应用荧光定量PCR技术监测玄武湖蓝藻水华

应用荧光定量PCR技术和显微计数法对玄武湖蓝藻水华进行了长期监测,结果表明,荧光定量PCR法可同步监测蓝藻、微囊藻和有毒微囊藻的数量,及时准确反映玄武湖蓝藻水华优势种群微囊藻和有毒微囊藻的动态变化。与显微计数法相比,具有需要的样品量少、时效性强、检出下限较低、自动化程度高等优势,可有效地应用于蓝藻水华的监测。     

Metribuzin impairs the unicell-colony transformation in the green alga Scenedesmus obliquus

Active growth is a prerequisite for the formation of grazing-protective, mostly eight-celled colonies by the ubiquitous green alga Scenedesmus in response to chemical cues from zooplankton. Colonies can also be evoked by chemically quite similar manmade anionic surfactants, such as FFD-6. In this study, it was hypothesized that growth-inhibiting concentrations of the herbicide metribuzin impair the ability of Scenedesmus obliquus to form colonies in response to the surfactant morphogen FFD-6. The results confirmed that the formation of colonies in S. obliquus was hampered by metribuzin. EC₅₀ values of metribuzin for colony inhibition (approximately 11 μg L⁻¹) were similar to those for growth and photosynthesis inhibition (12-25 μg metribuzin L⁻¹). In the absence of the colony-inducing surfactant FFD-6, S. obliquus populations were comprised of 92% unicells, having on average 1.2 cells per colony at all tested metribuzin concentrations (0-100 μg L⁻¹). In contrast, in the presence of FFD-6 and at low metribuzin concentrations (0 and 5 μg L⁻¹), S. obliquus had more than five cells per colony with a high portion of eight-celled colonies. However, increasing concentrations of metribuzin decreased the number of colonies in the FFD-6-exposed populations and caused them to remain mostly unicellular at the highest concentrations (50 and 100 μg L⁻¹). This study revealed that metribuzin impeded growth and by doing so, also obstructed the possibility for unicellular Scenedesmus to form colonies. Consequently, an increase in mortality of Scenedesmus from grazing is expected.     

太湖蓝藻水华分级及其时空变化

根据MODIS影像和实地监测叶绿素a浓度数据，采用太湖蓝藻水华分级评估方法，对2004~2008年太湖不同类型蓝藻水华类型进行评估并统计分析，探求太湖蓝藻水华特征及其时空变化规律，以期为太湖蓝藻水华预防和预警提供支持。结果表明：（1）2004~2008年，全湖共发生蓝藻水华414次，以小型蓝藻水华为主，发生333次，占总次数的80.43%；随着蓝藻水华级别的增加，发生次数逐渐减少；（2）空间上，蓝藻水华主要发生在太湖的北部和西部区域，并且蓝藻水华发生级别由高到低基本上沿西北-东南方向分布；（3）年际变化上，蓝藻水华发生次数呈逐渐增加趋势，蓝藻水华级别较高、次数较多的年份主要集中于2006年和2007年；（4）年内变化上，4~8月份，蓝藻水华发生次数呈增加趋势，8~11月，蓝藻水华发生次数逐渐减少。并且，蓝藻水华主要集中于5月和7~10月份，尤其是8~10月。     

巢湖蓝藻水华遥感监测初探

以巢湖为研究区,从2008年4月到11月,对巢湖水体的24个点位进行了连续的水体光谱测量,通过对蓝藻水华爆发程度与其光谱反射率之间关系的研究,确定遥感识别水华爆发级别的阈值,对四类不同爆发程度蓝藻水华光谱特征进行遥感识别,绘制巢湖蓝藻水华特征等级图。     

巢湖水华遥感监测与年度统计分析研究

介绍了巢湖蓝藻水华的日常遥感监测方法与流程,开展了基于日常监测的年度统计分析,为水华环境管理提供了科学依据。首先分析了蓝藻水华与正常水体的光谱差异,利用蓝藻水华在近红外波段的"陡坡效应",基于NDVI方法开展水华日常遥感监测。基于日常监测开展水华年度统计分析,获得水华最早发生日期、最晚发生日期、最大发生面积等,并以水华发生频率、水华起始日期和水华持续时间来分析巢湖一年内高发区、发展趋势及持续时间等时空分布规律。研究表明,2010年巢湖水华的高发区域在巢湖西北部水域,水华持续天数最长的区域是巢湖西北和中部部分区域,水华先在西部沿岸聚集,随时间推移向东部和中部扩散,巢湖西南、中部和东南沿岸是最后新增的水华区域。     

Environmental Control and Limnological Impacts of a Large Recurrent Spring Bloom in Lake Washington,USA

