Sandimirov S. Specific Features of Accumulation of Cu, Ni, Zn, Cd and Hg in Two Whitefish Coregonus lavaretus (L.). Morphs Inhabiting the Inari-Pasvik Lacustrine-Riverine System. Inland Water Biology. 2011, Vol. 4, №, p. 383-392.

SPECIFIC FEATURES OF ACCUMULATION OF Cu, Ni, Zn, Cd, AND Hg 389 Lake Kuetsjarvi and Skrykkebukta Reservoir were sig­ nificantly higher (t = 2 .72 .10 .13 , p > 0.05) compared to the fish o f other waterbodies. Mercury The highest levels of Hg were found in the whitefish from Lake Inari and the Skrykkebukta Reservoir (liver and kidney); the lowest were in the muscles of fish from Lake Kuetsjarvi (0.03 ^g/g in the sparsely rak- ered form; 0.02 ^g/g, in the medium-rakered). In the Vaggetem Reservoir, the Hg content in the muscles of the benthivorous form was <0.03 ^g/g; in Lake Inari, it was 0.18 ^g/g. The relevant values in the planktivo­ rous form in the latter waterbody reached 0.33 ^g/g. It is worth noting that Hg concentrations in the muscles of planktivorous fish were higher (Fig. 4). No clear regularity in the Hg accumulation in the whitefish organs was revealed (Fig. 4). The highest levels of metal were found both in kidney and muscles; the low­ est were in gill. In the whitefish from Lake Kuetsjarvi and the Skrykkebukta Reservoir, the Hg concentration was lowest in the muscle tissues (Table 2). Despite the similar patterns o f Hg accumulation in the studied fish morphs, the intraspecies differences were statistically significant in all organs of the fish from Lake Kuetsjarvi and the Skrykkebukta and Vaggetem reser­ voirs (t = 2 .61 .6 .74 , p > 0.05) and from Lake Inari (muscle tissues, t = 2.41, p > 0.05). The spatial pecu­ liarities of the Hg accumulation relate to the revealed significant differences in the fish from Lake Inari and the Skrykkebukta Reservoir relative to other water­ bodies (t = 2 .12 .1 4 .98 , p > 0.05). It was revealed that rise of the concentrations o f Zn and Hg in the whitefish tissues runs more intensively along with a decline in the N i inflow into waterbodies (Figs. 3—5). The interrelation between the contents of HMs in the indicator organs and tissues and the levels of their accumulation in a waterbody is most pro ­ nounced in the case o f the medium-rakered whitefish. The contents o f N i and Cd in fish kidney correlate well with the metal accumulation in the surface layer of BSs reflecting the gradient of pollution load. As for other metals (Cu and Zn), this regularity is less pro ­ nounced and exhibits an inverse relation in the case of Hg, which characterizes this metal as a globally wide­ spread element (Fig. 5). DISCUSSION In small amounts, some HMs are essential m icro­ elements [6, 7]. Complicated systems functioning at the cellular level provide the homeostasis of these ele­ ments in an animal organism, as well as detoxification and the excretion of excessive metals [5, 18]. However, if the detoxification system is insufficiently efficient, the excessive uptake of metals in living organisms brings about a number of negative processes resulting in the functional disorders in the organism and, finally, in its death [13, 16,21]. The biological consequences of HM accumulation by living beings are manifested both at the levels of organisms and populations [4, 10, 11]. The multidirectional processes of the uptake, biotransformation, and elimination o f HMs deter­ mine the levels of their accumulation at a certain moment; the rates of these processes depend on a number of factors determining the states of both the environment (the level o f technogenic load, tempera­ ture, pH , hydrological regime, seasonal phenomena, etc.) and an organism (stages o f ontogenesis or repro­ ductive cycle; intensity of feeding; level of metabolic processes, including an organism’s demand for a certain chemical element, etc.) [2]. The interactions between elements, depending on their chemical activities, also considerably affect the content of an element in the organism subject to the impact of a mixture o f chemical elements. It was shown earlier that, in the study region, the load by N i largely determines the contents of other elements in the organisms o f the fish [2, 3], and this trend persists. The pattern of interactions in the N i—Zn and N i—Hg systems in the whitefish’s organism (using the waterbodies under study as an example) indicates that N i plays the leading role in determining the pecu­ liarities o f Zn and Hg accumulation. It is revealed that the concentration of chemical elements is typical in the so-called “target organs.” For instance, Cu accumulates at the highest concen­ trations in fish liver when compared with other organs. Maximal levels o f N i and Cd were found in the white- fish kidney. As a rule, the highest concentrations o f Hg were revealed in liver and kidney; those of Zn were in gill and kidney. The concentrations of priority pollut­ ants, Cu and Ni, exhibited a regular decline in the whitefish liver and kidney along the increasing dis­ tance from the source o f pollution (the Pechengan- ickel smelter plant). Minimal average levels of Cu in the whitefish liver were found in Lake Inari and the Rajakoski Reservoir; the maximal were in Lake Kuetsjarvi. The liver content o f Cu in the planktivo- rous whitefish of Lake Kuetsjarvi was higher than in the benthivorous form. As opposite to Cu, the accu­ mulation of N i in the kidney of whitefish from Kuetsjarvi and Skrykkebukta was 6—10.5 times higher than in the fish from the Pasvik River upstream and midstream, where the levels of this element were <5 ^g/g. Maximal concentrations o f N i in the kidney o f sparsely rakered whitefish reached 74.46 ^g/g. The concentrations of Zn in the whitefish organs were more variable in the planktivorous form. The highest levels of Zn were revealed in the fish from the river midstream, which may indicate the global spread of this element in the atmosphere. Despite similar pat­ terns o f Cd accumulation in the studied fish tissues, it is likely that this process is more intensive in the sparsely rakered form. The pattern o f Hg accumula­ tion was reverse relative to the levels o f priority pollut­ ants originating from Pechenganickel smelter. The minimal levels of mercury in the whitefish muscles INLAND WATER BIOLOGY Vol. 4 No. 3 2011