Sandimirov S. Heavy metal contents in whitefish (Coregonus lavaretus) along a pollution gradient in a subarctic watercourse. Environ. Monit. Assess. 2011, V. 182, №1-4, p. 301-316.

312 Environ Monit Assess (2011) 182:301-316 A toxic effect could result from an interaction between Pb and the high levels of Ni and/or Cu, which were in ranges observed to impact on rainbow trout (Oncorhynchus mykiss) biology (Vosyliene et al. 2003). The Cu levels were highest in the liver, which is known to be an important detoxification centre in fish (McFarlane and Franzin 1980). Zn and Pb were in contrast found in highest concentrations in the gills, which may indicate a predominant uptake directly from water (Dallinger et al. 1987). Most of the studied metals are essential mi­ croelements (Nemova 2005), and homeostasis of these elements in the organism is supported by complex processes at the cellular level (Yoo and Janz 2003). However, an excess intake of met­ als may result in negative processes leading to both lethal and sub-lethal effects due to func­ tional disorders of the organisms (Akimova et al. 2000; Hollis et al. 2000; Cooley et al. 2002; Lukin et al. 2003; Veltman et al. 2008). The biologi­ cal consequences of heavy metal accumulations in living organisms may appear as direct toxic effects which potentially may lead to increased mortality. The influence of pollutants can change the chemical and morphological characteristics of cells and osmotic functions, and also lead to the development of pathologies, mutations and spatial orientation disorder (Hansen et al. 2002; Ptashynski and Klaverkamp 2002; Baldwin et al. 2003; Reynders et al. 2008; Weber et al. 2008; Gauthier et al. 2009; Otero-Muras et al. 2010). The accumulation levels of any heavy metal in the organism depend on complex processes related to the uptake from the environment, redistribution, biotransformation and finally detoxification and deposition as inert compounds (Hollis et al. 2000). Furthermore, the rate of these processes depends on both the state of the environment (load in­ tensity, temperature, pH other stressors) and the organism status (ontogenetic stage, sex, feeding success, metabolism including elements necessity etc.) (Power 1997; Flik et al. 2002; Otero-Muras et al. 2010). The highly elevated concentrations of heavy metals in whitefish from Kuetsjarvi are likely to induce a pollution stress which may lead to phys­ iological and histological alterations in the fish (e.g. Ptashynski-etal 2002; Rajotte and Couture 2002; Reshetnikov et al. 2002; Morozov et al. 2007; Couture and Pyle 2008). Several pathologies and histological abnormalities have accordingly been recorded in functionally important organs like gill, liver, kidney and gonads of whitefish in Kuetsjarvi (Kashulin and Reshetnikov 1995; Reshetnikov et al. 2002; Lukin et al. 2003; Stebel et al. 2007; N. A. Kashulin et al., unpublished data). The present study suggests that the pollu­ tion also may influence somatic growth, condition and sexual maturation of the whitefish popula­ tions in Kuetsjarvi. Both morphs exhibited the slowest growth performances and lowest condi­ tion factors and also showed a distinct dominance of small-sized fish in this highly contaminated lo­ cality relative to the other lake localities in the watercourse. The restrained growth and condi­ tion performances are most likely a direct result of pollution stress for the fish as similar effects have been documented in yellow perch (Perca f lavescens ) residing in metal-contaminated lakes in the vicinity of the Sudbury smelters (Rajotte and Couture 2002; Couture and Pyle 2008; Pyle et al. 2008; Rasmussen et al. 2008). Indirect effects of pollution can also arrive from negative re­ sponses in prey availability. Some indications of this exist, as zoobenthos studies documented re­ duced diversity and density of chironomid larvae in Kuetsjarvi relative to lake localities at more remote distances to the smelters (Mousavi et al. 2003). However, other factors such as variation in fish abundance may also affect growth and condition of fish in subarctic areas (Amundsen et al. 1997). Size and age at first reproduction of both whitefish morphs were also at a minimum in Kuetsjarvi compared to the other studied lakes. The early sexual maturation of the two whitefish morphs in Kuetsjarvi appears to represent a direct response to heavy metal impacts on reproduction processes as several pathological abnormalities have been revealed in gonads of whitefish in this particular lake (Akimova et al. 2000; Stebel et al. 2007). The early maturation may also reflect a “live fast and die young” strategy which has been suggested to occur in yellow perch as a response Springer