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Mixotrophs are increasingly recognized for their wide distribution in aquatic ecosystems and significant contributions to biogeochemical cycling. Many taxa within the phyla Chrysophyta, Cryptophyta, and Haptophyta are capable of phago-mixotrophy, however, phagotrophy in the Chlorophyta remains controversial due to insufficient research and solid evidence. In this study, we identified a new strain, Picochlorum sp. GLMF1 (Trebouxiophyceae), using 18S rRNA gene analysis and morphological observations. It displayed multi-cell division through autosporulation (two- or four-cell daughters) and has two unequal flagella that have never been reported in the genus Picochlorum. By using multiple methods, including 3D bioimaging analysis, acidic food vacuole-like compartment staining, and prey reduction calculation, we discovered and confirmed bacterivory in Picochlorum, which provided strong evidence for phago-mixotrophy in this green alga. In addition, we found that Picochlorum sp. GLMF1 cannot grow under complete darkness or prey-depleted conditions, suggesting that both light and bacteria are indispensable for this strain, and its mixotrophic nutrition mode is obligate. Like other phago-phototrophs, Picochlorum sp. GLMF1 is capable of regulating their growth and ingestion rates according to light intensity and inorganic nutrient concentration. The confirmation of mixotrophy in this Picochlorum strain advances our understanding of the trophic roles of green algae, as well as the photosynthetic picoeukaryotes, in marine microbial food webs.

The Peipsi-Pskov Lake is the largest freshwater body in Europe, ranking fourth in area and fifth in volume. It is characterized by shallow water and a high level of trophy. The water in the lake is poorly mineralized and has little transparency due to suspended sediments and the development of plankton. Phytoplankton acts as a primary link in trophic chains, quickly reacts to changes in the aquatic environment and serves as a convenient object in monitoring studies. The average concentrations of total nitrogen in the lake during the observation period were in the range of 525-818 µg/dm 3 . The content of ammonium, nitrate, and nitrite nitrogen in the samples was mostly below the detection limits. The values of total phosphorus varied from 20 µg/dm 3 to 54 µg/dm 3 , and its concentrations were lower than the sensitivity of the method during the flood recession. The maximum values of total nitrogen and phosphorus were recorded in August: in Lake Peipsi - 1.12 mg/dm 3 and 0.09 mg/dm 3 , in Lake Pskov - 1.59 mg/dm 3 and 0.14 mg/dm 3 , respectively. BOD 5 values ranged from 1.96 mg/dm 3 in autumn to 4.26 mg/dm 3 in summer. During the growing season of 2020, 244 species taxa of phytoplankton from 8 phylums were identified in the Peipsi-Pskov Lake: Chlorophyta, Bacillariophyta, Cyanobacteria, Chrysophyta, Euglenophyta, Cryptophyta, Dinophyta and Xanthophyta. Floristic complex was characterized as сhlorophyta-diatom-cyanobacterial. The number of phytoplankton varied between 2.1 and 16.2 million cells/l depending on the season. The average number was 7.6 million cells/l. The biomass values ranged from 0.9 g/m 3 to 3.6 g/m 3 . The average biomass was 2.3 g/m 3 . According to the ecological and geographical characteristics of the lake, widespread freshwater forms of microalgae predominated, preferring stagnant-flowing, slightly alkaline waters. Saprobiological analysis showed that the waters of the Peipsi-Pskov Lake were classified as moderately polluted, class III of water purity quality.

Water quality tools are necessary to control and prevent eutrophication in reservoirs, particularly reservoirs with aquaculture cages because these lead to nutrient loads from fish food. A combined bioenergetic and water quality model was implemented in this study to assess the contribution of aquaculture activity to algal growth in El Pane Reservoir, Peru. In addition to its complexity, four different algal groups (Chlorophyta, Cyanobacteria, Chrysophyta, and Cryptophyta) were modeled according to their dominance in the water column of El Pane Reservoir. Moderately reasonable distribution plots of chlorophyll-a were obtained when calibrating the model despite data scarcity and low R2 values (0.04 in the intermediate zone and 0.16 in the dam zone of the reservoir). Six scenarios of annual aquaculture production were analyzed, and the scenario with an annual fish production of 100 000 kg increased Cyanobacteria blooms to a dangerous level. Furthermore, the results indicate that an annual aquaculture production of 36 000 kg still requires careful consideration in terms of its impact on the water quality of El Pane Reservoir.

Sendang Biru beach is a one of the coastal area located in Sumbermanjing Wetan, Malang, East Java-Indonesia. As a sea tourism, there are another residents activities such as fishing, fish landing and auction in Malang. That activities can caused pollution on the Sendang Biru aquatic environment. The research aim were to describe the water quality of Sendang Biru aquatic environment based on phytoplankton diversity. This research used several data collection techniques, that were microalgae sampling technique and measurement of physical and chemical water quality. Phytoplankton found in Sendang Biru Beach consists of 47 genus that are genus from seven divisions, Bacillariophyta, Chlorophyta, Cyanophyta, Euglenophyta, Dinophyta, Chrysophyta and Charophyta. The most abundant phytoplankton while having the Indeks Nilai Penting (INP) at the edge zone is the genus Oscillatoria sp. (the abundance is 4368000 Ind/L and INP 26,288). In the central and inner zones are both dominated by Coscinodiscus sp. (The abundance of center zone 4992000 Ind/L and INP 30,499; the abundance of inside zone is 9464000 Ind/L and INP 40,773). The level of diversity of phytoplankton in the three area of Sendang Biru beach are 2,297 in the edge zone; 2,37 in the central zone, and 1,8 in the inner zone. The pollution status of Sendang Biru beach can be classified as polluted moderately based on diversity index value on three different zone in the Sendang Biru Beach.

