The role of zooplankton in the regulation of phytoplankton biomass growth and water transparency in water bodies polluted by nutrients

Experimental studies were carried out in a water body near Moscow and in a flow-through system in the territory of fertilized agricultural fields. It is shown that under high biogenic load, at the concentrations P_tot = 0.14 mg P/l, P_min = 0.07 mg P/l, and the ratio N: P = 7.9: 1, in early summer, and in the absence of plankton-eating fish, zooplankton was regulating phytoplankton development and contributed to the preservation of high water transparency. At the biomass ratio of plant-eating zooplankton to eatable phytoplankton from 0.6 to 42.2, zooplankton can reduce the eatable part of phytoplankton within a day. The main consumers of the eatable fraction of phytoplankton biomass were large-size filterers Daphnia longispina.     

Results of Hydrochemical Studies of Lake Azabach'e (Kamchatka)

The nutrient basis of Lake Azabach'e is studied. The distribution of pH and the concentrations of O₂, P_min, Fe, N–NH⁺ ₄, N–NO^– ₃, Si, and organic forms of N and P are considered. The chemical basis of biological production of Lake Azabach'e is assessed. It is found that the amount of Si is excessive everywhere and that phytoplankton production is limited by phosphate and mineral nitrogen deficiency in virtually equal degrees.     

The role of zooplankton in phytoplankton biomass decline and water transparency regulation in a water body subject to high organic and mineral load

Under biogenic load and at high abundance of ichthyofauna (the concentration of total phosphorus P_tot = 0.20 mg P/l, mineral phosphorus P_min = 0.13 mg P/l, and at the ratio N: P = 4: 1 in early summer), zooplankton reduced phytoplankton biomass during summer and autumn and determined high water transparency, reaching >50% of the depth of the water body. It was found that, with a passage of ichthyofauna to artificial food, the trophic press of plankton-eating fish on zooplankton decreases. Under such conditions, with the biomass ratio of plant-eating zooplankton to edible phytoplankton between 0.4 and 7.9, zooplankton can reduce phytoplankton biomass within a day. The major portion (up to 100%) in phytoplankton biomass reduction was due to large-size filterers-phytophages Daphnia longispina and verticators Asplanchna priodonta helvetica.     

Intra-annual variability in nutrients in the Godavari estuary,India

Daily variations in nutrients were monitored for 15 months (September 2007–November 2008) in the Godavari estuary, Andhra Pradesh, India, at two fixed locations. River discharge has significant influence on nutrients loading to the estuary, which peaks during June–August (peak discharge period; monsoon) whereas exchanges at the sediment–water interface, groundwater and rainwater contribute significantly during other period. Despite significant amount of nutrients brought by discharge to the study region, phytoplankton biomass, in terms of chlorophyll-a (Chl a), did not increase significantly due to high suspended load and shallow photic depth. Nutrients showed downward gradient towards downstream of the estuary from upstream due to dilution by nutrient poor seawater and biological uptake. The N:P ratios were higher than Redfield ratio in both upstream and downstream of the estuary during no discharge period suggesting PO₄ to be a limiting nutrient for phytoplankton production, at levels <0.10 μmol L⁻¹. On the other hand, Si:N ratios were always more than unity during entire study period at both the stations indicating that Si(OH)₄ is not a limiting nutrient. Our results suggest that suspended matter limits phytoplankton biomass during peak discharge period whereas PO₄ during no discharge period.     

