River Phytoplankton Research Articles

Structural Characteristics of Phytoplankton Communities and Its Relationship with Environmental Factors in Different Habitats of Hedi Reservoir

To explore the characteristics of phytoplankton communities and their relationship with environmental factors in different habitats of Hedi Reservoir, the inflow rivers, estuaries, and reservoir area of Hedi Reservoir were investigated in February （recession period）, April （flood period）, July （flood period）, and December （recession period） of 2022. During the investigation, 231 species of phytoplankton that belong to seven phyla were identified, and the cell density of phytoplankton ranged from 2.94 × 106 - 8.04 × 108 cells·L-1. Phytoplankton cell density in flood periods were higher than that in recession periods, and that was higher in estuaries and the reservoir area than that in inflow rivers. Meanwhile, the cell density of phytoplankton in the estuarine and reservoir area was dominated by Cyanobacteria throughout the year, especially Raphidiopsis raciborskii, whereas the cell density of phytoplankton in inflow rivers was dominated by Cyanophyta, Chlorophyta, and Bacillariophyta. In the inflow river area, the dominant species of cyanobacteria were Microcystis aeruginosa, Limnothrix redekei, Pseudanabaena circinalis, and Merismopedia punctata； the dominant species of Chlorophyta were Chlorella vulgaris and Crucigenia tetrapedia； and the dominant species of Bacillariophyta were Chlorella vulgaris and Melosira granulate. The highest biodiversity （Shannon-Wiener Index, Pielou index, and Margalef index） were observed in the inflow river area of Hedi Reservoir. The correlation analysis （Pearson） indicated that the environmental factors that were significantly correlated to phytoplankton communities included water temperature, dissolved oxygen, pH, conductivity, nitrogen, and phosphorus concentration. The RDA analysis indicated that phytoplankton communities in the inflow river area were mainly affected by pH and total nitrogen concentration, which were majorly affected by water temperature and pH in the estuarine area and chiefly affected by turbidity and pH in the reservoir. The pH affected the changes in phytoplankton communities in all three different habitats, whereas the inflow river area was significantly affected by total nitrogen concentration, and the estuarine and reservoir were significantly affected by water temperature and turbidity, respectively.

Assessing ecological status using phytoplankton functional groups in three urban rivers in Hainan Island, China.

The urban rivers, including Changwang, Meishe, and Wuyuan in Haikou City, Hainan Island, are vital water sources for agricultural production and support industrial and domestic activities. Despite the rivers experiencing anthropogenic impacts, limited studies have assessed their water quality. Accordingly, this study assessed the phytoplankton community structure, utilized the river phytoplankton assemblage index (Qr index) to evaluate the ecological status, and compared its performance with the comprehensive trophic level index (TLI). Sample collection and microscopy analysis was conducted seasonally in 2019. Two hundred ninety-eight phytoplankton species belonging to 8 phyla were identified, predominated by Chlorophyta, Bacillariophyta, and Cyanophyta. The phytoplankton biomass ranged from 0.04 to 34.98mg L-1, with averages of 3.06 ± 0.71, 5.16 ± 1.92, and 2.70 ± 0.76mg L-1 in Changwang, Meishe, and Wuyuan, respectively. The phytoplankton biomass varied seasonally, recording the highest and lowest values in summer and autumn, respectively. The phytoplankton species were classified into 26 functional groups, which exhibited spatial and seasonal differences in their biomass and composition. The redundancy analysis (RDA) revealed that NH3-N, TP, CODMn, Chl-a, salinity, and temperature were the main environmental factors influencing phytoplankton functional groups. The average Qr index values in Changwang, Meishe, and Wuyuan were 3.39 ± 0.61, 3.44 ± 0.51, and 3.22 ± 0.67, and all the rivers were rated "good" in status. Seasonally, the Qr index and TLI revealed that the rivers' ecological condition was better in autumn and winter compared to spring and summer. Generally, the Qr index performed better, indicating that parameters such as NH3-N, CODMn, TP, and Chl-a decreased with improving ecological conditions from "poor" to "excellent" status. In addition, the Qr index exhibited a significant negative relationship with TLI, suggesting that low Qr index values may indicate increased eutrophication or deteriorated water quality. Thus, the ecological condition of the urban rivers could be adequately assessed using the Qr index to guide their water quality monitoring and management.

