Unravelling tropical estuary health through a multivariate analysis of spatiotemporal phytoplankton diversity and community structure in relation to environmental interactions

Flood events can significantly affect the physical and biological processes of aquatic ecosystems in a short time, leading to rapid changes in phytoplankton community structure. The Huayanghe Lakes experienced extreme flooding in the summer of 2020, with the water level reaching 16.42 m. In order to understand the effects of flooding on phytoplankton diversity and community structure, eight samples were collected in the Huayanghe Lakes from 2019 to 2020. Water-level disturbance has a significant influence on lake-water quality and phytoplankton community structure. The results showed that the Secchi depth increased from 65.36 to 8.52 cm, while the concentration of total nitrogen (from 0.98 to 0.7 mg/L) and total phosphorus (from 0.04 to 0.031 g/L) decreased. In addition, flooding significantly increased the Shannon–Wiener diversity index, the Pielou index, and the Margalef richness index by an average of 43.5%, 36.7%, and 40.21%, respectively. The phytoplankton community structure in the Huayanghe Lakes changed due to the change of physicochemical environment caused by flood. While in the pre-flood period phytoplankton was composed of large diatoms (e.g., Aulacoseira granulata), cyanobacteria (e.g., Microcystis sp., Anabaena sp., and Aphanizomenon sp.) and other multicellular taxa, the flood period showed an increase in the proportion of chlorophytes and diatoms that quickly adapted to settle in new environments. Pearson correlations and redundancy analyses showed that water level fluctuation was the most significant environmental factor affecting the phytoplankton community between the regular hydrological cycle and flood periods. There are few studies on phytoplankton in the Huayanghe Lakes, and the present study provides basic data on phytoplankton diversity and community structure. In addition, it provides a theoretical basis for controlling water level change in the Yangtze River.

Phytoplankton communities play a significant role in the oceanic biological pump by forming the base of the trophic structure. Increase in nutrients loading affects spatial and temporal distribution of phytoplankton. This study examined the phytoplankton community structure and ecological indices in relation to nutrients dynamics in both estuarine and oceanic areas of Ramisi-Vanga systems along the Kenyan coast. Surface water samples were collected and analysed for nutrients (PO 4 3- -P, NO 3 - -N and NH 4 + -N) and phytoplankton abundance and community structure. This study reported very diverse phytoplankton community structure consisting of 88 taxa that were dominated by Chaetoceros sp., Coscinodiscus sp., Nitzschia sp., Pseudo-nitzschia sp., Alexandrium sp., Protoperidium sp. and Prorocentrum sp that are among the potentially harmful algae. Diatoms were the most abundant taxa in Ramisi-Vanga system. Phytoplankton abundance was found to be higher in the estuarine systems (1182.06±149.14 cells/L) as compared to the oceanic systems (551.99±166.70 cells/L) with high abundance observed in May for oceanic and estuarine systems. Shannon Weiner's species diversity index was greater than 2 in both oceanic and estuarine systems. Phytoplankton species' abundance, composition and diversity were found to be influenced by the availability of NH 4 + -N, NO 3 - -N and PO 4 3- -P. Phytoplankton cell density was below 4000 cells/ L, thus, this study has classified Ramisi-Vanga system as an oligotrophic system implying that the current level of land based activities are not having significant impacts on the phytoplankton communities.

