Planktonic Algae Research Articles

Nitrogen and Phosphorus Discriminate the Assembly Processes of Prokaryotic and Eukaryotic Algae in an Agricultural Drainage Receiving Lake

Phytoplankton and bacteria play key roles in material cycling and their consequent eco-functions in lakes, which are threatened by anthropogenic pressures, especially agricultural activities, which, in the watershed, are effective in changing the material composition and hydrodynamic conditions of the lake through material input and water withdrawal. This process theoretically changes the interaction and assembly pattern of microorganisms, which are important factors driving the structural and functional evolution of ecological communities in lakes. In this research, the community structure, interactions, and assembly of phytoplankton and bacteria were investigated during agro-irrigation seasons in a typical agricultural drainage receiving lake, Wuliangsuhai. The results showed that the seasonal variations in the community were driven by nitrogen and phosphorus. In particular, Cyanobacteria increased significantly during the seasons with the regulation of TP (λ = 0.56, p < 0.01, n = 30). The TN positively drove Chlorophyta and Bacillariophyta (λ = 0.42 and 0.65, p < 0.05, n = 30). Furthermore, MENA showed that planktonic algae and bacterial community interactions were enhanced, and interspecific competition increased at high trophic levels. The community assembly is primarily a stochastic process that is mostly related to hydrodynamic conditions. The second related factor, nitrogen and phosphorus inputs, had obvious effects on community assembly, which responded to its effects on species diversity, niche width, and interactions, and they jointly controlled community assembly. This study reveals that the assembly processes of bacteria and planktonic algae were driven by different environmental factors in specific ways, which provides a new view for understanding agriculture’s impacts on microecology and helps in developing lake protection strategies.

Primary production and destruction of organic matter in Lake Arakhley (Eastern Transbaikalia, Russia)

Global climate changes affect water ecosystems. Long-term observations of climatic variables are indicative of cyclic climate changes. The fluctuations result in changes in water levels in lakes, which, in turn, alter primary production processes. Planktonic algae are the main drivers of primary production. This research continues long-term studies on hydroecology of Lake Arakhley. The lake is used for fishery and recreation. This work aims to estimate production and destruction processes in Lake Arakhley during the current transitional period between dry and wet years. To this end, we performed field studies on Lake Arakhley in August from 2016 to 2021, during the season of maximum precipitation, in the central and littoral zones of the lake. Primary production of phytoplankton in water was estimated by the oxygen light and dark bottle method. Sampling was carried out to assess physical and chemical parameters of water using a multiparameter water quality instrument. Lake Arakhley features the low level of mineralization under alkali conditions and relatively stable level of mineralization registered from 2016 to 2021. Macrophytes zone expanded after the massive flooding of the shore in 2021 hence alterating the values of such environmental factors as oxygen levels, total and mineral phosphorus, with destruction prevailing over organic matter production. Depth and transparency however contribute to significant production of organic matter in the lake. The findings can be used as the groundwork for the sustainable management of the lake.

Spatial distribution of phytoplankton in the Serezha River (Nizhny Novgorod Region)

The investigation presents the results of studies of plankton in the area of the middle course of the riverSerezha in 2019. The floristic diversity of phytoplankton was characterized, its abundance and biomass were estimated, and the change in the morpho-functional groups of phytoplankton along the river was shown. The influence of some physical factors on the development of planktonic algae is considered. The water quality of this section of the watercourse was assessed by phytoplankton biomass, as well as using the community index and the Pantle-Bucksaprobity index.

