Phytoplankton Biodiversity Research Articles

PHYTOPLANKTON BIODIVERSITY AND POLLUTION BIOINDICATOR IN BOJONEGARA COASTAL WATERS, BANTEN BAY, INDONESIA

Coastal waters of Bojonegara in Banten Bay has a lot of pressure from the surrounding environment, including industry and sand mining. The high intensity and limited space encourage reclamation in coastal areas which can trigger changes in water quality. Research was conducted from October to December 2019, aims to analyze the phytoplankton biodiversity and pollution bioindicator of the waters. The phytoplankton was obtained through filtering 50 liters of water at a depth of 30 cm or surface waters. Observations were also made on water quality conditions including transparency, depth, color, temperature, pH, salinity, and dissolved oxygen (in-situ) and turbidity, Total Suspended Solid (TSS), nitrate, nitrite, and total phosphate (ex-situ). Data analysis was performed on abundance, diversity index, eveness and dominance, similarity index, and saprobic index. Based on observations, it is known that the phytoplankton found were in the class Bacillariophyceae, Chlorophyceae, Cyanophyceae, Dinophyceae, and Chrysophyceae. The index values of diversity, eveness, and dominance of phytoplankton each ranged from 0.2223-1.0070; 0,1289-0,5664; and 0.1550-0.8181, respectively. According to these values, the Bojonegara waters were classifeied as mild to moderate ecological pressure. The similar conditions are also indicated by the saprobic index values. The result of Main Component Analysis (PCA) shows the first component with 53.726% variance represented by turbidity parameters, TSS, total phosphate, transparency, depth, temperature, pH, and DO. These parameters have the most influence on the presence of phytoplankton.

Response of Phytoplankton Community Structure to Vegetation Restoration after Removal of Purse Seine in Shengjin Lake

Aquatic vegetation has been restored since the removal of seine nets from the lake surface of Shengjin Lake in 2018. Through four seasons of phytoplankton sampling surveys from 2019–2020, we analyzed spatial and temporal changes in phytoplankton communities, water quality, and aquatic plant recovery in conjunction with previous research literature to reveal the response mechanisms of phytoplankton community structure to rapidly recovering aquatic vegetation. The results showed that the Secchi depth increased (0.4 m to 0.7 m), the concentration of total phosphorus decreased (0.053 mg/L to 0.41 mg/L), the species of aquatic plants (5 species to 16 species), phytoplankton species (210 species to 254 species) and cell density increased after the removal of the seine. Since the removal of the seine of Shengjin Lake, the aquatic vegetation cover has exceeded 80%, the phytoplankton biodiversity has increased, and the water quality has recovered to II-III water status. Our results show that aquatic plants improve water quality through direct and indirect effects and influence phytoplankton community structure together with the water environment, which can provide guidance for the restoration situation of the middle and lower reaches of the Yangtze River through-river lake ecosystems.

An overview of Prorocentrum donghaiense blooms in China: Species identification, occurrences, ecological consequences, and factors regulating prevalence

Prorocentrum donghaiense Lu (also identified as Prorocentrum shikokuense Hada and Prorocentrum obtusidens Schiller) is a bloom-forming dinoflagellate species distributed worldwide. Blooms of P. donghaiense occur annually in adjacent waters of the East China Sea (ECS), especially in the waters near the Changjiang River Estuary. Blooms of this species have also been reported in nearby Japanese and Korean waters. There has been an apparent bloom-forming species succession pattern in the ECS since 2000, with diatom blooms in the early spring, shifting to long-lasting and large-scale dinoflagellate blooms dominated by P. donghaiense during the spring, and finally ended by diatom and/or Noctiluca scintillans blooms in summer. These bloom succession patterns were closely correlated with changes in environmental factors, such as temperature increase and anthropogenic eutrophication. Decreasing silicate by the construction of the Three Gorges Dam and increasing dissolved inorganic nitrogen flux were mainly influenced by high intensity human activities in the Changjiang River watershed, resulting in low Si/N ratio and high N/P ratios, possibly accelerating outbreak of P. donghaiense blooms. Phosphorous deficiency might be the most critical factor controlling the succession of microalgal blooms from diatoms to dinoflagellates. Prorocentrum donghaiense is a nontoxic species, but it can disrupt marine ecosystem by decreasing phytoplankton biodiversity and changing the structure of the food chain. Prorocentrum donghaiense blooms in the ECS have been intensively studied during the last two decades. Several possible mechanisms that contribute or trigger the annual blooms of this species have been proposed, but further research is required particularly on the aspect of nutrient budget, ecosystem impacts, as well as social-economic impact assessment.

