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Content of metal(oid)s in the muscle and liver of European eel (Anguilla anguilla l.) from the Raša River

The drainage area of the Raša River (Istria, Croatia) is geologically, hydrologically and pedologically interesting area, especially due to the nearness of the abandoned Raša coal mines. In the past, this coal was used by local households, factories and thermal power plants, which resulted in pollution of surrounding environment with inorganic and organic pollutants. Although large amount of coal and other terrigenous material rich with inorganic elements was deposited in the Raša Bay and the Raša River estuary, 'the special natural habitat' for many animal species, the elements profile in the biota of the Raša River have not yet been investigated. European eels are suitable environmental pollution indicators, often used for screening of toxic substances, including metals, due to specific physiological features (life cycle), bioaccumulation capacity (long- living animals), feeding and habitat ecology (benthic species). The aim of the study was to determine the content of metal(oid)s (Na, Mg, K, Ca, Fe, Cu, Zn, Se, Mn, Mo, V, Cr, Co, Ni, Tl, Sr, U, Ag, As, Cd, Hg, and Pb) in samples of muscle and liver of E. eels from the Raša River. Eels were collected at two sites: upstream near the Podpićan settlement (site 1) and 6 km upstream of the Raša River estuary (site 2), during summer June and July of 2020. Total length (TL) and body weight (BW) were measured, and samples of dorsal muscle and liver were taken. Element concentrations were determined by inductively coupled plasma – mass spectrometry (ICP-MS). There were significant differences between sites. Eels caught on site 2 had higher levels of Ni, Cu and Sr in muscle, and of Mn and U in liver then eels caught on site 1. Furthermore, eels caught on site 2 had higher levels of V, Cr, Mo, Cd, Tl and Ag in muscle and liver, and lower levels of Hg in muscle, and Mg and Ca in liver than at site 1. Negative correlations with TL and BW were found for Na, Mg, K, Ca, Mn, Mo, Sr and Tl in muscle, and Mg, K, Ca, Sr and Tl in liver, while positive correlations with TL and BW were found only in liver, for Fe, Cu, Zn, Se, Cd and Pb. The content of metal(oid)s in E. eels from the Raša River was similar or lower than values reported in other European regions. This point to the good status of the Raša river ecosystem with regard to inorganic elements. The study was funded by Croatian Science Foundation grant HRZZ-IP-2016-06-1998, METALORIGINS.

European eels ; toxic and essential elements ; freshwater fish ; ICP-MS

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