Macroalgal growth in nutrient-enriched estuaries: A biogeochemical and evolutionary perspective

Increased nutrient loading of a body of water leads to an increase in macroalgal growth. It is generally observed, however, that certain species thrive more than others, capitalising on the increased nutrient availability. These are usually small, fast-growing, ephemeral algae that often appear as nuisance blooms. This article discusses the correlation between nutrient increase and macroalgal bloom formation. From a historical perspective, the evolutionary history of nuisance macroalgae, and the habits available to them prior to anthropogenic influences on estuarine geochemistry are considered. The occurrence of macroalgal genera whose distribution is commonly related to estuaries with high nutrient loading is discussed, along with evidence suggesting that the ecophysiological traits of r-selected, ephemeral algae largely contribute to their ecological success and bloom-formation at nutrient-enriched sites.     

基于磷阈值的富营养化风险评价体系

选取北京市重要的地表水源密云水库作为实例研究,在识别影响富营养化发生的主要限制因子的基础上,采用外源营养盐输入对富营养化作用的流水藻类培养试验(AGP)方法,并结合数学方法拟合富营养化水体发生的阈值.研究表明,根据富营养化水体各水质指标之间的回归关系,确定出能够反映富营养化的水质指标阈值.运用水质模型模拟富营养化过程,进行基于阈值的富营养化风险评价,构建了富营养化风险评价方法体系,提供了一种基于阈值的水体富营养化风险评价的方法.     

用光触媒抑制淡水藻类增殖作用的研究

为维护和改善湖水、水库等大型蓄水设施的水质而寻找一种新的方法,在人工的明／暗光照射条件下,探讨了运用粉末状TiO2作为光触媒,抑制各种淡水藻类增殖的效果。粉末状的TiO2,在100mg／L的浓度下,对蓝藻的铜绿微囊藻原变种、鱼腥藻和绿藻的空星藻有明显的抑制增殖的效果;而对硅藻的钝脆杆藻,在此条件下则没有效果。     

Seasonal variation of Microcystis in Lake Taihu and its relationships with environmental factors

In order to monitor the changes of Microcystis along with temporal and spatial variations, seasonal variation of Microcystis in Lake Taihu was investigated by 16S-23S rRNA internal transcribed spacer denaturing gradient gel electrophoresis (16S-23S rRNA-ITS DGGE) and microscopic evaluation. Samples were collected quarterly at four sites (River Mouth, Meiliang Bay, Cross Area, and Lake Center) from August 2006 to April 2007. Results showed that Microcystis dominated total phytoplankton abundance at the four sites in all seasons except winter. The average annual abundance of Microcystis was relatively high at River Mouth and Meiliang Bay, reaching 81.22×106 and 61.32×106 cells/L, respectively. For temporal variations, Shannon-Wiener diversity index (H') according to DGGE profile revealed the richness of Microcystis in summer (H'=1.375±0.034) and winter (H'=1.650±0.032) was lower than that in spring (H'=2.078±0.031) and autumn (H'=2.365±0.032) (P<0.05). While for spatial variations, the richness of Microcystis at River Mouth (H'=2.015±0.074) was higher than at other sites during four seasons (P<0.01). Very few differences of Microcystis diversity in the same season were observed among the other three sites (P>0.05). Canonical correspondence analysis (CCA) was performed to elucidate the relationships between Microcystis operational taxonomic units (OTUs) composition and the environmental factors. Results of CCA revealed that temperature was strongly positively correlated with the first axis (r=0.963), while TSS was negative correlated with the second axis (r=-0.716). Phylogenetic tree based on the sequencing results of target bands on DGGE gel indicated that samples collected in summer and winter constituted two separated clusters.     

三峡水库支流大宁河水华特征研究

以三峡水库支流大宁河水华敏感期(2007年4~6月和2008年4~5月)水质和水华的调查数据为依据,研究了其水质变化、营养盐构成及水华特征.结果表明,水华敏感期大宁河自回水段以下氮磷含量较高,总氮范围为0.84~3.21 mg/L,总磷为0.011~0.531 mg/L,氮营养盐主要以TDN为主(TDN/TN为84%),而磷营养盐以TDP占优(TDP/TP为60%);N/P值均高于16,藻类生长受磷限制.高锰酸盐指数和溶解氧含量低且变化稳定.叶绿素a为1.41~219.04 mg.m-3.相关性分析表明Chl-a与TP、高锰酸盐指数、DO、pH呈显著正相关(rChla-TP=0.453、rChla-高锰酸盐指数=0.641、rChla-DO=0.584、rChla-pH=0.409,p0.01),与SD呈显著负相关(rChla-SD=-0.392,p0.01);pH受多参数影响,但受藻类生长影响较大.通过显微镜对藻类进行鉴定,发现大宁河自回水段以下水华敏感期藻类分布较广,共发现8门82属124种,其中硅藻门和绿藻门分布最多,其次为蓝藻门和甲藻门,其余藻种较少.大宁河在水华敏感期暴发了3次自回水段以下大规模水华,水华期间藻密度最高值是正常值的14~1427倍,水华优势种主要有绿藻门的波吉卵囊藻、小空星球藻、土生绿球藻、实球藻和小球藻;裸藻门的扁裸藻、矩圆囊裸藻;硅藻门的小环藻、冠盘藻和舟形藻;甲藻门的埃尔多甲藻等;发生多藻种同时水华的情况;出河口处藻类较少.     