Effects of suspended ecological beds on phytoplankton community structure in Baiyangdian Lake, China

To address the issues of submerged vegetation restoration in the deep-water area of Baiyangdian Lake, a type of suspended ecological bed was developed, which was constructed with aquatic plants, ropes and supporting poles. The depth of a suspended ecological bed could be adjusted based on the water level. From July to November 2019, the phytoplankton community structure in the water around the suspended beds was continually monitored, and the effects of the submerged plants present in the suspended beds on the phytoplankton community structure in the deep-water area of the lake were studied. The results showed that Myriophyllum spicatum L. grew well in the suspended beds, with 95% survival after 60 d. The maximum biomass was reached in 55 d, and the water surface coverage reached 23%. There were 71 species of phytoplankton belonging to seven phyla in the water surrounding the suspended ecological beds. Over half (36 species) were members of Prochlorophyta, and the average density and biomass of phytoplankton gradually decreased month by month. The proportion of cyanobacteria in the community showed a downwards trend, while the proportions of other phytoplankton phyla showed upwards trends. The annual average Shannon–Wiener diversity index was 0.88, the annual average Pielou evenness index was 0.32, and the annual average Margalef richness index was 1.21. The Shannon–Wiener diversity index and Pielou's evenness index both showed increasing trends. This comprehensive analysis shows that planting submerged plants in suspended beds can improve the phytoplankton community structure of the surrounding water and increase the biodiversity of phytoplankton, making this an effective measure for restoring submerged vegetation in algae-dominated northern lakes.

Phytoplankton Biodiversity in Two Tropical, High Mountain Lakes in Central Mexico

Lakes El Sol and La Luna, inside the crater of the Nevado de Toluca volcano, Central Mexico, are the only two perennial high mountain lakes [HML] in the country. HML are considered among the most comparable ecosystems worldwide. These lakes are “extreme” environments with diluted, oligotrophic, and cold waters exposed to high UV radiation doses. In this paper, we document the phytoplankton species inhabiting these two extreme tropical ecosystems. The phytoplankton diversity of Lakes El Sol and La Luna is low compared to the global phytoplankton diversity from other Mexican inland waters. Nonetheless, the phytoplankton diversity turned out to be high compared to other HML worldwide, both temperate and tropical. The phytoplankton community in Lake El Sol was formed by 92 morphospecies and in Lake La Luna by 63; in both, the most diverse groups were Bacillariophyceae and Chlorophyceae. All species found in Lake La Luna were present in Lake El Sol, but 29 species present in Lake El Sol were absent in Lake La Luna. Nevertheless, 57% of the most frequent and abundant taxa in Lake El Sol were rare in La Luna, and 47% of the most frequent and abundant taxa in Lake La Luna were rare in Lake El Sol. Associated with their shallowness and polymictic thermal pattern, 87.5% of the Bacillariophyceae morphospecies are tychoplantonic, while the remaining 12.5% are truly planktonic. Dominant taxa were Chlorophyceae in Lake El Sol and Cyanobacteria in Lake La Luna. The most extreme conditions of Lake La Luna (ultraoligotrophy, very low pH, high ultraviolet radiation) most likely explained the differences in the dominant species composition and lower species richness compared to Lake El Sol. Herein, we provide for the first time a taxonomic list of the phytoplankton community of Lakes El Sol and La Luna. This information constitutes a baseline needed to use these HML as sentinels of global and climate change.

