生物结皮中优势蓝藻胞外多糖对几种荒漠草本植物种子萌发的影响

蓝藻是荒漠生物结皮的重要组成。选取生物结皮中的优势蓝藻(具鞘微鞘藻(Microcoleus vaginatus)、眼点伪枝藻(Scytonema ocellatum)、地木耳(Nostoc commune)),通过提取其胞外多糖,研究了不同蓝藻胞外多糖对荒漠植物种子萌发的影响。结果表明:具鞘微鞘藻、眼点伪枝藻的胞外多糖对粗枝猪毛菜(Salsola subcrassa)的种子萌发表现为低浓度抑制、高浓度促进作用,地木耳的胞外多糖仅在高浓度时对粗枝猪毛菜的种子萌发具有促进作用(p<0.05);具鞘微鞘藻胞外多糖对小花荆芥(Nepeta micrantha)种子萌发无明显的影响作用,但眼点伪枝藻和地木耳对小花荆芥种子萌发具有抑制作用。具鞘微鞘藻、眼点伪枝藻和地木耳胞外多糖对琉苞菊(Hyalea pulchella)种子萌发具有明显的抑制作用。藻种胞外多糖组分的差异和不同种子的生物学特性差异可能是造成不同藻种胞外多糖对种子萌发产生不同影响的主要原因。     

Late Viséan–Serpukhovian foraminiferans and calcareous algae from the Adarouch region (central Morocco), North Africa

Three Upper Viséan to Serpukhovian limestone formations from the Adarouch region (central Morocco), North Africa, have been dated precisely using foraminiferans and calcareous algae. The lower and middle part of the oldest formation, the Tizra Formation (Fm), is assigned to the latest Asbian (upper Cf6γ Subzone), and its upper part to the Early Brigantian (lower Cf6δ Subzone). The topmost beds of this formation are assigned to the Late Brigantian (upper Cf6δ Subzone). The lower part of the succeeding Mouarhaz Fm is also assigned to the Late Brigantian (upper Cf6δ Subzone). The Akerchi Fm is younger than the other formations within the region, ranging from the latest Brigantian (uppermost Cf6δ Subzone) up to the Serpukhovian (E₁–E₂). The base of the Serpukhovian (Pendleian Substage, E₁) is repositioned, to coincide with the appearance of a suite of foraminiferans including Archaediscus at tenuis stage, Endothyranopsis plana, Eostaffella pseudostruvei, Loeblichia ukrainica, Loeblichia aff. minima and Biseriella? sp. 1. The upper Serpukhovian (Arnsbergian Substage, E₂) is marked by the first appearance of Eostaffellina ex. gr. paraprotvae and Globoomphalotis aff. pseudosamarica. The biostratigraphical scheme used for the reassessment of the foraminiferal zones and subzones in the Adarouch area closely compares with that for the British succession in northern England (Pennine Region), where the stratotypes of the Upper Viséan (Asbian and Brigantian) and Early Serpukhovian (Pendleian) substages are located. Thus, a succession equivalent to an interval from the Melmerby Scar Limestone to the Great (or Little) Limestone is recognized. These assemblages are also compared to other foraminiferal zones proposed in other regions of Morocco. Several foraminiferans have been identified that are proposed as potential Serpukhovian markers for other basins in Western Europe, and compared to sequences in Russia and the Donets Basin, Ukraine. Copyright © 2008 John Wiley & Sons, Ltd.     

南麂列岛附近海域浮游动物的分布及其与浮游藻类和营养盐的关系

本文描述了南麂列岛附近海域浮游动物的分布及其与浮游藻类和营养盐之间的关系。结果显示：浮游动物丰度与浮游藻类细胞总密度和硅藻细胞密度有正相关性,与硅酸盐和硝酸盐的浓度有负相关性。     

Lake evolution in a semi-arid montane environment: response to catchment change and hydroclimatic variation

Pollen, geochemical and sedimentological data from Sidi Ali, a montane Moroccan lake, provide a 7000 yr record of changes in climate, catchment vegetation and soil erosion intensity. Diatoms, non-silicious algae, macrophyte fossils and ostracods from the same core record the dynamics of the lake ecosystem. Oxygen isotope and trace-element ratios of benthic ostracods appear to be relatively insensitive to climatic variation in this open lake with low water-residence time, but diatom plankton / periphyton (P/L) ratios show lake-level variations that are probably climate controlled. At least two superimposed processes are recorded, but at different timescales: catchment vegetation and soils show long-term changes due to climate and human impact, whereas P/L ratios suggest century-scale oscillations in lake depth. The timing of changes in algal and macrophyte productivity and carbon cycling within the lake broadly corresponds to changes in terrestrial vegetation, suggesting either that lake nutrient status is linked to catchment vegetation and soils, or that both were influenced by climate. The lack of a sensitive and independent (non-biological) climate proxy makes it more difficult to assess the lake's ecological response to short-term climate variation. Overall, the lake's evolution has been influenced both by catchment-mediated nutrient flux and by changes in water balance, thus having characteristics in common with both temperate and arid zone lakes.     