This study investigates the dynamics of phytoplankton communities and nitrogen uptake in the Indian sector of the Southern Ocean during spring and summer. The study area is oligotrophic (Chl a stocks <50 mg m−2); nevertheless, a large spatial variation of phytoplankton biomass and community structure was observed. During both seasons the phytoplankton community in the seasonal ice zone showed higher biomasses and was mainly composed of large diatom cells. However, in the permanently open ocean zone the community had low biomass and was chiefly composed of nano- and picoflagellates. In the polar front zone, although biomass was higher, the community structure was similar to the open ocean zone. The results suggest that the variation in phytoplankton community structure on a larger scale resonates with gradients in water column stability and nutrient distribution. However, significant changes in biomass and nutrient stocks but little change in community structure were observed. Absolute nitrogen uptake rates were generally low, but their seasonal variations were highly significant. During spring the communities displayed high specific nitrate uptake (mean rate = 0.0048 h−1), and diatoms (in the seasonal ice zone) as well as nano- and picoflagellates (in the permanently open ocean zone and polar front zone) were mainly based on new production (mean ƒ-ratio = 0.69). The transition to summer was accompanied by a significant reduction in nitrate uptake rate (0.0048 h−1 → 0.0011 h−1) and a shift from predominantly new to regenerated production (ƒ-ratio 0.69 → 0.39). Ammonium played a major role in the seasonal dynamics of phytoplankton nutrition. The results emphasize that, despite a large contrast in community structure, the seasonal dynamics of the nitrogen uptake regime and phytoplankton community structure in all three subsystems were similar. Additionally, this study supports our previous conclusion that the seasonal shift in nitrogen uptake regime can occur with, as well as without, marked changes in community structure.

Temperature driving vertical stratification regulates phytoplankton community structure in the Bohai Sea and Yellow Sea

Phytoplankton abundance, community structure and diversity in the eutrophicated Orbetello lagoon (Tuscany) from 1995 to 2001

BackgroundEutrophication of freshwater systems can result in blooms of phytoplankton, in many cases cyanobacteria. This can lead to shifts in structure and functions of phytoplankton communities adversely affecting the quality of drinking water sources, which in turn impairs public health. Relationships between structures of phytoplankton communities and concentrations of the toxicant, microcystin–leucine–arginine (MC-LR), have not been well examined in large shallow lakes. The present study investigated phytoplankton communities at seven locations from January to December of 2015 in Tai Lake, and relationships between structures and diversities of phytoplankton communities and water quality parameters, including concentrations of MC-LR and metals, were analyzed.ResultsA total of 124 taxa of phytoplankton were observed, and the predominant taxa were Microcystis sp. and Dolichospermum flos-aquae of Cyanophyta and Planctonema sp. of Chlorophyta. The greatest diversities of phytoplankton communities, as indicated by species richness, Simpson, Shannon–Wiener, the Berger and Parker, and the Pielou evenness indices, were observed in spring. Furthermore, productivity of phytoplankton was significantly and negatively correlated with diversities. These results demonstrated that Simpson, Shannon–Wiener, the Berger and Parker, and the Pielou evenness indices of phytoplankton communities were significantly related to trophic status and overall primary productivity in Tai Lake. In addition, temperature of surface water, pH, permanganate index, biochemical oxygen demand, total phosphorus, arsenic, total nitrogen/total phosphorous ratio, and MC-LR were the main factors associated with structures of phytoplankton communities in Tai Lake.ConclusionThe present study provided helpful information on phytoplankton community structure and diversity in Tai Lake from January to December of 2015. Our findings demonstrated that Simpson, Shannon–Wiener, the Berger and Parker, and the Pielou evenness indices could be used to assess and monitor for status and trends in water quality of Tai Lake. In addition, MC-LR was one of the main factors associated with structures of phytoplankton communities in Tai Lake. The findings may help to address important ecological questions about the impact of a changing environment on biodiversity of lake ecosystems and the control of algae bloom. Further studies are needed to explore the relationship between MC-LR and phytoplankton communities in the laboratory.

