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1.
Harmful algal blooms often occurred in the East China Sea (ECS) and the German coastal waters of the North Sea but Karlodinium veneficum had not been taxonomically reported. Two strains of Karlodinium (LAMB090611 and LAMB010601) were isolated from the two areas in 2009. The morphological characteristics and molecular phylogeny of two strains are compared on the basis of observation of a light microscope, a scanning electron microscope (SEM), a laser scanning micro-scope (LSM) and an internal transcribed spacer (ITS) sequence data. The mean cell length of strain LAMB090611 is (14.2 ± 1.8) μm (range 11.1-18.7 μm) and mean width is (10.8 ± 1.5) μm (range 8.2- 14.7 μm). The mean cell length of strain LAMB010601 is (15.1 ± 1.2) μm (range 12.7-17.9 μm) and the mean width is (11.4 ± 1.1) μm (range 9.1-14.7 μm), respectively. The two strains are similar in morphological characteristics, including a straight apical groove, distinct ventral pore, sulcal extension, cingulum displacement, two or four irregular shaped chloroplasts within the cell and almost equal sized epicone and hypocone. The large and round nucleus is located at the center or at the hypocone of the cell. The sequence length of the ECS strain LAMB090611 and the German strain LAMB010601 is 640 and 646 bp, respectively. The GC content is 49%. The nucleotide similarity of the two strains is 98.1%. The sequence divergence is 0.003. Both strains are confirmed as Karlo-dinium veneficum (D. Ballantine) J. Larsen and this is the first taxonomic report from China and Germany coastal waters. The population dynamics of this toxic species in the ECS and German coastal waters needs to be investigated in the near future.  相似文献   

2.
无机碳与雨生红球藻(Haematococcus pluvialis)细胞调节物质   总被引:4,自引:0,他引:4  
以单细胞雨生红球藻为材料,采用酸碱滴定和CO2加富通气培养微藻的方法,对旧液中HCO3^-和CO3^2-浓度变化以及对红球藻细胞生长的影响进行了研究。结果表明,旧液具有限制红球藻细胞生长和诱导细胞转化的作用。同时,旧液中无机碳离子浓度明显高于新液。培养液中富含CO3^2-时,各细胞数量与CO3^2-浓度呈正相关,相关系数为0.88。溶液中仅有HCO3^-时,各细胞数与HCO3^-浓度也呈正相关性。因此,排除了CO3^2-和HCO3^-作为旧液中的调节物质,限制红球藻细胞生长和诱导细胞转化的可能性。旧液乙酸乙酯提取物生物检测实验表明,在粗提取物中有降低细胞增长和诱导细胞转化的活性,表明调节物质能溶于有机相,也反过来证实无机碳离子不是旧液中的调节物质。DNA含量和倍性分析结果表明,红球藻游动细胞DNA复制可以加倍后不经过原生质分裂就可以再次进行,因此推测旧液中的调节物质对原生质分裂过程产生抑制作用,而不对DNA复制过程产生抑制作用。  相似文献   

3.
基于雨生红球藻(Haematococcus pluvialis)培养过程中游动细胞和不动细胞的形态差异与转换,对比研究了两种细胞类型在离心收集与藻落形成效率上的差异。结果表明,雨生红球藻SCCAP K-0084在BYA培养基中培养4~6 d和9~12 d分别以绿色游动细胞与绿色不动细胞为主;早期游动细胞离心收集需要更高的离心力,但500~1 000 g离心5 min可以在不影响细胞存活率的情况下有效收获所有类型细胞;相比于传统直接涂布法,双层琼脂平板法可有效提高平板藻落形成效率,且游动细胞藻落形成效率比不动细胞藻落形成效率更高。TAP培养基由于藻落形成效率较低并不适合于雨生红球藻平板培养与筛选,自养型培养基虽然具有较好的藻落形成效率但是藻落形成速度较慢,相比而言,BYA培养基藻落形成效率较高且生长速度快,更适合用于雨生红球藻细胞的后期平板培养与筛选过程。  相似文献   

4.
雨生红球藻的细胞周期初探   总被引:15,自引:2,他引:13  
于1997年在青岛利用显微镜连续观察技术研究了雨生红球藻的细胞繁殖方式和动力学。结果表明,该藻细胞周期分为流动和不动2个阶段。每一阶段主要以无性生殖产生孢子的方式完成增殖。正常条件下游动细胞主要产生2、4个,偶尔产生2、4个,偶尔产生8个游动孢子,游孢子从孢子囊释放后为游动细胞。环境不适时流动细胞以及流动孢子失去鞭毛转入不动阶段。不动细胞主要形成4、8个,偶尔也能形成20多个不动孢子,该过程不一定  相似文献   

