The present study analysed the response of whitefish (Coregonus lavaretus L.) to reduced toxicity after the long-term contamination of subarctic Lake Imandra. High concentrations of Ni, Al, and Sr in fish organs and tissues were accompanied by nephrocalcinosis, scoliosis, and myopathy during the period of intense contamination. After reduction of the toxic impact on the lake, the accumulation of Cu, Al, Sr, Cr, Pb, and Hg in the kidney, which is the target organ for toxicity, was two-fold less and that of Cd was 10-fold less in whitefish from the contaminated part of the lake compared with those in whitefish from the non-contaminated parts of the lake. The ecological success of whitefish from the contaminated part of the lake was associated with the limited accumulation of metals in organs and tissues and a more favourable physiological state compared with whitefish from non-contaminated parts of the lake. Redistribution models were constructed for essential and non-essential metals in the fish liver and kidney depending on the physiological state of fish. The results revealed changes in Fe and Zn metabolism: an increase in Fe and a decrease in Zn accumulation in the liver with increasing stage of liver disease and decreasing blood haemoglobin concentration. Furthermore, under the sub-toxic (except for Cu) conditions of Lake Imandra, the strategy of adaptive fish response is to preserve and maintain acid-base regulation system.
Keywords: Fish response; Iron and zinc metabolism; Metal accumulation; Physiological condition; Reduced toxic impact.
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