Bioaccumulation of heavy metals in Ephemera danica larvae under influence of a trout farm outlet waters

Abstract

Trout farms are one of the major sources of pollution of highland streams and rivers. Since river sediment burdened with organic pollution binds greater amounts of heavy metals we investigated the influence of the trout farm on the accumulation of metals in the sediment, water and Ephemera danica larvae. Research was conducted seasonally (April, July, and October of 2015 and January of 2016) at one control locality (SK1) and three localities downstream from the farm (SK2-SK4). In agreement with the hypothesis the fish farm discharge induced localized and statistically significant increase of concentrations of Fe, Cu, Cr-,Cr- Ni, Pb and Cd in sediment and E. danica larvae, but not in water at locality SK2 just below the fish farm indicating that sediment is the main source of heavy metals for this organism. However, according to the values of Biota sediment accumulation factor (BSAF) only metals with low sediment concentrations (As, Cd and Cu) accumulated in the larvae. Moreover, BASF values for toxic metals (As, Cd and Cr) showed negative correlation with their concentrations in sediment indicating existence of defense mechanisms in E. danica against assimilation of these metals in high concentrations lethal for it. On the other hand, BSAF values for essential microelements (Cu and Fe) were positively correlated with their sediment concentrations. In conclusion the trout farm induced accumulation of heavy metals in river sediment and E. danica larvae proved to be a good bioindicators of the pollution of river systems by As, Cd and Cu.