Predicting river phytoplankton blooms and community succession using ecological niche modeling

AbstractExcessive phytoplankton concentrations in rivers can result in the loss of plant and invertebrate communities, and threaten drinking water supplies. Whilst the physicochemical controls on algal blooms have been identified previously, how these factors combine to control the initiation, size, and cessation of blooms in rivers is not well understood. We applied flow cytometry to quantify diatom, chlorophyte, and cyanobacterial group abundances in the River Thames (UK) at weekly intervals from 2011 to 2022, alongside physicochemical data. A niche modeling approach was used to identify thresholds in water temperature, flow, solar radiation, and soluble reactive phosphorus (SRP) concentrations required to produce periods of phytoplankton growth, with blooms only occurring when all thresholds were met. The thresholds derived from the 2011 to 2018 dataset were applied to a test data set (2019–2022), which predicted the timing and duration of blooms at accuracies of > 80%. Diatoms and nano‐chlorophyte blooms were initiated by flow and water temperature, and usually terminated due to temperature and flow going out of the threshold range, or SRP and Si becoming limiting. Cyanobacterial bloom dynamics were primarily controlled by water temperature and solar radiation. This simple methodology provides a key understanding of phytoplankton community succession and inter‐annual variation and can be applied to any river with similar water quality and phytoplankton data. It provides early warnings of algal and cyanobacterial bloom timings, which support future catchment management decisions to safeguard water resources, and provides a basis for modeling changing phytoplankton bloom risk due to future climate change.

Damming exacerbates the discontinuities of phytoplankton in a subtropical river in China

Phytoplankton is sensitive to changes in river ecosystems. Increasing dams disrupt the continuity of river ecosystems. However, the spatial impacts of dams on phytoplankton have not been well documented. In this study, using multiple statistical analyses, the relationships between environmental drivers and phytoplankton community structures in natural background reaches, reservoirs, and corresponding post-dam reaches were explored in the Jiulong River with multiple cascaded dams, which encountered eutrophication and algal blooms in the past 15 years. Results illustrated that damming exacerbated longitudinal discontinuities of phytoplankton communities. The relative abundance of phytoplankton varied in three types of river sections. The average phytoplankton abundance in the reservoirs (1.62 × 105 cell·L−1) was higher than those in the natural background reaches (5.15 × 104 cell·L−1) and the corresponding downstream reaches (4.55 × 104 cell·L−1). The total β diversity ranged from 0.38 to 0.89 with an average of 0.64 and dominated by species replacement and least by species richness. The water environmental factors and hydraulic parameters rather than nutrients were more attributable to phytoplankton community variability in three river sections. These findings facilitate the management of rivers with multiple cascade dams by releasing environmental flows, jointly operating cascade hydropower stations, and developing nutrient reduction schemes to mitigate the negative impacts of damming in the river.

Phytoplankton communities of reservoirs of the forest-steppe zone under conditions of technogenic load

On the example of the rivers Oskolets and Chufichka, flowing into the river Oskol, the phytoplankton of small rivers of the forest-steppe zone of the Belgorod region, which are of technogenic origin, is considered. The taxonomic and ecological composition of communities of microalgae and cyanobacteria was studied in order to determine the ecological and biological state of surface waters of the Starooskol-Gubkinsky mining region of the Kursk magnetic anomaly. Everywhere in the waters of the watercourses under consideration, cyanobacteria species characteristic of polluted habitats, as well as species recognized as producers of cyanotoxins, are observed. Among them are Ostillatoria granulata Gardner, Ostillatoria guttalata van Goor and Ostillatoria putrida Ag., Ostillatoria splendida Grev. The quality class of the studied waters is defined as the III-rd «Satisfactory purity», and in some cases - as the II-nd, that is, the waters are «Clean». It has been established that the processes of water self-purification proceed intensively. However, the quality of waters determined by the Pantle-Bukk saprobity index in the modification of V. Sladechek within the limits of III and
 II classes does not indicate their ecological well-being, since a number of species of cyanobacteria and diatoms show teratological changes, which are expressed in somewhat “blurred” outlines. their appearance. In addition, an abundance of mineral particles associated with the reduction activity of nitrogen bacteria is observed almost everywhere in the waters.