Owing to the dynamic nature of nutrient‐phytoplankton interactions, ambient macronutrient concentrations reveal little about the impact of nutrient availability on phytoplankton biomass and community composition at any given point in time or space. Here, however, we examine a global dataset (n = 262) where phytoplankton community structure and biomass are related to ambient concentrations of dissolved inorganic nitrogen (DIN), phosphate (P), and silicate. The macroecological patterns emerging from the analysis suggests plausible causal relationships between nutrient availability and global phytoplankton community responses: When DIN and P are below ca. 5 μM and 0.5 μM, respectively, increases in the concentration of either nutrient correlate with increases in both biomass and the contribution of large cells to the total phytoplankton biomass. At higher concentrations, increasing DIN or P concentrations do not correlate with increases in biomass. However, the fraction of large phytoplankton continues to increase with increasing concentrations suggesting DIN and P availability to be important factors in controlling phytoplankton community composition over the entire spectrum of potential macronutrient availability in the open ocean. Ambient silicate concentrations were not strongly associated with phytoplankton community structure or biomass. Nor did the DIN/P ratio correlate with community structure indicating that this ratio is a poor descriptor of phytoplankton limitation at the community scale. No empirical evidence was found for commonly referred threshold values for nutrient limitation (i.e., 2 μM, 0.2 μM, and 2 μM for DIN, P, and silicate, respectively) suggesting that these threshold values may not contain any practical information.

Phytoplankton community responses to nutrient and iron enrichment under different nitrogen to phosphorus ratios in the northern Baltic Sea

Inter-annual variability in the phytoplankton abundance and community structure of a tropical monsoonal estuary in response to variable monsoonal patterns

PDF HTML阅读 XML下载 导出引用 引用提醒 松花江哈尔滨段浮游植物群落格局及其与环境因子的相关性 DOI: 10.5846/stxb201909262022 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金资助项目（31870187）；哈尔滨师范大学博士启动金项目（XKB201912） Correlation between phytoplankton community patterns and environmental factors in Harbin section of the Songhua River Author: Affiliation: Fund Project: 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:松花江是黑龙江在我国境内的最大支流，流经吉林、黑龙江两省。松花江哈尔滨段是哈尔滨市工农业生产与生活用水的重要水资源，近年来由于人类活动的频繁影响，水体质量有所下降。鉴于此，于2018年春、夏、秋三季（4月、8月和10月），在松花江哈尔滨段设置14个采样点，对电导率、总氮和总磷等理化指标进行测定，同时对其浮游植物群落结构及环境因子相关性进行研究。利用群落相似性分析（ANOSIM）探讨浮游植物群落时空分布差异；通过SIMPER分析筛选出影响群落时空格局的关键物种。基于优势种和10项理化指标的冗余分析（RDA）揭示了浮游植物群落生态分布特征并对关键影响因子进行识别。研究结果表明，调查期间共鉴定浮游植物136种，其中优势种15种，群落结构主要以硅藻门和绿藻门的物种构成。松花江哈尔滨段浮游植物群落结构与过去10余年间相比较为稳定。ANOSIM和SIMPER分析表明，季节变化和人为活动干扰对浮游植物群落时空格局具有一定驱动作用，蓝藻门物种的空间分布活动干扰影响明显。RDA分析表明，浮游植物分布特征与水环境时空异质性关系密切，驱动松花江哈尔滨段浮游植物群落时空分布的主要水环境因子为电导率、总磷、浊度和pH。 Abstract:The Songhua River, the largest tributary of the Heilongjiang River, flows through Jilin and Heilongjiang province. The Harbin section of the Songhua River starts from the upstream of Zhu Shuntun and ends at the Dadingzi Mountain in the lower reaches. It is an important water resource for industrial, agricultural and domestic use in Harbin city. Recent years, the intensively anthropogenic activities have resulted in water pollution. The water quality and biodiversity of Harbin section of the Songhua river has been attracted wide attention. At present, more and more studies focused on phytoplankton diversity and community structure. However, the study on phytoplankton in Harbin section of the Songhua River is still in its infancy. To explore the phytoplankton community structure and its relationship with environmental factors in Harbin section of the Songhua River, multivariate statistical analysis was conducted in this study. All sampling sites of Harbin section of the Songhua River were divided into two parts, sampling sites under intense human disturbance and other less polluted sites. A total of 14 sampling sites, the phytoplankton community and 10 environmental parameters were investigated in the spring (April), summer (July), and autumn (October) of 2018. The spatial and temporal distribution differences of phytoplankton community were analyzed by analysis of similarity (ANOSIM). The key species with contribution to the spatio-temporal patterns were identified by similarity percentage (SIMPER) analysis. Additionally, the redundancy analysis (RDA) based on dominant species and 10 environmental variables revealed the ecological distribution of phytoplankton community and identified main factors. The results showed that a total of 136 species of phytoplankton were detected, including 15 dominant species. The species composition was dominated by Bacillariophyta and Chlorophyta (76%), followed by Cyanobacteria (12%), Cryptophyta (7%) and others. Compared with the past 10 years, the community structure belonging to Bacillariophyta-Chlorophyta was relatively stable. Among the three seasons, except for the physical and chemical indicators of specific conductivity (SpCond.), oxidation-reduction potential (ORP) and total phosphate (TP), others were significant differences (P<0.05). During the study, the abundance of phytoplankton in Harbin section of the Songhua River was 7.92×106-21.76×106 ind./L, and the average was 15.27×106 ind./L. The independent sample t-test showed that there were significant differences in total nitrogen (TN), chemical oxygen demand (CODMn) and chemical oxygen demand (BOD5) among the sampling sites affected by human disturbance and other sites (P<0.01). Additionally, there was significant difference of SpCond. at the 0.01 level in different sites, while other physical indicators such as pH did not change greatly (P>0.05). ANOSIM and SIMPER analysis showed that seasonal changes and human-induced disturbances in Site 4 to Site 7 had effects on the spatial and temporal patterns of phytoplankton community. The spatial distribution of Cyanobacteria species was significantly affected by human activity. The results of RDA analysis found that the distribution characteristics of phytoplankton were closely related to the spatio-temporal heterogeneity of water environment. SpCond., TP, turbidity (Tur.) and pH were the key driving factors of phytoplankton community in Harbin section of the Songhua River. 参考文献 相似文献 引证文献

