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.

Characteristic features of the structure and spatial distribution of phytoplankton in the Sotka river in the State nature reserve «Pinezhskii»

На территории Пинежского природного заповедника впервые исследован фитопланктон основного водотока ООПТ - карстовой р. Сотка. Приведены данные таксономического состава альгофлоры по основным ее отделам и данные анализа видового богатства. Установлено, что видовой состав фитопланктона представлен 56 таксономическими единицами, в том числе 46 диатомовыми, 6 зелеными, 2 эвгленовыми, 1 золотистой и 1 сине-зелёной. Для фитопланктонного сообщества р. Сотка характерны зональность и мозаичность распределения численности и биомассы, необычные для полугорных рек, к которым относится водоток. Отмечена неоднородность видового состава и комплекса доминант, наблюдаемая по всей исследованной акватории. Очевидно, это результат комплексного воздействия специфических экологических характеристик реки и в первую очередь - высокого уровня минерализации. В целом р. Сотка можно отнести к флористически обедненным олиготрофным водоемам со значительным преобладанием диатомовых водорослей, низкими количественными показателями численности и зонально-высокими значениями биомассы. Экологическое состояние водотока оценивается как хорошее, с умеренным содержанием органических веществ в воде. Phytoplankton of the main watercourse of the Pinezhsky Nature Reserve, the karst river Sotka, was studied for the first time. Taxonomic composition of the algal flora and the analysis of species richness are presented. The species composition of phytoplankton is represented by 56 taxonomic units, including 46 diatoms, 6 green, 2 euglena, 1 golden and 1 cyanobacteria. For the phytoplankton community of the river Sotka is characterized by zoning and mosaic distribution of abundance and biomass, unusual for semi-mountain rivers, to which the watercourse belongs. The heterogeneity of the species composition and complex of dominants, observed throughout the studied water area, was noted. Obviously, this is the result of the complex impact of the specific ecological characteristics of the river and, first of all, the high level of mineralization. In general, river Sotka can be attributed to floristically depleted oligotrophic water bodies with a significant predominance of diatoms, low quantitative indices of abundance and zonal high values of biomass. The ecological state of the watercourse is assessed as good, with a moderate content of organic matter in the water.

EARLY SUMMER ZOOPLANKTON OF LAKE VOZHE AND LACHA (VOLOGDA REGION)

In June 2015, zooplankton (Cladocera, Copepoda, Rotifera) of lakes Vozhe and Lacha, Svid’ River and the headwaters of the Onega River (catchment of the Onega River, White Sea basin) was examined. It was found that crustaceans (mainly the copepods Mesocyclops leuckarti and Eudiaptomus gracilis) dominated the community. The biomass of zooplankton (<1 g / m3) indicated a low food supply for fish (poorly fed water bodies), compared with the beginning of the 1970s, it decreased by 4–10 times. The composition and structure of the community characterized the ecosystem status of the Lake Vozhe as eutrophic, and Lake Lacha as mesotrophic. Changes in the structure of zooplankton over 40 years testified to the eutrophication of the ecosystem of Lake Vozhe and stabilization at the level of mesotrophy of Lake Lacha. In the lakes, the dispersal and relatively high abundance of some thermophilic species (Polyarthra luminosa, Thermocyclops crassus), indicators of eutrophic conditions that were previously absent in the community, were revealed. The productivity (14–34 cal / m2 × day) and the respiration rate of zooplankton (61–122 cal / m2 × day) of the lakes corresponded to the level of northern oligotrophic water bodies. It was shown that at the beginning of summer a significant part of the zooplankton production was consumed by planktonic predators (mainly copepods). Fishes had access to about 15% of the daily production of zooplankton in Lake Vozhe and up to 43% in Lake Lacha. A small proportion of filter feeders (30–60% of the total biomass) was recorded in the modern zooplankton of lakes. By 2015, the filtration capacity of plankton from lakes Vozhe and Lacha decreased by an order of magnitude compared to that in the 1980s. The low self-cleaning ability of lake waters is discussed as the main reason for the growing organic pollution and increased silt accumulation in their ecosystems.