Community structure of phytoplankton in Downstream of the Segedong River, Kubu Raya Regency, West Kalimantan

The Segedong River flows between the Tanjung Prapat Muda Mangrove Protected Forest in Kubu Raya Regency. Mangrove forests contribute nutrients to water. However, nutrients and fluctuative environmental conditions influence the existence of phytoplankton. People’s settlements and fish farming activities downstream of ​​the Segedong River influence environmental conditions. Research on phytoplankton is needed to determine the quality of the Segedong River. The aim of this research is to determine the abundance and diversity of phytoplankton in the downstream Segedong River. Sampling was carried out in the dry and rainy seasons using a survey method at 3 stations. Water physicochemical factors are measured in situ and ex situ. The identified phytoplankton species are then calculated for their abundance, diversity index, evenness, and dominance. 59 phytoplankton species are categorized into 6 classes, including Bacillariophyceae (35 species), Dinophyceae (15 species), Chlorophyceae (4 species), Cyanophyceae (3 species), Chrysophyceae (1 species) and Xanthophyceae (1 species). The phytoplankton abundance obtained in both seasons at all stations ranged from 1,314-10,185 Ind.L-1 or categorized into oligotrophic to mesotrophic. The diversity index ranges from 1.99-2.88 in the medium category. The evenness index ranges from 0.53-0.80, which is in the medium to high category, while the dominance index is low <0.4.

Reynolds phytoplankton functional classification approach helps evaluate the historical ecological status of the large European Southern Bug River (Ukraine)

AbstractThe phytoplankton functional group (FG) classification system sensu Reynolds enables evaluating the ecological status of rivers using the Q(r) compositional index. Here, we apply the Q(r) index to analyze the ecological conditions of the Southern Bug River, at the entire river length, in the early 20th century, testing it first on historic river phytoplankton data. Moreover, we combined the FG approach with the saprobic index and taxonomic richness to assess the ecological status of the river more reliably. The Bray–Curtis Similarity index highlighted the spatial clustering of river sites that corresponded well to the bioregions of the Eastern Lowlands and the Pontian Province. The Q(r) index revealed a higher variation in ecological status among sites than the saprobic index. Therefore, we argue that the FG approach provides a sensitive ecological status indication approach for river phytoplankton, including historical human impacts. The method may improve understanding of reference conditions and assessing the ecological status of Ukrainian rivers, as requested by the European Water Framework Directive.

The Relationship between Phytoplankton Diversity and Nitrate and Phosphate Content in the Bluru River, Buduran District, Sidoarjo Regency

The abundance of phytoplankton depends on the nutrient content in the waters such as nitrate and phosphate content. The concentration of nitrate and phosphate in a water is influenced by the quality of the water and the discharge of waste that enters the river waters. This study aims to determine the diversity of phytoplankton and also the relationship between nitrate and phosphate and the diversity of phytoplankton in the Bluru river. Sampling was taken from three locations, the research was conducted in June - July 2023 on the Bluru river, Buduran District, Sidoarjo Regency. Phytoplankton samples were analyzed using diversity index, uniformity index, dominance index and analysis of nitrate and phosphate content, regression test to determine the relationship between nitrate and phosphate and phytoplankton. The results showed that the highest nitrate and phosphate content was found in location 2 with 0.037 nitrate and 0.049 phosphate. For the phytoplankton diversity index for location 1 with a value of 2.177 it is classified as low, for location 2 with a value of 2.915 it is classified as high diversity, and at location 3 with a value of 2.371 the diversity is classified as moderate. So that the relationship between phytoplankton diversity and nitrate is very strong, illustrating that the nitrate content in the Bluru river contributes to the amount of plankton by 96.0%, while the remaining 4% is influenced by other factors, and for phosphate it also illustrates that the phosphate content in the Bluru river contributes to the amount of plankton is 64% while the remaining 34% is influenced by other factors.Keywords: Nitrate, Phospate, Phytoplankton

From national monitoring to transnational indicators: reporting and processing of aquatic biology data under the European Environment Agency’s State of the Environment data flow