The seasonal pattern of phytoplankton taxonomical composition and phytoplankton chlorophyll а content from pelagial and littoral locations with and without macrophyte beds in two interconnected lakes (north-west of Belarus) under contrasting trophic conditions were studied. We estimated influence of hydrochemical parameters on phytoplankton in studied lakes. There was “a clear water phase” in pelagial and low phytoplankton abundance in littoral of mesotrophic Lake Obsterno but we revealed a brief pulse of Chrysophyta and “a late spring bloom” with high total phytoplankton abundance in shallow macrophyte-covered low trophic state Lake Nobisto. It was found some prominent differences in total phytoplankton abundance and taxonomic composition in littoral and pelagial locations of both lakes. We used Phyto-Pam phytoplankton analyser for analysis of algae pigments. Phyto-Pam method allowed roughly identify two types of pigments - pigments of green algae and diatoms and revealed differences in concentrations of pigments between littoral locations and pelagial in both lake types. Results indicated that total chlorophyll a content has a pronounced seasonal cycle with high values during the early fall and low values throughout the late spring in mesotrophic lake and have shown differences in phytoplankton pigments between lakes littoral locations.

To further understand the effect of Kuroshio intrusion on phytoplankton community structure in the northeastern South China Sea (NSCS, 14°-23°N, 114°-124°E), one targeted cruise was carried out from July to August, 2017. A total of 79 genera and 287 species were identified, mainly including Bacillariophyta (129 species), Pyrrophyta (150 species), Cyanophyta (4 species), Chrysophyta (3 species) and Haptophyta (1 species). The average abundance of phytoplankton was 2.14×103 cells/L, and Cyanobacterium was dominant species accounting for 86.84% of total phytoplankton abundance. The abundance and distribution of dominant Cyanobacterium were obviously various along the flow of the Kuroshio, indicating the Cyanobacterium was profoundly influenced by the physical process of the Kuroshio. Therefore, Cyanobacterium could be used to indicate the influence of Kuroshio intrusion. In addition, the key controlling factors of the phytoplankton community were nitrogen, silicate, phosphate and temperature, according to Canonical Correspondence Analysis. However, the variability of these chemical parameters in the study water was similarly induced by the physical process of circulations. Based on the cluster analysis, the similarity of phytoplankton community is surprisingly divided by the regional influence of the Kuroshio intrusion, which indicated Kuroshio intrusion regulates phytoplankton community in the NSCS.

Jatigede Reservoir in Sumedang Regency is a land mass planning designed as a multi-function reservoir. The main water source for this reservoir is from Cimanuk River, which flows through Garut Regency, and has many industrial activities around the river flow. This research was conducted to assess the trophic status of water pollution in Jatigede Reservoir by utilizing plankton as a bioindicator agent. Samples were collected from 9 observation stations from November 2018 until January 2019. The results showed that 26 species of phytoplankton from 7 divisions including Dinophyta, Cyanophyta, Chlorophyta, Chrysophyta, Euglenophyta, Bacillariophyta , and Charophyta was found in Jatigede Reservoir at about 461 ind/m 3 . Zooplankton abundance of 6 species from 2 divisions of Rotifera and Copepoda at 2 ind/m 3 . The average phytoplankton diversity index was 0.93 and zooplankton diversity index was 0.23. The average phytoplankton evenness index was 0.44 and zooplankton evenness index was 0.24. The average dominance of phytoplankton was 0.58 and dominance of zooplankton was 0.25. Based on the plankton community structure, the trophic status of Jatigede Reservoir was classified to moderate polluted ( eutroph ) to heavily pollutants ( hypereutroph ). The dominant species was Perinidium sp from Dinophyta division.

The first electron-microscopic investigation of silica-scaled chrysophytes in water bodies of the protected area Kurgalsky Nature Reserve located in the North-West of European Russia has resulted in the discovery of two species that are new for the Russian flora, Mallomonas favosa and M. teres. Mallomonas teres is reported for the first time since its original descriptions. In addition, Paraphysomonas cf. ovalis and an unknown species of Mallomonas were observed. Descriptions, original photos, and habitat features of these four species are given.

Grazing behaviour between protozoa and phytoplankton exists widely in planktonic ecosystems. Poterioochromonas malhamensis is a well-known and widespread mixotrophic flagellate, which is recognized to play an important role within marine and freshwater planktonic ecosystems and regarded as the greatest contamination threat for mass algal cultures of Chlorella. In this study, a comprehensive range of factors, including morphological characters, biochemical compositions, and specific growth rate of ten species or strains of Chlorella, were evaluated for their effect on the feeding ability of P. malhamensis, which was assessed by two parameters: the clearance rate of P. malhamensis on Chlorella spp. and the specific growth rate of P. malhamensis. The results showed that the clearance rate of P. malhamensis was negatively correlated with cell wall thickness and specific growth rate of Chlorella spp., while the specific growth rate of P. malhamensis was positively correlated with carbohydrate percentage and C/N ratio and negatively correlated with protein, lipid percentage, and nitrogen mass. In conclusion, the factors influencing feeding selectivity include not only the morphological character and chemical composition of Chlorella, but also its population dynamics. Our study provides useful insights into the key factors that affect the feeding selectivity of P. malhamensis and provides basic and constructive data to help in screening for grazing-resistant microalgae.

