Adaptation of Fish Metabolism to Thermal Pollution of Subarctic Lake Imandra
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tation of Fish Metabolism to Thermal Pollution of Subarctic Lake Imandra N. A. Gashkinaa, * and T. I. Moiseenkoa aVernadsky
Institute of Geochemistry and Analytical Chemistry (GEOKhI), Russian Academy of Sciences, ul. Kosygina 19, Moscow, 119991 Russia *e-mail: [email protected] Received March 1, 2020; revised April 8, 2020; accepted April 8, 2020
Abstract—Kola nuclear power plant, which discharges warm water into one of the bays of sub-arctic Lake Imandra, significantly changes the fish habitat, creating temperature gradient from 2 to 8°C compared to water temperature in the other part of the lake. The permeation, metabolism and bioaccumulation of elements in the stenothermal cold-water species (Coregonus lavaretus L.) in warm water impact zone are characterized. One of the main adaptation mechanisms of ionic regulation is the intense metabolism of Na due to the high respiratory activity of whitefish in warmer water. This feature is associated with elevated accumulation of Rb and loss of Se, Mo, and Si. At elevated temperatures, the main metabolic need is caused by Se deficiency. An extensive metabolism of selenoproteins involves risks of toxic effects and bioaccumulation of Hg, As and Cu with an increase of existing stressor or appearance of new ones. Keywords: thermal pollution, elements, permeation, bioaccumulation, metabolism DOI: 10.1134/S0016702920100079
INTRODUCTION Nuclear power stations discharge heated waters in continental basins or seas, thus significantly affecting the coastal ecosystem of cooling basin. Variability of structural–functional organization of ecosystems in warming zones and ability of living organisms to survive at higher temperatures provide a unique anthropogenically induced model for study and prediction of the effect of possible climatic warming on aquatic ecosystems. Models of global climatic change predict a 5– 8°C increase of the average air temperature by 2100 in northern and central Europe and in the Arctic regions (IPCC, 2013). Arctic species are most sensitive to climatic changes: warming and its influence on wild animals and fish are more significant in the Arctic region (AMAP, 2018). Thus, further climate warming could both affect species under natural conditions and intensify the influence of existing thermal pollution. The Kola nuclear power plant (NPP) with direct cooling launched in 1974 at Lake Imandra provided near 50% of electric energy of the Murmansk oblast. Discharge is 1218 bil. m3 per year and enters into Molochnaya Bay of Lake Imandra (Report on Ecological Safety, 2018). This results in the formation of thermal pollution zone up to 25 km2 in area, where temperature gradient is >8°С near the discharge channel mouth and gradually decreases with propagation of thermal flow. Ecosystem differing from natural coldwater lake ecosystems has been formed for over 40-year period of NPP operation in a thermal impact zone.
The heated territory demonstrated an increase of bioproductivity, which resulted in the formation of high food base for fish, especially, for benthoph
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