Ecotoxicological assessment of water quality and ecosystem health: a case study of the Volga river / Moiseenko T. I., Gashkina N. A., Sharova Yu. N., Kudryavtseva L. P. // Ecotoxicology and Environmental Safety. - 2008. - Т. 71, № 3. - С. 837-850.

T.I. Moiseenko et al. / Ecotoxicology and Environmental Safety 71 (2008) 837-850 (ii) the underestimation of synergetic effects and the presence of other presumably toxic substances in the water, which could also have a negative impact on fish organisms; (iii) the persistent effect of toxic substances over the whole lifespan of the fish, the range and concentration of which could be different in different years and seasons; (iv) the subjective character of expert evaluation; measurement errors; small samples obtained, etc. However, despite the complexity of the synchronous studies that were carried out and the necessity of accounting for numerous factors, reliable dependencies were obtained. These dependencies confirm that the morbidity in fishes inhabiting the Volga River basin is related to the occurrence of various toxic substances in the water. Among the various negative ambient factors that cause pathologic disturbances in fish organs and tissues, it is very difficult to single out the most important factors. Table 5 presents the dependencies between the parameters of fish morbidity and the concentrations of toxic substances in the water. Depletion of certain blood parameters is most significantly related to the impact of V and Pb, whereas pathological disturbances in the fish liver and kidneys are associated with the negative effects of dioctylphthalate, derivatives of dioxane, and oil products, as well as those of Cu and Mn. The accumulation of toxic metals can also enhance (and, in certain cases, even directly cause) pathologies in fish. Therefore, the relationship between the accumulation of microelements in fish and pathological disturbances in the organs and tissues of bream in the Volga River basin was analyzed. The increase of metals in the water medium may bring adverse effects on fish health. The surplus of trace elements in the organism initiates some specific diseases: Hg causes neurological effects, Cd and Pb have carcinogenic properties, Sr leads to pathology of bone tissues, Cu to anemia, etc. (Conto-Cinier et al., 1997; Patriarca et al., 1998; Watras et al., 1998; Musibono and Day, 1999). Organisms have mechanisms of metal detoxification by induction of metallothionein synthesis. These proteins bind specifically to neutral essential trace elements, such as Zn and Cu, as well as to potentially toxic metals such as Cd and Hg (Phillips, 1995; Linde et al., 2001). The effects of metal accumula­ tion on fish and their pathologies, without the necessity of explaining the internal metabolism of metals, is the key purpose for our data. Notwithstanding the low sensitivity of the method applied, which prevented determination of the concentration of Hg in the water, the accumulation of this metal in fish was observed, especially in the Middle Volga. A reliable correlation was established between Hg accumulation in fish kidneys (Hgkidneys) and pathologic disturbances in this organ (Pat., %), as well as Z: Pat.Kidneys = 210 Hgkidneys- 9.68, r = 0.81, p < 0.005, Z = 53.8 Hgkidneys + 0.029, r = 0.85, p<0.005. Thus, irrespective of the fact that the concentration of Hg in the investigated water was lower than the analytical detection limit (less than 0.05 ng/l), its accumulation in the organism can cause pathogenic disturbances in fish. A reliable correlation was also established between the accumulation of Cd in fish gills (Cdgins) and hematologic parameters of fish—such as the concentration of hemoglobin in the blood (Hb), and neutrophils (N) in the leukocyte count: Hb = - 1 0 4 Cdgills + 103, r = 0.87, p < 0.001, N = 34.5 Cdgills + 3.35, r = 0.88, p <0.001. As mentioned above, the accumulation of Cd in the organism is accompanied by an increase in the concentrations of some other elements. Most probably, the joint accumulation of several toxic elements in the fish organism entails a decrease in the Table 5 Dependence of characteristics of the physiological state of fish on the concentration of hazardous substances in the water Toxic elements and compounds (x) Blood characteristics (y) Average Hb Hb not exceeding 90 g/1 Neutrophiles (%) Dibutyl phthalate у = -5.61n(x)+107.2 - - r = 0.65** у = 112.0е_0Л2* у = 52.01n(x)+16.9 у = 6.2е0-58* r = 0.58* г = 0.68*** г = 0.58* Pb у = 98.2 e-a07x у = 21.7Х+21.9 у = ІО.Зх+9.48 r = 0.64** г = 0.79**** г = 0.88*** Percentage of the fishes demonstrating different pathologic disturbances in (y) The whole organism The liver The kidneys Hydrocarbons of oil products у = 8.63 ln(x)+32.4 у = 10.11п(х)+24.6 у = 0.53Х+16.4 r = 0.53* г = 0.56* г = 0.74*** Dibutyl phthalate у = 0.63X+38.5 - - г = 0.61* Dioctyl phthalate у = 0.78Х+45.3 у = 1.17Х+37.9 у = 1.4ІХ+13.6 г = 0.59* г = 0.70*** г = 0.87**** Derivatives of 1,3-dioxane у = 0.47Х+48.7 у = 0.53Х+45.0 у = 0.8ІХ+20.2 г = 0.62** г = 0.59* г = 0.87**** Cu у = 8.73Х+34.3 у = 10.7Х+25.9 - г = 0.52* г = 0.57* Mn - у = 24.91п(х)-47.2 у = 0.38Х+5.08 г = 0.76*** г = 0.68*** Dash (- ) denotes absence of reliable data. * p<0.05. ** pcO.Ol. *** p < 0.005. **** p < 0.001.