Summer phytoplankton pigments and community composition related to water mass properties in the Gulf of Gabes   总被引：1，自引：1，他引：0  

M. Bel Hassen  Z. Drira  A. Hamza  H. Ayadi  F. Akrout  H. Issaoui 《Estuarine, Coastal and Shelf Science》2008,77(4):645-656

Variations in phytoplankton pigments and community composition were examined in the Gulf of Gabes in relationship to water mass properties, characterised by the influence of the Modified Atlantic Water and by the thermal stratification. Data were collected on board the R/V Hannibal during July 2005.Distinct water masses were identified using cluster analysis of temperature–salinity (T–S) characteristics. Three major clusters appeared based on the combined effects of temperature and salinity. The first cluster was identified as the cool and less salty bottom Modified Atlantic Water (MAW). The warmer and saltier Mediterranean Mixed Water (MMW) represented the second cluster. The third cluster was the Transition Water (TW) separating the two previous clusters.The pigment and taxonomic composition of these water masses were examined. Chlorophyll a was rather low (<200 ng l⁻¹). Chlorophyll b was generally the most abundant accessory pigment and fucoxanthin dominated the accessory pigments in the MAW. Proportions of chlorophyll a associated with different phytoplankton classes were estimated using CHEMTAX software, and did not present significant variations among water groups. The results pointed out variations in the relative contribution of each phytoplankton taxa in each station group. Chlorophytes and prasinophytes accounted for 65% of chlorophyll a in the MMW. Diatoms and chlorophytes were relatively abundant in the MAW contributing to almost 63% of chlorophyll a. An unstructured community, slightly dominated by prasinophytes, chlorophytes and cryptophytes, characterised the TW. Different trophic statuses were observed in these water masses, the MMW and the MAW being characterised by mesotrophy, while an oligotrophy was observed in the TW. Nutrient availability, particularly the P-limitation supported by the summer stratification, as revealed by the high N:P ratio (greater than 20), seems to enhance the development of small-sized phytoplankton, thereby supporting the regenerated production.  相似文献   

Spatial and temporal variations of <Emphasis Type="Italic">Synechococcus</Emphasis> and picoeukaryotes in the Taiwan Strait,China     

黄邦钦  林学举  洪华生 《中国海洋湖沼学报》2009,27(1):22-30

The size-fractionated phytoplankton biomass, and the spatial and temporal variations in abundance of Synechococcus (SYN) and picoeukaryotes (PEUK) were measured in the Taiwan Strait during three cruises (August 1997, February–March 1998, and August 1998). The results show that picophytoplankton and nanophytoplankton dominate the phytoplankton biomass, in average of 38% and 40%, respectively. SYN and PEUK varied over time in abundance and carbon biomass, greater in summer than in winter, in range of (7.70–209.2)×10⁶ and (0.75–15.4)×10⁶ cells/cm² in the abundance, and 1.93–52.3 and 1.57–32.4 μgC/cm² in the carbon biomass, for SYN and PEUK, respectively. The horizontal distributions of both groups were diurnal but heterogeneous in abundance, depending on the groups and layer of depths. Temperature is the key controlling factor for picophytoplankton distribution (especially in winter) in the Strait. Supported by Natural Science Foundation of China (No.40730846; 40521003)  相似文献   

Spatial and temporal variations of Synechococcus and picoeukaryotes in the Taiwan Strait,China     

黄邦钦  林学举  洪华生 《中国海洋湖沼学报》2009,27(1)

The size-fractionated phytoplankton biomass, and the spatial and temporal variations in abundance of Synechococcus (SYN) and picoeukaryotes (PEUK) were measured in the Taiwan Strait during three cruises (August 1997, February-March 1998, and August 1998). The results show that picophytoplankton and nanophytoplankton dominate the phytoplankton biomass, in average of 38% and 40%, respectively. SYN and PEUK varied over time in abundance and carbon biomass, greater in summer than in winter, in range of (7.70–20...  相似文献   

Community structure of picoplankton abundance and biomass in the southern Huanghai Sea during the spring and autumn of 2006   总被引：2，自引：0，他引：2  

LE Fengfeng  NING Xiuren  LIU Chenggang  HAO Qiang  SHI Junxian 《海洋学报(英文版)》2010,29(1):58-68