Phytoplankton community structure and driving mechanism of its construction process in autumn in Zhelin Reservoir, Lake Poyang Basin

研究环境过滤过程和空间扩散限制过程在构建水生浮游植物群落结构中的作用是了解这些因素如何驱动物种分布和影响群落结构的关键步骤.为了揭示鄱阳湖流域柘林水库浮游植物群落结构特征与环境因子的关系，以及明确环境因子和空间扩散限制性因子在浮游植物群落构建过程中的影响机制，于2020年10月，对柘林水库33个采样点的浮游植物和水质理化进行调查分析.共鉴定浮游植物7门122种，其中，以绿藻门种类最多，为34属62种，占总物种数的50.81%，硅藻门次之，为11属27种.柘林水库浮游植物优势种类主要是蓝藻门中的伪鱼腥藻属（Pseudoanabaena）、浮鞘丝藻属（Planktolyngbya）、小尖头藻属（Raphidiopsis）以及硅藻门中的针杆藻属（Synedra）.柘林水库浮游植物细胞丰度的变化范围为0.93×10⁶~172.12×10⁶ cells/L，平均值为95.42×10⁶ cells/L，生物量的变化范围为0.95~22.35 mg/L，平均值为9.35 mg/L.上游修河水域浮游植物生物多样性指数显著高于库心和库湾水域，库心与库湾水域之间浮游植物生物多样性指数差异性不明显.柘林水库上游修河水域浮游植物群落结构与库心和库湾水域存在明显分离，群落结构的差异性主要受水体透明度、电导率、氨氮和硝态氮的影响.变差分解结果显示，空间扩散限制性作用在驱动柘林水库浮游植物群落构建过程中占据主导地位.;Evaluation of the relative influences of environmental and spatial processes in structuring aquatic phytoplankton metacommunities is an essential step for understanding the species spatio-temporal distributions. To reveal the relationships between community structures of phytoplankton and the environment as well as clarify the driving mechanism of environmental factors and spatial diffusion limiting factors on phytoplankton community structure in Zhelin Reservoir, Lake Poyang Basin, the phytoplankton and water quality physicochemical characteristics of 33 sampling sites were investigated and analyzed in October 2020. A total of 122 species belong to 7 genera were identified, with 62 species in 34 genera were Chlorophyta, accounting for 50.81% of the total species, followed by Bacillariophyta with 27 species in 11 genera. The dominant species of phytoplankton in Zhelin Reservoir are Pseudoanabaena, Planktolyngbya and Raphidiopsis of Cyanophyta and Synedra of Bacillariophyta. The cell abundance of phytoplankton in the Zhelin Reservoir varied from 0.93×10⁶ to 172.12×10⁶ cells/L with an average of 95.42×10⁶ cells/L, and the biomass varied from 0.95 to 22.35 mg/L with an average of 9.35 mg/L. The phytoplankton biodiversity index in the upstream Xiuhe tributary area was significantly higher than that in the center of the reservoir area and the reservoir bay area, while no significant difference in the phytoplankton biodiversity index between the center of the reservoir area and the reservoir bay area was found. The phytoplankton community structure in the Xiuhe tributaries of Zhelin Reservoir was separated from that in the center reservoir and reservoir bay, and the differences were mainly affected by water transparency, electrical conductivity, ammonia nitrogen and nitrate nitrogen. The results of variation partitioning showed that the spatial diffusion limiting effect was dominant in driving the phytoplankton community structure in Zhelin Reservoir.

Biodiversity and Abundance of Phytoplankton from Auranga Estuary, Valsad District, Gujarat, India

This study describes phytoplankton abundance and diversity from site 1 (downstream) and site 2 (upstream) of Auranga Estuary (20˚63’ N and 72˚82’ E). A Total of 44 species of phytoplankton were recorded, 35 species from downstream and 24 species from upstream. The assessed abundance was 129 cells/mL and 86 cells/mL from the downstream and upstream, respectively. Bacillariophyceae (19) was the dominant group followed by Chlorophyceae (10), Cyanobacteria (07), Dinophyceae (07), and Chrysophyceae (01). Nitzschia, Coscinodiscus and Ceratium were abundant genera at site 1 and Spirogyra, Microcystis, Chlorella and Oscillatoria were abundant at site 2. Nitzschiaceae and Zygnemataceae had highest family contribution at the downstream and upstream, respectively. Members of Bacillariophyceae and Cyanobacteria were present in high numbers throughout the year. The abundance of Chlorophyceae did not fluctuate greatly. Chrysophyceae (Chromulina pascheri) was observed during the summer period. Spatially, downstream had higher species diversity and abundance than upstream whereas winter season was favorable for plankton growth compared to summer and monsoon. Species dominance (Site 1: 0.238; Site 2: 0.257) richness (Site 1: 1.13; Site 2: 1.36), evenness (Site 1: 0.88; Site 2: 0.79) and diversity were assessed using alpha biodiversity indices. The Shannon diversity index was 1.417 and 1.268 for downstream and upstream, respectively. It indicates less diversity level in this estuary.

