Assessment of the effect of heavy metal salts on the photosynthetic activity of aquatic plants

The status of the photosynthetic pigments in the aquatic plants Lemna minor L. and Elodea canadensis Michx. under the action of Ni2+, Co2+, Cu2+ and Pb2+ acetate in concentrations 5.00, 2.50, 1.25, 0.62, 0.31, 0.15, 0.07, and 0.03 mg/L was assessed by changes in the fluorescence intensity of chlorophyll a and b and their ratio. It was established that nickel acetate in original solutions in all the above concentrations caused an increase in the fluorescence intensity of chlorophylls a and b in L. minor in relation to the control while the lead salt suppressed it. Co2+ acetate inhibits the fluorescence of chlorophyll a with concentrations in the initial solutions of 0.03 to 0.15 and 2.50 mg/L and that of chlorophyll b at all concentrations, except 0.62, 1.25 and 2.50 mg/L. For E. canadensis it was found that the salts of all metals at all concentrations caused a reduction of the fluorescence intensity of chlorophyll a relative to the control and increased it in the case of chlorophyll b. The exception is the effect of copper and lead acetates with a concentration of 1.25 mg/L, when the fluorescence intensity of chlorophyll b is maintained at the control level. The presence of Ni2+, Co2+, Cu2+, and Pb2+ acetates in all concentrations in the culture medium influences the quantitative and qualitative characteristics of chlorophyll a and b, which indicates a violation of the photosynthesis process. Our data on the change in the chlorophyll a / b ratio leads to a conclusion about degradation of chlorophyll a relative to chlorophyll b after the effect of heavy metals.

Algoflora of lakes in the Kurgal’sky Nature reserve (Leningrad region)

Various algocenosises in the brackish Lake Lipovskoe and ultra-oligotrophic Lake Beloe located in the Kurgal’sky Nature reserve were studied in May and July of 2019. In the algal flora of the lakes studied, we found 291 taxa belonging to 9 orders. The both lakes were characterized by high species richness, namely: 179 and 181 algae taxa were identified in the Lake Lipovskoe and Lake Beloe, respectively. In the Lake Lipovskoe, its phytoplankton was dominated by Cyanophyta, Cryptophyta and Dinophyta, among which brackish-water and marine species were presented. In the periphyton of this Lake, brackish-water diatoms and green algae were the most abundant. In the Lake Beloe, its phytoplankton was dominated by Dinophyta, Bacillariophyta and Chlorophyta; the blue-greens, diatoms and green algae dominated in the periphyton of Lake Beloe. Despite that the lakes are located close to each other, their algal flora is quite different: the Sorensen similarity index between the two lakes was 38% only. The phytoplankton biomass in both lakes was low, increasing from spring to summer. In the Lake Lipovskoe, the phytoplankton biomass varied from 0.45 to 1.9 mg/L, chlorophyll a fluctuated from 3.9 to 7.1 µg/L. In the Lake Beloe, the phytoplankton biomass varied from 0.3 to 1.4 mg/L, chlorophyll a fluctuated from 0.45 to 1.3 µg/L. The periphyton biomass was 20 g/m2 (chlorophyll a being 22 mg/m2 ) and 17 g/m2 (chlorophyll a being 17 mg/m2 ) in the Lake Lipovskoe and Lake Beloe, respectively. Nowadays, the ecological status of both lakes can be considered satisfactory, because based on trophic conditions and species compositions they belong to waterbodies of clean and satisfactory clean conditions (II–III classes of water quality). To preserve the unique flora of the lakes in the Kurgal’sky Nature reserve, nature-protected measures should be strengthened.

Parameters of the autumn migration stopover of the chiffchaff (Phylloscopus collybita Vieillot, 1817) (Sylviidae, Aves) in the conditions of the middle taiga in the Eastern Russian plain

Parameters of the autumn migration stopover of the chiffchaff Phylloscopus collybita (Vieillot, 1817) in the taiga zone of the Eastern Russian plain were estimated. The studies were carried out in 2015–2019, a total of 1,634 birds were included in our analysis. It has been established that migrating chiffchaffs can be conditionally divided into two groups. The first group consists of transit individuals leaving their stopover just on the day of arrival, without delay. The other group includes individuals who make stopovers for a longer period (4.87 days on average). For the birds of both groups, changes in their body weight and fat accumulation rate were revealed during one day and throughout the entire migration stopover. During an average migration stopover, birds retain their energy reserves at a certain level. In general, they accumulate no more than 5% of the average body weight in the population during the average stop period. A smaller proportion of migrants make multi-day stops when the fat accumulation rate is low. Every day of staying at a migration stopover leads to temporary surges and losses in body weight, with no increase in body fat. Birds, at the end of their migration season, spend more time and energy for looking for food. The part of migratory birds deciding to stop finds themselves in the most optimal conditions. This small group is the main reserve for preserving the population during the difficult period of migration.