Biological monitoring data from aquatic ecosystems are collected from European countries on a yearly basis by the European Environment Agency (EEA) through the Water Information System for Europe (WISE). The WISE-SoE (State of Environment) data flows provide indicators of pressures, states and impacts of surface waters and groundwaters on a pan-European scale. The WISE-2 Biology was established to obtain a harmonised flow of biology data reported annually as Ecological Quality Ratios (EQRs) from European surface waters, as a supplement to the mandatory 6-yearly reporting of ecological status of water bodies for the Water Framework Directive. The purposes of this paper are 1) to describe the compilation of national aquatic biology monitoring data indicators and to inform about the public availability of these data, 2) to give an overview of the reported data and indicate the potential for assessments based on these data, and 3) to illustrate the potential for further use of the underlying species abundance data in biodiversity research and assessment. WISE-2 data are reported for the following biological quality elements: phytoplankton, phytobenthos, macrophytes, macroalgae, angiosperms, benthic invertebrates and fish in rivers, lakes, transitional and/or coastal waters. The EQR values represent the deviation from reference conditions. The final processed and quality-checked data are published in EEA’s database Waterbase - Biology, which currently holds data from more than 13,000 waterbodies in 26 countries from the reporting years 2011–2021. Examples of time series aggregated by geographic regions give an indication of the type of trends that can be obtained from the reported data at the nEQR scale. However, the current results are representative only for certain geographic regions with high coverage of water bodies. Within the European research project EuropaBON (Europa Biodiversity Observation Network), the use of WISE-2 data can be leveraged to support biodiversity policy and conservation planning. EuropaBON’s online database provides an overview of how biodiversity monitoring schemes across Europe flows through different integration nodes, to produce Essential Biodiversity Variables and other policy-relevant indicators. Here, we use the EuropaBON visualisation tool to illustrate the WISE-2 as a European integration node for 157 biology datasets via the national integration nodes.

Experimental additions of allochthonous dissolved organic matter reveal multiple trophic pathways to stimulate planktonic food webs

Abstract There is still considerable debate as to whether the allochthonous (terrestrial) dissolved organic matter (DOM) mobilised during large flow events plays an important role in supporting secondary production in riverine food webs. Understanding how food webs respond to large pulses of terrestrial DOM (tDOM) is important for conceptualising the relative importance of energy sources supporting food webs. A mesocosm experiment (1,000 L) using three concentrations of leachate (1, 4, 8 mg C/L and a control) made from floodplain DOM was run for 34 days in a dam filled with water from Gunbower Creek in Northern Victoria, Australia. Nutrients, phytoplankton, zooplankton and stable isotope (δ13C signatures) data were collected to examine how floodplain nutrients affected growth and community structure within the lower food web typical of an Australian lowland river. All leachate additions led to very high concentrations of zooplankton and mixotrophic algae compared to the control. Mixotrophs dominated the algal biovolume of all leachate additions until Day (D)20 and appeared to drive changes in δ13C signatures of particulate organic matter (POM) which were significantly related to changes in zooplankton δ13C signatures. tDOM additions did not significantly suppress obligate autotroph growth which also appeared important as a food source, as reflected in the δ13C signatures of zooplankton and POM after D10. These results show the ability of phytoplankton and zooplankton communities in lowland rivers to respond quickly to changes in resource availability and quality. Mixotrophs appeared to provide an important trophic link between allochthonous carbon and primary consumers, and increased complimentarily to autotrophic production. This resulted in large net increases to phytoplankton biovolume and potentially played a significant role in driving changes in zooplankton growth. We suggest that allochthonous DOM may be highly bioavailable and support production through several different trophic pathways, offering a large boost to production via both autotrophy and heterotrophy. Furthermore, we contend that mixotrophy may be an important pathway for allochthonous organic matter to enter riverine food webs and support secondary production.

Impacts of small dams on the phytoplankton and invertebrates in an Amazonian river

AbstractThe construction of small hydroelectric plants (SHPs) has increased greatly worldwide, and the impacts of these impoundments can cause changes in the aquatic biota. Here, we investigated the ecological attributes (abundance, richness, and species diversity) of three communities (phytoplankton, invertebrates in the water column, and benthos) and the functional groups of phytoplankton, before and after the construction of five SHPs in an Amazonian river. The communities were sampled at two sites, one upstream and another downstream of each dam or construction site, before the dam closure. The dam did not change the limnological factors, and the acid waters and low electrical conductivity, typical of “cerrado” rivers, were characteristic of both the pre‐ and post‐dam phases. For aquatic communities, the phytoplankton abundance increased and the diversity of groups decreased in the post‐dam phase. Regarding the morphology‐based functional groups (MBFG), there was an increase in groups I (small algae with a high surface/volume ratio) and V (phytoflagellates), with a reduction in groups VI (diatoms) and VII (large mucilaginous colonies) in the post‐dam phase. The relative abundance of zooplankton species increased in the post‐dam phase, and the opposite was observed for the benthic community, with reductions in abundance, richness, and group diversity in the post‐dam phase. The structure of the three communities differed between the pre‐ and post‐dam phases, but no difference in communities' similarity was observed between the upstream and downstream sites in both phases. The results show that the change in hydrodynamics, from lotic to semi‐lentic, in the reservoirs of the SHPs, was the main driving force for the alterations in the three communities. For phytoplankton, SHPs are favorable in the sense of decreasing the incidence of algal blooms, particularly of cyanobacteria.