Carbon, nutrient and metal controls on phytoplankton concentration and biodiversity in thermokarst lakes of latitudinal gradient from isolated to continuous permafrost

Shallow thaw (thermokarst) lakes abundant in regions of permafrost-affected peatlands represent important sources of carbon dioxide and methane emission to the atmosphere, however the quantitative parameters of phytoplankton communities which control the C cycle in these lakes remain poorly known. This is especially true considering the roles of permafrost, hydrochemical composition of lakes, lake sizes and season as major governing factors on phytoplankton abundance and biodiversity. In this work, we quantified phytoplankton characteristics of 27 thermokarst lakes (sizes ranging from 115 m2 to 1.24 km2) sampled in spring, summer and autumn across a permafrost gradient (isolated, sporadic, discontinuous and continuous zone) in the Western Siberia Lowland (WSL). The biodiversity indices were highest during all seasons in lakes of the continuous permafrost zone and rather similar in lakes of isolated, sporadic and discontinuous permafrost zone. Considering all seasons and permafrost zones, the biomass and cell number of phytoplankton correlated with Dissolved Organic Carbon (DOC), phosphate, and some metal micro-nutrients (Ni, Zn). The strongest correlations were observed for Cyanophycea during summer, with pH, Ni, Cu, Zn, Sr, Ba (cell number) and Cu, Zn, Ba (biomass), and during autumn, with DOC, K, Cr, Cu, Zn, Ba, Cd, Pb (biomass). Using a substituting space for time approach for climate warming and permafrost thaw and suggesting a shift in permafrost boundaries northward, we foresee an increase in cell number and biomass in continuous permafrost zone in spring and summer, and a decrease in phytoplankton abundance in the discontinuous and sporadic permafrost zones. The biodiversity of phytoplankton in the continuous permafrost zone might decrease whereas in other zones, it may not exhibit any sizably change. However, in case of strong deepening of the active layer down to underlaying mineral horizons, and the release of some limiting nutrients (Si, P) due to enhanced connectivity of the lake with groundwater, the share of cyanobacteria and diatoms may increase.

Sulfamethoxazole and Enrofloxacin Antibiotics Affect Primary Productivity of Phytoplankton in Fishery Environment

The antibiotics sulfamethoxazole (SMZ) and enrofloxacin (ENF) are commonly used in aquaculture in China, but their effects on the primary productivity of phytoplankton are unclear. On the basis of the fishery drug use standards (SMZ, 100 mg kg−1 d−1; ENF, 15 mg kg−1 d−1), these antibiotics were put into culture ponds to observe their effects on the phytoplankton community and primary productivity. The results showed that the changes in phytoplankton species at SMZ and ENF sites were different. At the ENF sites, Bacillariophyta species increased from 7 to 9, euglenophyta from 8 to 12 and cyanophyta from 11 to 9. Chlorophyta species at the SMZ sites increased from 10 to 15 and euglenophyta from 7 to 4. SMZ and ENF significantly promoted the number of cyanophyta (p < 0.05). The promoting effect of SMZ was more obvious than that of ENF. SMZ was more effective than ENF in promoting cyanophyta. The maximum number of cyanophyta at SMZ sites was 52.39 million L−1, and the concentration of SMZ was positively correlated with the number of cyanophyta. The maximum number of cyanophyta at ENF sites was 33.13 million L−1, and the promoting effect of low concentrations was more significant than that of high concentrations. Both SMZ and ENF promoted increased phytoplankton biomass, consistent with the residual time of the antibiotics in the aquaculture environment. The greatest biomass at the SMZ sites was 129.31 g m−³, and that at the ENF sites was 117.85 g m−³. The changes in the α diversity index showed that both SMZ and ENF led to a decrease in phytoplankton biodiversity, and that SMZ was more harmful to it. There were significant differences in the Shannon–Wiener, Pielou and Simpson indexes of the SMZ sites within groups (p < 0.05). The β diversity index showed that both antibiotics could change the phytoplankton habitat, but the effect of ENF on the habitat was recoverable, while that of SMZ prevented its restoration. These data will be valuable in protecting the ecological environment of fisheries and ensuring the safety and stability of fishery aquatic ecosystems.