Hydrochemical water quality monitoring of natural water bodies of the Ural river basin

A general characteristic of the river basin of the interstate Ural river and information on the economic use of the Ural river in its upper, middle and lower reaches are given. Information on the hydrology of the liquid and solid flow of the Ural river is presented. Hydrochemical monitoring of water bodies of the Ural river basin was conducted during the flood period, during the summer low water period and during the autumn low water period of 2017–2018. The hydrochemical monitoring of the water quality in natural reservoirs of the Ural drainage basin made it possible to identify an excess of the MPCs for residential use and for fishery of heavy metal ions in the water of the examined reservoirs. An excess of cadmium ions by (1.2–1.4) MPC for residential use was found in the Ilek river during its low water as well as in the Ural river near the border with the Russian Federation during the flood period in the amount of (3.1–3.4) MPC for residential use and near the village Zharsuat in the period of summer and autumn low water in the amount of (1.5–2.6) MAC for residential use. An excessive concentration of lead ions by (1.2–1.4) of MPC for fresh water fisheries in the middle and lower reaches of the Ural river at different times of the year was found. Excessive concentrations of ions of different heavy metals in comparison with their MPC for fresh water fisheries were found in all water bodies in different periods of the year. The greatest excess of zinc ions in comparison with its MPC for fresh water fisheries was observed during low water.

Use of Chlorella sorokiniana (Chlorellaceae, Chlorellales) microalgae for purification of waste water from the brewing industry

The paper presents some environmental problems of the brewing industry. The literature data on the methods of water purification using microalgae have been studied. The composition of wastewater from the brewing industry is shown to consist of few biogenic elements, namely: nitrogen, phosphorus and potassium, which are necessary for microalgae biomass cultivation. Therefore, the wastewater from the brewing industry can be used as a basis for making a nutrient medium to cultivate microalgae. In the experimental part, the effect of various dilutions of a suspension of microalgae Chlorella sorokiniana (C) grown on a nutrient medium with untreated wastewater (UWW) from the brewing industry was studied. Various percentage ratios of wastewater to microalga suspension were studied, namely: UWW/C = 70:30, 50:50, and 30:70 for the ability to absorb nitrogen, organic and inorganic carbon from dry matter, and to change the pH value. The dependences of the growth rate of microalgae at various percentage additives of the wastewater from the brewing industry are presented. It was shown that at a UWW:C = 30:70, this dependence is characteristic of the standard growth curve of a microorganism culture. A lag phase, phases of exponential growth and withering away are observed. At a 70:30 ratio, the harmful effect of effluents on the growth of microalgae is obvious, on the 3rd day their death occurs, the green solution acquiring a brown color to confirm the death of microalgae cells. It has been shown that the optimal UWW:C ratio is 30:70, with no loss of biomass, it grows well using pollutants for its nutrition. The color of the solution after cultivation was bright green, which corresponded to the color of healthy cells. At UWW:C = 30:70, the wastewater is purified up to 70% and 90% for total nitrogen and organic carbon, respectively. The pH value changes from acidic to neutral. Keywords: Chlorella sorokiniana, wastewater treatment, brewing industry

Dactylorhiza incarnata (L.) Soó (Orchidaceae, Liliopsida) on the northern border of its distribution area: Population structure and seed productivity

The results of the study of the population biology of the rare orchid Dactylorhiza incarnata (L.) Soó on the territory of the Komi Republic (north-east of European Russia), where the species is located on the northern border of its range, are presented. Data on the population structure, morphometric features of plants, and reproductive characteristics of the species are given. It was found that the size of plants and the number of flowers in the inflorescence of this species in the region is lower than in the more southern parts of its range. The populations size ranges from 30 to 350 individuals with their average density of 0.7–3.7 per 1 m2 , and it is common for this species in other parts of its distribution area. Reproductive success is associated with the weather of the second decade of June because the flowering time of the species in the region happens in this time. It was found that the seed size of D. incarnata (0.55×0.20 mm) on its northern border is smaller than in other parts of the range. The seed productivity is rather high: one fruit contains an average of 6.2 thousands of seeds and one individual could produce about 49.4 thousands of seeds. Temperature during flowering time and precipitation during seed ripening may affect seed quality. The presence of juvenile individuals (%) in all the studied populations shows seed recruitment in populations of this species at the northern limit of the range, despite a lower seed set in comparison with southern populations.