During spring and autumn of 2006,the investigations on abundance,carbon biomass and distribution of picoplankton were carried out in the southern Huanghai Sea(Yellow Sea,sHS) . Three groups of picoplankton-Synechococcus(Syn) ,Picoeukaryotes(PEuk) and heterotrophic bacteria(BAC) were identified,but Prochlorococcus(Pro) was undetected. The average abundance of Syn and PEuk was lower in spring(5.0 and 1.3 × 10 3 cells/cm 3,respectively) than in autumn(92.4 and 2.7 × 10 3 cells/cm 3,respectively) ,but it was opposite for BAC(1.3 and 0.7 × 10 6 cells/cm 3 in spring and autumn,respectively) . And the total carbon biomass of picoplankton was higher in spring(37.23 ± 11.67) mg/m 3 than in autumn(21.29 ± 13.75) mg/m 3 . The ratios of the three cell abundance were 5:1:1 341 and 30:1:124 in spring and autumn,respectively. And the ratios of carbon biomass of them were 5:7:362 and 9:4:4 in spring and autumn,respectively. Seasonal distribution characteristics of Syn,PEuk,BAC were quite different from each other. In spring,Syn abundance decreased in turn in the central waters(where phytoplankton bloom in spring occurred) ,the southern waters and inshore waters of the Shandong Peninsula(where even Syn was undetected) ;the high values of PEuk abundance appeared in the central and southern waters and the inshore of the Shandong Peninsula;the abundance of BAC was nearly three order of magnitude higher than that of photosynthetic picoplankton,and high values appeared in the central waters. In autumn,Syn abundance in central waters was higher than that in surrounding waters,while for PEuk abundance,it decreased in turn in the inshore waters of the Shandong Peninsula,the southern waters and the central waters;BAC presented a complicated blocky type distribution. Sub-surface maximum of each group of picopalnkton appeared in both spring and autumn. Compared with the available literatures concerning the studied area,the range of Syn abundance was larger,and the abundance of BAC was higher. In addition,the conversion factors for calculating picoplanktonic carbon biomass were discussed,with the conversion factors which are different from previous studies in the same surveyed waters. The result of regression analysis showed that there was distinct positive correlation between BAC and photosynthetic picoplankton in spring(r=0.61,P 0.001) ,but no correlation was found in autumn.  相似文献   

海洋微微型真核生物分子多样性的研究方法     

汪岷  江雪娇 《中国海洋大学学报(自然科学版)》2009,39(4)

微微型真核生物在海洋中广泛存在,是初级生产力的重要贡献者,也是微食物环的重要组成部分.由于微微型真核生物形体微小且不同种类缺乏明显形态学特点,故而难以利用电镜等传统方法精确研究其系统发生关系和种类组成.运用分子生物学技术直接对微微型真核生物种类组成进行研究已成为微微型真核生物多样性研究的重要方法.本文概述了目前世界范围内的微微型真核生物分子多样性研究进展以及我国在该领域中的研究状况.综述了微微型真核生物分子多样性研究中常用的靶标基因,包括18S rDNA和ITS序列等真核生物保守基因及psbA和rbcL等功能基因;常用的分子生物学方法,如克隆文库构建、DGGE/TGGE、PCR-RFLP/T-RFLP、FISH、宏基因组等;以及目前研究方法中存在的一些问题.  相似文献   

SIMULTANEOUS ESTIMATES OF SYNECHOCOCCUS SPP. GROWTH AND GRAZING MORTALITY RATES IN THE ENGLISH CHANNEL   总被引：1，自引：0，他引：1  

宁修仁 《中国海洋湖沼学报》1996,(1)

The marine chroococcoid phycoerythrin-containing Synechococcus spp.cyanobacterium has been impli-cated as a subsetantial component of the photosynthetic picoplankton in the ocean. Although its imppr-tance as food source for heterotrophic nanoplankton is now recognized, information about the cycling ofSynechococcus biomass and its diel pattern is limited and study methodology varies among authors. Theselective metabolic inhibitor method was used to simultaneously estimate growth and grazing disappearancerates of Synechococcus in the English Channel where growth rates ranged from 0.25 to 0.72/d (mean±SD=0.51±0.17/d) and grazing mortality rates ranged from 0.19 to 0.64/d (mean ±SD=0.48±0.17/d).Size-fractionated experiments demonstrated that up to 70% of Synechosoccus disappearance could be attri-buted to grazers going through a 2 μm Nuclepore filter. Synechococcus grazing mortality rates (mean=0.74±0.25/d) during the day were alwnys higher than that (mean=0.21±0.20d) during the night, while growthrat  相似文献   

Photosynthetic activity of an epiphytic diatom,gomphonema novo‐zelandicum,and its carpophyllum (phaeophyta) hosts     

W. E. Booth 《新西兰海洋与淡水研究杂志》2013,47(4):615-622

Net photosynthetic activities of epiphytic Gomphonema novo‐zelandicum diatoms and Carpophyllum maschalocarpum and C. flexuosum hosts from the littoral fringe at sites from the Wai‐temata Harbour. Auckland, New Zealand, were determined using infra‐red gas analyser, Winkler and ¹⁴C bicarbonate techniques. Gomphonema displayed a mean assimilation number of 1.970 and volumetric activity of 16.714 mg Ccrrr'rr¹ while mean rates for host primary leaves freed of diatoms and corrected for the effects of emersion were 0.873 mg C (g DW)^‐1h ¹for C. maschalocarpum and 1.266 mg C(g DW)^‐1h^‐1 for C. flexuosum. These activities when considered together with seasonal primary “leaf” and vertical primary axis diatom population densities indicated a 6–8% contribution by Gomphonema to the total photosynthetic activity of the host‐epiphyte association. On a volumetric basis, however, the diatoms displayed an activity which was 67 and 45 times higher than that of the C. maschalocarpum and C. flexuosum host material respectively.  相似文献   