Phytoplankton biodiversity is more important for ecosystem functioning in highly variable thermal environments

The 21st century has seen an acceleration of anthropogenic climate change and biodiversity loss, with both stressors deemed to affect ecosystem functioning. However, we know little about the interactive effects of both stressors and in particular about the interaction of increased climatic variability and biodiversity loss on ecosystem functioning. This should be remedied because larger climatic variability is one of the main features of climate change. Here, we demonstrated that temperature fluctuations led to changes in the importance of biodiversity for ecosystem functioning. We used microcosm communities of different phytoplankton species richness and exposed them to a constant, mild, and severe temperature-fluctuating environment. Wider temperature fluctuations led to steeper biodiversity-ecosystem functioning slopes, meaning that species loss had a stronger negative effect on ecosystem functioning in more fluctuating environments. For severe temperature fluctuations, the slope increased through time due to a decrease of the productivity of species-poor communities over time. We developed a theoretical competition model to better understand our experimental results and showed that larger differences in thermal tolerances across species led to steeper biodiversity-ecosystem functioning slopes. Species-rich communities maintained their ecosystem functioning with increased fluctuation as they contained species able to resist the thermally fluctuating environments, while this was on average not the case in species-poor communities. Our results highlight the importance of biodiversity for maintaining ecosystem functions and services in the context of increased climatic variability under climate change.

Comparative analysis of freshwater phytoplankton communities in two lakes of Burabay National Park using morphological and molecular approaches

We analyzed phytoplankton assemblages’ variations in oligo-mesotrophic Shchuchie and Burabay lakes using traditional morphological and next-generation sequencing (NGS) approaches. The total phytoplankton biodiversity and abundance estimated by both microscopy and NGS were significantly higher in Lake Burabay than in Lake Shchuchie. NGS of 16S and 18S rRNA amplicons adequately identify phytoplankton taxa only on the genera level, while species composition obtained by microscopic examination was significantly larger. The limitations of NGS analysis could be related to insufficient coverage of freshwater lakes phytoplankton by existing databases, short algal sequences available from current instrumentation, and high homology of chloroplast genes in eukaryotic cells. However, utilization of NGS, together with microscopy allowed us to perform a complete taxonomic characterization of phytoplankton lake communities including picocyanobacteria, often overlooked by traditional microscopy. We demonstrate the high potential of an integrated morphological and molecular approach in understanding the processes of organization in aquatic ecosystem assemblages.

Association of Seawater Nanoparticle Size Distribution With Diversity of Marine Plankton

Upon tangential ultrafiltration and asymmetric flow field analyses, seawater nanoparticle size distribution and the associations with the total number of bacteria and plankton diversity were evaluated. Of the nanoparticles in the Jiulong River Estuary, 79% were from 1 to 6 nm (C1). C2 (6–20 nm) was correlated with dissolved organic carbon, while C2 and C3 (>20 nm) were associated with dissolved inorganic nitrogen, suggesting that C2 and C3 were impacted by biogenic elements. The total number of bacteria was correlated with C1 and C3. The correlations of Shannon's diversity index (H′) and C3, richness (d), and C1 suggested a link of particle size with phytoplankton biodiversity. Significant correlations of the H′ of zooplankton and C3, and of Pielou's evenness index (J) and C3, suggested C3 as a primary digestion product of zooplankton. The negative correlations of nano-organic carbon (NOC) with d and J suggested NOC as a carbon source for zooplankton. Biodiversity was associated with seawater nanoparticle size distribution. Biological activities regulated the nanoparticle size distribution, which impacted the estuarine nutrient cycling, in turn affecting the stability and balance of biodiversity. Correlation analysis of the size distribution of seawater nanoparticles and the plankton diversity index provided a potential tool for evaluating ecological effects.