A series of statistical analyses were used to identify temporal and spatial patterns in the phytoplankton and nutrient dynamics of Lake Washington, an mesotrophic lake in Washington State (USA). These analyses were based on fortnightly or monthly samples of water temperature, Secchi transparency, ammonium (NH₄), nitrate (NO₃), inorganic phosphorus (IP), total nitrogen (TN), total phosphorus (TP), dissolved oxygen (DO), pH and chlorophyll a (chl a) collected during 1995–2000 from 12 stations. Lake Washington has a very consistent and pronounced annual spring diatom bloom which occurs from March to May. During this bloom, epilimnetic chl a concentrations peak on average at 10 μg/L, which is 3 times higher than chl a concentrations typically seen during summer stratified conditions. The spring bloom on average comprised 62% diatoms, 21% chlorophytes and 8% cyanobacteria. During summer stratification, diatoms comprised 26% of the phytoplankton community, chlorophytes 37% and cyanobacteria 25%. Cryptophytes comprised approximately 8% of the community throughout the year. Overall, 6 phytoplankton genera (i.e., Aulacoseira, Fragilaria, Cryptomonas, Asterionella, Stephanodiscus, and Ankistrodesmus) cumulatively accounted for over 50% of the community. These analyses also suggest that the phytoplankton community strongly influences the seasonality of NO₃, IP, DO, pH and water clarity. According to a MANOVA, seasonal fluctuations explained 40% of the total variability for the major parameters, spatial heterogeneity explained 10% of variability, and the seasonal-spatial interaction explained 10% of variability. Distinctive patterns were identified between offshore and inshore sampling stations. The results of our analyses also suggest that spatial variability was substantial, but much smaller than temporal variability.     

多源信息融合技术在内陆湖库水华预警中的研究进展与展望

面对水体富营养化愈来愈严重，水华爆发越来越频繁的严峻形式；为减少水华发生频率及由此造成的损失，开展水华预警已成当务之急。水华爆发是水体中营养盐的累积、气候条件与水力条件等众多因素非线性共同作用的产物；为此，有必要在众多水华影响因素的动态监测信息的融合基础上，寻求水华爆发与这些影响因素间的影射关系，这就需要信息融合技术。通过归纳总结多源信息融合技术在内陆湖库水华预警中应用的研究进展，结合目前我国水华预警的具体需求，提出建立基于多源信息融合技术的水华预警决策支持系统的研究前景与初步设想。信息融合技术为水华预警提供了一个良好的平台，它将与水华相关的不同信息源（水文、气象、水环境质量与环境遥感）所提供的局部不完整的观测信息加以集成与互补，消除多源信息之间存在的冗余和矛盾，形成对水华爆发环境相对完整的感知与描述；从而提高水华预警与应急响应决策的效率，提高预警信息的时间与空间分辨率，扩展信息的时空监测范围。     

Adaptive Management of Nonnative Species: Moving Beyond the “Either-Or” Through Experimental Pluralism

This paper develops the outlines of a pragmatic, adaptive management-based approach toward the control of invasive nonnative species (INS) through a case study of Kings Bay/Crystal River, a large artesian springs ecosystem that is one of Florida’s most important habitats for endangered West Indian manatees (Trichechus manatus). Building upon recent critiques of invasion biology, principles of adaptive management, and our own interview and participant–observer research, we argue that this case study represents an example in which rigid application of invasion biology’s a␣priori imperative to minimize INS has produced counterproductive results from both an ecological and social standpoint. As such, we recommend that INS control in Kings Bay should be relaxed in conjunction with an overall program of adaptive ecosystem management that includes meaningful participation and input from non-institutional stakeholders. However, we also note that adaptive management and INS control are by no means mutually exclusive, in Kings Bay or elsewhere. Instead, we suggest that adaptive management offers a means by which INS control efforts can emerge from—and be evaluated through—ongoing scientific research and participatory dialogue about the condition of specific places, rather than non-contextual assumptions about the harmfulness of INS as a general class.     

富营养化发生机理及水华暴发研究进展

概述了目前富营养发生的机理和水华暴发机制的最新研究方向。从营养物质的循环、水体热分层、水化学平衡方面论述和总结了富营养发生机理的研究现状;从氮磷比、其它营养元素限制、沉积物营养物质的循环等方面对水华暴发机制作用的研究进行了展望。本文对富营养化发生机理及水华暴发研究领域现状和未来的研究方向有一定的借鉴作用。     

大亚湾日本星杆藻种群动态及其与环境因子的关系

研究了1997～1998年及1999和2000年春季大亚湾日本星杆藻(Asterionella japonica)种群动态及其与环境因子之间的关系.日本星杆藻是大亚湾浮游植物常见优势种类,可在全年温度范围(14～32.8℃)内形成数量高峰,并发生水华.日本星杆藻在1998年和2000年春季不常出现,但1999年春丰富的营养盐含量及它们之间合适的比值、多变的水温、稳定的盐度和晴朗的天气使日本星杆藻迅速生长,并发生了水华,最高细胞密度达5255cells/mL.水华消耗了大量的营养,水华期间DIN、DIP和Dsi分别下降了76.0%、69.7%和58.8%,而且营养元素的消耗特别是DIN的耗尽是水华消退的重要原因,而桡足类等浮游动物摄食也是水华消退的原因之一.