Mallomonas is the largest and most speciose genus within the Synurales, a monophyletic clade of siliceous scale-bearing organisms within the class Chrysophyceae. The genus consists of unicellular, motile, photosynthetic organisms found in freshwater localities worldwide. Mallomonas diverged from other synurophytes during the lower Cretaceous at approximately 130 Ma. Recent discoveries of fossil species were used to examine shifts in scale and cell size over geologic time. On average, scales of fossil species were 2.5 times larger than those produced by modern species. However, a smaller subset of extinct fossil taxa lacking modern analogs had scales over four times larger than modern species, and the largest recorded specimens were six times larger. Data from modern species were further used to develop a model relating scale size to cell size, and applied to the fossil specimens. Based on the model, the mean size of fossil cells was almost twice as long and 50% wider compared to modern species, and cells of taxa lacking modern analogs close to three times as large. These large cells, covered with robust siliceous scales, were likely slow swimmers requiring significant energy to maintain their position in the water column, and possibly prone to increased predation.

Phytoplankton are known as important harbingers of climate change in aquatic ecosystems. This study investigated phytoplankton community structure in the western Pacific Ocean (WPO) in 2017 and revealed the spatial variability of phytoplankton in community composition and abundance, as well as their relationship to physical processes and environmental factors. The phytoplankton community was mainly composed of Dinophyta (221), followed by Bacillariophyta (105), Cyanophyta (4), and Chrysophyta (2). The cyanobacteria Trichodesmium were the dominants throughout the study period. Correlation analysis showed that dinoflagellates were mainly affected by temperature, while diatoms were significantly correlated with nutrients (silicate, phosphate, nitrite, nitrate). Phytoplankton was divided into five groups by cluster analysis, and the distribution of different groups was related to circulation and hydrological characteristics. In contrast, the highest abundance of diatoms and dinoflagellates was found in the New Guinea Coastal Current (NGCC) region, while the highest abundance of cyanobacteria was found in the Northern Equatorial Counter Current (NECC) region. Overall, we found that not only temperature and salinity, but also ocean currents and nutrients, influence the distribution of phytoplankton communities in the WPO.

The present paper is dealt with the composition and density of the population of pelagic phytoplankton collected from two studied stations, namely Watch Tower and Rauar Station of Tanguar Haor in Sunamganj District. Plankton belonging to the divisions Cyanophyta, Pyrrhophyta, Chrysophyta and Euglenophyta were studied from bimonthly collected samples during 2017 and 2018. Division Cyanophyta was represented by the occurrence of 17 species followed by Chrysophyta (16 spp.), Euglenophyta (4 spp.) and Phyrrhophyta (2 spp.). The most dominant plankton taxon was Dinobryon sertularia Ehrenberg whose density was 374 ×103 ind/l and 137.5 ×103 ind/l at Watch Tower and Rauar Station, respectively. Euglenoid population was relatively poorer compared to the other groups of phytoplankton. Abundant population of D. sertularia designates the Tanguar Haor ecosystem as moderate in terms of productivity. A total of 39 species recorded from three algal divisions, namely Cyanophyta, Pyrrhophyta, Chrysophyta and Euglenophyta. Tanguar Haor ecosystem was included with mean phytoplankton population of Cyanophyta, Pyrrhophyta, Chrysophyta and Euglenophyta. J. Biodivers. Conserv. Bioresour. Manag. 2019, 5(1): 105-112

A new species of the rare chrysophycean genus Dermatochrysis Entwisle & R.A. Andersen is described from eastern Himalayas (Arunachal Pradesh, India). The comparative morphology of this taxon with allied species showed its uniqueness in thallus structure and cellular arrangements, thus is proposed as a new species, i.e. Dermatochrysis himalayensis S. K. Das, P. Basu & R. K. Gupta.

Phytoplankton assemblages were investigated in 2015 along the seasonal changes of the Genhe River in the Greater Hinggan Mountains. The survey was performed in June (spring), August (summer), and October (autumn) at nine sampling stations to study the community composition, abundance, and biodiversity. The results showed that 61 species belonging to 16 genera were identified, including Bacillariophyta of 31 species, Dinophyta 2 species, Cyanophyta 2 species, Chlorophyta 20 species, Chrysophyta 2 species, and Cryptophyta 1 species; Besides, Bacillariophyta are dominant species. Shannon-Wiener (H′) and Pielou (J′) indices indicated that phytoplankton community was stable. And these two indices were significantly lower in summer than in spring and autumn. Phytoplankton abundance and biomass show significant differences in each season. The total phytoplankton abundance (1122.3 × 104 ind/L) and biomass (6.5709 mg/L) in summer are much higher than that in spring and autumn. There were few species and low abundance and biomass in the upper reaches of Genhe River; this fact can be explained by the cold climate in the Greater Higgnan Mountains region. Canonical correspondence analysis (CCA) was used to analyze the data. It revealed that Fe3+, Cu2+, pH, and water temperature (WT) were responsible for most of the variation in space in the phytoplankton community. These environmental parameters play an essential role in the community structure variation of phytoplankton in the upper reaches of Genhe River, the strong association between phytoplankton community structure and ecological factors is varied in each season.

