Phytoplankton Diversity Research Articles

Екологічні характеристики, біомаса, чисельність і домінуючі комплекси фітопланктону різнотипних водойм та водотоків пониззя Дунаю

In the context of modern environmental challenges, being under constant anthropogenic pressure, systematic study of the spatial and temporal dynamics of phytoplankton distribution, its quantitative and qualitative indicators, biomass and abundance, and determination of the dominant complex are indicative factors of biodiversity and water productivity. In the context of constant anthropogenic pressure, such research and monitoring of biodiversity and water quality are essential for the functioning of biocenosis. It was found that the diversity of phytoplankton in different hydroecosystems of the lower Danube River is represented by a wide floristic spectrum and amounts to 156 species (158 species) belonging to 8 divisions: Cyanobacteria, Bacillariophyta, Cryptophyta, Miozoa, Ochrophyta, Charophyta, Chlorophyta, Euglenozoa. The research of phytoplankton ecological characteristics showed that planktonic and planktonic-benthic forms are the most common in terms of biotopic habitat. Analyzing the phytoplankton by habitat, indifferent species dominate in all studied hydroecosystems. In relation to pH, most of the representatives belong to indifers, and fewer to alkalifers. The number of phytoplankton cells ranged from 375 thousand cells/m2 to 1320 thousand cells/m2, with Cyanobacteria being the most numerous. The main role in the formation of the biomass of water bodies in summer in the studied areas belongs to the divisions Chlorophyta, Miozoa, and Bacillariophyta and ranges from 0.3361 mg/dm3 to 0.944205 mg/dm3. The analysis of the dynamics of phytoplankton abundance and biomass showed that these indicators vary depending on the location of the algosampling stations. The structure of phytoplankton biomass in the lower Danube is unevenly represented, according to the hydroecosystem, and is formed mainly by the Bacillariophyta-Chlorophyta complex, but in some samples, representatives of the Mioza order dominate in terms of biomass. At the same time, summarizing the values of phytoplankton abundance, it was found that the leading role belongs to Cyanobacteria, with Chlorophyta and Bacillariophyta also widespread. It was noted that in shallow waters and in areas with high dynamics of hydrological processes, namely river-sea transition zones, there is a predominance of the diatom complex, formed mainly by planktonic-benthic and benthic forms. This spatial distribution is typical for areas with high intensity of water mass mixing.

Impact of a run-of-river dam in an Amazonian large river on the spatial and temporal patterns of phytoplankton beta diversity

Human activities degrade aquatic ecosystems and diminish biodiversity. Dams have a direct impact on river environments, notably affecting aquatic communities like phytoplankton. We investigated the impact of the damming of an Amazonian River on the composition and spatial and temporal beta diversity of phytoplankton, from October 2009 to July 2017. Also sought to understand how the contribution values for beta diversity (LCBD) changed over time. To achieve this, we performed a PERMANOVA to identify changes in phytoplankton composition between dam phases. Also calculated temporal beta diversity at local and regional scales and regressed these values over time to identify possible biotic homogenization and unidirectional changes in the community. Finally, we calculated the LCBD values of each site over time and regressed these values on species richness, environmental heterogeneity, and the site distance to the dam. We verified that the composition of the phytoplankton changed between the phases of the dam. The impact of time on both local and regional beta diversity was observable, particularly in the tributaries. This was attributed to shifts in community composition from the onset of the study to its conclusion, as well as to biotic homogenization detected in sites closest to the dam. These sites became similar over time, contributing less to beta diversity. This change was related to an increase in species richness. Therefore, it was possible to verify that the construction of the reservoir impacted the diversity of the community over time and that the tributaries backwaters were more affected than the main channel.

