喀斯特湿地水葫芦(Eichhornia crassipes)生长及表型可塑性特征对不同富营养化水体的响应

选择桂林会仙喀斯特湿地,以不同富营养化水体中生长时期为6月(生长旺盛期)和8月(暴发高峰期)的水葫芦(Eichhornia crassipes)为研究对象,探讨不同富营养化条件下水葫芦的生长及表型可塑性响应特征,以揭示水葫芦对不同富营养化水体的生态适应机制.结果表明:水葫芦的株高、根长和叶绿素含量均随水体富营养化程度的增加而降低,叶柄数、叶柄宽、叶片数、叶长、叶宽、匍匐茎数和分株速率随着水体富营养化程度的增加而升高;各性状参数在暴发高峰期均略高于生长旺盛期;根生物量、茎生物量、叶生物量和总生物量均随水体富营养化程度的加深而增加,茎生物量高于根生物量和叶生物量;水葫芦生物量的分配以及性状间的权衡关系(根生物量比、茎生物量比、叶生物量比和茎叶比等)因生长时期的不同而呈现差异性,表现出较强的表型可塑性特征;水体总有机碳、总氮、总磷、硝态氮、氨氮和叶绿素a浓度分别与水葫芦的茎生物量、叶宽、匍匐茎数和分株速率间存在显著的正相关关系,与根长、株高、叶生物量比和茎叶比间存在显著的负相关关系;水葫芦的表型可塑性指数在0.009~0.792之间,叶重比的可塑性指数最大,根冠比最小,重度富营养化水体下的可塑性指数最大.在会仙喀斯特湿地不同富营养化水体环境中,水葫芦通过外部形态结构调节和生物量的配比关系,产生了有利于其入侵和存活的较强的表型可塑性,是其生存繁殖的重要响应机制之一.     

温度对铜绿微囊藻(Microcystis aeruginosa)和鱼腥藻(Anabaena sp.)生长及胞外有机物产生的影响

以巢湖优势种铜绿微囊藻(Microcystis aeruginosa)和鱼腥藻(Anabaena sp.)为研究对象,研究不同温度(35、25和10℃)对这两种藻生长特性和胞外有机物产生的影响.结果表明,温度对铜绿微囊藻和鱼腥藻的藻细胞密度、碱性磷酸酶活性和胞外有机物浓度影响显著.25℃是铜绿微囊藻和鱼腥藻最适宜的生长温度,最高细胞密度分别达到3.12×107cells/ml和2.03×107 cells/ml.不同温度下两种藻的碱性磷酸酶活性特征,证实了高温对鱼腥藻生长的抑制和低温对铜绿微囊藻生长的抑制.胞外有机物释放总量受蓝藻生物量和单位细胞有机物释放速率的影响.铜绿微囊藻的溶解性有机碳和胞外总多糖释放量在25℃最高,最大值分别为49.28和38.46 mg/L;而鱼腥藻在35℃时释放量最高,最大值分别为45.82和40.60 mg/L;10℃条件抑制了两种藻的生长及胞外有机物的释放.鱼腥藻胞外多糖含量在35℃培养条件下最高,而铜绿微囊藻在10℃条件下最高,说明不利的生长条件会促进蓝藻胞外多糖的分泌.三维荧光图谱分析结果表明,铜绿微囊藻和鱼腥藻胞外有机物以类蛋白质和类腐殖酸为主,温度主要影响藻细胞胞外有机物浓度,而对有机物种类组成没有影响.     

刚毛藻(Cladophora)生态学研究进展

刚毛藻(Cladophora)在全球海洋及淡水中普遍存在,它为沿岸带微生物和无脊椎动物提供了生产力和微生存空间.随着水体富营养化程度的加剧,刚毛藻在沿岸带出现暴发现象,造成严重的环境污染,同时刚毛藻的存在也影响了湖泊生态修复过程中沉水植被的恢复.本文从刚毛藻形态与种类鉴定、生长与分布影响因素、生长周期与种群动态、种间关系及生物去除等研究前沿方面进行综述,并对相关研究领域进行展望,为进一步研究刚毛藻生态生理特征、有效控制和去除提供科学依据.     