Although eukaryotic microorganisms are extremely numerous, diverse and essential to global ecosystem functioning, they are largely understudied by evolutionary biologists compared to multicellular macroscopic organisms. In particular, very little is known about the speciation mechanisms which may give rise to the diversity of microscopic eukaryotes. It was postulated that the enormous population sizes and ubiquitous distribution of these organisms could lead to a lack of population differentiation and therefore very low speciation rates. However, such assumptions have traditionally been based on morphospecies, which may not accurately reflect the true diversity, missing cryptic taxa. In this study, we aim to articulate the major diversification mechanisms leading to the contemporary molecular diversity by using a colonial freshwater flagellate, Synura sphagnicola, as an example. Phylogenetic analysis of five sequenced loci showed that S. sphagnicola differentiated into two morphologically distinct lineages approximately 15.4 million years ago, which further diverged into several evolutionarily recent haplotypes during the late Pleistocene. The most recent haplotypes are ecologically and biogeographically much more differentiated than the old lineages, presumably because of their persistent differentiation after the allopatric speciation events. Our study shows that in microbial eukaryotes, species diversification via the colonization of new geographical regions or ecological resources occurs much more readily than was previously thought. Consequently, divergence times of microorganisms in some lineages may be equivalent to the estimated times of speciation in plants and animals.

To better understand the spatial-temporal variation in phytoplankton community structure and its controlling factors in Jiaozhou Bay, Qingdao, North China, four seasonal sampling were carried out in 2017. The phytoplankton community structure and various environmental parameters were examined. The phytoplankton community in the bay was composed of mainly diatoms and dinoflagellates, and several other species of Chrysophyta were also observed. Diatoms were the most dominant phytoplankton group throughout the year, except in spring and winter, when Noctiluca scintillans was co-dominant. High Si/N ratios in summer and fall reflect the high dominance of diatoms in the two seasons. Temporally, the phytoplankton cell abundance peaked in summer, due mainly to the high temperatures and nutrient concentrations in summer. Spatially, the phytoplankton cell abundance was higher in the northern part of the bay than in the other parts of the bay in four seasons. The diatom cell abundances show significant positive correlations with the nutrient concentrations, while the dinoflagellate cell abundances show no correlation or a negative correlation with the nutrient concentrations but a significant positive correlation with the stratification index. This discrepancy was mainly due to the different survival strategies between diatoms and dinoflagellates. The Shannon-Wiener diversity index (H′) values in the bay ranged from 0.08 to 4.18, which fell in the range reported in historical studies. The distribution pattern of H′ values was quite different from that of chlorophyll a, indicating that the phytoplankton community structure might have high biomass with a low diversity index. Compared with historical studies, we believe that the dominant phytoplankton species have been changed in recent years due mainly to the changing environment in the Jiaozhou Bay in recent 30 years.

Algae are eukaryotic photosynthetic organisms found in freshwater, marine, or brackish water. They are capable of surviving in harsh conditions such as in snow, deserts, hot water spring, and in mutual relationships with other organisms like lichens, making them as cosmopolitan species in environment. Algae play vital role in every aspect may it be as primary producers in food chain or fixing maximum amount of carbon dioxide in nature. But talking about applications of algae in this paper, we have focussed on Diatoms (class Bacillariophyceae) which are golden brown algae. Their ubiquitous presence, small size, and silicious frustule with peculiar ornamentation add uniqueness to their identity. Nowadays diatoms are considered as prime evidence in solving cases of drownings in the fields of forensics. Diatoms from the drowning site can tell about the physicochemical nature of environment and help in knowing the mode of death of a drowned victim. As during drowning, these small entities enter inside the body through body openings and once penetrated inside the body they get circulated and deposited in various organs till the victim dies. These penetrated diatoms are then recovered as evidence by various techniques and then their microscopic studies further help in their identifications. This helps in linking the crime scene and the victim during the investigation and thus helping the crime mystery of drowning to be solved. Because of their vast role in the drowning case investigation they are regarded as golden standards in the fields of forensics.

Tribonema biomass is considered promising biorefinery feedstock for the co-production of biodiesel and valuable bioproducts; however, the extraction of these useful compounds produces large amounts of algal residues, which produce increased environmental concerns. Herein, cellulose was extracted from the waste residue of T. utriculosum via alkalization and bleaching, followed by the production of high-value-added cellulose nanocrystals (CNCs) via acid hydrolysis. The hydrolysis was performed with 60% (wt%) H

Chrysophyte algae produce a siliceous stage in their life cycle, through either asexual or sexual reproduction, known as a cyst. Cysts form in response to shifts in environmental conditions, population density, or predation pressure, and upon germination provide a seed source for future populations. Cysts are morphologically distinct for each species, and since their remains become part of the sediment or fossil record cysts are valuable tools in ecological and paleolimnological investigations. However, their value as biological indicators is limited because the vast majority of cyst morphotypes have not been linked to specific vegetative species. In the current work, an exquisitely preserved and morphologically complex cyst type is described from a 48 million year old early Eocene fossil site. This finding is remarkable since many of the cysts were still associated with components of the living vegetative cells that produced them, enabling the morphotype to be immediately linked to the synurophyte, Mallomonas ampla. Fusion of identifiable components of the living cell post cyst formation is unknown in modern investigations. The identification of the cyst structure for M. ampla could be valuable in determining cyst morphotypes for other species in the lineage.