Water-Transmitted Fungi Are Involved in Degradation of Concrete Drinking Water Storage Tanks

Global warming, globalization, industrialization, and the rapidly growing population at present increasingly affect the production of safe drinking water. In combination with sustainable bio-based or recycled materials, used for water distribution systems, these factors promote emerging pathogens, including fungi. They can proliferate in oligotrophic water systems, affect the disinfection process, degrade building materials, and cause diseases in humans. In this study, we explored fungal-based degradation of modern concrete water storage tanks and the presence of fungi in chlorinated drinking water at the entrance and exit of the tanks. The degradation potential of isolated 52 fungal strains and their growth at different oligotrophic conditions was tested in vitro. Forty percent of strains grew at extremely oligotrophic conditions, and 50% classified as aerophilic. Two-thirds of tested strains produced acids, with Penicillium strains as the best producers. Only 29.7% of the strains were able to grow at 37 °C, and none of them was isolated from drinking water at consumers’ taps. Although not yet part of the guidelines for building materials in contact with drinking water, fungi should be taken into consideration in case of visible degradation. Their number of consumers’ endpoints should be checked to exclude possible health risks for consumers.

Primary Productivity of Jatigede Reservoirs in Sumedang, West Java

Jatigede Reservoir is a reservoir located in Sumedang West Java which is built for irrigation, raw water, power generation, tourism, and capture fisheries. This research aims to determine the value of primary productivity as one of the indicators of the water body feasibility of the Jatigede reservoir to capture fisheries activities. The study was conducted in August – September 2019. Sampling is carried out at 4 stations on the surface, half the depth of compensation, and the depth of compensation. Estimation of primary productivity using chlorophyll-a concentration measurement method. The results of measurement of water quality parameters in the Jatigede reservoir include transparency range of 19,5 cm – 116,5 cm, temperature with a spread of 26,58 – 27,48oC, pH with a range of 7,69 – 8,40, carbon dioxide with a range of 4,190 mg/L – 9,219 mg/L, current ranges from 0.136 m/s – 0,216 m/s, BOD5 with a range of 11,027 dissolved oxygen ranges from 6,4 mg/L – 7,1 mg/L, ammonia ranges from 0,006 mg/L – 0,039 mg/L, nitrates ranged from 0,168 mg/L – 0,216 mg/L, and phosphate range 0,139 mg/L – 0,185 mg/L. Results from the measurement of chlorophyll-a ranged from 0,035 mg/L – 0,062 mg/L. This results in showing the Jatigede reservoir of oligotrophic water because the primary productivity in the waters of the Jatigede Reservoir is relatively low if calculated based on the concentration of chlorophyll-a.

First Complete Genome Sequences of Janthinobacterium lividum EIF1 and EIF2 and Their Comparative Genome Analysis

We present the first two complete genomes of the Janthinobacterium lividum species, namely strains EIF1 and EIF2, which both possess the ability to synthesize violacein. The violet pigment violacein is a secondary metabolite with antibacterial, antifungal, antiviral, and antitumoral properties. Both strains were isolated from environmental oligotrophic water ponds in Göttingen. The strains were phylogenetically classified by average nucleotide identity (ANI) analysis and showed a species assignment to J. lividum with 97.72% (EIF1) and 97.66% (EIF2) identity. These are the first complete genome sequences of strains belonging to the species J. lividum. The genome of strain EIF1 consists of one circular chromosome (6,373,589 bp) with a GC-content of 61.98%. The genome contains 5,551 coding sequences, 122 rRNAs, 93 tRNAs, and 1 tm-RNA. The genome of EIF2 comprises one circular chromosome (6,399,352 bp) with a GC-content of 61.63% and a circular plasmid p356839 (356,839 bp) with a GC-content of 57.21%. The chromosome encodes 5,691 coding sequences, 122 rRNAs, 93 tRNAs, and 1 tm-RNA and the plasmid harbors 245 coding sequences. In addition to the highly conserved chromosomally encoded violacein operon, the plasmid comprises a nonribosomal peptide synthetase cluster with similarity to xenoamicin, which is a bioactive compound effective against protozoan parasites.