克隆整合和模拟沉积物淹埋对外来水生植物粉绿狐尾藻(Myriophyllum aquaticum)生长和抗氧化系统的影响

多数外来入侵水生植物都是克隆植物,而目前关于克隆整合属性对其入侵性潜在影响的研究仍旧缺乏.本文通过研究克隆整合(匍匐茎连接)和模拟沉积物淹埋(3 cm厚基质淹埋)对外来水生植物粉绿狐尾藻(Myriophyllum aquaticum)的生长、生物量分配和抗氧化酶活性的影响,探讨了克隆整合特性对粉绿狐尾藻耐受基质淹埋的作用机制.研究发现:基质淹埋显著降低了粉绿狐尾藻的生物量、总匍匐茎长度和分枝数,而克隆整合则显著促进了受淹埋分株的这些生长指标;基质淹埋显著降低了粉绿狐尾藻分株抗氧化酶(超氧化物歧化酶、过氧化物酶和过氧化氢酶)的活性,而克隆整合显著提升了受淹埋分株的抗氧化酶活性;此外,克隆整合显著降低了受淹埋分株的冠根比.以上结果表明:克隆整合效应能显著提升粉绿狐尾藻在基质淹埋胁迫下的活性氧清除能力,从而有助于其生长;能改变受胁迫分株生物量分配,提升其资源获取能力.因此,异质性环境胁迫下,粉绿狐尾藻的入侵性可能与其克隆整合属性密切相关.     

水深对沉水植物苦草(Vallisneria natans)和穗花狐尾藻(Myriophyllum spicatum)生长的影响

水深是影响浅水湖泊沉水植物生长的主要因素之一.莲座型苦草（Vallisneria natans）和冠层型穗花狐尾藻（Myriophyllum spicatum）是我国长江中下游浅水湖泊中常见的沉水植物种类,二者在形态特征上具有较大的差异.在自然水体中,水深变化对这两种植物的生长以及竞争格局的影响还有待研究.本文设计了3个水深梯度（水深0.5、1.5、2.5 m）,探讨混栽条件下苦草和穗花狐尾藻生长和竞争格局对水深变化的响应.结果显示在实验系统内,中水深（1.5 m）处理组对两种植物的生长均最有利,表现为两种植物的相对生长率和生物量均最高.低水深（0.5 m）处理组苦草的生物量和相对生长率均显著低于高水深（2.5 m）处理组;穗花狐尾藻则相反,高水深对其生长的抑制作用更大.2种沉水植物在高水深胁迫时均表现出地上部分（叶长或茎长）增加,地下部分（根长）减少的形态响应特征.此外,随着水深由高到低,苦草与穗花狐尾藻生物量之比逐渐减小,表明苦草在两种植物中的竞争优势逐渐降低.研究表明湖泊水深变化不仅能够影响沉水植物的丰度,同时还可能会影响沉水植物的群落结构,而在我国浅水湖泊的生态修复实践中,在通过水位调控恢复沉水植物时,调控范围应考虑目标植物（如苦草）的光合特征.     

鄱阳湖河湖转换期间鱼腥藻(Anabaena)的变化

鄱阳湖作为我国长江目前仅存的两个通江湖泊之一,年内水位变幅巨大.通过在鄱阳湖2013年河湖转换期间(5—11月)对鄱阳湖主航道都昌段进行每月3~4次的高频监测,以考察鄱阳湖水体中鱼腥藻(Anabaena)的动态变化,分析鄱阳湖中鱼腥藻生长并占优势的影响因素.结果表明,蓝藻为鄱阳湖浮游植物的次级优势种,8月蓝藻生物量平均占浮游植物生物量的57%,蓝藻取代硅藻成为暂时的优势种.夏、秋季水华蓝藻以固氮鱼腥藻为主,主要与夏、秋季水温较高以及适宜的营养盐条件等有关.研究期间鄱阳湖水体氮磷比平均在15左右,鱼腥藻能够产生有固氮能力的异形胞,并在水华蓝藻中成为优势种,也反映了鄱阳湖某些湖区存在氮相对缺乏的阶段.     