Diatoms of phytoplankton in rivers in the south of the taiga zone within the catchment area of the Middle Volga

The present research provides information on the taxonomic composition and some indicators of the quantitative development of diatoms in the phytoplankton of the left-bank tributaries of the river Volga basin. It was shown that the flora of the studied rivers is diatom-green-euglenic. In the taxonomic composition of diatoms, the leading genera Navicula, Nitzschia, Pinnularia, Gomphonema etc. were noted. The use of electron microscopy made it possible to expand significantly the list of centric diatom species, some of which were recorded for the first time in the flora of the studied rivers. At present, both planktonic and benthic invasive species of diatoms have been identified.

Deterministic processes dominate the geographic distribution pattern and community assembly of phytoplankton in typical plateau rivers

Deterministic processes dominate the geographic distribution pattern and community assembly of phytoplankton in typical plateau rivers

Особенности развития фитопланктона коренного русла реки Волги

Studies of the qualitative diversity and quantitative composition of phytoplankton of the Volga river general channel were carried out at eight stations (Dubovka village, Kamenny Yar village, Staritsa village, Solenoe Zaymishche village, Tsagan-Aman village, Enotaevka village, Seroglazovka village, Zamyany village) in June and August 2019-2021. During the study period there were collected and processed 56 samples. In the course of studying the taxonomic composition of microalgae there were recorded 200 species in three years. The predominant group in the phytoplankton species composition was diatoms, which accounted for more than 50% of the total amount. Phytocenosis of the Volga river was supplemented by green algae and cyanobacteria. The other groups of algae (Dinophyta, Euglenophyta, Chrysophyta) were of the least importance for overall development. The abundance and biomass of phytoplankton of the Volga River root bed have been changing abruptly for three years, the highest indicators were registered in 2020 (abundance = 550.06 million cells/m3, biomass = 1144.010 mg/m3). Quantitative indicators of phytocenosis unevenly developed yearly from June to August. The abundance increased by August in 2019 and 2021 and decreased in 2020. Algocenosis biomass de-creased by the end of summer in 2019 and 2020 and increased in 2021. Quantitative changes of algae are given. There was determined predominance of diatoms. Cyanobacteria and green algae were important mainly due to their growing abundance. The study of river phytoplankton helped reveal the stations with the greatest development of microalgae: the villages of Staritsa, Seroglazovka, Solenoe Zaymishche and Zamyany.

A simple metric for predicting the timing of river phytoplankton blooms

AbstractIn rivers, phytoplankton populations are continuously exported by unidirectional, advective flow. Both transport and growth conditions determine periods of excess phytoplankton growth, or blooms, in a given reach. Phytoplankton abundance, however, has mainly been compared to the state of either growth or transport conditions alone rather than in tandem. Previous studies have not yielded consistent driver–response relationships, limiting our ability to predict the timing of riverine phytoplankton blooms based on environmental factors. Here, we derive a simple joint metric that combines the state of growth and transport conditions, specifically the ratio of temperature and discharge (). We then compare the metric to biomass abundance data (daily, sensor‐based chlorophyll a [chl a] data) from a mid‐sized Great Plains river (the Kansas). was an excellent predictor of low to high biomass, outperforming either variable alone. However, it could not differentiate between very high biomass values, values well above the biomass threshold designating bloom conditions. Our findings of reduced performance at the highest values of T/Q indicated that could predict the occurrence (timing) but not magnitude of phytoplankton blooms, and we used T/Q to correctly predict 71% of days when bloom conditions occurred. Analyzing chl a abundance with also revealed likely switching from transport and temperature to nutrient control. offers a simple tool for (1) predicting the timing of river phytoplankton blooms, (2) forecasting how river ecosystems will respond to surrounding environmental changes, and (3) determining which environmental factors shape phytoplankton blooms at specific locations along a river.