Lake Shira, a Siberian salt lake: ecosystem structure and function. 3. The use of bioluminescent biotests to monitor ecological status

The specific composition, vertical distribution and daily migration of plankton in a meromictic salt lake, Lake Shira, have been investigated. The main structural components of the ecosystem are bacteria, algae and crustaceans. Since the late 1970s, blue-green algae are reported as dominant. Nowadays the phytoplankton is dominated byLyngbya contorta, Microcystis ichtyoblabe (Cyanophyta),Cyclotella tuberculata (Bacillariophyta) andDictyosphaerium tetrachotomum (Chlorophyta). The zooplankton of Lake Shira comprisesArctodiaptomus salinus (Copepoda),Brachionus plicatilis andHexarthra oxiuris (Rotatoria). Investigation revealed a stratified vertical distribution of all dominant species exceptCyclotella with a maximum at a depth of 12–15 m during the summer growth period. Zooplanktons differ in the pattern of distribution and daily migration, but most zooplankton tend to concentrate near the surface. The possible reasons for the vertical distribution of the plankton are discussed.     

太湖水华成因及控制途径初探

1990年8～12月对太湖水华9次调查表明,水华主要由漂浮性蓝藻—微囊藻组成,夏季SE风时其漂移集聚是西北湖区形成严重水华的主要原因。这种漂移使得藻类所含营养物逆吞吐流方向传输,形成了一种“生物营养滤器”,加速了太湖尤其是西北湖区的富营养化进程。太湖外源N、P负荷量分别为12.0和0.85g/(m~2·a),足以引起富营养化;表层5cm底泥中含丰富的N、P,其释放也成为湖水中部分营养的来源。因2～8月藻类总生物量的增长基本遵守Logistic方程dN/dt=N·r(1—N/K),故对藻类控制可从N、r入手,即通过收获藻类达到控制藻类总量和营养输出的双重功效;提高水位增加非光合层厚度,有效地降低水柱中藻类生产力;建立有水生植被的水质保护区也是一种局部藻类控制方法。     

基于ELCOM-CAEDYM模型的淀山湖营养物投入响应关系的模拟

针对淀山湖严重富营养化的问题,应用三维水动力-水质耦合模型ELCOM-CAEDYM对淀山湖水质进行了模拟,确定了一套可应用于淀山湖水质模拟的参数,并对模拟结果进行了验证;验证结果显示,ELCOM-CAEDYM耦合模型较好地模拟了常规水质和藻类浓度动态变化,模拟结果的总体变化趋势与实测结果相符合.同时运用该模型对淀山湖营...     

冰藻对南大洋大西洋扇区南极磷虾越冬期间碳源的贡献

南极磷虾是南大洋生态系统的关键物种, 种群聚集在南大洋的大西洋扇区。海冰在南极磷虾生活史中起着重要作用, 海冰及其冰下环境为磷虾越冬提供了避难场所, 但海冰是否为磷虾越冬提供了重要的饵料存在一定的争议, 对此问题的解决需要量化源于海冰的冰藻对南极磷虾越冬期间饵料及碳源的贡献。基于2020年冬季(3~8月)于南大洋大西洋扇区48.1亚区(布兰斯菲尔德海峡周边区域)和48.3亚区(南乔治亚岛周边海域)采集的磷虾样品, 通过两种高支链类异戊二烯化合物(IPSO₂₅和HBI III)分别作为源于海冰的冰藻和源于水体浮游植物的生物标志物, 对两个区域冬季磷虾对冰藻和浮游植物的依赖进行研究。结果显示, 处于较高纬度、海冰密集度较高的48.1亚区的南极磷虾体内含有更高的IPSO₂₅, 而处于开阔水域48.3亚区的磷虾体内有更高比例的HBI III, 另外48.3亚区磷虾的δ¹³C和δ¹⁵N稳定同位素显著高于48.1亚区的磷虾。48.1亚区南极磷虾越冬期间对浮游植物和冰藻的依赖与体长相关, 其中体长相对较短的早期成体呈现更高的依赖性, 同时该区域磷虾对冰藻的摄食提高了其营养级地位。48.3区南极磷虾越冬期间两种类异戊二烯含量与δ¹⁵N稳定同位素数值呈负相关关系, 表明该区域南极磷虾在初级生产匮乏时会摄食动物性饵料。若未来南大洋大西洋扇区海冰持续减少, 这将对整个磷虾种群、磷虾渔业的可持续发展和区域生态系统的稳定性产生威胁。     

滇池流域入湖河流丰水期着生藻类群落特征及其与水环境因子的关系

着生藻类是重要的水环境指示生物,其物种组成、生物密度以及多样性指数等群落特征被广泛用于监测和评价人为活动干扰对水生生态系统所造成的影响.本文根据滇池流域29条入湖河流2009年7-8月着生藻类调查数据,以及2008年9月至2009年8月逐月水环境指标监测数据,通过运用等级聚类分析、因子分析和典型对应分析,来探讨滇池流域...     

南极长城站附近海区冰藻色素的初步分析

本文报道了 1 988年 6 - 1 2月 (结冰期 )南极长城站附近海区冰藻色素的分离、鉴定结果。探讨了该海区冰藻色素的种类组成 ,季节变化以及冰藻色素在海洋生态系中的作用。结果表明 ,该海区冰藻已分离出色素 1 5种 ,可鉴定的有 1 3种 ,分别为 :胡萝卜素 ,脱镁叶绿素 a,叶绿素 a、b、c,叶黄素 ,岩藻黄质 ,脱植基叶绿酸 a,紫黄质 ,脱镁叶绿素 c,叶绿酸 a,叶绿素 c的衍生物 ,di-adinoxanthin,二种色素未能鉴定。该海域冰藻色素具明显的季节变化。