水网藻(Hydrodictyon reticulatum)水华在鄱阳湖的纪录

水网藻水华在国外出现较多,在国内鲜有报道.2013年5月对鄱阳湖进行采样时首次发现水网藻水华;结合现场观测及遥感影像确定其分布范围为老爷庙至落星墩水域,分布面积约为26 hm²,推测水网藻可能是由上游稻田等静止水体迁移至鄱阳湖,在相对静水区进行聚集生长,加上合适的理化条件(温度及营养盐),从而形成水华.在此基础上,本文进一步分析了水网藻水华对鄱阳湖水生态环境可能产生的影响.     

铵胁迫对狐尾藻(Myriophyllum spicatum)和金鱼藻(Ceratophyllum demersum)生物量分配和形态的影响

选取了两种常见的沉水植物狐尾藻和金鱼藻,通过测定其单株生物量、株高、根生物量/单株生物量、茎生物量/单株生物量和叶生物量/单株生物量,研究这两种沉水植物在2 mg/L的铵态氮持续处理4 d以及铵态氮胁迫解除后的生长情况.结果表明:铵胁迫阶段,与对照组相比,处理对狐尾藻各测定参数均无显著影响,而使金鱼藻株高显著增加.在铵胁迫解除阶段,与对照组相比,处理组狐尾藻单株生物量增加不显著,而金鱼藻单株生物量显著增加;处理组2种沉水植物株高均显著增加;处理组狐尾藻叶生物量/单株生物量显著增加,而根生物量/单株生物量显著减少,茎生物量/单株生物量保持不变.认为高光照环境下(约400μmol/(m²·s)),水体中铵态氮浓度短时间内(4 d)适当增加对沉水植物生长没有抑制作用;金鱼藻对高铵态氮浓度水体的适应能力较狐尾藻强.     

光照强度对铜绿微囊藻(Microcystis aeruginosa)和斜生栅藻(Scenedesmus obliqnus)生长及吸收特性的影响

在不同的光照强度下,测定了铜绿微囊藻、斜生栅藻在不同生长期的藻细胞密度、粒径、叶绿素a浓度、浮游植物吸收系数以及比吸收系数.单因素方差分析表明,在整个培养周期中,光照强度对铜绿微囊藻及斜生栅藻的藻细胞密度、叶绿素a浓度以及440、675 nm处吸收系数均有着显著的影响.两种藻在光照强度为50μmol/(m2.s)条件下,藻细胞密度、叶绿素a浓度及吸收系数值相对最大.相关性分析表明:藻类特征波段440、675 nm吸收系数与叶绿素a浓度、藻细胞密度在不同光照条件下都存在着显著的正相关性,其中叶绿素a浓度与藻类吸收系数存在着幂函数的关系,而线性关系能更好的说明藻细胞密度与吸收系数之间的关系.在不同光照强度及培养时期,藻类比吸收系数在一定的范围内波动,随光强增加比吸收系数呈上升趋势.铜绿微囊藻440、675 nm处比吸收系数与叶绿素a浓度呈显著的负相关关系,而斜生栅藻比吸收系数与叶绿素a浓度之间无显著相关,体现了不同藻类由于色素组成及比例差异其色素包裹效应也各不相同.对不同光照强度下的铜绿微囊藻及斜生栅藻进行400～700 nm波段积分,得到了两者在5、50及100μmol/(m2.s)不同种光强下的平均比吸收系数分别为0.0144、0.0134、0.0160,0.0086、0.0088、0.0105 m2/(mg Chl.a),铜绿微囊藻比吸收系数明显大于斜生栅藻.     

Zn2+浓度对固氮鱼腥藻(Anabaena azotica Ley)光能转化特性的影响

本实验对在不同Zn^2 浓度条件下培养的固氮鱼腥藻（Anabaena azotica Ley）的生长、光合放氧速率和叶绿素荧光参数Fv/Fm进行了测定。结果表明,当Zn^2 浓度为1.0μmol/L时,其比生长速率（Specifie growth rate）最大,光合放氧速率和Fv/Fm值最高,当Zn^2 浓度大于等于5.0μmol/L是会抑制A.azotica Ley的生长和光合作用,对在0μmol/L和5.0μmol/L Zn^2 发生反应的藻蓝蛋白溶液的可见光吸收光谱的分析,发现前者624nm处藻胆体的吸收峰和后者620nm处藻蓝蛋白的吸收峰都因Zn^2 的作用而下降,推测藻蓝蛋白为Zn^2 影响光合作用的位点之一,碳酸酐酶活性的测定表明Zn^2 的浓度水平会影响其活性大小,推测是Zn^2 影响光合作用的另一途径。     