Yunandar, Effendi H, Widiatmaka, Setiawan Y. 2020. Plankton biodiversity in various typologies of inundation in Paminggir peatland, South Kalimantan, Indonesia on dry season. Biodiversitas 21: 1012-1019. The aim of the study was to analyze the typology of inundation areas and plankton biodiversity in Paminggir peatland, South Borneo, Indonesia. Typology of inundation was determined by image processing and spatial analysis using supervised classification method from Landsat 1994, 2014, 2019. Plankton biodiversity was determined using purposive sampling in detected inundation from spatial analysis. Some environmental factors like temperature, Ph and DO were also analyzed. Confirmation of the results of spatial analysis of peatland typology made from overall accuracy and Kappa informed 88.48% and 0.8. The typology of permanent inundation decreased by 30% from 1994 to 2019 during the dry period from June to August of the total study area of 43275,584 hectares due to sedimentation, land conversion for settlement, and increase in water weeds. Inundation criteria with duration throughout the year were was categorized as permanent, whereas temporary inundation was tentative even in certain dry season. Plankton index biodiversity in permanent inundation was more varied compared to temporary inundation. Phytoplankton from the freshwater Chrysophyta group was more dominant, while zooplankton from the Nauplius group, which were the natural food for fish larvae always presented in the typology of permanent inundation.

Human viruses are ubiquitous contaminants in surface waters, where they can persist over extended periods of time. Among the factors governing their environmental persistence, the control (removal or inactivation) by microorganisms remains poorly understood. Here, we determined the contribution of indigenous bacteria and protists to the decay of human viruses in surface waters. Incubation of echovirus 11 (E11) in freshwater from Lake Geneva and seawater from the Mediterranean Sea led to a 2.5-log10 reduction in the infectious virus concentration within 48 h at 22°C, whereas E11 was stable in sterile controls. The observed virus reduction was attributed to the action of both bacteria and protists in the biologically active matrices. The effect of microorganisms on viruses was temperature dependent, with a complete inhibition of microbial virus control in lake water at temperatures of ≤16°C. Among three protist isolates tested (Paraphysomonas sp., Uronema marinum, and Caecitellus paraparvulus), Caecitellus paraparvulus was particularly efficient at controlling E11 (2.1-log10 reduction over 4 days with an initial protist concentration of 103 cells ml−1). In addition, other viruses (human adenovirus type 2 and bacteriophage H6) exhibited different grazing kinetics than E11, indicating that the efficacy of antiviral action also depended on the type of virus. In conclusion, indigenous bacteria and protists in lake water and seawater can modulate the persistence of E11. These results pave the way for further research to understand how microorganisms control human viral pathogens in aquatic ecosystems and to exploit this process as a treatment solution to enhance microbial water safety. IMPORTANCE Waterborne human viruses can persist in the environment, causing a risk to human health over long periods of time. In this work, we demonstrate that in both freshwater and seawater environments, indigenous bacteria and protists can graze on waterborne viruses and thereby reduce their persistence. We furthermore demonstrate that the efficiency of the grazing process depends on temperature, virus type, and protist species. These findings may facilitate the design of biological methods for the disinfection of water and wastewater.

Marine environment is a home to a very wide diversity of flora and fauna, which includes an array of genetically diverse coastline and under seawater plant species, animal species, microbial species, their habitats, ecosystems, and supporting ecological processes. The Earth is home to an estimated 10 million species, of which a large chunk belongs to marine environment. Marine plants are a store house of a variety of antimicrobial compounds like classes of marine flavonoids—flavones and flavonols, terpenoids, alkaloids, peptides, carbohydrates, fatty acids, polyketides, polysaccharides, phenolic compounds, and steroids. Lot of research today is directed toward marine species, which have proved to be a potent source of structurally widely diverse and yet highly bioactive secondary metabolites. Varied species of phylum Porifera, algae including diatoms, Chlorophyta, Euglenophyta, Dinoflagellata, Chrysophyta, cyanobacteria, Rhodophyta, and Phaeophyta, bacteria, fungi, and weeds have been exploited by mankind for their inherent indigenous biological antimicrobial compounds, produced under the extreme stressful underwater conditions of temperature, atmospheric pressure, light, and nutrition. The present study aims at presenting a brief review of bioactive marine compounds possessing antimicrobial potency.

Phytoplankton seasonal succession and spatial distribution were studied in Gorgan Bay, Iran, which is a semi-enclosed bay located in the southeastern Caspian Sea. Monthly phytoplankton and physicochemical samples were taken from March 2014 to September 2015. A total of 51 genera from six algal divisions were observed with phylum Bacillariophyta being the most represented (16 genera and on average ~ 59% of biomass). While diatoms were prevalent year-round, strong inter-seasonal variations of other phytoplankton groups were observed in response to environmental parameters. The seasonal succession of other taxa started with Chlorophyta (Chlorella sp.) in spring followed by Cyanophyta (Anabaena sp. and Microsystis sp.) and Euglenophyta (Euglena sp.) in summer, then Chrysophyta (Syndera) and Pyrrophyta (Prorocentrum sp., Exuviella sp., and Peridinium sp.) in the autumn and winter. The sites near the mouth of Gorgan Bay were characterized by slightly higher salinity with an annual mean of ~ 12 PSU compared with ~ 11 PSU for inner regions of the bay. Nitrate was higher in the mouth of the bay as well, with an annual mean of ~ 1.4 ppm compared with ~ 0.80 ppm in the inner region. Orthophosphate was also higher in the mouth of the bay with an annual mean of ~ 0.30 ppm compared with ~ 0.23 ppm in inner part of the bay. Euglena sp. and Microsystis sp. performed better in the mouth of the bay compared with their performance in the inner regions. Nutrients and salinity correlated strongest with phytoplankton in Gorgan Bay. During the period when Cyanophyta biomass was maximum, Microsystis sp. was the dominant taxa of the cyanobacteria present. Inorganic pollution from domestic wastewater in the eastern part of Gorgan Bay appears to be the cause of the Euglena maximum. According to the Palmer pollution index, Gorgan Bay experienced pollution from agricultural discharge and domestic wastewater.