Detection Algorithm of Planktonic Algae Based on Improved YOYOv3

Detection Algorithm of Planktonic Algae Based on Improved YOYOv3

STATUS OF PLANKTON AND BENTHOS IN THE AQUACULTURE FIELD OF BANGLADESH

Phytoplankton is a key food item in both aquaculture and mariculture. Phytoplankton is utilized as food for the animals in aquaculture directly. The plankton are collected from a body of water or cultured. Phytoplankton is used as a food stock for the production of rotifers and also used to feed molluscs, pearl oysters and giant clams. Plankton is divided into two groups belonging to phytoplankton and zooplankton. Phytoplankton has chlorophyll to capture sunlight, and they use photosynthesis to turn it into chemical energy. Zooplankton is a small floating or weakly swimming organism. Zooplankton moves vertically in the water column each day, feeding on the phytoplankton, small floating plants such as algae. Zooplankton serves as an intermediary species in the food chain, transferring energy from planktonic algae to the larger invertebrate predators and fish. Benthos is the community of organisms that live on, in, or near the seabed, river, lake or stream bottom, also known as the benthic zone. This community lives in or near marine or freshwater sedimentary environment, from tidal pools along the foreshore, out to the continental, and then down to the abyssal depths.

TAXONOMY, DISTRIBUTION AND DIVERSITY OF PLANKTONIC ALGAE AT PINDIGA DAM, NIGERIA

Taxonomic identification of algae at both generic and species levels is problematic owing to several reasons including cells’ fragility, sensitivity to chemical fixatives and inconspicuous morphological features. The planktonic algae in tropical African dams have been particularlyproblematic given the paucity of algal taxonomic experts in this region. In this study, we presentfor the first time the taxonomic and geographic appraisal of planktonic Algae at Pindiga Dam. Further, planktonic algal flora and its monthly variations at the Pindiga Dam were investigated. The study revealed a total of 35 genera. Species in the family Chlorophyceae were the most abundant (42%), followed by those in the families Bacillariophyceae (38%) and Charophyceae(25%). Other taxonomic groups present were Chryophyceae, Cryptophyceae, Cynophyceae and Euglenophyta (7%) each. Trachelomonas, Tetrahedrom and Pleurozester were the most abundant taxa. The Important Value Index (IVI) and species diversity of algae are dependent on the sampling month. For instance, Trachelomonas recorded the highest IVI (23.67) and thelowest was recorded by Cryptomonas (8.18) in April, but it was observed that in May; Tetrahedrom recorded the highest IVI (22.57) and the lowest was recorded by Zygnema (9.38). In June, another set of taxa recorded the highest and the Lowest IVI namely: Pleurogaster, Crucigenia (17.63) and Netrium, Oedogenium (8.93) each. The composition of planktonic algae families in Pindiga Dam could be said to be Chlorophyceae, Bacillariophyceae, and Cyanophyceae in order of the IVI. The Simpson’s index of diversity of planktonic algae at Pindiga Dam was 0.94542, 0.94708 and 0.95364 in April, May and June respectively. The species richness in April was 1.97, in May was 1.92 and in June was 2.10. The values were high indicating a more complex plankton community with a good measure of abundance and diversity. This study has provided baseline information on the taxonomy, distribution and diversity of planktonic algae in Pindiga Dam. This knowledge is useful to groups involved in water utilities; irrigation and drainage districts, industries, private pond owners, fish farmers and aqua culturist.

Glyceroglycolipids in marine algae: A review of their pharmacological activity.

Glyceroglycolipids are major metabolites of marine algae and have a wide range of applications in medicine, cosmetics, and chemistry research fields. They are located on the cell surface membranes. Together with glycoproteins and glycosaminoglycans, known as the glycocalyx, they play critical roles in multiple cellular functions and signal transduction and have several biological properties such as anti-oxidant and anti-inflammatory properties, anti-viral activity, and anti-tumor immunity. This article focused on the sources and pharmacological effects of glyceroglycolipids, which are naturally present in various marine algae, including planktonic algae and benthic algae, with the aim to highlight the promising potential of glyceroglycolipids in clinical treatment.