Freshwater phytoplankton communities are currently experiencing multiple global change stressors, including increasing frequency and intensity of storms. An important mechanism by which storms affect lake and reservoir phytoplankton is by altering the water column's thermal structure (e.g., changes to thermocline depth). However, little is known about the effects of intermittent thermocline deepening on phytoplankton community vertical distribution and composition or the consistency of phytoplankton responses to varying frequency of these disturbances over multiple years. We conducted whole‐ecosystem thermocline deepening manipulations in a small reservoir. We used an epilimnetic mixing system to experimentally deepen the thermocline via five short (24–72 hr) mixing events across two summers, inducing potential responses to storms. For comparison, we did not manipulate thermocline depth in two succeeding summers. We collected weekly depth profiles of water temperature, light, nutrients, and phytoplankton biomass as well as bottle samples to assess phytoplankton community composition. We then used time‐series analysis and multivariate ordination to assess the effects of intermittent thermocline deepening due to both our experimental manipulations and naturally occurring storms on phytoplankton community structure. We observed inter‐annual and intra‐annual variability in phytoplankton community response to thermocline deepening. We found that peak phytoplankton biomass was significantly deeper in years with a higher frequency of thermocline deepening events (i.e., years with both manipulations and natural storms) due to altered thermal stratification and more variable depth distributions of soluble reactive phosphorus. Furthermore, we found that the depth of peak phytoplankton biomass was linked to phytoplankton community composition, with certain taxa being associated with deep or shallow biomass peaks, often according to functional traits such as optimal growth temperature, mixotrophy, and low‐light tolerance. For example, Cryptomonas taxa, which are low‐light tolerant and mixotrophic, were associated with deep peaks, while the cyanobacterial taxon Dolichospermum was associated with shallow peaks. Our results demonstrate that abrupt thermocline deepening due to water column mixing affects both phytoplankton depth distribution and community structure via alteration of physical and chemical gradients. In addition, our work supports previous research that phytoplankton depth distributions are related to phytoplankton community composition at inter‐annual and intra‐annual timescales. Variability in the inter‐annual and intra‐annual responses of phytoplankton to abrupt thermocline deepening indicates that antecedent conditions and the seasonal timing of surface water mixing may mediate these responses. Our findings emphasise that phytoplankton depth distributions are sensitive to global change stressors and effects on depth distributions should be taken into account when predicting phytoplankton responses to increased storms under global change.