Lake victoria: The water hyacinth (Eichhornia crassipes [Mart.] Solms), its socio-economic effects, control measures and resurgence in the Winam gulf

The aquatic weed Eichhornia crassipes [Mart.]Solms was introduced in Lake Victoria from Rwanda via the Kagera River by the activities of man. After originally infesting Lake Victoria (Uganda), it eventually spread into the Winam gulf, where its proliferation was spectacular, resulting in an enormous public outcry. The aim of this study was to find out how a beach/bay covered by a weed carpet affected the life of a lakeshore community, if there were any seasonal changes in carpet sizes and to establish if the water hyacinth is a friend or an enemy. Surveys were conducted in selected beaches between June 1995 and November 1999. When surveys were complete, it became clear that this weed is nomadic, except in lagoons and beaches that had little external interference. The open waters remained generally clear due to constant wave action. Interviews conducted on selected beaches/bays indicated that weed carpets impacted both positively and negatively, i.e. they disrupted fishing activities, transport, irrigation, water treatment, enhanced breeding grounds for vectors of human diseases, impacted on biodiversity and had become a source of raw materials for making furniture, paper and artefacts. After successful biological control by the Kenya Agricultural Research Institute (KARI), resurgence and succession were observed. The impact of water hyacinth on the life of the lakeshore communities in the Winam gulf is serious and needs to be quantified. Further research is necessary to establish whether this weed is an enemy or a friend of the lakeshore communities.     

洞庭湖湿地柳属木本植物与薹草属草本植物群落土壤与水环境特征

木本与草本是植物存在的两种主要生活型,生态功能差异明显,尤其在植物被周期性洪水淹没的湿地生态系统中.为此,以洞庭湖湿地二门闸、五门闸、藕池河口、白沙大桥4个研究点的原生柳属木本植被与薹草属草本植被为研究对象,通过对枯水期土壤理化性质与汛期水流速度、水环境的对比监测,揭示两者生态防护功能的差异.对土壤粒径组成而言,在二门闸与白沙大桥2个研究点,木本与草本植物群落土壤样本之间无显著差异;而在五门闸与藕池河,与草本植物相比,木本植物导致土壤上层(0~30 cm)与下层(60~90 cm)粉粒含量降低,砂粒含量增加,中层(30~60 cm)黏粒与粉粒含量增加,砂粒含量降低.对土壤化学性质而言,木本植物总体上导致土壤有机质与全氮含量升高,而对全磷与全钾含量无显著影响.与草本植物相比,木本植物能显著减缓水流速度,提高水体氧化还原电位与溶解氧浓度,而对水温与p H值无明显影响.可见,洞庭湖湿地木本与草本植物生活型的差异,是导致二者土壤与水环境特征差别的主要原因,与草本植物相比,木本植物具有更强的生态防护功能.     

火烧对洞庭湖湿地荻(Miscanthus sacchariflorus)和苔草(Carex brevicuspis)群落土壤性质的影响

火烧作为调控因子,对植物群落结构和生态系统功能具有重要影响,但在湖泊湿地中研究较少.通过野外调查取样与实验室分析,探讨火烧对洞庭湖湿地主要群落类型——荻(Miscanthus sacchariflorus)和苔草(Carex brevicuspis)土壤化学性质的影响.结果表明:火烧后,苔草群落土壤硝态氮含量显著减少64.6%,有机质含量增加26.3%;而荻群落土壤与之相反,硝态氮含量增加186.9%,有机质含量减少22.9%.火烧后,苔草群落的全氮、铵态氮、全碳和全磷含量均显著增加,分别增加了75.4%、36.3%、102.7%和76.9%,而荻群落土壤与对照组间无显著差异.总体上,火烧对荻群落土壤养分影响不大,可作为芦苇场的一种管理方式,但火烧促进苔草群落土壤养分释放,有助于苔草群落提前萌芽和生长,并引起牲畜牧食增加.     