基于15N稳定同位素示踪技术的太湖梅梁湾浮游植物群落氮吸收动力学研究

浮游植物对氮的吸收与其生长繁殖密切相关,太湖梅梁湾湖区蓝藻水华频频暴发,对该水域浮游植物氮吸收进行研究具有重要意义.本文分别在冬、春、夏、秋4个季节于梅梁湾采样,对水体常规理化指标和浮游植物群落结构进行分析,并利用¹⁵N稳定同位素示踪技术研究了浮游植物对铵态氮（NH₄⁺-N）、硝态氮（NO₃^--N）和尿素态氮（Urea-N）吸收的动力学特征.结果表明,太湖梅梁湾浮游植物群落除了秋季对NH₄⁺-N的吸收不符合米氏方程外,其余均符合.冬季和春季3种形态氮最大吸收速率（V_max）的大小依次为：NH₄⁺-N > NO₃^--N > Urea-N,而夏季为：NH₄⁺-N > Urea-N > NO₃^--N.3种形态氮V_max的季节变化规律为夏季 > 秋季 > 春季 > 冬季.V_max在不同季节以及不同形态氮之间的差异性可能与浮游植物群落组成以及水体中NH₄⁺-N浓度不同有关.浮游植物对NH₄⁺-N吸收的K_S值在冬、春季高于夏季,对Urea-N吸收的K_s值则在夏、秋季高于冬、春季,而对NO₃^--N吸收的K_s值则在夏季显著高于其他3个季节.冬季和春季梅梁湾浮游植物群落最容易受到NO₃^--N限制,而最不容易受到Urea-N的限制;而夏季,则最容易受到NO₃^--N限制,而最不容易受到NH₄⁺-N的限制,且浮游植物群落对NH₄⁺-N的亲和力最高.与NO₃^--N相比,秋季浮游植物更容易受到Urea-N的限制.不同季节,容易对浮游植物产生限制作用的氮的形态不同.     

Seasonal dynamics of phytoplankton with relation to physicochemical water parameters above and below the hydroelectric plant on the Pasłęka River (North-East Poland)

The study of seasonal dynamics of net phytoplankton was carried out above and below the hydroelectric plant (HP) on the Pas ka River. Correlations were found between the abundance of diatoms and conductivity, O₂, PO₄; the abundance of cyanobacteria and water temperature and conductivity, and the abundance of chlorophytes and O₂ and N_tot. Multiple correlations revealed the most significant factor for diatom development is PO₄, for cyanobacteria is water temperature, and for chlorophytes is N_tot. A lower abundance and biomass of phytoplankton, and less species diversity and nutrient concentrations were registered below the HP than above it. The seasonal dynamics of phytoplankton abundance provided similar results. The maximum biomass of the assemblage was found earlier below the HP, in April, than above it, in May. However, no differences were recorded in the dominant species within phytoplankton abundance. The phytoplankton biomass was dominated by the Melosira varians and Spirogyra sp., which are typical taxa of plant periphyton and possibly emanate from the concrete elements of the dam. This HP changed the local hydrological and environmental conditions, affecting available nutrients, and thereby phytoplankton development in the vegetative season.     

西藏巴松错浮游植物功能群垂直分布特征及其与环境因子的关系

为了解青藏高原湖泊浮游植物功能群垂直分布特征与环境因子的关系,本文选取西藏东南部最大的高山冰川堰塞湖之一的巴松错为研究对象,于2017年11月(枯水期)和2018年9月(丰水期)在湖心利用挂锤式深水采样器进行浮游植物垂直分层采样,共设置7个断面,采集水样84个.应用浮游植物功能群、相关性分析、冗余分析(RDA)等方法,对巴松错浮游植物功能群垂直分布特征及其与环境因子的关系进行了研究.结果表明:1)巴松错水体稳定性强,水温有明显的分层现象,枯水期在30~60 m处形成温跃层,丰水期在1~15 m和30~60 m处形成双温跃层;2)巴松错浮游植物群落共鉴定7门76属242种,物种组成均表现为硅藻蓝藻绿藻型结构;3)根据浮游植物功能群分类方法,可划分为25个功能群,分别为A、B、C、D、E、F、G、H1、H2、J、L M、L O、M、MP、N、P、S1、S2、T、W1、W2、X1、X2、X3和Y,优势功能群从枯水期的MP、D、L O、P转变为丰水期的D、F、L O、MP、N、P,其中MP功能群为巴松错浮游植物群落绝对优势群;4)通过RDA表明,不同水情期浮游植物功能群垂直分布特征受环境因子影响差异较明显,整体上,pH、总氮和氨氮浓度是影响浮游植物功能群分布格局的主要环境因子.     