Resource partitioning of a Mexican clam in species-poor Baltic Sea sediments indicates the existence of a vacant trophic niche

Invasive species are often generalists that can take advantage of formerly unexploited resources. The existence of such vacant niches is more likely in species-poor systems like the Baltic Sea. The suspension feeding wedge clam, Rangia cuneata, native to estuarine environments in the Gulf of Mexico, was sighted for the first time in the southeastern Baltic in 2010 and a few years later in the northern Baltic along the Swedish coast. To explore possible competition for food resources between R. cuneata and the three native clams inhabiting Baltic shallow soft bottoms, stable isotope and fatty acid analyses were conducted. There was no overlap between R. cuneata and any of the native species in either stable isotope or fatty acid niches. This suggests efficient partitioning of resources; multivariate analyses indicate that separation was driven mainly by δ13C and by fatty acids reflecting diatoms and cyanobacteria, respectively (e.g. 16:1ω7 and 18:3ω3). R. cuneata reflected seasonal variation in phytoplankton more than other clams reflecting higher trophic plasticity. In conclusion, the addition of R. cuneata to the Baltic shallow soft bottoms suggests the existence of a vacant trophic niche in these sediment habitats, however the long-term effects on other species and nutrient cycling requires further studies focusing on the population dynamics of R. cuneata and its impact on the Baltic Sea ecosystem.

Investigating the differences in driving mechanisms for phytoplankton community composition under various human disturbances in cold regions

In river ecosystems, phytoplankton are essential components, and this study delves into their response to critical environmental indicators. We analyzed the spatiotemporal variations of phytoplankton diversity in cold regions, employing techniques such as Principal Component Analysis (PCA), Spearman correlation coefficient, and Generalized Additive Model (GAM) to unveil the critical environmental factors influencing phytoplankton diversity and habitat suitability under varying degrees of human interference. With 37 monitoring stations across two cold region rivers, phytoplankton and water bodies were monitored in spring, summer, and autumn, resulting in the collection and analysis of 111 phytoplankton samples and 13 environmental indicators at each station. By identifying critical water quality indicators and exploring nonlinear relationships, the study revealed intricate interactions between phytoplankton diversity and environmental factors. Our findings suggest that overall phytoplankton species diversity is lower in rivers with high human interference, with turbidity, NH4+-N, chlorophyll-a, and total phosphorus (TP) deemed critical factors. Conversely, chlorophyll-a, NH4+-N, and electrical conductivity (EC) were identified as important factors in rivers with lower human interference, indicating differences in phytoplankton driving mechanisms between the two rivers. These insights provide valuable references for the sustainable development and effective assessment of cold region river ecosystems in the Anthropocene.

Arctic phytoplankton microdiversity across the marginal ice zone: Subspecies vulnerability to sea-ice loss

Seasonal phytoplankton blooms are important Arctic phenomena, contributing to global primary production and biogeochemical cycling. The decline in sea-ice extent and thickness favors a longer open-water period with impacts on phytoplankton dynamics. Arctic net productivity is influenced by microalgae living associated with sea ice, with distinct species thought to be favored by ice-covered and ice-free waters. In this study, we investigated the phytoplankton community structure in Baffin Bay, a semi-enclosed sea where Arctic and North Atlantic water masses interact. We compared communities from the ice-free Atlantic-influenced eastern, the marginal ice zone, and the ice-covered Arctic-influenced western Baffin Bay. The community was characterized using 18S rRNA high-throughput amplicon sequencing and flow cytometry cell counting, and compared to environmental data collected during the Green Edge campaign. We sampled 16 stations grouped by sectors according to sea-ice cover. In the sectors associated with sea ice, phytoplankton formed a highly diverse community of smaller taxa, which contrasted with a low-diversity community in ice-free sectors, dominated by larger centric diatoms and Phaeocystis pouchetii adapted to high light/low nutrient conditions. Several phytoplankton species were flagged as indicators for the under-ice and marginal ice zone sectors, including ice-associated taxa such as the diatoms Melosira arctica and Pseudo-nitzschia seriata, but also subspecies representatives of the early-blooming alga Micromonas polaris and the cryptophyte Baffinella frigidus. The strong association of certain taxa with under-ice and marginal ice zone sectors, including Pterosperma sp., Chrysochromulina sp., Micromonas polaris, and B. frigidus, suggest that they might be indicators of diversity loss due to ongoing sea-ice changes in Baffin Bay. We report new intra-species variability of Micromonas polaris suggesting that seasonal specialists could wax and wane over the bloom and non-bloom periods, highlighting the need for detailed year-long studies and the importance of microdiversity when assessing the diversity and distribution of polar phytoplankton.