Exploring the Cumulative Selectivity of Polycyclic Aromatic Hydrocarbons in Phytoplankton, Water, and Sediment in Typical Urban Water Bodies

To understand the interactions among eutrophication, algal bloom, and POPs (persistent organic pollutants) in freshwater ecosystems, the cumulative selectivity of PAHs (polycyclic aromatic hydrocarbons) in phytoplankton, water, and sediment with different eutrophication level waters were identified in a typical plain river network region located in Nanjing City. Results showed that a total of 33 algal species belonging to 27 genera and 4 phyla were identified in 15 sites of urban water bodies, and most of them belonged to the type Cyanobacteria–Bacillariophyta. The eutrophication level of these rivers and lakes led to the sample site specificity of algal composition and abundance. The planktonic algae mainly accumulated the 2-ring and 3-ring PAHs, and the sediment mainly enriched the high-ring PAHs. However, the enrichment capacity of planktonic algae on PAHs was much higher than that of sediment. Cyanophyta and some species of Bacillariophyta and Chlorophyta in mesotrophic (βm) and meso-eutrophic water bodies (ßαm) preferentially accumulated lower-ring PAHs (naphthalene, acenaphthylene, and phenanthrene). Some other specific algae species, such as Euglenophyta, some species of Bacillariophyta, and most Chlorophyta in mesotrophic and moderate eutrophic water bodies, had strong capacities to enrich high-ring PAHs subsuming benzo[a]anthracene, chrysene, and anthracene. The eutrophication level of water bodies affected the cumulative selectivity of PAHs by shaping the site specificity of phytoplankton composition, which may be related to water quality, sediment characteristics, phytoplankton composition, and the algal cell walls.

Effects of Two Quinolone Antibiotics on Growth of Four Species of Planktonic Algae

Quinolone antibiotics, especially enrofloxacin and ciprofloxacin, are currently found to be at high levels commonly in natural waters. Studying the effects of these two quinolones on the growth of common microalgae in water is valuable for understanding the ecological effects of quinolones in the aquatic environment. Therefore, the effects of different concentrations of enrofloxacin and ciprofloxacin hydrochloride on the population growth of four species of planktonic microalgae (Chlorella vulgaris, Tetradesmus obliquus, Scenedesmus quadricauda, and Microcystis aeruginosa) were studied. The results showed that there was a significant effect-dose regression relationship between the concentration of nofantibiotic and the growth inhibitory rate of the algae population. The 96h half maximal inhibitory concentration (96h-IC50) of enrofloxacin on T. obliquus, S. quadricauda, M.aeruginosaI and C. vulgaris were 195.6, 88.8, 56.1, and 22.6 mg/L respectively, and the order of sensitivity of the four microalgae to enrofloxacin was T. obliquus＜S. quadricauda＜M. aeruginosa＜C. vulgaris. Another 96h-IC50 of ciprofloxacin hydrochloride to S. quadricauda, T. obliquus, M. aeruginosa, and C. vulgaris were 588.6, 546.3, 49.8, and 44.7 mg/L respectively. The sensitivity of the four microalgae to ciprofloxacin hydrochloride was ranked as follows: S. quadricauda＜T. obliquus＜M. aeruginosa＜C. vulgaris. Among the four species of planktonic microalgae, two species of Scenedesmus were less sensitive to the quinolone antibiotics. Therefore, these two species of Scenedesmus were more resistant to the two quinolone antibiotics, while C. vulgaris was the most sensitive to them. According to the data of IC50, the toxicity of enrofloxacin to three green microalgae was higher than that of ciprofloxacin, while the toxicity of enrofloxacin to M. aeruginosa was lower than that of ciprofloxacin. The population growth of the four planktonic microalgae was inhibited in the first 4 days after being treated by these two quinolone antibiotics, but the microalgae could gradually detoxify and restore their population growth after 96 h. Moreover, the toxicity of enrofloxacin to the four algae increased with time. The toxicity of ciprofloxacin hydrochloride to T. obliquus and S. quadricauda increased, and the toxicity to M. aeruginosa and C. vulgaris decreased. The recovery degree of ciprofloxacin hydrochloride was at least 39% higher than that of enrofloxacin. Low concentrations of enrofloxacin (<36mg/L) provoked a higher density of M. aeruginosa than that of the control group after 10 days of exposure. In this case, the algal density of M. aeruginosa could be more than 107 cells/L when the concentration of enrofloxacin was below 36mg/L.

