74 research outputs found
Multilocus phylogenetic analyses reveal that habitat selection drives the speciation of Didymozoidae (Digenea) parasitizing Pacific and Atlantic bluefin tunas
Parasite communities of wild and reared bluefin tuna display remarkable diversity. Among these, the most prevalent and abundant are the Didymozoidae (Monticelli, 1888) (Trematoda, Digenea), considered one of the most taxonomically complex digenean families. The aim of this study was to evaluate phylogenetic structure of Didymozoidae occurring in Pacific (Thunnus orientalis) and Atlantic bluefin tuna (T. thynnus) in order to increase our knowledge of didymozoid zoogeography and identify species that could successfully be employed as biological tags for stock assessment studies. For the present analyses we used 2 nuclear ribosomal DNA loci, part of the 28S gene and the second internal transcribed spacer (ITS-2) as well as a portion of the mitochondrial cytochrome c oxidase subunit 1 gene (cox1). In most parasitic groups, morphology is the primary factor in the structuring of phylogenetic relationships. In rare examples, however, habitat has been suggested as a primary factor affecting parasite evolution. During their evolution, didymozoids have spread and inhabited a remarkable number of different sites in their hosts, colonizing exterior as well as strictly interior niches. Our data suggest that habitat selection has been the leading force in shaping didymozoid phylogenetic relationships. For 2 didymozoid species (D. wedli and D. palati), cox1 sequences indicate intraspecific differences between Mexican and Adriatic populations
Feeding habits and helminth parasites of sardine (S. pilchardus) and anchovy (E. encrasicolus) in the Adriatic Sea
We examined the stomach contents of two of the most economically and ecologically important small pelagic fish species, the sardine, Sardina pilchardus and the anchovy, Engraulis encrasicolus, obtained monthly from commercial purse-seine catches operating on Croatian fishing grounds during a one-year period (January–December, 2011). Both species generally showed a similar diet, with copepod and decapod larvae as dominant prey groups. The composition of anchovy and sardine stomach contents was not size- or sex-related, but throughout the year, a significant difference in diet composition was observed for each species as well as between species. Two gastrointerstinal helminths; the digenean Parahemiurus merus and nematode Hysterothylacium aduncum, were recorded during the stomach content analysis. Differences in population dynamics between the two parasites are congruent with differences in the prey composition of sardine and anchovy, reflecting fine-tuned interactions in the trophic web between parasites and intermediate or paratenic hosts included in the sardine and anchovy diet
Host-Parasite Interaction between Parasitic Cymothoid Ceratothoa Oestroides and Its Host, Farmed European Sea Bass (Dicentrarchus labrax)
Parasitic isopod Ceratothoa oestroides (Cymothoidea, Isopoda) is a common and generalist
buccal cavity-dweller in marine fish, recognised for its detrimental effect in fingerling and juvenile
farmed European sea bass (Dicentrarchus labrax). Although distributed throughout the Mediterranean,
the isopod provokes acute outbreaks mainly limited to particular endemic areas in Croatia
(Adriatic Sea) and Greece (Aegean Sea). While numerous studies have previously evidenced its
gross effect on farmed fish (i.e. decreased condition index, slower growth rate, lethargy and mortality),
details on the host-parasite interaction are still lacking. Therefore, using a multimethodological
approach, we closely examined the structure and appearance of isopod body parts acting in the
attachment and feeding (stereomicroscopy, scanning and transmission electron microscopy), and
the extent of host tissues damage (histology, immunohistochemistry, micro-computational tomography)
induced by parasitation. Interestingly, while hematophagous nature of the parasite has been
previously postulated we found no unambiguous data to support this; we observed host tissues
fragmentation and extensive hyperplasia at the parasitation site, and no structures indicative of
heme detoxifying mechanisms in the parasite gut, or other traces of a blood meal. The bacterial
biofilm covering C. oestroides mouthparts and pereopods suggests that the isopod may play a role
in conveying secondary pathogens to the infected host, or alternatively, it serves the parasite in
normal interaction with its environment
In vitro testing of alternative synthetic and natural antiparasitic compounds against the monogenean sparicotyle chrysophrii
Gill monogenean Sparicotyle chrysophrii is considered the most detrimental fish parasite to the Mediterranean aquaculture. Treatment of sparicotylosis relies on frequent gill inspections correlated with the seasonal increase in seawater temperature, application of functional feeds, and treatments with formalin baths where permitted. While the latter is bound to be banned in Europe, other synthetic anthelminthics, such as praziquantel and ivermectin, are prone to induce resistance in the parasites. Therefore, we investigated, in vitro, 14 synthetic and natural compounds against adult S. chrysophrii, developing dose–response modelsm and estimated toxicity levels at 20%, 50%, and 80% parasite mortality. Bactericidal activity of target compounds was also tested in two important aquaculture bacteria; Vibrio harveyi and V. anguillarum, while their potential host toxicity was evaluated in gilthead seabream SAF-1 cell line. Synthetic compound bithionate sodium exerted the most potent toxicity against the monogenean, no host cytotoxicity, and a medium and high potency against two bacterial pathogens. In comparison, target natural compounds were approximately 20 (cedrol) or up to 154 times (camphor) less toxic for the monogenean. Rather than completely dismissing natural compounds, we suggest that their application in combination with synthetic drugs, especially if administered in the feed, might be useful in sparicotylosis treatment