Plankton diversity in the Rowo Klampok Swamp, Malang District, East Java, Indonesia

Abstract. Arfiati D, Zakiyah U, Anitasari S, Inayah ZN, Orchida K, Pratiwi RK. 2024. Plankton diversity in the Rowo Klampok Swamp, Malang District, East Java, Indonesia. Biodiversitas 25: 1846-1855. Wetlands are a productive ecosystem and have high biodiversity, including plankton. Plankton can be used to assess the health status of wetlands. This research aims to determine the diversity and abundance of phytoplankton and zooplankton and to analyze the water quality conditions of the tropical wetland (Rowo Klampok Swamp, Malang District, East Java, Indonesia). This research was conducted from May to June 2023 and it's a survey research. The research results show that the phytoplankton found in Rowo Klampok Swamp consists of 4 divisions with 13 genera, while there are 3 divisions with 3 genera in zooplankton. Phytoplankton divisions are Bacillariophyta, Chlorophyta, Cyanophyta, and Dinoflagellate, while zooplankton divisions are Arthropoda, Ciliophora, and Rotifera. The average value of total phytoplankton abundance reached 2,618,684 cells/L, while zooplankton was 10,504 Ind/L. The Chlorophyta division is the most commonly found phytoplankton, with a percentage ranging between 32.5 and 53.1%, respectively. Dictyosphaerium is a phytoplankton genus often found with the highest average abundance of 1,922,929 cells/L. The diversity index, uniformity index, and dominance index of phytoplankton ranged between 1.965-2.439, 0.945-1.173, and 0.125-0.213, respectively, while those of zooplankton were 0.496-0.529, 0.317-0.593 and 0.458-0.684, respectively. Rowo Klampok Swamp has a medium trophic level (mesotrophic) and shows moderate pollution. The water quality conditions are considered suitable for aquatic organisms, but we need to monitor and reduce phosphorus input into the bodies of water.

Influence of river tide dynamics on phytoplankton variability and its ecological implications in three Brazilian tropical estuaries (Delta do Parnaíba Environmental Protection Area)

ABSTRACT The Delta do Parnaíba Environmental Protection Area (EPA) represents one of the largest deltaic systems in the Americas. This study investigated the spatiotemporal variability of phytoplankton communities and their correlation with environmental factors and assessed their trophic status and water quality across three mesotidal estuaries (Parnaíba-PRE, Comum-CRE, and Bom Gosto-BGRE) over a year-long sampling period. Multivariate analyses explored the interplay between environmental parameters, phytoplankton communities, and trophic indices. Salinity has emerged as a key determinant in these estuaries. Trophic components influence nutrient dynamics, with Redfield ratios indicating colimitation by orthophosphate ( PO 4 3 − ) and silicate ( SiO 2 − ). This study identified 355 taxa within the phytoplankton community, with Chlorophyta predominating in the PRE and diatoms dominating in estuaries with relatively high salinities (BGRE and CRE). Environmental drivers vary across estuaries, with temperature, dissolved oxygen (DO), total nitrogen (TN), chlorophyll-a (Chll-a), and the trophic index (TRIX) influencing the phytoplankton community in the PRE, while salinity, PO 4 3 − , total phosphorus (TP), and TN affect the CRE, and salinity and Chll-a influence the BGRE. The Delta do Parnaíba EPA exhibits eutrophic to hypertrophic conditions, emphasising the need for comprehensive environmental monitoring, nutrient management, and conservation efforts to safeguard biodiversity, water quality, and ecosystem health.

Phytoplankton and zooplankton paleocommunity change before and during the onset of the Lau Extinction Event (Ludlow, Silurian)

The Ludlow epoch of the Silurian period was a time of significant geobiological perturbations, the most significant being the mid-Ludfordian Lau Event and associated huge positive carbon isotopic excursion. On the other hand, the impact of the Lau Event on ecosystems is far from understood, with the majority of studies being concentrated on conodonts, graptolites, and brachiopods. Therefore, here we present the high-resolution Gorstian to mid-Ludfordian Baubliai-2 core section record of the phytoplankton (acritarch and green algae) change from the deep shelfal facies belt of the Silurian Baltic Sedimentary Basin. Seven distinct phytoplankton assemblages are distinguished. The general feature of the assemblage change is an overarching trend toward higher relative abundances of the green algae disaster taxon Leiosphaeridia spp., which peaked during the Lau Event. The absolute abundance variability of the various components of the plankton including the hyper-abundant Leiosphaeridia spp. and Tasmanites spp. revealed the presence of consistent 0.93 Ma cyclicity. The diversity of phytoplankton is directly correlated with graptolite species diversity, which suggests common driving mechanisms of evolution for different components of the plankton community. The recurrence and joint recurrence plots and recurrence quantification analysis revealed a coordinated evolution of phytoplankton and graptolite diversities. The Lau Event interval stood out as a distinct coordinated low diversity state in both phytoplankton and in graptolites. Similar anomalous community states were previously detected in benthic communities (brachiopods), and in communities of pelagic predators (conodonts). Therefore, the current evidence suggests that the Lau Event had a significant impact across the whole range of communities and ecosystems.