5.
鼠尾藻(Sargassum thunbergii)有性生殖过程与育苗   总被引:7,自引:1,他引:7       下载免费PDF全文
采用室内培养和野外实地观测的方法,研究了鼠尾藻的生长发育和有性生殖过程,并在此基础上进行了有性生殖人工育苗实验。结果表明,鼠尾藻在海水温度高于22℃时,生殖托开始发育,海水温度超过23℃以后,生殖托的生长速度加快,海水温度超过24℃时,生殖托生长速度最快并迅速成熟,在海水温度达到26℃时,观察到了卵的集中排放挂托现象。鼠尾藻卵的排放较为齐整且有一定的先后顺序,生殖托基部的卵最先排出,中部次之,最后是顶部,雄托排精时间要稍晚于雌托排卵时间。受精卵大约在受精1h后进行第一次细胞分裂,分裂面与长轴垂直,大约2h后进行第二次分裂,下端细胞的分裂面平行于第一次分裂方向,而上端细胞的分裂面则垂直,随后大约每2—4h细胞分裂一次。从卵挂托到幼胚脱落一般需要24—48h。观察发现,生殖窝不仅存在于生殖托上,在部分生殖枝上也有分布。在鼠尾藻的人工育苗的实验中,胚苗在苗帘上的生长状态良好。  相似文献   

6.
The exclusively deep-sea ascidian family Octacnemidae comprises several genera in which the oral siphon has hypertrophied to form two large lips which create an “oral hood” capable of capturing motile prey. Megalodicopia hians is typical of this carnivorous family and has been reported to prey upon small epibenthic crustaceans. Distribution of M. hians in the Monterey Canyon system (36°45′N, 122°00′W) (California) was determined with remotely operated vehicles. M. hians was found sparsely to depths of at least 3800 m throughout the canyon; however, abundance was greatest within the oxygen-minimum zone (400–800 m). Eggs, sperm, and recently fertilized embryos were obtained repeatedly from adults returned to the laboratory in vivo, indicating that this species free-spawns routinely. Overall egg diameter (ovum plus chorion, plus follicle cells) was 175–190 μm—considerably smaller than previously reported for this species. Embryonic development at temperature and oxygen concentrations equivalent to the oxygen-minimum zone was 2–4 d and, embryos gave rise to typical phlebobranch “simple” tadpole larvae. Larval period was extremely variable, and settlement/metamorphosis occurred up to 3 months post-hatching. These results are discussed within the context of settlement-site selection and fertilization ecology of the species.  相似文献   

7.
The different mineral phases of the ferromanganese (Fe–Mn) crusts stem from the interaction of biotic and abiotic components. It is therefore vital to study the activity of these components to decipher their contribution to the enrichment/depletion of metals in the crust. Thus, the present study examined sorption and release of Co and Ni by Fe-Mn crusts with associated microbial communities in the presence and absence of the metabolic poison sodium azide (15?mM). The study was conducted in the presence (G+) and absence (G?) of added glucose (0.1%) at temperatures of 4?±?1°C and 28?±?2°C. Results showed that the microbial community had maximal sorption of Co of 66.12?µg?g?1 at 4?±?1°C in the absence of added glucose and 479.75?µg?g?1 at 28?±?2°C in the presence of added glucose. Maximum sorption of Ni in the absence of added glucose was 1.89?µg?g?1 at 4?±?1°C and release of Ni was 51.28?µg?g?1 in the presence of added glucose. Under abiotic conditions with 15?mM sodium azide as a metabolic inhibitor, significant amounts of Co and Ni were released in the G+ medium. Total cell counts on the Fe-Mn crust in the presence of added glucose increased by an order of magnitude from 106 to 107 cells g?1 and in the absence of added glucose remained within the order of 106 cells?g?1 irrespective of temperature of incubation. Microscopic observation of the samples from biotic incubations showed numerous bacterial cells, exopolysaccharides, and structures resembling secondary minerals formed by bacteria. The results indicate that bacteria promote the enrichment of Co and Ni on the hydrogenetic Fe-Mn crusts by sorption processes and release of Ni by reductive dissolution of the oxides. The higher enrichment of Co than Ni is attributed to the way in which microbes interact with the metals.  相似文献   