CDOM Absorption Properties of Natural Water Bodies Along Extreme Environmental Gradients

&lt;p&gt;We present absorption properties of colored dissolved organic matter (CDOM) sampled in six different water bodies along extreme altitudinal, latitudinal, and trophic state gradients. Three sites are in Norway: the mesotrophic Lysefjord (LF), Samnangerfjord (SF), and R&amp;#248;st Coastal Water (RCW); two sites are in China: the oligotrophic Lake Namtso (LN) and the eutrophic Bohai Sea (BS); and one site is in Uganda: the eutrophic Lake Victoria (LV).&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;The site locations ranged from equatorial to subarctic regions, and they included water types from oligotrophic to eutrophic and altitudes from 0 m to 4700 m. The mean CDOM absorption coefficients at 440 nm [a&lt;sub&gt;CDOM&lt;/sub&gt;(440)] and 320 nm [a&lt;sub&gt;CDOM&lt;/sub&gt;(320)] varied in the ranges 0.063&amp;#8211;0.35 m&lt;sup&gt;-1&lt;/sup&gt; and 0.34&amp;#8211;2.28 m&lt;sup&gt;-1&lt;/sup&gt;, respectively, with highest values in LV, Uganda and the lowest in the high-altitude LN, Tibet.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;The mean spectral slopes S&lt;sub&gt;280-500&lt;/sub&gt; and S&lt;sub&gt;350-500&lt;/sub&gt; were found to vary in the ranges of 0.017&amp;#8211;0.032 nm&lt;sup&gt;-1&lt;/sup&gt; and 0.013&amp;#8211;0.015 nm&lt;sup&gt;-1&lt;/sup&gt;, respectively. The highest mean value for S&lt;sub&gt;280-500&lt;/sub&gt; as well as the lowest mean value for S&lt;sub&gt;350-500&lt;/sub&gt; were found in LN. Scatter plots of S&lt;sub&gt;280-500&lt;/sub&gt; versus a&lt;sub&gt;CDOM&lt;/sub&gt;(440) and a&lt;sub&gt;CDOM&lt;/sub&gt;(320) values ranges revealed a close connection between RCW, LF, and SF on one side, and BS and LV on the other side.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;CDOM seems to originate from terrestrial sources in LF, SF, BS, and LV, while RCW is characterized by autochthonous-oceanic CDOM, and LN by autochthonous CDOM. Photobleaching of CDOM is prominent in LN, demonstrated by absorption towards lower wavelengths in the UV spectrum. We conclude that high altitudes, implying high levels of UV radiation and oligotrophic water conditions are most important for making a significant change in CDOM absorption properties.&lt;/p&gt;&lt;p&gt;Considering all study sites, we find a strong negative linear relationship between the base-10 logarithm of a&lt;sub&gt;CDOM&lt;/sub&gt;(440) and the spectral slope S&lt;sub&gt;280-500&lt;/sub&gt;, and also between the base-10 logarithm of a&lt;sub&gt;CDOM&lt;/sub&gt;(320) and the spectral slope S&lt;sub&gt;280-500&lt;/sub&gt;.&lt;/p&gt;

Oligotrophic bacterium Hymenobacter latericoloratus CGMCC 16346 degrades the neonicotinoid imidacloprid in surface water