Composition and Abundance of Phytoplankton in Segara Anakan Lagoon and Cibeureum River, Central Java

Segara Anakan Lagoon and Cibereum River are located south of Java Island, precisely on the border between West Java Province and Central Java. This study aimed to reveal phytoplankton community structure related to water quality. Observations were made in May 2021 at seven locations. Ten liters of water were filtered using a plankton net with a mesh size of 53 μm and preserved using Lugol. The parameters observed were the abundance and composition of phytoplankton, dissolved oxygen, pH, temperature, turbidity, conductivity, total dissolved solids, and salinity. Phytoplankton community structure was analyzed using the Diversity Index, Evenness Index, and Dominance Index. The phytoplankton found consisted of Bacillaryophyta, Chlorophyta, Cyanophyta, Dinophyta, and Euglenophyta. Bacillaryophyta had more diversity of species than other phyla, with an abundance range from 38–4,037 individuals/L. Station 7 (at Cibereum River) had a different phytoplankton composition, with a higher abundance and species number, and Oscillatoria sp. as a dominant species. This station has low diversity and evenness index values (0.649 and 0.054, respectively), and the dominance index close to 1 (0.858) indicated unstable habitat for the phytoplankton community. Dissolved oxygen, pH, conductivity, total dissolved solids, and salinity were lower, while turbidity was higher than other stations.

Annual dynamics of eukaryotic and bacterial communities revealed by 18S and 16S rRNA metabarcoding in the coastal ecosystem of Sagami Bay, Japan

Sagami Bay, Japan is influenced by both the warm Kuroshio Current and the cold Oyashio Current and rich nutrients are supplied from multiple river sources and the deep-sea, forming a dynamic ecosystem. The aim of the present study was to investigate eukaryotic and bacterial communities in the coastal waters of Sagami Bay, using 16S rRNA and 18S rRNA sequencing and to assess the seasonal and vertical dynamics in relation to physicochemical and biological conditions. Eukaryotic and bacterial communities showed synchronous seasonal and vertical changes along with environmental variability. Diversity of plankton community suspended in the surface was lower than those at the subsurface layers in both the eukaryotes and bacteria communities; however, community diversity showed different characteristics in the subsurface where the eukaryotic community at the deeper layer (100 m) was as low as the surface and highest in intermediate depth layers (10–50 m), while that of bacterial community was highest in the deeper layer (100 m). The annual variability of the coastal microbial communities was driven, not only by the seasonal changes of abiotic and biotic factors and short-term rapid changes by river water inflow and phytoplankton blooms, but also largely influenced by deep-seawater upwellings due to the unique seafloor topography.

Influência dos níveis de nutrientes, tempo de viagem e disponibilidade de luz nas concentrações de clorofila-a fitoplanctônica em uma bacia de rio neotropical

Abstract: Aim Knowledge of the factors influencing the biomass of phytoplankton in rivers is important with reference to the characterization of water quality and predicting the effects of environmental change on such ecosystems. The present study quantified the concentrations of chlorophyll-a in the water column of the Miranda River Basin, located in western Brazil, contributing to form the Pantanal Wetland, and attempted to identify the primary environmental influences on the phytoplankton biomass. Methods Temperature, depth, current speed, turbidity, Secchi transparency and concentrations of nutrients, suspended solids and chlorophyll-a were measured at approximate monthly intervals during the course of a year, at five upland and three lowland sites. Relationships between chlorophyll-a and nutrient concentrations, travel times and light availability were examined. Results Nutrient levels were generally low, being oligo- to mesotrophic. High levels of suspended solids were recorded (up to approximately 250 mg.L-1), especially in the rainy season at the upland sites. The latter showed low chlorophyll-a concentrations, while lowland sites, with the exception of one, showed two peaks, one in winter (dry season) and the other in summer (wet season), of 4.9 and 2.4µg.L-1, respectively, coincident with reduced concentrations of suspended solids. Conclusions The low nutrient levels recorded may have been due to the main land use being cattle rearing. The high solids concentrations found may have been due to the degradation of native vegetation, especially riparian, that has occurred over the past decades. Travel times of approximately three to four days may have been a factor in retarding algal abundance in the upland sites, as opposed to approximately ten days in the lowland sites, where light limitation may have been a factor reducing algal growth.