夏季短期调水对太湖贡湖湾湖区水质及藻类的影响

贡湖湾作为"引江济太"工程长江来水进入太湖的第一站,湖湾水体生态环境的变化是对调水工程净水效果的最好响应,因此本文针对贡湖湾一次夏季短期调水展开调查研究,分别取2013年7月24日(调水前)和2013年8月18日(短期调水后)两次监测水样的水体理化指标和浮游藻类群落数据进行了对比分析,并对浮游藻类群落与环境因子做了相关性分析.结果表明:受来水影响,短期调水后监测区水体的p H略有下降,溶解氧、浊度、硝态氮、总氮、总磷以及高锰酸盐指数等水体理化指标浓度均较调水前有所升高;其中受调水影响最为显著的区域为望虞河的入湖口区、湾心区.两次监测调水前后湖区水体优势藻种属未发生变化,仍以微囊藻为主,但蓝藻种属比例有所下降,绿藻和硅藻等种属比例则有所上升.望虞河入湖口区和贡湖湾湾心区的Shannon-Wiener多样性指数和Pielou均匀度指数受调水的影响升高.同时,浮游藻类群落结构与受水水体理化参数的冗余分析结果表明,此次监测的短期调水后,太湖贡湖湾监测湖区水体p H、溶解氧、硝态氮、总氮、总磷、高锰酸盐指数等环境因子与浮游藻类的群落分布呈显著相关,是影响受水水体中藻类群落的主要环境因子.     

Comparison of transfer functions in statistical downscaling models for daily temperature and precipitation over Canada

This study compares three linear models and one non-linear model, specifically multiple linear regression (MLR) with ordinary least squares (OLS) estimates, robust regression, ridge regression, and artificial neural networks (ANNs), to identify an appropriate transfer function in statistical downscaling (SD) models for the daily maximum and minimum temperatures (T_max and T_min) and daily precipitation occurrence and amounts (P_occ and P_amount). This comparison was made over twenty-five observation sites located in five different Canadian provinces (British Columbia, Saskatchewan, Manitoba, Ontario, and Québec). Reanalysis data were employed as atmospheric predictor variables of SD models. Predictors of linear transfer functions and ANN were selected by linear correlations coefficient and mutual information, respectively. For each downscaled case, annual and monthly models were developed and analysed. The monthly MLR, annual ANN, annual ANN, and annual MLR yielded the best performance for T_max, T_min, P_occ and P_amont according to the modified Akaike information criterion (AICu). A monthly MLR is recommended for the transfer functions of the four predictands because it can provide a better performance for the T_max and as good performance as the annual MLR for the T_min, P_occ, and P_amount. Furthermore, a monthly MLR can provide a slightly better performance than an annual MLR for extreme events. An annual MLR approach is also equivalently recommended for the transfer functions of the four predictands because it showed as good a performance as monthly MLR in spite of its mathematical simplicity. Robust and ridge regressions are not recommended because the data used in this study are not greatly affected by outlier data and multicollinearity problems. An annual ANN is recommended only for the T_min, based on the best performance among the models in terms of both the RMSE and AICu.     