Impact of Dynamic Phytoplankton Stoichiometry on Global Scale Patterns of Nutrient Limitation, Nitrogen Fixation, and Carbon Export

AbstractPhytoplankton stoichiometry modulates the interaction between carbon, nitrogen and phosphorus cycles. Environmentally driven variations in phytoplankton C:N:P can alter biogeochemical cycling compared to expectations under fixed ratios. In fact, the assumption of fixed C:N:P has been linked to Earth System Model (ESM) biases and potential misrepresentation of responses to future change. Here we integrate key elements of the Adaptive Trait Optimization Model (ATOM) for phytoplankton stoichiometry with the Carbon, Ocean Biogeochemistry and Lower Trophics (COBALT) ocean biogeochemical model. Within a series of global ocean‐ice‐ecosystem retrospective simulations, ATOM‐COBALT reproduced observations of phytoplankton N:P, and compared to static ratios, exhibited reduced phytoplankton P‐limitation, enhanced N‐fixation, and increased low‐latitude export, improving consistency with observations and highlighting the biogeochemical implications of dynamic N:P. We applied ATOM‐COBALT to explore the impacts of different physiological mechanisms hypothesized to underlie N:P variation, finding that two mechanisms together drove the observed patterns: proportionality of P‐rich ribosomes in phytoplankton cells to growth rates and reductions in P‐storage during scarcity. A third mechanism which linked temperature with phytoplankton biomass allocations to non‐ribosomal proteins, led only to relatively modest impacts because this mechanism decreased the temperature dependence of phytoplankton growth rates, compensating for changes in N:P. We find that there are quantitative response differences that associate distinctive biogeochemical footprints with each mechanism, which are most apparent in highly productive low‐latitude regions. These results suggest that variable phytoplankton N:P makes phytoplankton productivity and export resilient to environmental changes, and support further research on the physiological and environmental drivers of phytoplankton stoichiometry and biogeochemical role.

Integrated machine learning reveals aquatic biological integrity patterns in semi-arid watersheds

Semi-arid regions present unique challenges for maintaining aquatic biological integrity due to their complex evolutionary mechanisms. Uncovering the spatial patterns of aquatic biological integrity in these areas is a challenging research task, especially under the compound environmental stress. Our goal is to address this issue with a scientifically rigorous approach. This study aims to explore the spatial analysis and diagnosis method of aquatic biological based on the combination of machine learning and statistical analysis, so as to reveal the spatial differentiation patterns and causes of changes of aquatic biological integrity in semi-arid regions. To this end, we have introduced an innovative approach that combines XGBoost-SHAP and Fuzzy C-means clustering (FCM), we successfully identified and diagnosed the spatial variations of aquatic biological integrity in the Wei River Basin (WRB). The study reveals significant spatial variations in species number, diversity, and aquatic biological integrity of phytoplankton, serving as a testament to the multifaceted responses of biological communities under the intricate tapestry of environmental gradients. Delving into the depths of the XGBoost-SHAP algorithm, we discerned that Annual average Temperature (AT) stands as the pivotal driver steering the spatial divergence of the Phytoplankton Integrity Index (P-IBI), casting a positive influence on P-IBI when AT is below 11.8 °C. The intricate interactions between hydrological variables (VF and RW) and AT, as well as between water quality parameters (WT, NO3–N, TP, COD) and AT, collectively sculpt the spatial distribution of P-IBI. The fusion of XGBoost-SHAP with FCM unveils pronounced north-south gradient disparities in aquatic biological integrity across the watershed, segmenting the region into four distinct zones. This establishes scientific boundary conditions for the conservation strategies and management practices of aquatic ecosystems in the region, and its flexibility is applicable to the analysis of spatial heterogeneity in other complex environmental contexts.

