Sandimirov S.S. Assessment of the habitat conditions for the freshwater pearl mussel Margaritifera margaritifera (l.) In the headwaters of major rivers of Murmansk region. Conservation of freshwater pearl mussel Margaritifera margaritifera populations in Northern Europe. Proceedings of the International Workshop. Karelian Research Centre of RAS. 2010, p. 29-34.

N.A. Kashulin, V. A. Shirokov, S. S. Sandimirov, L. L. Shchurov, P. M. Terent'ev, D. B. Denisov, S. A. Valkova ASSESSMENT OF THE HABITAT CONDITIONS FOR THE FRESHWATER PEARL MUSSEL MARGARITIFERA MARGARITIFERA (L.) ASSESSMENT OF THE HABITAT CONDITIONS FOR THE FRESHWATER PEARL MUSSEL MARGARITIFERA MARGARITIFERA (L.) IN THE HEADWATERS OF MAJOR RIVERS OF MURMANSK REGION N.A. Kashulin*, V. A. Shirokov**, S. S. Sandimirov*, I. L. Shchurov**, P. M. Terent'ev*, D. B. Denisov*, S. A. Valkova* Institute fo r Industrial Ecology o f the North (INEP KSC RAS), Apatity, Russia Northern Fisheries Research Institute (SevNIIRKh), Petrozavodsk, Republic o fKarelia, Russia p_terentjev@inep.ksc.ru Surveys to assess habitats o f the European pearl mussel Margaritifera margaritifera (L.) in upper reaches of the major rivers of Murmansk Region were carried out. The main aim was to investigate the upper reaches of the main rivers with the “salmon-inhabited” status - the area around the deposit proposed for mining - a s a potential habitat of the pearl mussel. It was found that the distribution of M. margaritifera depends on the hydrological and hydrochemical parameters of waters and the availability of river sites suitable for spawning and growth of salmonids. On the whole, the conditions in the very upstream o f the rivers surveyed are not favorable for the mollusk because of heavily silted channels and the absence of host-fish species. Among-year variation of the water level in rivers was found to be one of the key factors for mollusk finding. Key words : pearl mussel, headwaters, habitat conditions, water quality INTRODUCTION The freshwater pearl mussel Margaritifera margaritifera (L.) has become endangered as the result of growing anthropogenic pressure. Very high water quality requirements and peculiarities of the life cycle, which is strongly dependent on symbiotic relations with salmonids - Salmo salar L. and Salmo trutta L., make this species unique. The freshwater pearl mussel is widespread in the biggest salmon rivers of Murmansk Region, but there is little information about potential habitats of M. margaritifera in the headwaters of these watercourses, although quite a number of papers deal with its biology in their middle and lower courses (Prokhorov, 1995, 1996; Zyuganov et al., 1993, 1998, 2000, 2001). However the existing populations of mussels are exposed to human impact and their abundance it therefore decreasing. More detailed information is needed on the population abundance and the spatial limits of its extension upstream. As a rule, habitat conditions in the headwaters of so-called “salmon” rivers are not favorable for M. margaritifera, but any human activity there would be a serious threat to the mussel populations downstream. The main aim of this study was to monitor potential habitats of the freshwater pearl mussel in the area of the planned mining and ore processing enterprise (headwaters of the Murmansk Region major rivers: Umba, Varzuga, Voron’ya). MATERIALS AND METHODS The study area is situated in the vicinity of the planned mining and ore processing enterprise right in the middle of the Kola Peninsula, where its three main river systems originate (Fig. 1). Three river sites were investigated: Kitsa-Umba river system - the 5 km long stretch upstream of the Kitsa River mouth; Tsaga-Voron’ya river system - from the source to the point 2 km downstream of Lake Nizniy Tsagajavr; Pana-Varzuga river system - from the source of the Pana River to the point 1 km downstream of its confluence with the Chernaya River. Hydrochemical analysis . Water sampling was carried out in the rivers during the year in the period of 2004-2008. Chemical analyses were performed in the laboratory. The samples were analyzed for pH, total mineralization, organic matter, water color, P, N, Fe, oxidation characteristics. All the analytical methods applied to determine the above hydrochemical parameters conformed to international standards (Lurje, 1984; Standard method..., 1975). 29