Spatio-temporal variability of phytoplankton assemblages in the Pearl River estuary, with special reference to the influence of turbidity and temperature

The Pearl River Estuary is among the largest estuaries in the subtropical areas of the world. Along the salinity and turbidity gradient between the freshwater reach of the Pearl River and the marine water of the South China Sea, the spatial and temporal composition and abundance of phytoplankton was examined in relation to physic-chemical variables during the dry and wet seasons of 2009. Water samples for phytoplankton and environmental parameters were collected from 18 stations during two seasons along a transect from upper estuary to estuarine and marine sectors. A total of 162 species belonging to 7 phyla were identified, with diatoms dominated in both seasons while dinoflagellates proliferated in autumn. Two main clusters and three sub-clades under each main cluster corresponding to seasons and water sectors were defined with multivariate analysis (cluster and nMDS). Based on the species composition and abundance of phytoplankton, both seasonal and spatial variability were observed at a significant level (ANOSIM: season effect, R=0.896, P<0.01; station effect, R=0.463, P<0.01). The correlation analysis between biotic and abiotic variables indicated that instead of the “proverbial” anthropogenic nutrients loading and salinity gradient, the best 2-variable combination (temperature and turbidity) showed a significant effect on the pattern of phytoplankton assemblages (ρ_w=0.49, BIOENV analysis) between wet and dry seasons in the Pearl River Estuary. This result suggests that physical disturbance either natural or manmade is a more important factor in regulating the phytoplankton community structure within the hydrologically distinct zone of estuaries.     

江汉平原长湖浮游植物初级生产力的季节性变化及其驱动因子

为探究长江中下游富营养化浅水湖泊的浮游植物初级生产力季节性演替特征及其驱动因子,本研究于2020年4月(春)、8月(夏)、10月(秋)及2021年1月(冬)对湖北长湖浮游植物进行采样调查,同时运用黑白瓶测氧法及VGPM模型估算法分别估算了其浮游植物生产力水平,并探究驱动初级生产力季节性变化的主要环境因子。结果显示,4个季节共鉴定出浮游植物194种,其中绿藻门(95种,49%)和硅藻门(40种,21%)居绝对优势地位;黑白瓶法测得浮游植物水柱总生产力(P_t)季节变化为:夏季((1841.24±345.93) mg C/(m²·d))>秋季((1324.14±208.34) mg C/(m²·d))>春季((847.50±247.72) mg C/(m²·d))>冬季((711.43±133.52) mg C/(m²·d)),其中M2站位在夏季采样时(2424.66 mg C/(m²·d))水柱总生产力最高;在垂直空间上,浮游植物总生产力(G...     

Effet de la composition des micas trioctaedriques sur les distributions de Rb et Cs a l'etat de traces

An experimental study is reported on the distributions of trace amounts of Rb and Cs between some trioctahedral micas and a hydrothermal solution at 600°C and 1000 bars. The equilibrium constant K_X^min = (X/K)_aq/(X/K)_min varies considerably with the composition of micas. K_Cs^min is equal to 4.2 for phlogopite of theoretical composition, whereas it becomes equal to 8 for a mica close to eastonite. It reaches up to 17 for a mica in which Mg is largely substituted by Al. In annite, Fe(II) analogue of phlogopite, K_Cs^min becomes equal to 1.8. With Rb, the variations of the equilibrium constant are smaller than with Cs. K_Rb^min is 0.65 for phlogopite and increases up to 1.9 for a more aluminous mica. It is 0.44 for annite.The distributions depend very much on the ratios Mg/Fe and Si/Al of the trioctahedral micas. Consequences in geothermometrical interpretation of alkali trace element distributions in natural rocks are considered.     