Characteristics of phytoplankton community structure and its response to hydro-meteorology in summer of Qiantang River

河流中浮游植物的动态变化能够较好的指示河流水质状况.为探索水文气象过程对筑坝河流浮游植物群落结构的影响，2020年夏季，以钱塘江干流为例，对包括富春江水库在内的11个河段开展了浮游植物群落结构及相关环境因子的调查分析.结果表明：夏季在钱塘江干流共鉴定出浮游植物6门59属95种，优势属为沟链藻（Aulacoseir）、菱形藻（Nitzschia）、平裂藻（Merismopedia）、长孢藻（Dolichospermum）、假鱼腥藻（Pseudoanabaena）和微囊藻（Microcystis），其中梅雨期优势属主要隶属于硅藻门，梅雨后蓝藻门种属则迅速占优，浮游植物总细胞密度快速增加；整个夏季浮游植物的平均细胞密度为（1.57±2.96）×10⁶ cells/L，其中梅雨期细胞密度为（0.37±0.36）×10⁶ cells/L，显著低于梅雨后的细胞密度（4.06±4.38）×10⁶ cells/L.空间上，大坝拦截形成的河流型水库对浮游植物群落结构和藻密度均产生极显著的影响，浮游植物密度在富春江库区段最高，兰江及以上江段其次，新安江库区段及钱塘江河口较低；梅雨后富春江库区水温分层，显著促进了蓝藻和硅藻的增殖.冗余分析表明，气温和降雨是夏季钱塘江干流浮游植物群落结构变化的主要驱动因子，蓝藻门、绿藻门细胞密度与气温呈显著正相关，与降雨呈显著负相关，而硅藻门细胞密度与之相反；梅雨后气温快速增高显著增加库区段水体的蓝藻门细胞密度，蓝藻水华暴发风险迅速增高，水安全管理中应予以重点防范.;The dynamic changes of phytoplankton in rivers can better indicate the water quality of rivers. In order to explore the effects of hydro-meteorological processes on the phytoplankton community structure of damming rivers, taking the main stream of Qiantang River as an example, the phytoplankton community structure and related environmental factors were investigated and analyzed in 11 river reaches including Fuchunjiang Reservoir in the summer of 2020. The results showed that:A total 95 species belonging to 6 phyla and 59 genera of phytoplankton were identified during the summer in the main stream of Qiantang River. The dominant genera were Aulacoseir, Nitzschia, Merismopedia, Dolichospermum, Pseudoanabaena, and Microcystis. During the Meiyu period, the dominant genera belonged to the diatoms, while after the rain, the cyanobacteria quickly became dominant. The average cell density of phytoplankton in summer was (1.57±2.96)×10⁶ cells/L, and the cell density during Meiyu period was (0.37±0.36)×10⁶ cells/L, which was significantly lower than that in Meiyu period ((4.06±4.38)×10⁶ cells/L). Spatially, the river reservoir formed by dam interception has an extremely significant effect on phytoplankton community structure and algal density. The phytoplankton density is the highest in the Fuchunjiang River reservoir section, followed by the Lanjiang River and its upper reaches, and the Xin'anjiang River reservoir section and the Qiantang River estuary. After the Meiyu period, the water temperature stratification in the Fuchunjiang River reservoir significantly promoted the proliferation of cyanobacteria and diatoms. Redundancy analysis showed that temperature and rainfall were the main driving factors of phytoplankton community structure change in the main stream of Qiantang River in summer. Cyanophyta and Chlorophyta cell densities were positively correlated with temperature and negatively correlated with rainfall, while Diatomophyta cell densities were contrary to Cyanophyta. The rapid increase of temperature after the Meiyu period can rapidly increase the cell densities of cyanobacteria in the reservoir area, and the risk of cyanobacteria blooms increases rapidly. Therefore, the prevention of cyanobacteria blooms should be emphasized in water safety management.

