Metal accumulation and biochemical variations in the freshwater mussels (Unio mancus) collected from Ataturk Dam Lake, Turkey

Abstract

In this study, we aimed to determine the toxic effects of metals on mussels (Unio mancus) selected as biomonitor organisms in the Ataturk Dam Lake. The effect of metal pollution was evaluated using some biochemical markers [glutathione-S-transferase (GST), acetylcolinesterase (AChE), carboxylesterase (CaE), glutathione reductase (GR), metallothionein (MT)] in the digestive gland of the mussels. Mussels were collected from four sampling sites of dam lake in the winter and summer of 2016. The metal levels in the mussel samples varied significantly across the sites and seasons (p < 0.05). Fe was the most accumulated metal, followed by Zn, Cu, and As, while Hg was the least accumulated metal. There were significant differences among sites and between seasons for enzyme activities and MT levels (p < 0.05). Although AChE was inhibited in summer at all sites, the lowest level of AChE was determined for the Sitilce site. Our results showed that there were statistical differences for CaE, GR, and GST activities among sites and between seasons. MT levels were statistically higher in summer than in winter at all sites (p < 0.05). The highest MT level was detected at the Sarisu site in summer, while the lowest MT level was detected at Sitilce in winter. According to the results of correlation analysis, we observed strong correlations between MT and some metal concentrations in both winter and summer (p < 0.05). Our data suggest that industrial activities and domestic wastes along the coast of Ataturk Dam Lake are the main sources of metal pollutants at these sites.