西藏麦地卡湿地的浮游植物——1.优势种的时空生态位

为了解青藏高原湿地浮游植物在时空不同维度上的分布特征,本文选取西藏四大国际湿地之一的麦地卡湿地作为研究地点,于2019年7月和10月在麦地卡湿地主要水系——麦地藏布及其支流和湖泊,设置了14个样点,采集了2个水情期（丰水期和枯水期）浮游植物的水样共252个.通过活体观察和固定染色方法鉴定浮游藻类物种,使用直接计数法统计浮游藻类的数量.计算麦地卡湿地浮游植物优势种的优势度指数（Y）、更替率（r）、生态位宽度（B_i）、生态位重叠值（O_ik）和生态响应速率（R）,运用生态位分化的方法,对麦地卡湿地浮游植物优势种的生态位进行了不同时空维度的研究.结果表明：本研究中鉴定出浮游植物优势种（Y>0.02）共8种,其中克洛脆杆藻（Fragilaria crotomensis）和窗格平板藻（Tabellaria fenestrata）是2个水情期的共有优势种.生态位宽度值差异较大,可分为三大生态位类群,且优势度指数与生态位宽度值呈极显著正相关.总体上浮游植物优势物种的生态位重叠值高,在时间、空间和时空三个维度上O_ik>0.6的分别占89.29%、60.71%和28.57%.生态响应速率之和在时间维度上为负数,在空间和时空维度上为正数,说明该湿地浮游植物群落处于发展阶段.冗余分析表明,酸碱度、溶解氧、总氮和浊度是影响麦地卡湿地浮游植物优势种分布的重要因素,浮游植物优势种在这些环境因子上存在明显的生态分化现象.     

太湖草/藻型湖区沉积物-水界面环境特征差异

在太湖草、藻型湖区进行冬、夏两季多点采样,分别对采样点的水环境特征、泥面以上5 cm上覆水中营养盐以及沉积物的含水量、中值粒径、有机碳、氮、磷、金属元素和溶解氧进行测定.结果表明:夏季藻型湖区表层水体pH高于中、底层,冬季草型湖区各层水体pH高于藻型;草型湖区水体浊度夏季低于藻型,冬季反之;藻型湖区上覆水中的硝态氮和磷酸根浓度显著高于草型;草型湖区沉积物中含水量冬季显著高于夏季;草型湖区沉积物中总有机碳显著高于藻型;Fe、Zn、Ca、Pb、Na和K等元素在草、藻型湖区间差异显著;沉积物中溶解氧表现为冬季深于夏季,藻型深于草型的规律.     

山东某新建水库浮游藻类的群落结构特征及其环境驱动因子

基于山东某新建水库中2014年4月-2017年12月的浮游藻类和水质监测结果,研究了藻类群落结构特征,采用非度量多维尺度分析了各年份不同季节藻类群落结构的相似性,利用冗余分析探究了藻类群落结构和环境因子的关系.结果表明：尖针杆藻（Synedra acus）、湖泊伪鱼腥藻（Pseudanabaena limnetica）和小球藻（Chlorella vulgaris）为此水库的主要优势藻种.水库藻类群落结构的季节演替不稳定,冬、春季多以硅藻和绿藻占优势,不同年份夏、秋季藻类结构差异较大,蓝藻和硅藻在夏、秋季存在一定的竞争优势.该水库于2013年底开始启用,由于水体环境的波动,藻类群落结构有所变化,整体上是由蓝藻-绿藻-硅藻向硅藻-绿藻-蓝藻变化.水库浮游藻类生长主要受到氮盐和高锰酸盐指数影响,但不同年份的主要环境影响因子存在一定差异.     

太湖叶绿素a的时空分布特征及其与环境因子的相关关系

2012年3月至2013年2月逐月对太湖水体叶绿素a含量、主要环境因子及不同门类浮游植物密度进行测定,分析太湖叶绿素a含量和不同门类浮游植物密度的时空分布特征,探讨太湖叶绿素a含量和环境因子与不同门类浮游植物密度之间的相关关系并建立逐步回归方程.结果表明:太湖叶绿素a含量全年平均值为22.33±37.65 mg/m³,变幅为0.48~347.85 mg/m³;叶绿素a含量随季节变化明显,夏季最高、秋冬季次之、春季最低;在空间分布上,太湖北部和西北部最高,东部和南部最低.蓝藻门、隐藻门、硅藻门、绿藻门密度随时间呈峰型变化,均在10月份达到最大值,黄藻门、金藻门和裸藻门密度的变化趋势呈"V"型,在春、冬两季出现较大值;不同门类浮游植物密度基本在西北区出现最大值.全湖叶绿素a含量的显著影响因子有总有机碳、亚硝态氮、溶解氧、pH、水温和磷酸盐;lg(Y_Chl.a)与lg(X_TN)呈显著负相关,与lg(X_TP)呈极显著正相关,与lg(X_N/P)呈极显著负相关.太湖叶绿素a含量与蓝藻门、隐藻门、裸藻门与甲藻门密度有显著相关关系.     