Photo-Reactivity and Photo-Transformation of Algal Dissolved Organic Matter Unraveled by Optical Spectroscopy and High-Resolution Mass Spectrometry Analysis

The rapid proliferation of planktonic algae induced by eutrophication and climate warming make algae dissolved organic matter (AOM) an important source of dissolved organic matter (DOM) in surface waters, but the understanding of the link between AOM composition and photo-reactivity/photo-transformation of DOM in aquatic systems is limited. Here, intracellular organic matter (IOM) from Microcystis aeruginosa was extracted and subjected to molecular weight (MW) fractionation. Results indicated that IOM had lower aromaticity and higher photosensitive activity compared to Suwannee River fulvic acid (SRFA). The photosensitive activity of IOM relied on both its molecular weight distribution and fluorescence components. The IOM fraction with the highest MW proteins had the lowest quantum yields of reactive intermediates (ΦRIs), which increased with the decrease of MW, while the fractions with more low-excitation tyrosine-like components had relatively higher ΦRIs. Parallel factor analysis and high-resolution mass spectrometry revealed that light radiation of IOM resulted in the composition transformation from tryptophan-like and tyrosine-like components to humic-like components, forming less aromatic and more saturated recalcitrant dissolved organic carbon. Our findings provide new insights into the photo-reactivity and photo-transformation of algae-derived organic matters and help to predict DOM formation involved in carbon cycling in water environment.

Non-Diatomic Diversity and Community Structure in Hoor-Al- Azime Marshes, Iran

This study was conducted to delineate diversity and species composition of non-diatoms planktonic algae in Hoor- Al- Azime marshes, Iran. The samples were collected from four sites at monthly basis from April 2011 to March 2012. A total 88 taxa were identified, out of which (40 taxa, 45.45%) belonging to Cyanophyta followed by Chlorophyta (29 taxa, 32.96%), Euglenophyta (18 taxa, 20.45%) and (1 taxa, 1.14%) of Dinophyta recorded. Comparing species richness (65 taxa, 34.76%) at Shat- Ali (St4) was the highest and the lowest (34 taxa, 18.18%) was observed at Rafi (St2). Species occurrence was associated with temperature where in summer (66 taxa) and (25 taxa) encountered winter. The phytoplankton density ranged from 51.04 ×103 cells/Liter in summer to 2.17 ×103 cells/Liter in winter for Cyanophyta and from 20.58 ×103 cells/Liter in summer to 2.92 ×103 cells/Liter in winter for Chlorophyta. St4 is characterized by the highest density 36.33×103 cells/Liter (43.96 %), while St2 recorded the lowest phytoplankton density 7.33×103 cells/Liter (8.93%). Euglenophyta and Dinophyta did not record a noticeable density during study period. This study document updated knowledge of non-diatom plankton diversity and seasonal oscillation an important wetland ecosystem.

Biological monitoring of inhibitory effects of antifouling agent Irgarol 1051 on growth and essential metabolites of marine alga Chlorella salina

Irgarol 1051 (2-(tert-butylamino)-4-(cyclopropylamino)-6-(methylthio)-1,3,5-triazine) is a biocide used in antifouling paint on ships to prevent fouling growth. It is widely used booster herbicides and it may exert potent toxic effects on marine primary producers such as microalgae, where majority of the toxicity data are based on changing in growth and inhibition of essential metabolites. Data of the toxic effects on microorganisms may be used to define the upper limits for concentration of pollutants and to predict environmental toxicity risk. So, the aim of this work was concentrated on the effect of the booster biocide Irgarol 1051 on growth and content of some essential metabolites namely protein, carbohydrates, amino acids and fatty acids of marine planktonic alga Chlorella salina. The result obtained proved that, increasing of antifouling concentration caused notable decreasing in growth depending on the concentration used. The presence of antifouling agent Irgarol 1051 in the seawater especially in areas with heavy shipping activity due to its application in antifouling paints will cause decreasing in nutrient value of proteins in this type of algae as well as the negative impact on the essential amino acids. Carbohydrates content decreased by increasing the concentration of Irgarol. A serious decrease in the content of Omega-3 fatty acids and in turn this will affect the crop of the marine fish since fishes cannot synthesis these types of fatty acids.