Cyanobacteria-/cyanotoxin-contaminations and eutrophication status before Wuxi Drinking Water Crisis in Lake Taihu, China

After the appalling “Wuxi DrinkingWater Crisis”, increasing investigations concerning the contaminations of cyanobacterial blooms and their toxins in Lake Taihu have been performed and reported in the last two years. However, information regarding these issues before the crisis in 2007 remained insu cient. To provide some background data for further comparisons, the present study reported our investigations conducted in 2004, associated with the cyanotoxin contaminations as well as the eutrophication status in Lake Taihu. Results from the one-year-study near a drinking water resource for Wuxi City indicated that, unlike the status in recent two years, cyanobacteria and chlorophyta are the co-dominance species throughout the year. The highest toxin concentration (34.2 ng/mL) in water columns occurred in August. In bloom biomass, the peak value of intracellular toxin (0.59 g/mg DW) was determined in October, which was lag behind that in water column. In addition, MC-RR was the major toxin variant throughout the year. During the study period, nutrients levels of total nitrogen and phosphorus were also recorded monthly. Results from the present study will lead to a better understanding of the eutrophication status and the potential risks before “Wuxi Drinking Water Crisis”.     

洞庭湖浮游藻类功能群的组成特征及其影响因素研究

2013年3月、6月、9月及12月采集了洞庭湖11个断面的浮游藻类,并对所采集的藻类进行了功能群划分,结果显示,洞庭湖的浮游藻类可以分为24个功能群：A、B、C、D、E、F、G、H1、J、L_O、L_M、M、MP、N、P、S1、S_N、T、W1、W2、X1、X2、X3、Y,所反映的生境特征主要表现为对分层敏感、频繁扰动且混合程度较高的浑浊型中-富营养型水体.不同时期调查的藻类优势功能群存在明显差异,其中,B（中营养水体、对分层敏感）、D（较浑浊的浅水水体）、J（混合型高富营养浅水水体）、MP（扰动频繁的浑浊型浅水水体）、P（混合程度较高中富营养浅水水体）、Y（广适性）在四次调查中的优势度均>0.02,成为洞庭湖的绝对优势功能群,洞庭湖藻类优势功能群不同时期的演替规律为：3月MP+P+D+B经6月MP+J+P+D+B与9月MP+J+P+D+B+L_O+Y转变成12月MP+J+D+Y.CCA分析结果显示,洞庭湖藻类功能群分布受水环境因子影响较为明显.整体上,T、pH值、DO、COD_Cr、NH₃-N及TP是影响洞庭湖藻类功能群分布格局的主要因素.     

Comparison of four measuring techniques to assess growth inhibition in standardized tests with seven freshwater algae and cyanobacteria

As representatives of primary producers, algae and cyanobacteria play an important role in assessing the risk of chemicals. However, the list of standard algal species commonly used for toxicity testing comprises very few species so that there is an urgent demand to identify further non-standard species which can be used for higher-tier risk assessment in general and the analysis of species sensitivity distributions in particular. In this study, four measuring techniques to assess growth inhibition were compared using five non-standard and two standard algal species and 3,5-dichlorophenol as reference substance. Regarding sensitivity and suitability, the measuring techniques were ranked in the following descending order: delayed fluorescence, prompt fluorescence, photometric absorbance, and microscopic cell count. All five non-standard species fulfilled the validity criteria if tested with delayed fluorescence.     

Impact of Land-Based Sources On Marine Environment: Phytoplankton Blooms Within an Annual Cycle

The discharge water into the western region of Alexandria (Egypt), creates suitable conditions for the acceleration of the phytoplankton growth; daily replenishment of nutrients and development of density stratified water column. Water transparency and ammonia concentrations seem to be affecting the variations of the numerical standing crop. Eight phytoplankton bloom pulses of different causative species were observed. Asterionella glacialis represents a newly recorded red tide species in the neritic waters of Alexandria.     

太湖重污染湖区和水源地水质概况及藻毒素污染环境风险

近年来太湖流域局部水质状况有所改善,但太湖藻型生境条件还未根本改变,水污染防治任务依然艰巨。确保太湖湖体水质稳定达标,尤其是加强对太湖重点湖区和水源地重点污染物的调查研究十分重要。在此背景下,本文调研了太湖重点湖区和水源地水质概况、藻毒素污染时空分布特征、环境影响因子和迁移转化规律,并总结了藻毒素的环境和健康风险研究的最新进展,指出了太湖西部湖区和饮用水源地的主要环境风险,以及未来太湖藻毒素污染相关研究需解决的关键技术问题,以期为促进太湖流域重点污染物的控制和治理,确保太湖饮用水源地安全提供有益借鉴。