南极乔治王岛燕鸥湖晚第四纪硅藻（Ⅰ）：Coscinodiscales

南极乔治王岛燕鸥湖Ａ孔岩芯长７．７ｍ,其中发现有丰富的淡水及海相硅藻植物群。本文仅涉及该孔海相地层中的Ｃｏｓｃｉｎｏｄｉｓｃａｌｅｓ硅藻植物群的系统分类及其古环境意义。系统描述１４种和２变种（其中１个为新变种）,分属７属,５科,另有１种硅鞭藻。该植物群为南大洋中常见的浅海类型,它们对于指示南大洋水体的波动及古气候变化具有一定意义。     

The Presence and Localization of Thioredoxins in Diatoms,Unicellular Algae of Secondary Endosymbiotic Origin

Diatoms are unicellular algae of great ecological importance. So far, very little is known about the regulation of carbon fixation in these algae; however, there are strong indications that in diatom plastids, the ferredoxin/thioredoxin system might play a minor role in redox regulation of the photosynthetic reactions compared to land plants. Until now, it is unknown whether there are fewer or other target enzymes of thioredoxins in diatoms. Only a single potential target enzyme for thioredoxin, the plastidic fructose-l,6-bisphosphatase, has yet been identified. Nevertheless, during the annotation of the genome of the diatom Phaeodactylum tricornutum, we identified several genes encoding different thioredoxins. Utilizing in vivo expression of GFP：presequence fusion proteins in P. tricornutum, we were able to show that these thioredoxins are targeted either into plastids, mitochondria, or remain in the cytosol. Surprisingly, two of the three usually cytosolic thioredoxin h proteins are apparently plastid associated and, together with a thioredoxin reductase, putatively located in the periplastidic compartment. This is one of the few indications for so far unknown enzymatic reactions in the space between the two pairs of diatom plastid envelope membranes.     

肇庆市七星岩里湖水化学因子相关性研究

广东省肇庆七星岩是我国著名的风景游览胜地 ,里湖是其中的重要组成部分。面积约 2 .6× 1 0 5 ｍ2 ,近年来 ,里湖水质有劣化趋势 ,表观上出现不同颜色 ,有藻类突发现象。对景区产生不良影响。既往研究表明 ,影响里湖水质的关键组分除浮游藻类叶绿素ａ与氮、磷含量之外 ,水中的ＤＯ和ＣＯＤ、ＢＯＤ也是极其重要的指标。研究它们的相互关系 ,旨在探讨其内在联系及变化规律 ,对于湖泊生态环境的保护和水污染的治理具有重要意义。1　研究材料与方法1 .1　主要仪器日立Ｆ -30 0 0型荧光分光光度计 (日本) ;ＷＺ -80 0Ｄ2 型紫外分光光度计(北京…     

对虾综合养殖围隔中浮游细菌生产力的研究

用5个养虾实验围隔研究了对虾综合养殖生态系浮游细菌的生产力。结果表明,生产量(μgC/L·d)变动在90～909之间,平均为292±141。对虾-罗非鱼-缢蛏混养及对虾-扇贝混养生态系细菌生产量相对稳定;对虾单养及对虾-缢蛏、对虾-罗非鱼混养生态系细菌生产量却变化较大。细菌生产量与水温、细菌生物量及浮游生物群落呼吸量均呈现显著相关性。细菌的日P/B系数变化在0.22～1.67(d-1)之间,平均为0.93±0.37(d-1)。细菌生产量与浮游植物毛生产量比值平均为0.15。     