Remote Sensing Estimation of Long-Term Total Suspended Matter Concentration from Landsat across Lake Qinghai

Total suspended matter (TSM) is one of the most widely used water quality parameters, which can influence the light transmission process, planktonic algae, and ecological health. A comprehensive field expedition aiming at water quality assessment was conducted for Lake Qinghai in September 2019. The in-situ measurements were used to support the calibration and validation of TSM concentration using Landsat images. A regional empirical model was established using the top-of-atmosphere (TOA) radiance of Landsat image data at the red band with a wavelength range of 640–670 nm. The coefficient of determination (R2), mean relative error (MRE), and root mean square error (RMSE) of the TSM estimation model were 0.81, 17.91%, and 0.61 mg/L, respectively. The model was further applied to 87 images during the periods from 1986 to 2020. A significant correlation was found between TSM concentration and daily wind speed (r = 0.74, p < 0.01, n = 87), which revealed the dominance of wind speed on TSM concentration. In addition, hydrological changes also had a significant influence on TSM variations of lake estuaries.

Palaeo-environmental evolution and organic matter enrichment of Eopalaeozoic shales, northwestern Tarim Basin, China: Integrated organic and inorganic geochemistry approach

The Eopalaeozoic was a pivotal transitional period following the Neoproterozoic glaciation that witnessed dramatic changes in global ocean environments. The black rock series were extensively sedimented, preserving the original seawater signature. However, due to the scarcity of geological records, the palaeo-environment and organic matter (OM) enrichment in the Tarim Basin, China, are poorly constrained. Herein, Eopalaeozoic shales from typical outcrops in the Kalpin block, northwestern Tarim Basin, have been subjected to integrated organic and inorganic geochemistry research. In the study area, Eopalaeozoic black rock series can be found in the Yuertusi Formation (YUF), Saergan Formation (SAF) and Yingan Formation (YIF) from bottom to top. Although the maturity is moderate (~1.2%), the OM abundance varies greatly vertically. Microscopic observations and biomarkers revealed that the OM source was dominated by diverse planktonic algae. The chemical alteration index indicates a transition from cold and dry climates with low chemical weathering to warm and humid climates with moderate chemical weathering, and subsequently back to cold and dry climates. The stratified water column and euxinic–suboxic conditions are revealed by redox proxies (Mo, enrichment factors, Th/U, MoU covariation pattern, pristane/phytane and gammacerane index). The YUF was deposited in a euxinic environment. Productivity proxies (biogenic Ba, Cu/Al, Ni/Al and carbon isotopes) show that primary productivity was superelevated in the lower YUF and moderate in the other formations. Primary productivity and preservation conditions were heavily influenced by complementary hydrothermal activities and upwelling currents. The hydrothermal activities and upwelling currents provide abundant nutrients and highly reductive environments, creating enormous possibilities for the formation of excellent source rocks with considerable hydrocarbon geological significance.

Monitoring effect of nickel, copper, and zinc on growth and photosynthetic pigments of Spirulina platensis with suitability investigation in Idku Lake

Owing to the increase of pollutant sources in oceans, seas, and lakes, there is an expected effect on growth and metabolism of planktonic algae which are considered primary producers in the ecosystem. Therefore, it becomes urgent to carry out laboratory studies to test to what extent these pollutants can affect the growth of algae which is necessary as a food for marine fishes. Spirulina is considered the most important algal species due to its high nutritional value for humans and animals. Therefore, this work investigated the effect of different concentrations of Ni2+, Zn2+, and Cu2+ metal ion pollutants on growth of the blue-green alga Spirulina platensis. EC50 was identified to be around 2 mg/l for the three heavy metals. The suitability of Idku Lake for Spirulina platensis growth was investigated using multi-criteria spatial modeling integrated with remotely sensed data processing. Spatial distribution maps of turbidity, water nutrients, and phytoplankton were the input criteria used to assess Idku Lake’s suitability. The results obtained proved that low concentrations of the tested heavy metals stimulated growth and pigment fractions (chlorophyll a, carotenoids, and total phycobilins content) but to different degrees. The inhibitory effect was more prominent in the case of copper ions than zinc and nickel ions with all concentrations used. The overall suitability map of Spirulina platensis in Idku Lake showed that the whole lake is suitable for growth and proliferation except for the northwestern corner due to the high salinity levels. The present paper helps to understand the behavior of algae responding to environmental pollution, which supports environmental planners with the necessary baseline for investigating the fate of pollutants and the potential risk.