Melting summer snow in the Austrian Alps exhibited a yellowish bloom that was mainly comprised of an unidentified unicellular chrysophyte. Molecular data (18S rRNA and rbcL genes) showed a close relationship to published sequences from an American pond alga formerly identified as Kremastochrysis sp. The genera Kremastochrysis and Kremastochrysopsis are morphologically distinguished by the number of flagella observed with the light microscope, and therefore we assigned the Austrian snow alga and an American pond alga to the genus Kremastochrysopsis. Transmission and scanning electron microscopy revealed that swimming cells had two flagella oriented in opposite directions, typical for the Hibberdiales. Molecular phylogenetic analyses showed that both new species were closely related to Hibberdia. Kremastochrysopsis ocellata, the type species and only known species, has two chloroplasts per cell and the zoospores have red eyespots. Our two organisms had only a single chloroplast and no zoospore eyespot, but their gene sequences differed substantially. Therefore, we described two new species, Kremastochrysopsis austriaca sp. nov and Kremstochrysopsis americana sp. nov. When grown in culture, both taxa showed a characteristic hyponeustonic growth (hanging below the water surface), whereas older immotile cells grew at the bottom of the culture vessel. Ecologically, Kremastochrysopsis austriaca sp. nov., which caused snow discolorations, had no close phylogenetic relationships to other psychrophilic chrysophytes, for example, Chromulina chionophilia, Hydrurus sp., and Ochromonas-like flagellates.

The chrysophyte genus Dinobryon Ehrenberg consists of 44 taxa, which occur in freshwaters, rarely marine waters, mostly in temperate regions of the world. The taxa of Dinobryon produce characteristic solitary or dendroid colonies and resting stages called stomatocysts. Only 20 Dinobryon taxa have information on produced stomatocysts and only four stomatocysts are reliably linked with vegetative stages using modern identification standards employing scanning electron microscopy (SEM) analyses. In this study, an encysted material of Dinobryon pediforme (Lemmermann) Steinecke was collected in two lakes in contrasting regions of Poland. Light microscopy (LM) and scanning electron microscopy (SEM) analyses revealed that Dinobryon pediforme produces stomatocyst #61, Piątek J. that is described here as new morphotype following the International Statospore Working Group (ISWG) guidelines. This raises to five the number of reliable links between vegetative stages of Dinobryon species and corresponding stomatocysts. Phenotypic similarities between Dinobryon species and their stomatocysts, analysed for five reliably established links, showed no relationships in size and shape between loricas and stomatocysts belonging to the same species. The morphological characters of loricas and stomatocysts mapped onto the phylogenetic tree of the five Dinobryon species revealed only little congruence between their morphology and phylogenetic relationships.

Kostryukova AM, Mashkova V, Krupnova TG, Egorov NO. 2018. Phytoplankton biodiversity and its relationship with aquatic environmental factors in Lake Uvildy, South Urals, Russia. Biodiversitas 19: 1422-1428. Lake Uvildy is one of the largest and the most unique of the South Ural region lakes. This mountain deep lake, which has the status of a natural monument. The purpose of this paper was to study the phytoplankton community structure and the aquatic environmental factors in Lake Uvildy. The phytoplankton samples were collected from 5 sites of Lake Uvildy, then filtered through the plankton net and were preserved in 5% formalin. Species were identified using the handbooks by Sladecek, Yarushina, and Al-Kandari. Water samples were taken for water quality analysis. The several physicochemical parameters were measured in situ by a Portable Meters (Multitest IPL-513 and Multitest KSL-111, Semico Ltd, Russia, Novosibirsk). The others parameters were measured in the laboratory of the Department of Chemistry of the South Ural State University according to the standard methods. The sampling was made during the vegetation period in June-July 2014. The water quality was evaluated using the Shannon biodiversity index. A total of 38 species (11 phyla, 31 genera), including 9 species of Chlorophyta, 13 species of Bacillariophyta, 9 species of Cyanophyta, 4 species of Euglenophyta, 2 species of Chrysophyta, 1 species of Dinophyta, were identified. The phytoplankton species in the lake were mainly represented by Cyanophyta and Bacillariophyta. There were 5 dominant species: Fragilaria crotonensis, Asterionella formosa, Dolichospermum lemmermannii, Microcystis aeruginosa, and Coenococcus planktonicus. The Shannon index value comprised 1.27-2.21. According to the saprobity index values (1.63-2.35), the water in the late is evaluated as satisfactorily clean. Physico-chemical parameters were factors driving the change in phytoplankton community composition in Lake Uvildy.