应用快速光曲线方法研究两株海洋超微型真核藻光合特性的差异     

廖渝  吴文学  黄邦钦 《台湾海峡》2014,(3):312-317

超微型浮游植物是海洋中重要的初级生产者,浮游植物吸收的光一部分用于光合作用,另一部分以荧光或热的形式耗散.本文利用调制叶绿素荧光仪（Pulse-Amplitude-Modulation,PAM）测定2株海洋超微型真核藻：细小微胞藻（Micromonas pusilla）和梨形脂金藻（Pinguiochrysis pyriformis）在不同光强下的叶绿素荧光和快速光曲线.结果表明细小微胞藻和梨形脂金藻在不同光强下的光系统II（PS II）的最大光量子产量（Fv/Fm）分别为0.572-0.634和0.624-0.426;最大相对电子传递速率（rETRmax）分别为61.58-163.56和76.69-143.17μmol/m2·s-1;半饱和光强（Ik）分别为212.37-946.00和307.44-671.28μmol·m-2·s-1;光能利用效率（α）分别为0.29-0.17和0.25-0.21.细小微胞藻和梨形脂金藻分别属于高光型和低光型的超微型浮游植物,光照条件会显著影响超微型浮游植物的光合特性,但不同类型的超微型浮游植物的光合特性对光的响应存在差异.  相似文献   

Involvement of anti-oxidative enzymes, photosynthetic pigments and flavonoid metabolism in the adaptation of Reaumuria soongorica to salt stress     

YuBing Liu  Bo Cao  MeiLing Liu 《寒旱区科学》2013,5(6):0684-0690

Reaumuria soongorica is a short woody shrub widely found in semi-arid areas of China. It can survive severe environ- mental stress including high salinity in its natural habitat. Thus, we investigated the involvement of anti-oxidative enzymes, photosynthetic pigments and flavonoid metabolism in the adaptation of R. soongorica to saline environments. R. soon- gorica was treated with 0, 100, 200 and 400 mM NaC1 solutions for 14 days. Soil salt content increased significantly by watering with high content of NaC1 solution, and no variation between 8 and 14 days during treatment. The levels ofpe- roxidation of lipid membranes （measured by malondialdehyde content） and the activities of three antioxidant enzymes （superoxide dismutase （SOD）, peroxidase （POD） and ascorbate peroxidase （APX）） increased under salt stress. Chlorophyll and carotenoid content decreased with increasing salt content. The ratio of Chl a/Chl b and carotenoid/Chl exhibited sig- nificant increase under 400 mM NaC1. However, total flavonoid and anthocyanin contents and key enzyme activities in the flavonoid pathway including phenylalanine ammonialyase （PAL） and Chalcone isomerase （CHI） decreased under salt stress. These findings possibly suggest that R. soongorica has an adaptation protection mechanism against salt-induced oxidative damage by inducin~ the activity of antioxidant enzymes and maintaining a steady level of carotenoid/Chl.  相似文献   

梭梭(Haloxylon ammodendron)叶片气孔导度与气体交换对典型降水事件的响应     

杨淇越  赵文智 《中国沙漠》2014,34(2):419-425

C4植物以其较高的水分利用效率而表现出较强利用荒漠环境有限降水的能力,但对其气孔行为和气体交换对降水响应的理解并不深入。本研究选择荒漠区沙丘上6~7年生的梭梭(Haloxylon ammodendron),利用自制的降水拦截设施,将每次降水事件后样地中接受的降水量分别减少和增加10%、20%和30%,形成包括对照在内的7个降水梯度,研究梭梭气孔导度(Gs)与净光合速率(Pn)对典型降水事件的响应。结果表明:6~12mm的降水对土壤水分的补给集中在50cm土壤深度范围内。降水量每增加10%,Gs和Pn分别增加9.17%和4.17%;Gs和Pn在降水前后呈现先增加后降低的单峰型趋势,峰值出现在降水后第1天,两者与土壤水分含量(SVWC)、空气相对湿度(RH)以及水汽压差(VPD)显著相关。降水后梭梭黎明前叶水势在-2.08~-2.74 MPa时叶片气体交换主要受气孔因素影响,而当叶水势降至-3.16MPa以下时主要受非气孔因素控制。  相似文献