Ecosystem and human health assessment to define environmental management strategies: the case of long-term human impacts on an Arctic lake / Moiseenko T. I., Gashkina N. A., Voinov A. A. [et al.] // The Science of the Total Environment. - 2006. - Т. 369, № 1-3. - С. 1-20.

6 T.I. Moiseenko et al. /Science o f the Total Environment 369 (2006) 1-20 than 1.1-1.4 g/m2 (Krogius, 1930) and these values corresponded with an a-oligotrophic lake level. Values of biodiversity index of communities were up to 3.5 bit/ind (Table 3) . Fishes were represented by 16 species (Berg and Pravdin, 1948) . By contents of fish catches the lake was a typical whitefish-loach lake with presence of trout. In catches of 1945-1960 predominated species were species of freshwater-arctic complex, their contents in catches were: 90% — Coregonus lavaretus (L) — 20% and C. albula (L) — 50%, Salvelinus alpinus (L) — 7% and Salmo trutta trutta (L) — 3% (Galkin et al., 1966) . Estimated fish productivity for lakes was 4 kg/ha. Multiyear anthropogenic pressure on the lake caused changes to all structural components of the ecosystem. Structure of phytoplankton, zooplankton, and benthos became poor. It consists of eurybiontic species that are widespread in the Arctic, and cosmopolitans. The structure of dominating complexes has changed, their biodiversity was reduced, and the biomass was increased (Table 3) . In phytoplankton structure Green algae of genus Scenedesmus , Paldorina and some species of diatoms are dominant in polluted areas. During this period such species as Asterionella formosa and Tabellaria fenes- trata, common for the Lake, were not observed. Species of genus Fragilaria, Synedra, Diatoma, Aulacoseira, Stephanodiscus were dominant. Phytoplankton biomass has increased in all the lake; in some parts it could be over 20 g/m3 (Sharov, 2002) . For algae no species- indicators of heavy metal pollution were found, and community diversity parameter is not a reliable indicator in these conditions (Moore, 1981) . Increasing of biomass of chlorophyceans and cryptomonads, proba­ bly, can be an indicator of lake eutrophication. In zooplankton of this period adult species were rare or absent for Calanoida and Cyclopoida. Also missing were predatory Cladocera (Leptodora kindtii, Polyphe­ mus pediculus), Collotheca sp., Conochilus sp., Holo- pedium gibberum (see Table 2) . Eurybiontic species (Asplanchna priodonta, Keratella nochlearis, K. qua- drata, Notholca caudata, Bosmina obtusirostris) were predominant. Note that Asplanchna priodonta was 40­ 50% of their average number of species (Yakovlev, 1998; Vandish, 2000, 2002) . Domination of this species in polluted waters was registered by Maclsaac et al. (1987). The total number and biomass of zooplankton increased. Index of biodiversity by number of species fluctuated in the range of 1.5-2.3 bit/ind. The most significant degradation of macro-zoo- benthos was in the 1980s. Biodiversity decreased while biomass of benthic communities increased. In the zones of copper-nickel pollution Chironomus spp., Procladius spp., Dytiscidae, Nematoda (biomass up to 20.0 g/m2) were predominant. In the zones of mining industries and intensive eutrophication, Chironomus, Tubifex tubifex, Limnodrilus hoffmeisteri, Procladius spp. were predominant (Table 2) . In general for the lake by the 1980s values of benthic biomass in polluted parts have increased 20 times, which indicates an intensive process of eutrophication alongside with toxic pollution (Moiseenko and Yakovlev, 1990) . Resilience of Midges (mainly of genera Chironomus and Procladius) and Nematoda to the impact of heavy metals was notices by several authors (Nalepa, 1987; Yakovlev, 1998; Iliyaschuk, 2002b) . Oligochaetes develop well when organic material and apatite-nepheline mining industry waste are accumulated at the bottom (Milbrink, 1983) , while metal concentrations in water and sediments are low. Biodiversity is low in areas of high pollution from both metallurgic and apatite-nepheline industries (0.5­ 1.0 bit/ind). From two relict species Monoporea relicta and M. affinis, found before in Lake Imandra, only the last one is still present. The more vulnerable M. relicta is no longer there (Yakovlev, 1998) . In the period of maximal water pollution the amount of typical Arctic fish species - salmon trout and arctic char - has sharply decreased, due to their vulnerability to water pollution. Fish productivity decreased to less than 1 kg/ha, while there was no commercial fishing on the Lake. In catches whitefish and perch now prevail. There was a mass development of minnow, while the number of smelt has increased. Mass diseases of whitefish were registered in 1970­ 1980: change of the integument colour (de-pigmenta­ tion), anal inflammation, tousling of scales, oedema gills and appearance of anaemia rims, destructive changes in liver (increase of size, change of colour and friability) and kidneys (colour, granulation, thickening of renal and presence of nephritic calculi), anomalies in gonad texture, etc. Main types of registered fish pathologies are reflected i n Table 4. Together with universal attributes of organism intoxication, some specific diseases of fish appear, which are observed for this lake. A rather rare disease of whitefish, nephrocalsitosis (stones in kidney), is found. Productive areas of benthic biocenoses play a role of specific “traps”, which attract whitefish by high biomass of zoobenthos. Migrating to food-rich areas, fish becomes exposed to heavy metals (Moiseenko and Yakovlev, 1990) . Diseases in fish caught in these areas were so dramatic that the lethal outcome was inevitable. In last decades of decreased toxic pollution there was a recolonization of the Lake by Arctic inhabitants. This is seen from changing dominant complexes, and increased biodiversity index for plankton communities