Climatic changes were studied using siliceous algae (diatoms and Chrysophyta stomatocysts) analyses in four mountain lakes in the Retezat Mountains in the South-Carpathian Mountains with the aim to search for synchrony in aquatic ecosystem responses. According to the basal radiocarbon dating of the lake sediment cores, these lakes were formed around 17,000–15,000 cal yr BP. High resolution diatom analyses were carried out together with loss-on-ignition (LOI) and biogenic silica (BiSi) measurements on the lakes. Comparison of the proxy results suggests that despite the different slope aspect, water-depth and basin parameters, diatom assemblage changes show clear synchrony. The most remarkable changes in the aquatic ecosystems were observed around 6500 cal yr BP on the northern slope and around 6100 cal yr BP on the southern slope during the Holocene. Evidences for sharp concomitant shifts were found between 9200–9000 and 3200-3000 cal yr BP in the siliceous algal communities on both slopes. The Late Glacial/Holocene boundary was not pronounced in the shallow lakes, but was significant in a deep lake. The signs of a dry and bipartite Younger Dryas (GS-1) were evident, but floristic changes differed in the lakes. Principal component analyses explained very similar variances along the first and second axes for three lakes, while the fourth lake (Lake Bucura) proved less sensitive to climate change due to the dominance of moss-inhabiting diatom assemblages. Lake level changes have only been reconstructed on the basis of diatom life forms in one of the deep lakes (Lake Gales). High lake levels were inferred between 9300–9000 and 3000-1700 cal yr BP. In addition to LOI, biogenic silica content (BiSi) was measured on the sediments of the northern slope and pointed to different seasonal biological productivities; increasing LOI was often coupled with low BiSi values.

Este artículo contiene 11 páginas, 2 tablas, 5 figuras., A rich eukaryotic planktonic community exists in high-mountain lakes despite the diluted, oligotrophic and cold, harsh prevailing conditions. Attempts of an overarching appraisal have been traditionally hampered by observational limitations of small, colorless, and soft eukaryotes. We aimed to uncover the regional eukaryotic biodiversity of a mountain lakes district to obtain general conclusions on diversity patterns, dominance, geographic diversification, and food-web players common to oligotrophic worldwide distributed freshwater systems. An unprecedented survey of 227 high-altitude lakes comprising large environmental gradients was carried out using Illumina massive tag sequencing of the 18S rRNA gene. We observed a large Chrysophyceae dominance in richness, abundance and novelty, and unveiled an unexpected richness in heterotrophic phagotrophs and parasites. In particular, Cercozoa and Chytridiomycota showed diversity features similar to the dominant autotrophic groups. The prominent beta-dispersion shown by parasites suggests highly specific interactions and a relevant role in food webs. Interestingly, the freshwater Pyrenean metacommunity contained more diverse specific populations than its closest marine oligotrophic equivalent, with consistently higher betadiversity. The relevance of unseen groups opens new perspectives for the better understanding of planktonic food webs. Mountain lakes, with remarkable environmental idiosyncrasies, may be suitable environments for the genetic diversification of microscopic eukaryotic life forms., This research was funded by Grants BRIDGES CGL2015–69043-P from the Spanish Office of Science (MINECO) and European funding (ERDF) and DISPERSAL (Ref. 829/2013) from the Spanish National Parks research program (OAPN-MAGRAMA), to EOC, and LACUS CGL2013–45348-P (MINECO-ERDF) to JC. We thank technicians and students who participated in the field sampling expeditions, and specially M Sala and C Palacin for their excellent performance, and X Torras for ArcGIS support

This study aims to investigate the phytoplankton dynamics (distribution, composition) and their relation to water quality parameter in Ismailia canal and Abbassa fish farm (inlet, outlet and the fish ponds).The study was carried out from April, 2014 to May, 2015. Physical, chemical parameters and phytoplankton estimation were measured in situ and laboratory. The results showed that, the physico- chemical parameters of water were significantly varied among different seasons and the studied sites. Phytoplankton communities are represented by eight phyla namely; Chlorophyta, Cyanophyta, Euglenophyta, Bacillariophyta, Chrysophyta, Dinophyta, Cryptophyta and Xanthophyta. Their major number (22724 Org./ml) was detected at the fishponds (site C), while their minor number (9374 Org./ml) was detected at the main feeder (MF), (site A). Chlorophyceae was the predominant class at all studied sites except at (MF) where; Bacillariophyceae occupied the first predominant position. Results demonstrated that occurrence of 247 taxa of phytoplankton at (MF), 273 taxa at (inlet), 304 taxa at fishponds and 292 taxa at outlet. Also, Shannon and Weaver diversity index (H-) was studied and the results showed that the mean range of the phytoplankton diversity index (H-) was low (< 2.0) at all the studied sites and this is indication of moderate pollution. It is concluded that, both seasonal variations and physico-chemical parameters of water have great impact on phytoplankton dynamics and its biological diversity.

The Danau Panggang swamp is one of the potential swamp waters as a producer of swamp fish in South Kalimantan. The objective of the research is to identify the potential of fish resources, macrophytes, and plankton in Danau Panggang swamp. The results showed that fish caught in Swamp Danau Panggang waters are 22 species. The macrophytic water plants found in the Danau Panggang Swamp Waters are 11 species. The results of phytoplankton and zooplankton analyzes are found for phytoplankton dominated by Chrysophyta phyla, while zooplankton is dominated by the Protozoa order. The condition of the Danau Panggang swamp water quality is still relatively in accordance with the Baku Mutu Air Kelas 2 PP No 82 Tahun 2001