The intensive and extensive application of imidacloprid in agriculture has resulted in water pollution and risks to aquatic invertebrates. However, pure bacteria remediation of imidacloprid in surface water environments has not been studied. Here, we isolated an imidacloprid-degrading bacterium from a water environment, examined its imidacloprid degradation in pure culture and surface water, sequenced its genome, and compared its Clusters of Orthologous Groups (COG) protein categorization with that for another imidacloprid-degrading bacterium. The isolate was an obligate oligotrophic bacterium, Hymenobacter latericoloratus CGMCC 16346, which degraded imidacloprid via hydroxylation by co-metabolism in pure culture. Resting cells degraded 64.4% of 100 mg/L imidacloprid in 6 d in the presence of co-substrate maltose, and growing culture degraded 40.8% of imidacloprid in 10 d. H. latericoloratus CGMCC 16346 degraded imidacloprid in surface water without co-substrate supplementation and retained imidacloprid-degrading activity after 30 d. The half-life of imidacloprid in surface water was decreased from 173.3 d in the control to 57.8 d by CGMCC 16346 inoculation. Genome sequencing and COG analysis indicated that carbohydrate metabolism and transport, cell wall/membrane biogenesis, and defense mechanisms are enriched in H. latericoloratus CGMCC 16346 compared with the copiotrophic imidacloprid-degrading Pseudoxanthomonas indica CGMCC 6648, indicating that H. latericoloratus CGMCC 16346 is adapted to live in oligotrophic water environments and biofilms. H. latericoloratus CGMCC 16346 is a promising bioremediation agent for elimination of imidacloprid contamination from surface water.

CDOM Absorption Properties of Natural Water Bodies along Extreme Environmental Gradients

We present absorption properties of colored dissolved organic matter (CDOM) sampled in six different water bodies along extreme altitudinal, latitudinal, and trophic state gradients. Three sites are in Norway: the mesotrophic Lysefjord (LF), Samnangerfjord (SF), and Røst Coastal Water (RCW); two sites are in China: the oligotrophic Lake Namtso (LN) and the eutrophic Bohai Sea (BS); and one site is in Uganda: the eutrophic Lake Victoria (LV). The site locations ranged from equatorial to subarctic regions, and they included water types from oligotrophic to eutrophic and altitudes from 0 m to 4700 m. The mean CDOM absorption coefficients at 440 nm [ a CDOM ( 440 ) ] and 320 nm [ a CDOM ( 320 ) ] varied in the ranges 0.063–0.35 m − 1 and 0.34–2.28 m − 1 , respectively, with highest values in LV, Uganda and the lowest in the high-altitude LN, Tibet. The mean spectral slopes S 280 − 500 and S 350 − 500 were found to vary in the ranges of 0.017–0.032 nm − 1 and 0.013–0.015 nm − 1 , respectively. The highest mean value for S 280 − 500 as well as the lowest mean value for S 350 − 500 were found in LN. Scatter plots of S 280 − 500 versus a CDOM ( 440 ) and a CDOM ( 320 ) values ranges revealed a close connection between RCW, LF, and SF on one side, and BS and LV on the other side. CDOM seems to originate from terrestrial sources in LF, SF, BS, and LV, while RCW is characterized by autochthonous-oceanic CDOM, and LN by autochthonous CDOM. Photobleaching of CDOM is prominent in LN, demonstrated by absorption towards lower wavelengths in the UV spectrum. We conclude that high altitudes, implying high levels of UV radiation and oligotrophic water conditions are most important for making a significant change in CDOM absorption properties.

Nitrogen Removal in Oligotrophic Reservoir Water by a Mixed Aerobic Denitrifying Consortium: Influencing Factors and Immobilization Effects

Nitrogen pollution in reservoirs has received increasing attention in recent years. Although a number of aerobic denitrifying strains have been isolated to remove nitrogen from eutrophic waters, the situation in oligotrophic water environments has not received significant attention. In this study, a mixed aerobic denitrifying consortium screened from reservoir samples was used to remove nitrogen in an oligotrophic denitrification medium and actual oligotrophic source water. The results showed that the consortium removed 75.32% of nitrate (NO3−-N) and 63.11% of the total nitrogen (TN) in oligotrophic reservoir water during a 24-h aerobic cultivation. More initial carbon source was helpful for simultaneous removal of carbon and nitrogen in the reservoir source water. NO3−-N and TN were still reduced by 60.93% and 46.56% at a lower temperature (10 °C), respectively, though the rates were reduced. Moreover, adding phosphorus promoted bacterial growth and increased TN removal efficiency by around 20%. The performance of the immobilized consortium in source water was also explored. After 6 days of immobilization, approximately 25% of TN in the source water could be removed by the carriers, and the effects could last for at least 9 cycles of reuse. These results provide a good reference for the use of aerobic denitrifiers in oligotrophic reservoirs.