Varying influence of phytoplankton biodiversity and stoichiometric plasticity on bulk particulate stoichiometry across ocean basins

Concentrations and elemental ratios of suspended particulate organic matter influence many biogeochemical processes in the ocean, including patterns of phytoplankton nutrient limitation and links between carbon, nitrogen and phosphorus cycles. Here we present direct measurements of cellular nutrient content and stoichiometric ratios for discrete phytoplankton populations spanning broad environmental conditions across several ocean basins. Median cellular carbon-to-phosphorus and nitrogen-to-phosphorus ratios were positively correlated with vertical nitrate-to-phosphate flux for all phytoplankton groups and were consistently higher for cyanobacteria than eukaryotes. Light and temperature were inconsistent predictors of stoichiometric ratios. Across nutrient-rich and phosphorus-stressed biomes in the North Atlantic, but not in the nitrogen-stressed tropical North Pacific, we find that a combination of taxonomic composition and environmental acclimation best predict bulk particulate organic matter composition. Our findings demonstrate the central role of plankton biodiversity and plasticity in controlling linkages between ocean nutrient and carbon cycles in some regions.

Phytoplankton Composition in Relation to Its Nutritional Value in Burullus Lagoon, Egypt

Burullus Lagoon is a brackish water lake in the Nile Delta of Egypt. This study assumed that changes in environmental conditions affect phytoplankton species composition and their biochemical structure. The biochemical content of phytoplankton is considered as an initiatory study at Lake Brullus. Winter versus summer cruises from twelve sites representing the eastern, middle and western main lake basins were performed during 2018. Phytoplankton revealed a seasonally variation which attained the lowest value during winter season (72300 Unit/L) and the highest levels during summer season (88700 Unit/L). This is coincided with high total protein content (2692.5 mg/l) in summer. Chlorophyceae was the first major class by (37.9 %) followed by Bacillariophyceae (29.31%), then Cyanophyceae (20.7%), while, Euglenophyceae and Dinophyceae are rare classes constitute (8.63% and 3.4% respectively). Middle of the lake recorded the maximum total biochemical contents in winter (870.5, 57.6 and 6.1 mg/l of proteins, carbohydrates and lipids, respectively), this results corresponding to the elevation of total phytoplankton density at this central basin (29200 Unit/L), especially the Chlorophyceae (13700 Unit/L). The western basin had an optimum total biochemical structure in summer (1909.1, 55.4 and 6.5 mg/l) of proteins, carbohydrates and lipids, respectively, where phytoplankton was increased to 56000 Unit/L. The middle and western basins lied in mesotrophic to eutrophic state according to the Q index. Excessive nutrients loads by drainage water into the lagoon lead to significant pronounced effect in the phytoplankton biodiversity raise the urgent need for lagoon management strategies.

Biodiversity and community of phytoplankton in the mahseer conservation area at Bungo and Kerinci Regencies, Jambi Province, Indonesia

Mahseer (Tor spp.) conservation programs require information related to habitat characteristics including phytoplankton biodiversity and community structure as biological characteristics. This study aimed to evaluate phytoplankton diversity and community structure in the mahseer habitat, namely reservation and protection area in Muara Bungo and Kerinci Districts of Jambi Province. This study was conducted four times samplings i.e. December 2018, April 2019, July 2019, and October 2019, at three sites of the protected area, namely in Lubuk Alai, Senamat River, and the protected area of Tarutung Village. Furthermore, the data at the three sites were compared with data outside the protected area. Biological indices of the phytoplankton were calculated. The results showed that the mahseer habitat had a high diversity of phytoplankton. The results showed that the mahseer habitat had 8 genera of phytoplankton diversity, dominated by the Bacillariophyceae class, especially Synedra sp. with a dominance rate of more than 60% at each station. The diversity index ranged from 0.95 to 1.18, the evenness index ranged from 0.40 to 0.82, and the dominance index ranged from 0.39–0.43 in protected areas.

