Bioaccumulation of heavy metals in the dice snake Natrix tessellata (Reptilia, Colubridae) from ecosystems of different anthropogenic loads in modern conditions of the steppe Dnieper area

Abstract

We studied the peculiarities of bioaccumulation and distribution of heavy metals (cadmium, lead, zinc and copper) in the bone tissue, liver and kidneys of the dice snake Natrix tessellata (Laurenti, 1768) inhabited ecosystems under different anthropogenic loads in 2015-2016. Mature individuals were caught in anthropogenically transformed ecosystems of the sanitary-protective zone of the Dniprovska Thermal Power Plant (SPZ DTPP) (48.402°N, 35.111°E, n = 7), coastal ecosystems of the National Nature Park «Velykyi Luh» (47.443°N, 35.149°E, n = 8) and in the Maiorka gully ecosystems (48.260°N, 35.170°E, n = 7). The gross content of metals in the organs of N. tessellata was determined after their dry ashing in a muffle furnace. Determination of the trace elements was performed by atomic absorption spectrophotometry. Among the studied trace elements, zinc has the highest concentrations in the liver, kidneys and bones of N. tessellata. The kidneys and liver are characterized by such amount of concentrations: Zn> Cu> Pb> Cd, but bone tissue has the following ratio Zn> Pb> Cu> Cd. The highest concentration of cadmium is found in the kidneys, and the lowest one – in the bones of snakes. There are the highest contents of lead and copper in the snakes’ liver, but the lowest in the kidneys and bones. The lead bioaccumulations in organs of snakes from different ecosystems are dissimilar. Zinc content in bones is higher than in kidneys and liver, but the lowest concentration is found in the kidneys. It has been found that the highest contents of toxic metals (Cd, Pb) were in the kidneys and liver of the snakes dwelled in the SPZ DTPP ecosystems in comparison with both studied natural ecosystems. In addition, snakes caught in anthropogenically transformed ecosystems of SPZ DTPP are characterised by increased zinc content in all studied organs and enlarged copper concentration in the kidneys. Considering the obtained results on the metals bioaccumulation, the dice snake can be considered as a potential bio-indicator of environmental pollution by heavy metals.