Browsing by Subject "European eel"

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    An endangered species living in an endangered ecosystem: Population structure and growth of European eel Anguilla anguilla in a Mediterranean coastal lagoon
    (2022-01-13) Barcala, Elena; Romero García, Diego; Bulto, Cristina; Boza, Cristina; Peñalver, José; María-Dolores, Emilio; Muñoz, Pilar; Sanidad Animal
    Mediterranean coastal habitats constitute a nonmarginal fraction of the overall continental habitats of the European eel. It has been suggested that the recovery of the eel global stock may depend closely upon the contribution of Southern European and North African countries within the Mediterranean basin, therefore It is essential to know all the aspects related with its biology and populations dynamic to ensure that the European Commission conservation plan works in this habitats. The aims of this study were to ascertain the structure of the endangered A. anguilla populations in the Mar Menor and obtain essential data for future management plans in the Mediterranean catchment area. In total, 1151 wild fish were caught by local fishermen in 2015–2016 and 2016–2017, and their biological traits were determined. Our findings show that the Mar Menor’s A. anguilla population consists of resident females (1:0.008, female:male), yellow and silvering individuals (56.56% and 43.27% respectively), with a mean age of 3 years. The traditional view of long-lived eels with low growth rates does not fit the picture of Mediterranean eel populations. The effect of fishing techniques used, and the eutrophication processes noted during the study period are also discussed.
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    European eels and heavy metals from the Mar Menor lagoon (SE Spain)
    (Elsevier, 2020-06-20) Romero García, Diego; Barcala, Elena; Maria Dolores, Emilio; Muñoz, Pilar; Sanidad Animal
    Heavy metal pollution is related to the fall in European eel (Anguilla anguilla) populations. The Mar Menor lagoon (SE Spain) is home to an endangered population of this species, which is still caught for human consumption. The presence of Pb, Cd and Hg in the livers and muscles and the Se:Hg ratio in muscle of 150 eels from this lagoon were determined. Pb concentrations were higher than those reported from other populations in the world, while Cd and Hg concentrations in the tissues analysed were lower. In terms of food safety, Se concentrations play an important role in sequestering Hg in eels from this lagoon.
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    Influence of adult Anguillicoloides crassus load in European eels swimbladder on macrophage response
    (Elsevier, 2015) Muñoz, Pilar; Peñalver, José; Ruiz de Ybanez, R.; Garcia, J.; Sanidad Animal
    Anguillicoloides crassus has become one of the most important threats to the European eel (Anguilla anguilla). Adult parasites colonize the swimbladder leading to an impaired functioning of this organ. The infection is also responsible for an increased in the stress level of infected eels, that could produce an altered immune response as well. Differences in parasite loads and effects in the European and Japanese eel (Anguilla japonica) have been described. We have studied the influence of the number of adult parasites present in the swimbladder of wild eels on the macrophage response (phagocytosis and respiratory burst) as part of the first immune response to pathogens. Our results show an increased phagocytozed bacterial survival 24 h post-infection in macrophages of eels infected with more than ten adult parasites compared to macrophages from eels infected with less than those ten adult parasites. Respiratory burst results also showed a less efficient response in macrophages from eels infected with more than ten adult parasites, although in this case results were not found to be significant.
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    Monitoring for Anguillicoloides crassus, Anguillid herpesvirus 1, aquabirnavirus EVE and rhabdovirus EVEX in the European eel population of southern Spain
    (2023-01) Ruiz de Ybáñez Carnero, María del Rocío; Del Río Alonso, Laura; Flores Flores, César; Muñoz Ruiz, Pilar; Berriatua Fernández de Larrea, Eduardo; Rubio, Silvia; Martínez Carrasco-Pleite, Carlos; Sanidad Animal
    European eel is critically endangered in Europe. Among other stressors, pathogens are well-known to harm eels' fitness. One hundred and eighty-two eels were captured in three Eel Management Units in Andalucía (SE Spain) and analysed for Anguillicoloides crassus, Anguillid herpesvirus 1 (AngHV1), the rhabdovirus Eel Virus European X (EVEX) and the aquabirnavirus Eel Virus European (EVE). A. crassus adults and preadults were isolated and morphometrically identified, and the eel swimbladders were artificially digested to count A. crassus larvae. Also, eel tissues were examined by PCRs for the presence of viruses. EVEX and EVE were not detected in any of the eels. The estimated prevalence (95% confidence limits) was 71 (64–78)% for A. crassus and 35 (28–42)% for AngHV-1, varying these prevalences significantly between and within EMUs. Moreover, A. crassus prevalence was highest in smaller eels, in sites closest to the sea and eels sampled in the autumn. By contrast, AngHV-1 prevalence was highest in biggest eels, in sites far from the sea and sampled in the summer or winter. However, in mixed effects logistic models including site as a random variable, the risk of infection was associated with distance to the sea in both A. crassus and AngHV-1 infections and also to winter sampling in the case of AngHV-1 and not to other variables. These results are evidence that both pathogens are highly endemic in eels from Andalusian habitats. Further studies are needed to better understand the risk factors associated with these pathogens on eel populations.
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    Prevalence of Anguillicoloides crassus (Nematoda, Dracunculoidea) in wild European eels (Anguilla anguilla L.) from Mar Menor lagoon (Western Mediterranean, Spain)
    (École Nationale Vétérinaire de Toulouse, 2011) Martínez Carrasco-Pleite, Carlos; Ruiz de Ybáñez Carnero, María del Rocío; Peñalver, José; Mayo-Hernández, Elvira; Muñoz, Pilar; García Ayala, Alfonsa; Sanidad Animal
    Anguillicoloides crassus infection in wild European eels (Anguilla anguilla) from Mar Menor, a hypersaline coastal lagoon situated on the shores of theM editerranean in south-east Spain, was evaluated. As well, an artificial digestion is described for the detection, isolation and counting of larval stages in the swimbladder wall. A total of 109 eels were collected between November 2008 and March 2009 and adult worms were recovered from the swimbladders of infected eels. The detected prevalence was 7.34%. Second-stage larvae (L2) numbers ranged from one to thousands per swimbladder. This developmental stage was the most prevalent parasite tsage detected in infected eels. L2 were even found in eels harbouring neither pre-adult nor adult nematodes, which could indicate that infected eels are chronically infected. The lack of a suitable intermediate host for this nematode or the recent introduction of A. crassus into this environment could be the causes of the low prevalence of this parasite in eels from Mar Menor lagoon.