Spatial and environmental factors contributing to phytoplankton biogeography and biodiversity in mountain ponds across a large geographic area

Exploring phytoplankton biodiversity and biogeographic patterns, and the factors that control them, can help to understand the structure and function of aquatic ecosystems. We selected mountain ponds with minimal anthropogenic disturbance to reveal the biogeographic patterns of phytoplankton and to assess the influence of spatial and environmental factors on phytoplankton biodiversity. On a large regional scale, the phytoplankton communities in the mountain ponds showed geographic patterns—the community composition differed between eastern and western areas. A total of seven phyla and 73 genera were identified. Alpha diversity indices did not significantly correlate with nutrient concentrations. Environmental factors and principal coordinates of neighbour matrices together explained 28.5% of the total variation in phytoplankton community composition in the 41 ponds, with each uniquely explaining 3.0% and 14.4% of the total variation, respectively. Therefore, compared with environmental factors, spatial factors predominantly contributed to the distribution of phytoplankton across the study area. With increasing trophic status, the relative influence of spatial factors decreased, while that of environmental factors increased.

Impacts of the Physico-chemical Properties of Al-Chibayish Water Marshes on The Biodiversity of Phytoplankton

Phytoplankton, as one of the most important primary producers in aquatic ecosystems, has been widely used to indicate the health of ecosystems. Nine physico-chemical parameters of water, as well as the phytoplankton community, of Al-Chibayish marsh were studied. Samples were collected from four sites and analyzed every two months from January to October 2019.
 Seasonal variations in physical and chemical properties were observed at all sites during the study period. The results indicated that 154 species of phytoplankton were recorded. The highest percentage of species was recorded to be 64.28% for Bacillariophyceae (diatoms) (Centrales 3.24% and Pennales 61.03%), followed by Chlorophyceae (16.23%), Cyanophyceae (11.68%), and Charophyceae and Euglenophyceae (3.24%), while Pyrrophyceae recorded the lowest value (1.29%) The numbers of phytoplankton species were 102, 94, 102, 99 in sites 1, 2, 3 and 4 ,respectively, during the study period. The total density of phytoplankton ranged from 223.769 cells x103 during January to 2784.693 cells x103 during September in site 2, with a clear increase during March and September, while the lowest number was 223.796 - 237.248 cells x103 in January and May, respectively. The dominance of diatoms was observed in all sites by 49.07% of the total density of phytoplankton, while the lowest abundance was 0.04% for the Pyrrophyceae. The results of the statistical analysis showed significant differences among sites and months, concerning the physical, chemical, and biological factors measured during the study period, at p-value <0.05.

Impact of the Water–Sediment Regulation Scheme on the phytoplankton community in the Yellow River estuary

The Water–Sediment Regulation Scheme (WSRS) transports large amounts of water, sediment, and nutrients to the Yellow River estuary (YRE) in a very short time, which significantly changes the ecological environment of the estuary area in summer (wet season). The influence of these changes on the distribution and abundance of phytoplankton communities in the YRE are still inadequately understood. We studied the spatial distribution of environmental factors, zooplankton abundance and biomass, and phytoplankton abundance and community in the YRE at different WSRS stages during 2018 (WSRS year) and compared with corresponding durations in 2017 (non–WSRS year). Our results demonstrate that the WSRS (1) promoted phytoplankton growth in estuarine areas at the pre-stage and decreased phytoplankton abundances in the entire study area during the inter-stage, (2) decreased phytoplankton biodiversity and increased abundance and proportion of Synedra sp., and (3) led to a temporary rapid increase in zooplankton abundance and biomass. Bottom–up effects dominated phytoplankton variability at the pre- and end-stages of the WSRS, while top–down effects dominated the inter-stage. Redundancy analysis indicated that phytoplankton assemblages were primarily influenced by nitrate and the ratio of nitrogen to phosphorus at the pre-stage, by zooplankton abundance and biomass at the inter-stage, and by ammonium and dissolved silica at the end-stage. Our findings provide essential information for understanding and predicting the changes in the phytoplankton community due to increases in hydrodynamics, nutrients, and turbidity conditions in river estuaries.