Classification of eco-zones from the factors and processes controlling phytoplankton biomass

Phytoplankton is of utmost importance to the marine ecosystem and, subsequently, to the Blue Economy. This study aims to explain the reasons for variability of phytoplankton by estimating the dependency of Chlorophyll-a (Chl-a) on various limiting factors using statistics. The global oceans are classified into coherent units that display similar sensitivity to changing parameters and processes using the k-means algorithm. The resulting six clusters are based on the limiting factors (PAR, iron, or nitrate) that modulate Chl-a yield divisions of the oceans, similar to regions of different trophic statuses. The clusters range from the polar and equatorial regions with high nutrient values limited by light, to open oceanic regions in downwelling gyres limited by nutrients. Some clusters also show a high dependency on marine dissolved iron. Further, oceans are also divided into eight clusters based on the processes (stratification, upwelling, topography, and solar insolation) that impact ocean productivity. The study shows that considering temporal variations is crucial for segregating oceans into ecological zones by utilizing correlation of time-series data into classification. Our results provide valuable insights into the regulation of phytoplankton abundance and its variability, which can help in understanding the implications of climate change and other anthropogenic effects on marine biology.

Phytoplankton community structure and its driving factors in autumn in Jinan, China

Human activities often cause multiple impacts on aquatic ecosystems, including changes in water quality, biodiversity, community composition, etc. However, the effects of human activities on phytoplankton in highly urbanized aquatic ecosystems are poorly understood. In this study, we conducted an in-depth analysis of phytoplankton communities and water environment factors in the Jinan City watershed in September 2020, focusing on 18 water environment factors. We found that nitrate nitrogen, total nitrogen, total phosphorus, and phosphate were the key drivers affecting the quality of the water environment in the area through principal component analysis (PCA). The results of the phytoplankton investigation showed that 143 species of phytoplankton from 8 phyla were found in the Jinan watershed, dominated by Chlorophyta, Bacillariophyta, and Cyanobacteria, of which cyanobacteria were dominant in density, while cryptophytes were the first in biomass. The assessment of phytoplankton diversity showed that the Jinan City watershed had high biodiversity, with an average Shannon Wiener Diversity Index of 3.12. RDA analysis revealed that permanganate index, total phosphorus, bathymetry, chlorophyll a, pH, and phosphate were significantly correlated with the structure of the phytoplankton community. Comprehensive trophic index (TLI) analysis showed that most of the watersheds in Jinan were moderately eutrophic. These results provide essential information for understanding the water quality status and aquatic biodiversity in Jinan City watersheds and provide a scientific basis for water environment management and protection.

The Impact of Natural Stone Waste Pollution on The Distribution and Abundance of Phytoplankton in Cirebon District

The natural stone industry in Cirebon Regency produces large amounts of liquid waste which is directly discharged into rivers. The sludge resulting from the natural stone washing process contains high levels of suspended material, causing water pollution and disrupting the life of aquatic organisms including phytoplankton. Phytoplankton have an important ecological role as primary producers and food sources for other organisms, where their distribution and abundance are strongly influenced by various environmental factors. This research aims to determine the impact of natural stone waste pollution on the abundance and structure of phytoplankton communities in several water locations in the Jamblang watershed. A total of three observation stations were selected using a purposive sampling method at several points in the Jamblang Watershed, Cirebon Regency. The research results showed that phytoplankton were found at all observation stations with the identified types consisting of four classes, namely Bacillariophyceae (16 genera), Chlorophyceae (4 genera), Cyanophyceae (4 genera) and Euglenophyceae (2 genera). Bacillariophyceae is the most diverse class, while Oscillatoria sp. from the Cyanophyceae class was found to be the most abundant at all stations. The abundance of phytoplankton ranged between 716,587 - 1,332,122 cell/m3, where the highest abundance was found at station 2. The ecological index showed that the diversity and uniformity of phytoplankton at all stations was in the medium category. Species dominance at station 2 and station 3 is low, while at station 1 tends to have greater dominance than at other stations. Overall, from the results of calculations of abundance and community structure, several phytoplankton species show resistance to water conditions polluted by natural stone waste and other anthropogenic waste, especially from the Bacillariophyceae and Cyanophyceae classes which can be used as indicators of polluted waters.

