculture were found to be heavily infected with nematodes referable to Contracaecum larvae. Prevalence of infection in hybrid tilapia and red drum was 53.8% and 40.9%, respectively. A combined (morphological and molecular) approach revealed that both infected fish species were parasitized by the same species of Contracaecum, although larvae in hybrid tilapia were localized in the pericardial cavity whereas in red drum, they were observed in the abdominal cavity. Genetic analysis of internal transcribed spacer rDNA and cox2 mtDNA showed high similarity to unidentified Contracaecum larvae detected in several fish species in Ethiopia, Egypt and Kenya. In this study, molecular and morphological analyses place the possible new species in the C. multipapillatum complex and was provisionally named C. multipapillatum E. Further analyses combining morphological and molecular approaches are required on adult specimens collected from piscivorous birds living in the same area to support the identification of a potentially new species
Impact of abiotic factors and husbandry on saprolegniosis in salmonid farms
Funding Information: This work was financially supported by the EU H2020 [ H2020-SFS-10a-2014 (ParaFishControl, grant agreement No. 634429) (PT, MS, RG, JD-U, PvW, BO & MF)], the BBSRC [ BB/P020224/1 (MS & PvW) & BB/M026566/1 (MS & PvW)] and the University of Aberdeen (MS & PvW). The authors would like to thank all the fish farmers/staff and colleagues who collaborated in the fieldwork and provided valuable information for the study. Publisher Copyright: © 2022 The AuthorsPeer reviewedPublisher PD
Molecular and morphological studies on Contracaecum rudolphii A and C. rudolphii B in great cormorants (Phalacrocorax carbo sinensis) from Italy and Israel
Isopod (Crustacea: Eumalacostraca) and Arguloid (Crustacea: Branchiura) parasites of fish and cephalopods from central Mediterranean Sea
Parasites and diseases of worldwide cephalopods: an update
Cephalopods are known to harbor parasitic organisms in almost every organ of their body. The
growing importance of cephalopods for both commercial and research purposes requires a better
understanding about their health and welfare, which includes a detailed characterization of their
parasites and diseases, especially of those infectious agents that are able to affect the physiology
of cephalopod hosts or their marketability as fishery products. Information about the parasitic
fauna of cephalopods also prove very useful for scientists since it may help elucidating some
aspects of cephalopod biology and ecology in natural environment.
During the last decades, the development of new investigation techniques, such as the increased
use of molecular tools, allowed the identification of new parasite species and helped to solve the
taxonomic uncertainty resulting from difficulties associated with morphological identification of
small-sized and often cryptic organisms, which had produced, over time, a high synonymy rate
among parasitic taxa. The present work intends provide an update of the last 25 years of research
about cephalopod infectious agents, by considering over two hundred new publications, since
they were first extensively surveyed in 1990. The number of new parasite descriptions, new host
records and new infection reports was reviewed as well as the geographic distribution of reports
in order to characterize the worldwide pattern of research efforts in cephalopod parasites.
The total amount of literature available so far was also considered and analyzed in order to detect
potential variations in parasite biodiversity among cephalopod groups as well as among
geographic areas and to identify parasitic groups, host groups and geographic areas that require
more investigation. Special attention is paid to potentially pathogenetic agents and to treatments
available or attempted so far
Chapter Spread of Pathogens from Marine Cage Aquaculture - A Potential Threat for Wild Fish Assemblages Under Protection Regimes?
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