广东省高州水库春季蓝藻水华成因初步探讨

高州水库为广东省茂名市重要的饮用水源地,2009年和2010年春季相继出现蓝藻水华,给居民饮水带来安全隐患.对高州水库2009年和2010年春季水华情况进行分析,结果表明:两年浮游藻类细胞密度最高分别达4.08×107 cel1s/L和1.47 x 108cells/L,其中蓝藻所占比例分别为98.2%和98.7%,优...     

A hydrobiological study to interpret the presence of desmids in Lake Zirahuén, México

Monthly collections of phytoplankton were supported by physical–chemical data and measures of chlorophyll a concentrations in the search for particular environmental factors that could explain the constant presence of desmids in a Mexican tropical lake, a characteristic not common among the phytoplanktic communities of Mexican lakes. Samplings were taken from the water column in the deepest part of the lake (40 m) and intensified in the metalimnetic zone, whose establishment was monitored by observations of temperature and oxygen profiles. The general behavior of Lake Zirahuén was typical of warm monomictic tropical lakes at high elevation: a short mixing phase during the hemispheric winter. The depth of Z_MIX and Z_eu revealed a well-illuminated epilimnion, suggesting that phytoplankton communities are not likely to be light-limited. The oligotrophic nature of the lake is indicated by discrete concentrations of inorganic nutrients, P_TOT in the interval of 0.01–0.03 mg l⁻¹ and chlorophyll a between 0.23 and 3.98 μg l⁻¹. These characteristics together with a low concentration of calcium, define a lacustrine environment different from other Mexican lakes, and one that could be suitable for desmids communities.     

中国太湖物理—生物工程实验中菱对水质影响的模式

A model on a physico-biological engineering experiment for purifying water in Wulihu Bay of Lake Taihu by using Trapa natans var. bispinosa was constructed. The state variables in water in the physico-biological engineering were ammonium nitrogen (NH₄⁺-N); nitrate nitrogen (NO₃^--N); nitrite nitrogen (NO₂^--N); phosphate phosphorus (PO₄^3--P); dissolved oxygen (DO); nitrogen (N) and phosphorus (P) in detritus; biomass density, N and P in phytoplankton and in Trapa natans var. bispinosa, N and P in the substance adsorbed by the membrane of the engineering and the rootstocks of Trapa natans var. bispinosa. The state variables in bottom mud layer were PO₄^3--P in the core water,exchangeable P and N. The external forcing functions were solar radiation, water temperature, NH₄⁺-N; NO₃^--N; NO₂^--N; PO₄^3--P; N and P in detritus; DO; phytoplankton concentrations in inflow water and the retention time of the water in physico-biological engineering channel. The main physical, chemical and biological processes considered in the model were:growth of Trapa natans var. bispinosa and phytoplankton; oxidation of NH₄⁺-N and NO₂^--N, of detritus break down; N and P sorption by the enclosure cloth of the experimental engineering and by the rootstocks of Trapa natans var. bispinosa in water; reaeration of water; uptake of P, NH₄⁺-N, NO₃^--N by phytoplankton and Trapa natans var. bispinosa:mortality of the phytoplankton and Trapa natans var. bispinosa:settling of detritus; and nutrient release from sediment. Comparison of calculated results and observed results showed that the model was constructed reasonably for the experiment. The mechanism of purifying lake water in the experiment engineering was discussed by the use of the model.