极端天气陆地河流面源污染对珠江河口叶绿素分布的影响——评价方法构建与应用

PDF HTML阅读 XML下载 导出引用 引用提醒 极端天气陆地河流面源污染对珠江河口叶绿素分布的影响——评价方法构建与应用 DOI: 10.5846/stxb202103130681 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 南方海洋科学与工程广东省实验室（广州）人才团队引进重大专项（GML2019ZD0303）；热带海洋环境国家重点实验室自主研究项目（LTOZZ2103）；国家自然科学基金面上项目（42077057，41876136） Impacts of non-point source pollutants from river on chlorophyll distribution in the Pearl River Estuary under the extreme weather conditions: the framework and application Author: Affiliation: Fund Project: 100 Talents Program of the Chinese Academy of Sciences，The National Natural Science Foundation of China (General Program, Key Program, Major Research Plan), Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou) talent team introduced major special projects 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:近十年来，随着我国粤港澳大湾区的建设，珠江流域人口增长十分迅速，食品和能源需求急剧增加，导致流域上游省份农业用地面积增加，下游省份城市化进程加速，随之导致含农业化肥的农田灌溉用水和生活污水排放大幅度增加。流域的面源污染物进入珠江河口，导致河口海域赤潮发生频率明显增高。此外，全球变暖加剧了南海和西太台风等极端天气事件的发生频率，大量的台风在珠江口附近登陆，对人类活动产生的营养盐在海水中再分布产生较大影响。现场及卫星观测表明，台风等极端天气影响浮游植物时空分布的4个主要影响因子为：海水的垂直混合、流域的降水增加、河流淡水及营养盐的大量输入及风场变化。但是，尚未对这些因子如何影响叶绿素分布进行过清晰阐释。研究构建了粤港澳大湾区陆海气集成模拟系统，一方面通过控制实验来对模式敏感性进行测试，另一方面以台风"天鸽"过境珠江口为例，来对台风过境期间海表叶绿素时空变化机理进行探究。结果表明，陆地模式径流分辨率的提高对模拟结果有很大影响，台风"天鸽"过境时，向岸的风抑制了珠江冲淡水排出，促进外海水涌入，提高海表盐度，降低叶绿素浓度。而台风所致的陆地降水在过境后四天（8月27日）通过径流输出至河口，此次剧烈的增水向珠江口输入大量的营养盐，促进浮游植物持续生长，使叶绿素浓度在台风过境两周（9月1日）后仍在增加。研究所构建的集成模拟系统可适于其它受河口面源污染影响的海湾及近海系统。为未来实现赤潮、缺氧等生态灾害预报提供可能性。 Abstract:Over the last 10 years, progressive development of the Guangdong-Hong Kong-Macau Greater Bay area in our country has caused rapid population growth within the Pearl River watershed. In the meantime, demand for food and energy has increased dramatically. These result an expansion of agriculture land in the upper reaches of the Pearl River catchment and an increase in the rate of urbanization in the downstream area. As a result, groundwater and surface runoff entering the Pearl River up-stream now contains higher levels of fertilizer than previous, whilst in urban areas sewage and effluent production has increased considerably. A side effect of these changes is that the amount of pollution entering the estuary in a non-point source manner has increased, leading to widespread eutrophication there. Besides, global warming increased typhoons from South China Sea and Western Pacific making landfall near the Pearl River estuary, resulting in the enhanced redistribution of anthropogenic nutrients into the oceanic water. Both in-situ and satellite have been used to investigate the impact these typhoons have on Pearl River phytoplankton dynamics. They identified four factors impacting the redistribution of phytoplankton include the vertical mixing of oceanic water, high precipitation in the watershed, the large freshwater discharge and nutrients loading, and the variation of wind fields. To date, there have been no studies address how these four factors work together to influence the distribution of chlorophyll in the Pearl River estuary. In this research, we built a land-ocean-atmosphere modeling system for the China Great Bay Area. We conducted numerous controlled experiments to examine the sensitivity of the system to multiple forcing conditions. We also investigated the effect of each controlling mechanism has on phytoplankton dynamics, using the incidence of Hurricane Hato's arrival in the area as an opportunity to collect first-hand, real-time observations. Our results show that the temporal resolution of river runoff data used in the modeling system has a profound impact on the simulation results. Using daily river runoff data from land surface models produced very different results from those using monthly data. As Hato passed by, strong onshore winds inhibited the spread of freshwater from the Pearl River, increasing the influx of seawater which in turn increased sea surface salinity and reduced the concentration of surface chlorophyll. Four days (August 27th) after Hato had passed by, water that had fallen on land as precipitation during the typhoon entered the Estuary as runoff. The dramatic increase of river discharge coincident with this event enhanced the level of nutrient loading and caused dramatic phytoplankton growth. Chlorophyll levels were still increasing two weeks after the typhoon Hato passing by (September 1st). The land-ocean-atmosphere modeling system built for the Pearl River Estuary in our research could be adapt to other estuarine and coastal regions and would ultimately help predict algal blooms, hypoxia within the aquatic environment, and other ecological hazards in the future. 参考文献 相似文献 引证文献