中国近海浮游植物生产的二甲基硫和二甲基硫丙酸的分布状况及其影响因素

于1994～1998年期间调查了浮游植物生产的生源气候气体二甲基硫(DMS)及其前身二甲基硫丙酸(DMSPp)在我国胶州湾、芝罘湾、东海的分布状况及其影响因素.结果表明,自然海区中二者浓度都存在明显的时空变化.地理分布规律是,高值出现在沿岸海区和陆架海区,低值出现在外海特别是贫营养海区.就不同季节而言,高值出现在春季或夏季,低值出现在秋季.DMS或DMSPp的分布在大尺度上主要受海流和水团的影响,而在小尺度上营养条件和生物因子则更重要.在近岸海区,硅藻是DMS和DMSPp的重要贡献者.研究海区硝酸盐与DMSPp的关系有两种情况:当硝酸盐浓度低于1μmol/L时,二者为正相关,硝酸盐浓度高于这个阈值时,二者为负相关.表明浮游植物细胞中二甲基硫丙酸作为渗透压调节物质其含量受到氮源可得性的调控.此外,研究结果还显示,生活污水入海、海水养殖等也对DMS和DMSPp的浓度分布有一定影响.     

Formation and Growth of Bryopsis hypnoides Lamouroux Regenerated from Its Protoplasts

Tissue culture, SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and spectra analysis were used for studying the aggregation mechanism of protoplasts from Bryopsis hypnoides Lamouroux and the discrepancy between the protoplast-regenerated plants and the wild type. The aggregation of protoplasts from B. hypnoides was observed in natural seawater and artificial seawater with different pH values, and the location and mechanism of the materials causing the aggregation were also studied. Results showed that the protoplasts could aggregate into some viable spheres in natural seawater and subsequently grow into mature individuals. Aggregation of the protoplasts depended exclusively upon the pH value (6-11), and the protoplasts aggregated best at pH 8-9. Some of the extruded protoplasts were separated into two parts by centrifugation: the pellet (PO) and the supernatant (PL). The PO could aggregate in artificial seawater (pH8.3) but not in PL. No aggregation was found in PO cultured in natural seawater containing nigericin, which can dissipate the proton gradients across the membrane. These experiments suggest that the aggregation of protoplasts is proton-gradient dependent and the materials causing the aggregation were not in the vacuolar sap, but located on the surface or inside the organelles. Furthermore, the transfer of the materials across the membrane was similar to △pH-based translocafion (△pH/TAT) pathway that occurs in the chloroplasts of higher plants and bacteria. Obvious discrepancies in both the total soluble proteins and the ratio of chlorophyll a to chlorophyll b between the regenerated B. hypnoides and the wild type were found, which may be related to the exchange of genetic material during aggregation of the organelles. In the process of development, diatom Amphora coffeaeformis Agardh attached to the protoplast aggregations, retarding their further development, and once they were removed, the aggregations immediately germinated, which showed that diatoms can affect the development of other algae.     

Causes and Consequences of Changes in Nutrient Structure in the Jiaozhou Bay

Concentrations and ratios of nutrients in Jiaozhou Bay, China, have changed much in the past decades, with trends indicating an increase in nitrogen and a decrease in silicate. Statistical analysis has shown that the long-term variations of nutrients are associated with agricultural activities, precipitation, and anthropogenic factors. Stoichiometric calculations indicate that the nutrient structure has become more and more unbalanced. There has been almost no possibility for nitrogen limitation since the 1980s, the probability of P limitation has increased, and the probability of Si limitation has also increased markedly from the 1980s to the 1990s. As a consequence of changes in nutrient structure, a decrease in the abundance of net phytoplankton was evident, whereas total chlorophyll a levels have remained roughly unchanged at around 3.55μg/L. Thus, it is likely that smaller species have taken the niche vacated by the larger species. Changes in phytoplankton size and species composition may ultimately lead to various functional and structural changes at the system level.     

Relationship Between Surface Sediment Diatoms and Summer Water Quality in Shallow Lakes of the Middle and Lower Reaches of the Yangtze River

