T. A. Zotina

Gut content analysis of Gammarus lacustris from a Siberian lake using biochemical and biophysical methods

We studied the gut contents of Gammarus lacustris from the littoral of Shira lake, a Siberian salt lake, by microscopic analysis in conjunction with measuring of fluorescence of chlorophyll and composition of fatty acids. Gammarus ingested primarily fresh seston, probably settled on the bottom. Additionally, the amphipods obtained essential polyunsaturated fatty acids of ω3 family by selectively consuming bottom sediment particles. A considerable part of the ingested seston comprised cells of Botryococcus sp., which passed the intestinal tract in living form and their photosynthetic activity increased. This viable gut passage was likely one of the causes of bloom of Botryococcusin the littoral. Unlike a number of literature data, there was no selective digestion of any fatty acid species, including polyunsaturated acids, in the intestinal tract.

Feeding spectra of Arctodiaptomus salinus (Calanoida, Copepoda) using fatty acid trophic markers in seston food in two salt lakes in South Siberia (Khakasia, Russia)

During two vegetation seasons (2004–2005), we compared feeding spectra of Arctodiaptomus salinus (Calanoida, Copepoda) populations inhabiting two neighboring salt lakes, Shira and Shunet, Khakasia, Russia, using fatty acid (FA) trophic markers. Sestonic FA composition in two lakes moderately differed, whereas levels of diatom FA markers were higher in Lake Shunet and of Cyanobacteria and green algae markers in Lake Shira. In general, markers in storage lipids—triacylglycerols (TAG) of A. salinus—reflected the differences in sestonic composition of the two lakes. Nevertheless, TAG fraction was also enriched by FA trophic markers of the minor components of seston, which were selectively ingested by the animals. In Lake Shira, A. salinus had significantly higher concentrations of bacterial FA markers in TAG. In Lake Shunet, TAG of A. salinus contained significantly higher relative amounts of 18:4ω3, 18:5ω3 and C22 polyunsaturated fatty acids (PUFA), which indicated marked contribution of cryptophytes or (and) flagellates into the diet. Laboratory experiments showed feeding on Cryptomonas and sulfur purple bacteria in Lake Shunet and ciliates and colonial picoplankton in both lakes, and generally confirmed the differences in FA trophic markers in A. salinus between the lakes. The two populations of A. salinus markedly differed in levels of essential long-chain PUFA, eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, although the levels of these FA in seston were quite similar between the two lakes. The higher levels of the essential ω3 PUFA in A. salinus in Lake Shunet may be an adaptive response of the animals to a vertical stratification of physico-chemical conditions and significantly higher salinity levels at the boundary of adjacent bottom layer in this lake.

Accumulation of 241Am by suspended matter, diatoms and aquatic weeds of the Yenisei River.

In this work we experimentally estimated the capacities of the key components of the Yenisei River (Russia): particulate suspended matter (seston), diatom microalgae, and submerged macrophytes for accumulating (241)Am from water. In our experiments large particles of seston (>8mum), comparable in size with diatoms, took up most of americium from water. The accumulation of americium by isolated diatom algae (Asterionella formosa and Diatoma vulgare) was lower than by total seston. The concentration factors (CFs) of (241)Am for seston of the Yenisei River in our experiments were (2.8-6.9).10(5); for diatoms - (1.5-4.2).10(4). The CFs for aquatic plant Elodea canadensis were within the same order of magnitude as those for diatoms. Activity concentration and CFs of (241)Am were nearly the same in experiments under dark and light conditions. This is indicative of an energy independent mechanism of americium uptake from the water by diatoms and submerged macrophytes.

Use of the aquatic plant Elodea canadensis to assess toxicity and genotoxicity of Yenisei River sediments

The toxicity, cytotoxicity, and genotoxicity of bulk sediments from the Yenisei River (Siberia, Russia) were estimated in laboratory bioassays based on several endpoints in the aquatic plant Elodea canadensis. The bottom sediment samples were collected in the Yenisei River upstream and downstream of the sources of chemical and radioactive contamination. The testing revealed different sensitivities of Elodea endpoints to the quality of the bottom sediment: weight of shoots < length of shoots < mitotic index < length of roots < percentage of abnormal cells. The response of the genotoxicity endpoint (percentage of cells with chromosome abnormalities in roots of Elodea) was the highest in sediments with chemical pollution, whereas the highest inhibition of toxicity endpoints (shoot and root length) occurred in sediments with the highest level of radioactive pollution. The extreme response of Elodea endpoints to the quality of certain sediment samples may be regarded as related to the possible presence of unknown toxicants. The results show that E. canadensis can be used as an indicator species in laboratory contact testing of bottom sediment. The responses of shoot and root length growth endpoints of Elodea can be recommended as basic sensitivity indicators of bottom sediment toxicity. Analysis of cells carrying abnormal chromosomes in the apical root meristem of Elodea can be performed optionally in the same test to assess the genotoxicity of sediments.

