Heavy metals in droppings of Eurasian otters (Lutra lutra) from mountain stream Javorinka, the Tatra Mountains

Abstract

The research is focuses on the analysis of the content of heavy metals and other elements in the feces of river otter in the Javorinka mountain stream in the High Tatras in Slovakia. The aim of the study is to follow the cycles of concentrations of measured elements such as Hg, P, S, Cl, K, Ca, Ti, Cr, Mn, Fe, Cu, Zn, Se, Rb, Sr, Zr, Mo, Sb, Ba and Pb in otter feces, with a special focus on heavy metals, which were analysed at two sites, during four seasons and individually in each year. Comparison of the results from the two sites showed an almost twofold increase in the concentrations of the elements Ti, Mn, Fe and Sr at the site with the lower gradient and slower water flow. At the same time, seasonal variations are observed, with some elements such as P, S, Cl and K reaching their highest concentrations in the autumn months, while other elements such as Ti, Mn, Fe and Rb reach their peaks in the summer and autumn months. The concentration of the element Hg has also been found to vary with food availability, especially in the spring season. The average Hg concentrations reached 0.1 mg/kg in otter feces. Inter-annual variations in concentrations of heavy metals such as Hg, Pb, Ba and Cr may be related to a variety of factors including changes in otter diet, fish and otter breeding cycles and geological processes affecting water and sediment in the river. The results of this study contribute to a better understanding of the ecological stability of upland aquatic ecosystems and to the conservation of endangered species in these environments.