Bottlenecks in diagnostics of Mediterranean fish diseases
Three independent Horizon 2020 projects are prioritising a common task of solving diagnostic issues using different approaches and strategies. PerformFISH focuses its research objectives on diagnostic methods, MedAID has prepared a diagnostic manual for the most devastating fish diseases of the Mediterranean and ParaFishControl has prepared a diagnostic manual on parasitic diseases of European aquaculture species. Currently, the projects are investing large collaborative efforts to reinforce their tasks and to deliver mutual and cutting-edge material on the subject. Nevertheless, further efforts for the harmonisation, standardisation and validation of diagnostic methods for infectious diseases in Mediterranean aquaculture are needed, involving as many relevant stakeholders and
experts as possible. The main goal of the workshop (WS) “Bottlenecks in diagnostics of Mediterranean fish diseases”, organised during the 19th International EAFP conference on Diseases of Fish and Shellfish, was to present results already obtained from the projects and discuss the bottlenecks in diagnostic procedures of target groups of pathogens. The WS provided an ideal environment and opportunity to exchange and discuss experiences and data with international experts in the
diagnostic field attending the conference. Interactive discussions on diagnostics for a specific group of pathogens have resulted in highlighting new initiatives needed in the management of diseases in Mediterranean aquaculture. Furthermore, the WS emphasised a need for the establishment of this strong interactive network which will collaborate to receive, collect, compile and analyse all information gathered from different parts of the region.info:eu-repo/semantics/publishedVersio
The marine myxosporean Sigmomyxa sphaerica (Thélohan, 1895) gen. n., comb. n. (syn. Myxidium sphaericum) from garfish (Belone belone (L.)) uses the polychaete Nereis pelagica L. as invertebrate host
Sigmomyxa sphaerica (Thélohan, 1892) gen. n. (Myxozoa, Myxosporea) with myxosporean stages in the gall bladder of Belone belone (L.) (Teleostei, Belonidae) uses the polychaete Nereis pelagica L. (Nereidae) from shallow water in the northern Øresund, Denmark, as invertebrate host. The nearly spherical tetractinomyxon-type actinospores of S. sphaerica differ from those of two species of Ellipsomyxa which also use Nereis spp. as invertebrate host. Pansporocysts of S. sphaerica were not seen. S. sphaerica is redescribed on the basis of myxospore stages from B. belone and actinospores from N. pelagica, and the phylogenetic affinities examined on the basis of ribosomal small subunit gene sequences. S. sphaerica is closest related to Ellipsomyxa spp., and is not congeneric with morphologically similar Myxidium spp. from gadids. This is the fifth elucidated two-host life cycle of a marine myxozoan
Patterns of genetic variation and life history traits of Zeuxapta seriolae infesting Seriola lalandi across the coastal and oceanic areas in the southeastern Pacific Ocean: potential implications for aquaculture
Development of "Land Rent Model" Using Multicriterional Analysis and Geographical Information Systems
The application of multicriterional analysis and geographical information systems in the development of land rent model, is presented in this paper. The objective of the model is to provide the basis for the evaluation of urban areas. The aim of the research is to find out the most su itable model for definition of the city rent in coastal urban areas. The presented research is based on information technology, including graphical and numerical processing of appropriately handled and structured information. The rent model includes all the relevant factors considering values of the urban environment, especially historical and cultural heritage. Such evaluation, together with information technologies, represent very useful and practical tool for environmentally sound management of urban areas, and a support to decision makers
Sustainability through production networks
Global economic crisis has brought into question sustainability of many industrial enterprises, especially Large-sized Enterprises (LEs). However, the strength of the European economy are not Large-sized Enterprises, but Small and Medium-sized industrial Enterprises (SMEs). As an alternative to LEs there is networking of SMEs into flexible production networks. Inside production network SMEs can collaborate on new product development forming Virtual Enterprise. SMEs collaborating as one Virtual Enterprise can be seen as a sustainable Large-sized Enterprise. However, to achieve sustainability through production networks, i.e. Virtual Enterprises, it is essential to choose an optimal combination of SMEs in Virtual Enterprise formation process. Since it is a complex task that requires the use of multi-criteria decision-making methods, in this paper PROMETHEE method is used
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