Chromosomal abnormalities in roots of aquatic plant Elodea canadensis as a tool for testing genotoxicity of bottom sediments

Submersed freshwater macrophytes are considered as relevant indicators for use in bulk bottom sediment contact tests. The purpose of this study was to estimate the validity of endpoints of aquatic plant Elodea canadensis for laboratory genotoxicity testing of natural bottom sediments. The inherent level of chromosome abnormalities (on artificial sediments) in roots of E. canadensis under laboratory conditions was lower than the percentage of abnormal cells in bulk sediments from the Yenisei River. The percentage of abnormal cells in roots of E. canadensis was more sensitive to the presence of genotoxic agents in laboratory contact tests than in the natural population of the plant. The spectra of chromosomal abnormalities that occur in roots of E. canadensis under natural conditions in the Yenisei River and in laboratory contact tests on the bulk bottom sediments from the Yenisei River were similar. Hence, chromosome abnormalities in roots of E. canadensis can be used as a relevant and sensitive genotoxicity endpoint in bottom sediment-contact tests.

Evaluation of cytogenetic abnormalities in cells of submerged plant Elodea canadensis in the Yenisei River section affected by industrial pollution: Field studies and laboratory experiments

27 The Yenisei River, one of the largest rivers in the world which, is exposed to radiation impact for at least 50 years because of the weapon grade plutonium pro duction in the Mining and Chemical Plant (MCP) of Rosatom in Zheleznogorsk [1–4]. Bottom sediments and floodplain of the Yenisei River are polluted with artificial radionuclides, including transuranic ones, not only in the vicinity of MCP, but also at a consider able distance downstream the river. During operation of MCP nuclear reactors, at least 20 of the anthropo genic radionuclide typical of MCP outlets were inden tified in biomass on the Yenisei submerged macro phytes [2]. Elodea canadensis Michx belongs to mass macrophyte species vegetating in zones of anthropo genic pollution and on the background areas [5]. Pre vious studies suggest that, in the Yenisei area contam inated with radionuclides, cytogenetic abnormalities in the elodea root cells were more frequent than in similar plants vegetating in the Yenisei section above MCP outlets [6]. Cytogenetic damages of the plant root meristem serve as indicators of cyto and geno toxicity in assessing the environmental quality [7, 8].

Cytogenetic abnormalities in aquatic plant Elodea canadensis in anthropogenic contamination zone of Yenisei River

Chromosome abnormalities in ana-telophase cells of apical root meristem of aquatic plant Elodea. canadensis (elodea), sampled in 2011–2012 in the Yenisei River at a site with background level of contamination and at several sites on the stretch contaminated with artificial radionuclides, and with chemical pollutants from municipal and industrial discharges of the Krasnoyarsk city. Lowest rate (5.2%) of cells with chromosome abnormalities was registered at sampling site with background level of contamination upstream of the Krasnoyarsk, highest rate of cells with abnormalities (39.7%)—in roots of elodea sampled in bottom sediments with highest concentration of 137Cs. Sum of rates of cells with abnormalities and rates of cells with all types of abnormalities positively correlated with total concentration of artificial and natural radionuclides, with concentration of artificial radionuclides and 137Cs in bottom sediments of the Yenisei River (r2 = 0.91–0.96, p < 0.0005 for sum of rates of cells with abnormalities; r2 = 0.58–0.92, p < 0.05 for all types of abnormalities).

Estimation of transfer of technogenic radionuclides in food chains of the Yenisei river

The efficiency of the transfer of gamma-emitting radionuclides in food chains, including macrophytes, zoobenthos, and bentho- and ichthyophagist fish, was estimated in the radiation-polluted region of the Yenisei river. Significant differences in the efficiency of the transfer of natural and technogenic radionuclides between components of different trophic levels were revealed. Substantial species-related differences in the accumulation of radionuclides in ichthyophagist fish from food were revealed.

The effect of γ-radiation on resting eggs and life cycle of cladoceran Moina macrocopa.

We investigated the effects of γ-irradiation on the survival of resting eggs of the cladoceran Moina macrocopa and on the parameters of the life cycle of neonates hatched from the irradiated eggs. It was shown that γ-irradiation in a wide range of doses (from the background level to 100 Gy) had no effect on survival of eggs and mortality of neonates hatched from the irradiated eggs. However, exceeding the absorbed dose of 40 Gy sharply decreased the reproductive potential of the neonates hatched from irradiated eggs.

Bioaccumulation, inter-organ distribution, and retention of waterborne and dietary 241Am in silver crucian carp

The bioaccumulation of actinide 241Am from food and water in bodies of freshwater fish (Carassius auratus gibelio, silver crucian carp) has been investigated in laboratory experiments. Homogenized biomass of submerged macrophytes labeled with 241Am was injected into the fish gullet. Internal organs and tissues of crucian carp could be ranked according to activity concentration of dietary 241Am after depuration of the digestive tract as follows: liver > gonads > bones > muscles. Accumulation of waterborne 241Am in internal organs and tissues of crucian carp mainly occurred via the digestive tract. While the concentration of 241Am in liver of crucian carps decreased during depuration time, its concentration in bones increased indicating slower transfer of 241Am to skeleton compared to muscles and liver. The retention of dietary 241Am in the bodies of crucian carp reached 35%–46% of ingested 241Am: 20%–31% was retained in liver, 0.6%–0.8% in skeleton, and 1.4%–2.0% in muscles. The concentration factor of 241Am from water was 0.4 for the whole body, 0.3 for liver, 0.01 for muscles, and 0.01 for skeleton. Trace amounts of 241Am were recorded in viscera and muscles of a wild population of silver crucian carp inhabiting a radioactively contaminated part of the Yenisei River.