Local intraspecific aggregation in phytoplankton model communities: spatial scales of occurrence and implications for coexistence.

The coexistence of multiple phytoplankton species despite their reliance on similar resources is often explained with mean-field models assuming mixed populations. In reality, observations of phytoplankton indicate spatial aggregation at all scales, including at the scale of a few individuals. Local spatial aggregation can hinder competitive exclusion since individuals then interact mostly with other individuals of their own species, rather than competitors from different species. To evaluate how microscale spatial aggregation might explain phytoplankton diversity maintenance, an individual-based, multispecies representation of cells in a hydrodynamic environment is required. We formulate a three-dimensional and multispecies individual-based model of phytoplankton population dynamics at the Kolmogorov scale. The model is studied through both simulations and the derivation of spatial moment equations, in connection with point process theory. The spatial moment equations show a good match between theory and simulations. We parameterized the model based on phytoplankters' ecological and physical characteristics, for both large and small phytoplankton. Defining a zone of potential interactions as the overlap between nutrient depletion volumes, we show that local species composition-within the range of possible interactions-depends on the size class of phytoplankton. In small phytoplankton, individuals remain in mostly monospecific clusters. Spatial structure therefore favours intra- over inter-specific interactions for small phytoplankton, contributing to coexistence. Large phytoplankton cell neighbourhoods appear more mixed. Although some small-scale self-organizing spatial structure remains and could influence coexistence mechanisms, other factors may need to be explored to explain diversity maintenance in large phytoplankton.

Zooplankton seasonal vertical migration in an optimality-based plankton ecosystem model

Abstract Several species from various zooplankton taxa perform seasonal vertical migrations (SVM) of typically several hundred meters between the surface layer and overwintering depths, particularly in high-latitude regions. We use OPtimality-based PLAnkton (OPPLA) ecosystem model) to simulate SVM behavior in zooplankton in the Labrador Sea. Zooplankton in OPPLA is a generic functional group without life cycle, which facilitates analyzing SVM evolutionary stability and interactions between SVM and the plankton ecosystem. A sensitivity analysis of SVM-related parameters reveals that SVM can amplify the seasonal variations of phytoplankton and zooplankton and enhance the reduction of summer surface nutrient concentrations. SVM is often explained as a strategy to reduce exposure to visual predators during winter. We find that species doing SVM can persist and even dominate the summer-time zooplankton community, even in the presence of Stayers, which have the same traits as the migrators, but do not perform SVM. The advantage of SVM depends strongly on the timing of the seasonal migrations, particularly the day of ascent. The presence of higher (visual) predators tends to suppress the Stayers in our simulations, whereas the SVM strategy can persist in the presence of non-migrating species even without higher predators.

Phytoplankton Diversity and Distribution in the Festac Creek, Lagos, Nigeria

Phytoplankton Diversity and Distribution in the Festac Creek, Lagos, Nigeria

Comprehensive assessment of eutrophication in Tangxun Lake, a large urban lake in the middle reaches of the Yangtze River

Urban lakes play an important role in supporting the ecological environment and human society, yet increasing pollution poses a threat to water quality. Tangxun Lake, a typical Large urban lake in the middle reaches of the Yangtze River, has experienced cultural eutrophication in recent years; however, few studies have comprehensively examined the water quality of this lake. Therefore, we aimed to evaluate the water quality of the Tangxun Lake Basin using the Nemerow pollution index, principal component analysis (PCA), phytoplankton density and diversity, and the comprehensive trophic level index (TLI). Additionally, we analyzed the main influencing factors to provide a reference for the management of the aquatic environment of Tangxun Lake. The Nemerow pollution index evaluation showed that the annual degree of pollution in Tangxun Lake ranged from mild to heavy. The PCA results showed that the main pollution factors affecting water quality were total phosphorus (TP) and total nitrogen (TN). According to the results of TLI, the water in Tangxun Lake was moderately to severely eutrophic. Evaluation of algal cell density showed that Tangxun Lake was mesotrophic, and the phytoplankton diversity index showed that the eutrophication level was high. The degree of pollution in Tangxun Lake varied seasonally and was in the order of spring > winter > summer > autumn. The pollution in inner Tangxun Lake was relatively serious in spring, summer, and autumn, whereas that in outer Tangxun Lake was more serious in winter. This study provides a scientific basis for the comprehensive management of the ecological environment in the Tangxun Lake Basin.