The relationship between surface sediment diatoms and summer water quality was investigated at 49 lakes in the middle and lower reaches of the Yangtze River. Lakes ranging from oligomesotrophic to hypereutrophic were examined, providing an obvious nutrient gradient. With the shift from mesotrophic to eutrophic levels, diatom multi-ecotypes dominated by epiphytic and facultative planktonic taxa were replaced by nutrient-tolerant planktonic taxa, such as Cyclotella meneghiniana Skvortzow, C. atomus Hustedt, Cyclostephanos Round, and Stephanodiscus Ehrenberg etc., reflecting the nutrient changes in the lake. The relationship between diatoms and summer water quality indices was explored further using numeric analysis. Canonical correspondence analysis (CCA) with forward selection and a Monte Carlo permutation test revealed that of all 25 summer water environmental variables, total phosphorus (TP), chlorophyll a (Chl a), Secchi depth (SD), dissolved inorganic phosphorus, Cl–, SO42–, Mg2+, CO32–, and water depth were significant variables (P<0.05) in explaining diatom distributions. Of these, TP, Chl a, SD, and Cl–, were the most important variables. The result of the correlation analysis also showed that a significant correlation exists among these variables, implying that these indices are either interconnected or independent in explaining the diatom data. For phosphorus-limited sites, TP was the most significant variable affecting the diatoms, also affecting changes in Chl a, SD, and iron concentrations. The independence of Chl a may be related to algal competition induced by lake eutrophication, resulting in the feedback to diatom community. In addition to TP, SD can be related to sediment disturbance by wave action and the growth of macrophytes in large shallow lakes. These relationships between diatom ecotypes and water quality provide the basis for a future quantitative reconstruction of historic lake nutrient evolution in the study area and will also provide a wealth of modern ecological knowledge that can be used to interpret fossil diatom records.     

象山港网箱养殖区与非养殖区的细菌群落分布

近海集约化养殖是导致我国近海污染的主要来源之一。浮游细菌在近海生态系统的物质循环过程中发挥重要作用,研究海洋浮游细菌群落对养殖活动的响应,对于指示和评价海水养殖生态系统健康具有重要意义。采集了象山港网箱养殖区与非养殖区3个深度,包括表层(0.5 m)、中层(2.5 m)、底层(8.0 m)的水样,利用焦磷酸测序技术测定16S rRNA基因,研究浮游细菌的群落结构和多样性。结果表明:网箱养殖活动不仅使得附近区域水体理化性质发生改变,如化学需氧量浓度显著高于非养殖区域,而且显著地(P0.05)改变了浮游细菌的群落结构,但不同深度间群落结构和多样性的差异不显著。网箱养殖区和非养殖区中主要浮游细菌类群为α-变形菌(Alphaproteobacteria)、γ-变形菌(Gammaproteobacteria)、拟杆菌(Bacteroidetes)、放线菌(Actinobacteria)、β-变形菌(Betaproteobacteria)、ε-变形菌(Epsilonproteobacteria)和其它变形菌(Unclassified Proteobacteria),占细菌总序列数的98.64%。有些细菌类群的平均相对丰度从网箱区到非养殖区差异显著,如拟杆菌(P0.01)和放线菌(P0.05)显著降低,而γ-变形菌(P0.05)显著增加。相似度分析表明γ-变形菌、α-变形菌和拟杆菌是造成网箱区和非养殖区群落差异的主要类群,对群落差异总贡献率达到45.02%。偏冗余分析表明,影响细菌群落分布的主要环境因子有化学需氧量、磷酸盐、铵盐和总有机碳,共解释38.18%的群落变异,空间距离单独解释10.66%的群落变异。实验结果表明,养殖活动导致浮游细菌群落的改变,其中拟杆菌、放线菌和γ-变形菌的丰度显著变化,可能用于评价养殖水体的水质状况。     

大兴安岭曲壳类硅藻分类研究

对大兴安岭曲壳类硅藻进行了分类学研究,结合国际通用的分类系统对Karayevia RoundBukhtiyarova(卡氏藻属)、Lemnicola RoundBasson(附萍藻属)、Planothidium RoundBukhtiyarova(平面藻属)和Psammothidium BukhtiyarovaRound(沙生藻属)4个属的分类特征进行了描述,对在大兴安岭地区观察到的曲壳类硅藻12个分类单位进行了详细的形态学描述,并给出了他们的生境分布特点。研究观察到中国新记录3个分类单位:Achnanthes tumescens SherwoodLowe(膨胀曲壳藻)、Planothidium lanceolatoide(Sovereign)Lange-Bertalot(近披针形平面藻)、Psammothidium rossii(Hustedt)BukhtiyarovaRound(罗斯沙生藻)。