Contamination, parasitism and condition of Anguilla anguilla in three Italian stocks

Abstract

In conjunction with habitat loss and overfishing, pollution and parasitism are believed to be relevant causes of collapse of Anguilla, as these can affect eel swimming ability and the development of gonads and embryos. The present study investigated Persistent Organic Pollutant (POP) concentrations, infection levels of Anguillicoloides crassus, lipid content and gonad abnormalities in eels sampled in 2007-2008 in three Italian water bodies (Caprolace Lake, Lesina Lagoon and Tevere River) that vary in salinity, trophic condition, contamination level and fishing pressure. Our analysis revealed that low-to-moderate levels of contamination and parasitism were not associated with gonad abnormalities in Caprolace Lake and Lesina Lagoon. On the contrary, POP concentrations and abundances of swim bladder nematodes were remarkably high in eels from the heavily urbanized Tevere River and were associated with significant gonad and swim bladder alterations. Contamination and infestation levels were so high to potentially impair spawner successful migration and reproduction. POP concentrations in Tevere eels also exceeded levels considered safe for food consumption. Though marginally contaminated, eels from the oligotrophic Caprolace Lake were in critical health condition: their lipid reserve was so low as to be considered insufficient to sustain the energetic costs of the transoceanic migration. Lesina eel stock was the only one displaying relatively good quality but here spawner abundance is likely limited by overfishing. Our results suggest that multiple stressors may potentially affect eel reproductive success. More definitive studies are needed to assess whether health effects caused by these multiple stressors are additive, compensatory or synergistic.

Reproductive potential of silver European eels (Anguilla anguilla) migrating from Vistonis Lake (Northern Aegean Sea, Greece)

“…Quadroni et al, 2013;Amilhat et al, 2014). However, available data suggests this may not typically be the case in the eastern Mediterranean; Vistonis Lake eels were all large females (905 mm mean body length), as were those from the nearby River Nestos in Greece (656 mm mean body length in 2008; Koutrakis et al, unpublished data) and from the Göksu Delta, Turkey (729 mm mean body length between 2007 and 2010; Rad et al, 2013).…”

“…However, the extent of the relationship between A. crassus infection and oocyte diameter in Vistonis Lake silver eels is difficult to determine, due to the small sample size. Quadroni et al (2013) proposed that A. crassus induced stress may affect gonad development, although their observations mainly refer to yellow eels and male silver eels, and bioaccumulation of lipophilic contaminants may have been a contributory factor. Nonetheless, body size and the influence of A. crassus could be important considerations for future A. anguilla artificial maturation programmes.…”

“…However, studies are primarily focused on eel subpopulations migrating from western and northern Europe, the Baltic region and the western Mediterranean (e.g. MacNamara & McCarthy, 2012;Marohn et al, 2013;Quadroni et al, 2013;Amilhat et al, 2014). The eastern Mediterranean (defined here as east of 20° E) is distinctly under-represented, even in 'pan-European' type studies (Jakob et al, 2009;Belpaire et al, 2011).…”

Silver European eels health in Mediterranean habitats

“…Nagel et al (2012) studied the impact of silvering on polycyclic aromatic hydrocarbons (PAHs) metabolite concentrations in bile. One recent study by Quadroni et al (2013) looked at both contamination (POPs and dioxins) and parasites in three Italian stocks (lagoons and river). Finally, S€ uhring et al (2013) studied brominated flame retardants and dechloranes in silver eels from German rivers.…”

Is the tapeworm able to affect tissue Pb-concentrations in white rat?

“…Primarily, adult stages of Cestodes and Acanthocephalans accumulate these elements to a greater extent than do their host tissues (Schludermann et al 2003;Torres et al 2004Torres et al , 2006Retief et al 2006;Jirsa et al 2008). Even though environmental pollution may adversely affect the GIH assemblages (Oros and Hanzelova, 2009), simultaneous treatment of helminths and contaminant exposure in wild animals is common in natural habitats (MacKenzie et al 1995;Quadroni et al 2013). Therefore, the use of GIH as accumulative indicators of environmental contamination is frequently discussed in scientific literature (Sures, 2004;Vidal-Martinez et al 2010;Nhi et al 2013).…”