利用湖泊内源性饵料饲喂中华绒螯蟹(Eriocheir sinensis)的养殖与净水效应

在东太湖网围养殖区进行不同放养密度(3000、6000、9000只/hm²)饲喂太湖水草与螺蛳的中华绒螯蟹(Eriocheir sinensis)养殖实验,各处理组均设投喂鱼肉与玉米等外源性饵料的对照,以获得不同养殖模式对中华绒螯蟹生长、品质及养殖水环境的影响,以及利用浅水草型湖泊内源性饵料养殖中华绒螯蟹的适宜放养密度.结果表明,规格和增肉倍数虽然均显著小于相同养殖密度下投喂外源性饵料的对照组,但是各实验组商品蟹体重均能达到150 g;低密度养殖组(3000只/hm²)的产量与对照组无显著差异,其余两组显著低于对照组;而低密度养殖组的河蟹回捕率显著低于对照组,其余两组则无显著差异.实验养殖区水质状况优于投喂外源性饵料的对照区,其TP含量显著低于对照区,投喂外源性饵料会增加水体N、P含量,导致水体富营养化.投喂太湖水草与螺蛳等内源性饵料进行中华绒螯蟹养殖不但可以有效地抑制浅水湖泊水草的疯长,还可通过中华绒螯蟹收获从水体输出N、P营养盐,起到净化水质的作用.不同密度养殖的生态与经济效益对比结果显示,利用草型湖泊内源性饵料养殖中华绒螯蟹的适宜放养密度为6000只/hm²左右.     

Hydrological effects of water reservoirs on hydrological processes in the East River (China) basin: complexity evaluations based on the multi‐scale entropy analysis

Using the multi‐scale entropy analysis (MSE), we study the effects of water reservoirs on the river flow records based on long streamflow series covering January 1, 1954 and December 31, 2009 at four representative hydrological stations, i.e. the Longchuan, the Heyuan, the Lingxia and the Boluo stations. Hydrological effects of two major water reservoirs, the Xinfengjiang and the Fengshuba water reservoirs, are evaluated. The results indicate that: (1) before the construction of the water reservoirs, the complexity of the streamflow series comes to be decreasing from the upper to the lower East River and which should be attributed to the topographical properties and buffering effects of the river channel; (2) construction of water reservoirs greatly increases the complexity degree of the hydrological processes, and this influence is subjected to a damping process with the increase of distance between the water reservoirs and the hydrological stations; (3) power generation is the major function of the water reservoirs in the East River basin. The results of this study should be of theoretical and scientific merits in terms of conservation of the ecological environment and also water resources management under the influences of climate changes and intensifying human activities. Copyright © 2011 John Wiley & Sons, Ltd.     

Effect of Copper on Activity and Feeding in the Subtidal Prosobranch Babylonia lutosa (Lamarck) (Gastropoda: Buccinidae)

Individuals of the subtidal gastropod Babylonia lutosa were exposed to three sublethal concentrations of copper (0.02, 0.06 and 0.20 ppm) for four weeks. The percentage of normally active individuals (body extended and moving with the foot attached) decreased and the percentage of snails retracted (body extended, foot not attached, unable to move) and in a distressed stage (body retracted within the shell) increased with increase in copper concentration. Exposure to copper also decreased significantly the ability of an individual to move, and to burrow, but the effect was only observed in week 1, individuals were fully recovered in week 2. Feeding, however, was not affected, both in terms of the percentage number of individuals which fed, and the time spent feeding. Results were discussed with respect to the potential of using this animal as a bioassay tool in monitoring the effect of environmental perturbations on the subtidal community in Hong Kong.     

The effects of partial rootzone drying on root, trunk sap flow and water balance in an irrigated pear (Pyrus communis L.) orchard