Transcriptomic Analysis of the Molecular Response Mechanism of Microcystis aeruginosa to Iron Limitation Stress

Iron is an essential micronutrient for cyanobacteria. It is involved in physiological activities such as photosynthesis, respiration, and the synthesis of pigments. The impact of iron limitation on planktonic algae growth occurs in surface oceans globally, as well as in freshwater ecosystems. However, the molecular and physiological effects and response mechanism of cyanobacteria under iron-limited conditions have not been reported in detail. In this study, the effects of iron limitation on the cell density, chlorophyll content, and photosynthetic activity of Microcystis aeruginosa were determined, and transcriptome sequencing was undertaken. In a severely iron-deficient environment, the cell density and chlorophyll-a content of M. aeruginosa were significantly lower than in the iron-rich group (a 55.42% and 83.51% reduction, respectively). Similarly, the photosynthetic efficiency of M. aeruginosa was also inhibited by iron deficiency, and the maximum photochemical efficiency (Fv/Fm) of the severe iron deficiency group was only 66.72% of the control group. The transcriptome results showed that to cope with the iron-deficient environment, most genes involved in iron absorption and transport in M. aeruginosa were up-regulated. In particular, the fur and perR genes that regulate the iron uptake regulatory protein (Fur) were both up-regulated. Due to the high demand for iron in the photosynthetic electron transport chain of M. aeruginosa, most photosynthesis-related genes were down-regulated, for example, petJ, which regulates iron-containing cytochrome c6. In contrast, most of the genes related to glycolysis and respiration were up-regulated. These changes in gene expression may be a survival strategy for M. aeruginosa to cope with a long-term iron-deficient environment. This study provides insights into the molecular response mechanism of M. aeruginosa under iron limitation stress.

Effects of Elevated Temperature on Resources Competition of Nutrient and Light Between Benthic and Planktonic Algae

Climate warming, a serious environmental problem worldwide, is considered a major threat to aquatic ecosystems. A primary feature of climate warming is elevated temperatures which in shallow aquatic ecosystems might affect competition for light and nutrient between benthic algae on the sediment surface and planktonic algae in the water. The outcomes of such competition would not only affect the distribution of primary production, but also determine the fundamental character of shallow aquatic habitats as clear water or turbid water systems. We conducted a mesocosm study to evaluate the effects of elevated temperature on competition between planktonic algae and benthic algae for light and nutrients. We found that elevated temperature increased the concentrations of total nitrogen (TN), total phosphorus (TP), and total suspended solids (TSS) in overlying water and enhanced the growth of planktonic algae (measured as chlorophylla, Chla), but decreased light intensity and benthic algal biomass (Chla). Our results indicate that elevated temperature can increase the growth of planktonic algae and enhance their competitive advantage over the benthic algae in shallow lakes, thereby contributing to eutrophication and a decline in water quality. These findings shed further light on the effects of global warming on aquatic ecosystems.

Hydrocarbon potential, organisms, and depositional environments of the Lower Cambrian shales along the southern margin of the Ordos basin, Northern China