A comprehensive study on the phytoplankton standing stocks, species composition and dominant species in the eutrophic Changjiang (Yangtze River) Estuary (CE) was conducted to reveal the response of phytoplankton assemblage to Changjiang Diluted Water (CDW) and upwelling in the spring. Phytoplankton presented peak standing stocks (13.03 μg/L of chlorophyll a, 984.5×103 cells/L of phytoplankton abundance) along the surface isohaline of 25. Sixty-six species in 41 genera of Bacillariophyta and 33 species in 19 genera of Pyrrophyta were identified, as well as 5 species in Chlorophyta and Chrysophyta. Karenia mikimotoi was the most dominant species, followed by Prorocentrum dentatum, Paralia sulcata, Pseudo-nitzschia delicatissima and Skeletonema costatum. A bloom of K. mikimotoi was observed in the stratified stations, where the water was characterized by low nitrate, low phosphate, low turbidity, and specific ranges of temperature (18–22 °C) and salinity (27–32). K. mikimotoi and P. dentatum accumulated densely in the upper layers along the isohaline of 25. S. costatum was distributed in the west of the isohaline of 20. Benthonic P. sulcata presented high abundance near the bottom, while spread upward at upwelling stations. CDW resulted in overt gradients of salinity, turbidity and nutritional condition, determining the spatial distribution of phytoplankton species. The restricted upwelling resulted in the upward transport of P. sulcata and exclusion of S. costatum, K. mikimotoi and P. dentatum. The results suggested that CDW and upwelling were of importance in regulating the structure and distribution of phytoplankton assemblage in the CE and the East China Sea.

Water collected from 8 selected floodplain wetlands (beels) of Brahmaputra valley basin were examined using both filtered method (FM) and sedimentation method (SM) for the assessment of phytoplankton diversity and abundance. A total 22 and 41 species were recorded by employing FM and SM, respectively. There was a significance difference (p

The ecological province based on phytoplankton species composition is important to understanding the interplay between environmental parameters and phytoplankton species composition. The aim of this study was to establish phytoplankton species composition ecological pattern thus elucidate the relationship between environmental factors and the phytoplankton species composition in the ecological provinces. Phytoplankton samples were collected from 31 stations in Yellow Sea (121.00°–125.00°E, 32.00°–39.22°N) in November 2014. The samples were enumerated and identified with the Utermohl method under an optical inverted microscope-AE2000 with magnifications of 200 × or 400 ×. In the present study, a total of 141 taxa belonging to 60 genera of 4 phyla of phytoplankton were identified, among them 101 species of 45 genera were Bacillariophyta, 36 species of 11 genera were Dinophyta, 3 species of 3 genera were Chrysophyta and 1 species of 1 genera was Chlorophyta. The study area was divided into 4 ecological provinces according to an unsupervised cluster algorithm applied to the phytoplankton biomass. A T-S (Temperature-Salinity) scatter diagram depicted with data of water temperature and salinity defined by environmental provinces matched well with the ecological provinces. The results of Canonical Correspondence Analysis (CCA) indicated that the phytoplankton species composition was mainly correlated with temperature, salinity and silicate concentration in the studied area. A method of establishing ecological provinces is useful to further understanding the environmental effects on the marine phytoplankton species composition and the consequent marine biogeochemistry.

Spatial and seasonal heterogeneity in phytoplankton communities are governed by many biotic and abiotic drivers. However, the identification of long-term spatial and temporal trends in abiotic drivers, and their interdependencies with the phytoplankton communities' structure is understudied in tropical brackish coastal lagoons. We examined phytoplankton communities' spatiotemporal dynamics from a 5-year dataset (n = 780) collected from 13 sampling stations in Chilika Lagoon, India, where the salinity gradient defined the spatial patterns in environmental variables. Generalized additive models showed a declining trend in phytoplankton biomass, pH, and dissolved PO4 in the lagoon. Hierarchical modelling of species communities revealed that salinity (44.48 ± 28.19%), water temperature (4.37 ± 5.65%), and season (4.27 ± 0.96%) accounted for maximum variation in the phytoplankton composition. Bacillariophyta (Indicator Value (IV): 0.74) and Dinophyta (IV: 0.72) emerged as top indicators for polyhaline regime whereas, Cyanophyta (IV: 0.81), Euglenophyta (IV: 0.79), and Chlorophyta (IV: 0.75) were strong indicators for oligohaline regime. The responses of Dinophyta and Chrysophyta to environmental drivers were much more complex as random effects accounted for ~70–75% variation in their abundances. Prorocentrum minimum (IV: 0.52), Gonyaulax sp. (IV: 0.52), and Alexandrium sp. (IV: 0.51) were potential indicators of P-limitation. Diploneis weissflogii (IV: 0.43), a marine diatom, emerged as a potential indicator of N-limitation. Hierarchical modelling revealed the positive association between Cyanophyta, Chlorophyta, and Euglenophyta whereas, Dinophyta and Chrysophyta showed a negative association with Cyanophyta, Chlorophyta, and Euglenophyta. Landsat 8-Operational Land Imager satellite models predicted the highest and lowest Cyanophyta abundances in northern and southern sectors, respectively, which were in accordance with the near-coincident field-based measurements from the lagoon. This study highlighted the dynamics of phytoplankton communities and their relationships with environmental drivers by separating the signals of habitat filtering and biotic interactions in a monsoon-regulated tropical coastal lagoon.

The spatial distribution of species richness of phytoplankton was studied along the Balkhash Lake water area during the summer of 2004. With statistically weak connections of phytoplankton with environmental parameters, three-dimensional graphs revealed a complex character of its spatial variability in the gradient of environmental factors. Macrophytes had a stimulating effect on the species richness of planktonic algae. We found a correlation between species richness of Cyanobacteria, Chrysophyta, Euglenophyta and Dinophyta and the ionic composition of water. The important role of temperature was traced. Species richness of algal communities increased with increasing temperature in the gradient of nutrients and correlated with the abundance of macrophytes.