Diversity Patterns of Eukaryotic Phytoplankton in the Medog Section of the Yarlung Zangbo River

As one of the important biodiversity conservation areas in China, the ecosystem in the lower reaches of the Yarlung Zangbo River is fragile, and is particularly sensitive to global changes. To reveal the diversity pattern of phytoplankton, the metabarcode sequencing was employed in the Medog section of the lower reaches of the Yarlung Zangbo River during autumn 2019 in present study. The phytoplankton assemblies can be significantly divided into the main stem and the tributaries; there are significant differences in the phytoplankton biomass, alpha and beta diversity between the main stem and the tributaries. While both the main stem and the tributaries are affected by dispersal limitation, the phytoplankton assemblages in the entire lower reaches are primarily influenced by heterogeneous selection. Community dissimilarity and assembly process were significantly correlated with turbidity, electrical conductivity, and nitrogen nutrition. The tributaries were the main source of the increase in phytoplankton diversity in the lower reaches of the Yarlung Zangbo River. Such diversity pattern of phytoplankton in the lower reach may be caused by the special habitat in Medog, that is, the excessive flow velocity, and the significant spatial heterogeneity in physical and chemical factors between stem and tributaries. Based on the results and conclusions obtained in present study, continuous long-term monitoring is essential to assess and quantify the impact of global changes on phytoplankton.

Composition, Density and Diversity of Phytoplankton in Rathi Cheruvu, Bhadradri Kothagudem, Telangana, India

The current study deals with composition, density and diversity of phytoplankton during January 2023 to December 2023 monthly in the Rathi cheruvu, Bhadradri Kothagudem, Telangana, India. Samplings were collected from different locations of the study site during a one year research period. Several physico-chemical parameters were studied from two sampling stations such as water temperature, pH, DO, BOD, SO4, NO3, PO4 and Cl-, of which pH, DO and BOD were shown to be the most significant in growth and development of phytoplanton. In the current study revealed a total number of 43 species of phytoplankton belonging to four major classes i.e. Chlorophyceae with 16 species, Bacillariophyceae with 14 species, Euglenophyceae with three species and Cyanophyceae with 10 species. The maximum population of phytoplankton diversity was observed during summer followed by monsoon with a total 1058 phytoplankton species during one year of study period. Finally the study showed that the study site has a well balanced phytoplankton community.

Sedimentary DNA reveals phytoplankton diversity loss in a deep maar lake during the Anthropocene

AbstractAnthropogenic‐driven environmental change, including current climate warming, has influenced lake ecosystems globally during the Anthropocene. Phytoplankton are important indicators of environmental changes in lakes and play a fundamental role in maintaining the functioning and stability of these ecosystems. However, the extent to which lake phytoplankton were affected by anthropogenic or climatic forces during the Anthropocene remains unclear. Here, we investigated the 160‐yr‐long dynamics of the phytoplankton community (cyanobacteria and eukaryotic microalgae) in response to anthropogenic forcing in Sihailongwan Maar Lake—a candidate for a Global boundary Stratotype Section and Point for demarcation of the Anthropocene—using DNA metabarcoding and traditional paleolimnological approaches. Our results show a significant decline in phytoplankton diversity and an abrupt shift in community composition around the 1950s, corresponding to the beginning of the “Great Acceleration” period. Specifically, phytoplankton taxa coexistence patterns, niche differentiation, and assembly mechanisms changed significantly after the 1950s. Overall, increases in air temperature and anthropogenic forcing appear to be the dominant controls for community reorganization and diversity decline of the phytoplankton from this deep maar lake. A neutral community model suggests that phytoplankton community composition was mainly controlled by stochastic processes before the 1950s; however, as time progressed, deterministic effects driven by anthropogenic global warming increased. The results of this study imply that anthropogenic perturbations have led to a loss of phytoplankton diversity and a further decline in ecological resilience in deep lakes, with likely knock‐on effects on the productivity and function of lake ecosystems.