Accumulation of metals relevant for agricultural contamination in gills of European chub (Squalius cephalus)

The study of metal bioaccumulation in the gills of European chub (Squalius cephalus) was conducted in September 2009 at medium-size rural river Sutla, characterized by agricultural and municipal type of water contamination. The concentration ranges were established for the first time in the soluble, metabolically available fractions of chub gills for 12 metals, which are environmentally extremely relevant and yet only seldom studied, as follows in a decreasing order: K, 225-895 mg L-1 ; Na, 78-366 mg L-1 ; Ca, 19-62 mg L-1 ; Mg, 13-47 mg L-1 ; Rb, 164-1762 µg L-1 ; Sr, 24-81 µg L-1 ; Ba, 13-67 µg L-1 ; Mo, 1.3-16 µg L-1 ; Co, 0.7-2.7 µg L- 1 ; Li, 0.4-2.2 µg L-1 ; Cs, 0.2-1.9 µg L-1 ; and V, 0.1-1.8 µg L-1. The concentrations of Fe (1.6-6.4 mg L-1) and Mn (16-69 µg L-1) were also determined and were in the agreement with previous reports. By application of general linear modeling, the influence of different abiotic (metal exposure level) and biotic parameters (fish sex, age, size and condition) on metal bioaccumulation was tested. It was established that bioaccumulation of many metals in fish depended on various physiological conditions, wherein Ba could be singled out as metal exhibiting the strongest association with one of biotic parameters, being significantly higher in smaller fish. However, it was also undoubtedly demonstrated that the concentrations of three metals can be applied as reliable indicators of metal exposure even in the conditions of low or moderate water contamination, such as observed in the Sutla River, and those were nonessential elements Li and Cs, and essential element Fe. The results of our study present an important contribution to maintenance of high ecological status of European freshwaters, through enrichment of knowledge on the bioaccumulation of various metals in gills of European chub as frequently applied bioindicator species in monitoring of water pollution