Mobility of carbohydrates, proteins, phenol and eutrophication assessment in a brackish Egyptian lake; predicted equations

ABSTRACT Although great efforts have been devoted in assessing the ecological risks in aquatic environments, a lack of information is still present. An integrative approach was proposed concerning the mobility of carbohydrates, proteins and phenol among water, sediments and macrophytes in relation to the physical, chemical and geochemical parameters of Lake Mariout. Total carbohydrates, proteins and phenol showed averages of 6.80 mg L−1, 116.90 mg L−1 and 19.46 µg L−1; 89.82 mg g−1; 29.21 mg g−1 and 1.80 µgg−1; and 60.80 mg g−1, 15.27 mg g−1 and 9.29 mg g−1 in water, sediments and macrophytes, respectively. Protein/carbohydrate ratios in sediments were used as the trophic indicator. This study cleared out that all stations had ratios (<1) refereeing to aged organic matter. Station 6 indicated fresh organic matter. Moreover, the ratio of total organic carbon to total nitrogen (TOC/TN) suggested a primarily marine origin at eleven stations (<10) and a mixture of terrestrial input and marine materials (>10) at stations 1 and 7 located in the North-West Basin. Relatively high phenol concentrations of 54.5, 38.25 and 45.37 µgL−1 in water were measured at stations (3 & 5) located in the Main Basin, and station 11 located at El-Qalaa drain, respectively. The partition coefficient of phenol (Kd) varied from 0.053 to 0.199 (<1 Lg−1) revealing high mobility and an underground disposal facility. The low biodiversity of phytoplankton (38 spp.), seagrasses (4 spp.) and seaweed (3 spp.) inside the lake reflected the impact of wastewater discharged. Two phytoplankton blooms were observed at stations 3 and 7. According to the Diversity Index of Boyd, all Mariout stations (<4) are moderately polluted. Multivariate analyses were adopted to describe the lake chemistry. This study gives a conceptual framework helps decision-makers to express the problem of sustainability at Lake Mariout.

Lake Poyang ecosystem services changes in the last 30 years

鄱阳湖是我国最大淡水湖，在维持区域生态安全和生态平衡中发挥重要作用.为了解近30年鄱阳湖生态系统服务变化情况，本文对已有文献与监测数据进行收集整理，直接获取鄱阳湖水资源供给、渔业资源供给、水环境净化服务数据，通过输沙量法、Berger-Parker优势度指数计算泥沙淤积调控和生物多样性维持服务，利用RMSD方法分析1992—2014年鄱阳湖生态系统服务关系.结果表明：（1）渔业资源供给和水环境净化服务不断下降，水资源供给和泥沙淤积调控服务在2010s有所恢复；（2）冬候鸟种类和数量增加，鱼类种群结构逐渐恢复，但Berger-Parker指数总体上升；（3）浮游植物、底栖动物多样性上升，浮游动物多样性下降；（4）不同时间尺度各服务间均为高权衡关系，水环境净化服务相对收益始终高于其他服务.;As the largest freshwater lake in China, Lake Poyang plays a vital role in maintaining regional ecological security and ecological balance. Due to natural changes and human activities, the hydrology and hydrodynamics of Lake Poyang changed, and the ecosystem of Lake Poyang was seriously threatened, which directly led to the degradation of ecosystem services. In order to capture ecosystem services changes of the Lake Poyang in the past 30 years, the existing literature and monitoring data were systematically collected and sorted to obtain data on Lake Poyang's water supply, fish supply, and water depuration services directly. Sediment transport method and Berger-Parker index were used to estimate sedimentation control and biodiversity protection services. The root mean square deviation (RMSD) method was applied to explore the temporal change of the trade-off relationships of Lake Poyang from 1992 to 2014. The results show that: (1) Fish supply and water depuration services continued to decline. Water supply and sedimentation control services recovered gradually in the 2010s. (2) The biodiversity of winter migratory birds and fish biodiversity increased slightly, characterised by the increased species and number of winter migratory birds and the fish population composition. (3) The biodiversity of phytoplankton and benthic animals increased, and the biodiversity of zooplankton decreased. (4) All the ecosystem service pairs had high trade-off relationships, and water depuration service always had a relatively higher benefit than other services.