Partial rootzone drying (PRD) means that part of the root system is watered as in full irrigation while the rest is exposed to soil drying. This practice is predicted to influence field hydrological circle. We studied the effect of this practice on soil water distribution, root and trunk sap flow, water consumption of pear trees, and capillary contribution from ground water table and water balance for three months in an irrigated orchard with a shallow ground water table. The irrigation treatments included: (a) conventional flooded irrigation (CFI), (b) fixed partial rootzone drying (FPRD), and (c) alternate partial rootzone drying (APRD). Root and trunk sap flows were monitored using a heat-pulse sap flow meter. The results showed that there were significant differences of soil water content in both sides of rootzone under partial drying. The capillary contribution from ground water table was significantly increased in APRD and FPRD when compared with CFI. More significantly, the total irrigation amount was greatly reduced, by 43.64 and 45.84%, respectively, for APRD and FPRD. The two PRD treatments used more soil-stored water while CFI had more drainage. The root sap flow on the wet side was substantially enhanced as a result of PRD, and was greater than that from same side in CFI. The trunk sap flow in FPRD and APRD was smaller than that in CFI. On average, both APRD and FPRD reduced plant daily water consumption by about 9.96 and 17.97%, respectively, when compared to CFI during the PRD period. Daily root water flow was a significant function of the reference evapotranspiration. The daily trunk water flow was also related to the reference evapotranspiration but the CFI carried more water than APRD and FPRD under the same evaporation demand, suggesting a restriction of transpirational water loss in the PRD trees. CFI needed a higher soil water content to carry the same amount of trunk flow than the PRD trees, suggesting the hydraulic conductance of roots in PRD trees enhanced, and the roots had a greater water uptake capacity than in CFI when the average soil water content in the rootzone was the same.     

The effect of mining and related activities on the sediment–trace element geochemistry of Lake Coeur d'Alene,Idaho, USA. Part III. Downstream effects: the Spokane River Basin

During 1998/1999, surface and subsurface sediment samples were collected along the entire length of the Spokane River from its outlet at the northern end of Lake Coeur d'Alene (CDA), Idaho, to Lake Roosevelt on the Columbia River, Washington. The study was conducted to determine if the trace element enrichments observed in Lake CDA and on the floodplain and in the CDA River extend through the Spokane River Basin (SRB). As in Lake CDA, surface sediments in the SRB are enriched in Pb, Zn, As, Cd, Sb and Hg relative to local background levels. Pb, Cd and Zn are the most elevated, with maximum enrichment occurring in the upper Spokane River in close proximity to Lake CDA. On average, enrichment decreases downstream, apparently reflecting both increased distance from the inferred source (the CDA River Basin), as well as increased dilution by locally derived but unenriched materials. Only Cd and Zn display marked enrichment throughout the SRB. Pb, Zn and Cd seem to be associated mainly with an operationally defined iron oxide phase, whereas the majority of the As and Sb seem to be matrix‐held. Subsurface sediments also are enriched in Pb, Zn, As, Cd, Sb and Hg relative to background levels. Based on ¹³⁷Cs and excess ²¹⁰Pb dating, trace element enrichment began in the middle part of the SRB (Long Lake) between 1900 and 1920. This is contemporaneous with similar enrichments observed in Lake CDA, as well as the completion of Long Lake Dam (1913). In the most downstream part of the basin (Spokane River Arm of Lake Roosevelt), enrichment began substantially later, between 1930 and 1940. The temporal difference in enrichment between Long Lake and the River Arm may reflect the latter's greater distance from the presumed source of the enrichment (the CDA River Basin); however, the difference is more likely the result of the completion of Grand Coulee Dam (1934–1941), which formed Lake Roosevelt, backed up the Spokane River, and increased water levels in the River Arm by about 30 m.     

A methodology for historical assessment of compliance with environmental water allocations: lessons from the Crocodile (East) River,South Africa

Abstract

Environmental flow provisions are a legal obligation under South Africa’s National Water Act (1998) where they are known as the “ecological reserve”, which is now being realized in river operations. This article presents a semi-quantitative method, based on flow–duration curve (FDC) analysis, used to assess the compliance of the Crocodile (East) River with the reserve in an historical context. Using both monthly and daily average flow data, we determine the extent and magnitude of non-compliant flows against environmental water requirements (EWRs) for three periods (1960–1983, 1983–2000, and 2000–2010). The results suggest a high degree of non-compliance, with the reserve increasing with each of these periods (14%, 35%, and 39% of the time), respectively, where effects were most pronounced in the low-flow season. The results also suggest that, whilst the magnitudes of reserve infringements for the latter period are relatively high, there appears to have been some improvement since the implementation of the river’s operating rules.

Editor Z.W. Kundzewicz; Guest editor M. Acreman

Citation Riddell, E., Pollard, S., Mallory, S., and Sawunyama, T., 2014. A methodology for historical assessment of compliance with environmental water allocations: lessons from the Crocodile (East) River, South Africa. Hydrological Sciences Journal, 59 (3–4), 831–843.