The spatial distribution of environmental factors, chlorophyll a (Chla), phytoplankton abundance, and community structure in the Laizhou Bay were investigated in August 2018 (wet season after pollution control) to clarify the effects of the pollution control of the Xiaoqing River, which is a major source of pollution, on environmental factors and phytoplankton community structure in this area. The results showed that the environmental factors changed significantly after pollution control of the Xiaoqing River. The concentrations of dissolved inorganic nitrogen (DIN), dissolved inorganic silicon (DSi), NO3-, and NO2- decreased significantly, with values only 40.1% to 60.4% of those from the same period of in 2017 (the nearest year before the pollution control), whereas dissolved inorganic phosphorus (DIP) and NH4 increased by 2.5 and 1.4 times that of their concentrations in 2017. The spatial distribution of environmental factors changed significantly, with the nutrient concentrations around the Xiaoqing River estuary noticeably decreasing. The abundance of phytoplankton cells was 21.5×106 cell·m-3, which was close to the results of a previous study, whereas the ρ(Chla) was 2.43 μg·L-1, which decreased obviously. Both microscopic analysis and pigment taxonomy suggested that phytoplankton community structure in the Laizhou Bay changed clearly, with the dominant community shifting from diatoms alone to the co-dominance of diatoms and cyanobacteria. Chaetoceros curvisetus, Skeletonema costatum, and Cerataulina pelagica, which were commonly observed in the Laizhou Bay before pollution control of the Xiaoqing River, decreased in 2018, whereas the abundance of common dominant freshwater species (e.g., Merismopedia sp. and Synedra spp.) increased significantly. Redundancy analysis (RDA) showed that the phytoplankton community was significantly related to nitrogen, phosphate (negative correlation), and salinity (negative correlation) after pollution control of the Xiaoqing River, indicating that the variation in nutrient concentration and the structure of river runoff input may be the main factors affecting phytoplankton community and dominant species structure.

The aquatic ecosystem is the ultimate sink for consumer and industrial waste discharge that contains nanometals such as titanium dioxide nanoparticle (n-TiO2). In this environment, nutrient availability and nanometals influence phytoplankton community structure and function. In a mesocosm experiment, we evaluated the interactive effect of n-TiO2 (48 mg L−1) and two nitrogen (N) levels (limited, LN; and replete, HN) on the phytoplankton community structure (biomass, species diversity and richness, algal species divisions), biochemical composition (carbohydrates, proteins, and lipids), and antioxidant response (peroxidase activity, POD). n-TiO2 decreased total phytoplankton biomass, and its combination with HN led to the highest decrease. Species diversity was not affected by N level, n-TiO2, and their interaction, while species richness decreased in combined n-TiO2 and HN treatment. All these recorded effects of n-TiO2 on the phytoplankton community structure were enhanced by increasing temperature over time. LN initially reduced phytoplankton carbohydrate content but increased by the presence of n-TiO2 and its interaction with N levels. Total protein and lipid content were not affected by n-TiO2 or its interaction with N levels. POD activity was increased by the interaction between n-TiO2 and the N levels tested. Our results indicate that the influence of n-TiO2 on the phytoplankton community was dependent on the concentration of N. Also, phytoplankton carbohydrate content and community structure varied with increasing water temperature. A few species thrived concerning biomass during exposure to the LN + n-TiO2 (Scenedesmus quadricauda, Coelastrum reticulum, and Microcystis sp.) and HN + n-TiO2 (Microcystis sp.) treatments. Members of the Chlorophyta were generally susceptible to the presence of n-TiO2 regardless of the N level. Thus, the presence of n-TiO2 in aquatic ecosystems can alter phytoplankton community structure and dynamics.

Phytoplankton community structure is influenced by seabird guano enrichment in the Southern Ocean

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