The dark shales of the Lower Cambrian Dongpo Formation, along the southern margins of the Ordos Basin, were researched based on biomarkers and carbon isotope analyses of outcrop samples to reveal their hydrocarbon potential, organism composition, and depositional environment. Similar to the Yangtze and Tarim blocks, the Lower Cambrian in the southern margin of Ordos Basin, which is a part of North China block, also deposited high abundance marine source rocks. The shales displayed good to excellent total organic carbon (TOC) content (up to 13.75%). The crossplot of phytane/nC18 vs. pristane/nC17 and organic carbon isotopes indicate the kerogen to be primarily type I-II. The low Hydrogen index values, and high pyrobitumen reflectance (>3.0%) indicate that the Dongpo shales are currently in over-mature stage. The Dongpo shales thus exhibit high hydrocarbon generation potential and might have produced and discharged massive amounts of hydrocarbons during their geological history. The G/C30H ratios (0.17–0.29) and extended tricyclic terpanes Ratio (ETR) values (0.54–0.61) suggest sedimentary environments of stratified water and relatively moderate salinity. In addition, the Dongpo shales display low Pr/Ph (<0.63), low C30*/C29Ts (<0.44), high C35 22S/C34 22 S (>0.47), and relatively abundant elemental sulfur. These parameters indicate that Dongpo shales were formed in anoxic waters. The abundant steranes and hopanes in the Dongpo shales suggest the diversity of organisms, including eukaryotes and prokaryotes. The composition of eukaryotes (planktonic algae) is consistent with that of the Yangtze and Tarim blocks, but there are obvious differences with Oman, reflecting the heterogeneity in the global distribution of eukaryotes during the Early Cambrian. In addition, compared with the Yangtze and Tarim, the relatively contribution of prokaryote to Dongpo shale is low, which may also be an important reason for the obvious enriched of 13C in kerogen. The positive relationship between TOC and Pr/Ph and C27 St (%) suggests that high primary productivity in the paleoenvironment probably attributed to red algae. The Pr/Ph, C35/C34 values and others indexes are related to anoxic conditions, which is good for preserving deposited organic matter.

Phytoplankton and ecological state of Dolgoe Lake (Pskov Region)

The paper deals with the planktonic algoflora of Dolgoe Lake in the Pskov Region. The studies were carried out in the summers of 2017-2020. The taxonomic composition of the phytoplankton of the lake was revealed, including 156 species and intraspecific taxa from 8 phylums: Chlorophyta, Bacillariophyta, Cyanobacteria, Charophyta, Ochrophyta, Dinophyta, Euglenophyta, Cryptophyta. The basis of the floral complex was made up of representatives of the phylums Chlorophyta and Bacillariophyta, as well as Cyanobacteria. The greatest similarity in the species composition of phytoplankton communities was noted in 2017 and 2019 (the Sierensen-Chekanovsky coefficient was 60%), the lowest - in 2018 and 2019, as well as in 2018 and 2020 (39%). The maximum quantitative development of microalgae was noted in 2019 (32,9 million cells/l), with 90,7% of the total number accounted for cyanobacteria Merismopedia minima G. Beck. The smallest number of planktonic algae was observed in 2020 - 1,3 million cells/l. The total biomass of phytoplankton was the highest in July 2019 - 0,45 mg/l, and the lowest in 2020 - 0,15 mg/l. According to the Milius trophic index, the waters of the lake are oligotrophic. According to the ecological and geographical characteristics, widespread freshwater species of phytoplankton prevailed in the lake, preferring slightly alkaline waters. Saprobiological analysis showed that the waters of Dolgoe Lake are moderately polluted and belong to the 3rd class of quality. The saprobity index of the Pantle-Buck, depending on the year of the study, varied from 1,80 to 1,98.

Deciphering the origin of riverine phytoplankton using in situ chlorophyll sensors

AbstractRiverine algal groups with distinct life histories can generate unique patterns of structural and functional behavior. As such, novel methods to discriminate between these groups can improve the understanding of river ecosystem processes. We examined benthic vs. planktonic contributions to suspended algal biomass by monitoring suspended chlorophyll concentration and turbidity during 48 storm events at 2 locations with contrasting hydraulic storage associated with low‐head dams. Upstream from the dams, chlorophyll hysteresis showed concentrating effects and counterclockwise rotation, suggesting stormflow concentrated algae from benthic sources. When autotrophic conditions (P/R &gt; 1) preceded storms, chlorophyll hysteresis switched to more proximal benthic sources (faster mobilization). Downstream of the dams, hysteresis showed greater dilution effects and more proximal sources of planktonic algae than at the upstream site, in contrast to high similarly in turbidity hysteresis between sites. Our study supports the analysis of chlorophyll and turbidity hysteresis to infer sources and transport of suspended algal biomass.