Estimation of the growth rate of wild ungulate populations in the territory of the Saratov region by the dynamic series of their numbers

The present paper is devoted to the study of the possibility of estimating the reproductive potentials of wild ungulate populations, and possibly other large mammals, by the time series of their numbers. We have found out that this is possible, which is confirmed by the high quality of approximation of the time series of abundance by logistic curves, and the corresponding coefficients of their determination for different species ranged from 75 to 96%. For such calculations, one circumstance is necessary, which is that the population of the studied species has been briefly exposed to some unfavorable factor causing a significant reduction in its numbers with subsequent restoration to the previous level, or the time series should contain a well-expressed and extended section of the transition of the population from some lower level to the upper level of the population, passing into a stationary state. The values of the maximum exponential growth rates of ungulate populations that we obtained do not fundamentally differ from the data available in other researchers’ works. In addition, it should be borne in mind that our method for assessing the reproductive potentials of ungulates is statistical, with features accompanying all such methods, for example, in the presence of statistical errors in all determined parameters. However, the evaluation of the magnitude of these errors is a topic for a separate study.

Screening and identification of thermophilic cellulolytic bacteria isolated from sawdust compost

Composting process mainly depends on the metabolic pathways of the microorganism and involves the activity of different enzymes. Thermophilic cellulase-producing bacteria isolated from sawdust compost were tested for formation of a visible zone around the colonies on the agar plates medium containing carboxymethyl cellulose at 50ºC. Screening of carboxymethyl cellulase producing isolates was further realized on the basis in liquid medium by DNS method. Among 29 isolates investigated, V1 and V11 strains exhibited maximum enzyme activity of 1.9 and 2.3 U/mL, respectively. These isolates were selected for morphological, physiological and biochemical studies and 16S rRNA gene analysis. They were found a Gram-positive, rod-shaped spore forming cells, which were identified as Bacillus megaterium (V1) and Bacillus subtilis (V11) based on cell morphology, nucleotide homology and phylogenetic analysis. The optimal temperature for activity of endoglucanases (CMCase) ranged from 35–45°C (strain V1) and 40– 50ºC (strain V11). Our findings showed that Bacillus megaterium (V1) and Bacillus subtilis (V11) cellulase demonstrate thermophilic characteristics within wide range of temperature and meets the requirements for commercial enzymes.

Phytoplankton and water quality of Lake Kuchane (Pskov region, Russia)

The phytoplankton communities of Lake Kuchane, located in the Mikhailovskoye Museum-Reserve, were studied during different 2016–2017 seasons for the first time. 213 specific and intraspecific taxa from 9 phylums were identified in the phytoplankton, namely: Bacillariophyta, Chlorophyta, Chrysophyta, Euglenophyta, Cyanobacteria, Dinophyta, Cryptophyta, Charophyta, and Xanthophyta. The ratio of the main phylums of microalgae during the studied seasons was similar. The floristic complex of the lake's algoflora consisted of diatoms (36.6%), green (27.2%) and golden (10.8%) algae. Most of the phytoplankton genera contained one species taxon only. The specific composition of the phytoplankton community in 2017 was similar from spring to autumn. The minimum specific similarity of the phytoplankton communities was noted in July, 2016, and August, 2017. According to the level of biomass of planktonic algae, the lake belongs to oligotrophic water bodies. The planktonic algoflora of Lake Kuchane is characterized by the predominance of cosmopolitan freshwater forms of microalgae. In relation to pH, the predominant representatives preferred slightly alkaline waters. The Milius trophic index varied in the range 18.0–39.6 with a maximum value in summer. The Pantle–Bukk saprobity index almost did not change during the entire study. The waters of Lake Kuchane corresponded to the betamesosaprobic self-purification zone, quality class III.

Spatial distribution of picoseston in the Saratov reservoir in summer

The structure and spatial distribution of picoseston in the Saratov reservoir in July 2011 and August 2014 are described. On average, the total abundance of cells and particles forming picoseston was 1.87±0.73×106 cells (part.)/mL; and the total biomass of picoseston was 43.8±19.4 µg C/L. During the study period, solitary heterotrophic bacteria and phototrophic picocyanobacteria prevailed in the picoseston of the Saratov reservoir, amounting to 77–100% of its total abundance and biomass. The proportion of picodetrital particles was extremely small (on average, 4.1% of the total biomass of picoseston). The high heterogeneity of picoceston distribution (Cv is 130% and 110% for abundance and biomass, respectively) was found in the Saratov reservoir during the study period. On average, the abundance and biomass of heterotrophic bacterioplaknton and picodetritus at stations of the tributary estuaries were slightly higher than in the riverbed. At the same time, the abundance of picocyanobacteria was higher, and the biomass was lower at the estuarine stations compared to the riverbed ones. The total number of bacterioplankton and autotrophic picoplankton in the Saratov reservoir in 2011 and 2014 corresponded to the mesotrophic level of productivity. Picodetrital particles, in contrast to the Upper Volga and Kama reservoirs, make no significant contribution to the planktonic food webs of the Saratov reservoir, at least during the study period.