8.
ABSTRACT

To investigate the uptake and depuration of polycyclic aromatic hydrocarbons associated with the Rena oil spill we sampled the surf clam Paphies subtriangulata at two open coast locations (6?km apart) just prior to oil coming ashore (7 October 2011), then at 1–3 week intervals for the next 4 months. Total polycyclic aromatic hydrocarbons (tPAH) increased at both sites from 1 to 96–124?µg?kg?1 (wet weight) by 18 October before declining to low levels (<4?µg?kg?1) by February 2012. Ongoing sampling throughout 2012–2014 included three additional sites to the north east (up to 30?km away) and a site 5?km to the south east revealing tPAH levels generally <10?µg?kg?1 except in October 2013 where levels ranged between 39–45?µg?kg?1 at all sites. A comparison of PAH component profiles with oil-contaminated beach sediment indicated that the high levels observed in surf clams between October–December 2011 were clearly associated with the Rena spill. However, the October 2013 peak had a PAH profile inconsistent with weathered Rena oil, suggesting an alternative source of contamination. Our results highlight the potential for P. subtriangulata as a PAH monitoring tool but recognise more study is needed to better quantify baseline levels and uptake and depuration dynamics.  相似文献   

9.
The distributional ranges of Cape anchovy Engraulis encrasicolus and Natal anchovy Stolephorus holodon presently overlap at their eastern and western extremes, respectively, off South Africa’s east coast. These species might become more strongly sympatric as a consequence of changed distributions caused by climate change, possibly leading to intensified interspecific competition for trophic and other resources. A comparative analysis of the trophodynamics of the two species, which set out to assess elements of current niche partitioning between them, was conducted through morphological, dietary and stable-isotope analyses of specimens caught off South Africa’s east coast. Cape anchovy have larger gillraker spacing, gain the majority of their dietary carbon from large (>3 000 µm total length) planktonic crustaceans and occupy a higher trophic level than Natal anchovy, which have smaller gillraker spacing and gain the majority of their dietary carbon from planktonic crustaceans of two size classes (900–1 400 µm and 2 800–3 200 µm total length). These results indicate an element of trophic partitioning between the two species that will mitigate against interspecific competition.  相似文献   

10.
Stomach content analyses and measurements of gillraker morphology were used to assess the diet and feeding ecology of the East Coast redeye round herring Etrumeus wongratanai and provide data for comparisons with other small pelagic fishes off South Africa. Samples were collected by jigging from a kayak off Scottburgh, KwaZulu-Natal (KZN), over the period July 2013–May 2014. In total, 66 stomachs (containing 4 407 prey items) and 66 gill arches were examined. Stomach content analyses indicated that East Coast redeye round herring, at the time of sampling, fed on large (1 500–2 500?µm) particles, with ~2 500?µm particles making the greatest contribution to dietary carbon. The species feeds on larger particles than do anchovy Engraulis encrasicolus and sardine Sardinops sagax, but on particles of a similar size to those consumed by West Coast redeye round herring Etrumeus whiteheadi. There were significant differences in mean gillraker gaps between East Coast redeye round herring and both sardine and anchovy, but not between East Coast and West Coast redeye round herring. The differences in gillraker gaps between East Coast redeye round herring, sardine and anchovy are indicative of resource partitioning through differential feeding, based on zooplankton size. The data suggest that there is no resource partitioning between East and West coast redeye round herring, indicating that competition is likely to occur between them. However, such competition is minimised by limited spatial overlap between these two species.  相似文献   

11.
本文以圆紫菜的绿色突变体(LT)和红色突变体(HT)进行杂交实验,证实了圆紫菜减数分裂发生的时期,并观察了圆紫菜的早期发育和形态建成过程。杂交F1叶状体中,出现了2种亲本色和2种重组色,它们分别为绿色(G,母本色)、红色(R,父本色)、野生色(W)和黄褐色(Y)。4种颜色在F1叶状体中形成了大量由2—4个色块组成的颜色嵌合体,色块出现了分离并呈线性排列。F1叶状体中嵌合体所占比例为82.9%,其中两嵌合最多,三嵌合次之,四嵌合最少。4种颜色在嵌合体的分离比为1G:0.97R:0.88W:0.69Y。上述结果证实圆紫菜的减数分裂发生在壳孢子萌发初期。减数分裂产生的四分子呈线形排列,随后继续发育成叶状体,叶状体发育至7—9个细胞时进行第一次纵向分裂,叶状体形态变宽。随后,圆紫菜梢部开始大量形成和放散单孢子,最终导致圆紫菜的形状为圆形或肾脏形。  相似文献   

12.
Lugworms are important members of the macrobenthos of sheltered intertidal sediments, and this study assessed the abundance and distribution of Abarenicola affinis in Otago, southern New Zealand. Using a faecal cast:lugworm ratio (1.00:1.09) revealed a patchy distribution across inlets, with an overall mean abundance of 11.1 individuals/m2 (range: 3.8 to 21.3 individuals/m2). Distribution patterns varied among inlets, with lugworms mostly confined to the high intertidal zone, but spread across all intertidal zones in one inlet. The lugworm habitat was characterised by muddy to medium sand (55–233 µm mean grain size) with low organic matter (< 2%) and chlorophyll a (1–12 µg/g dry sediment) contents. Depending on the inlet, lugworm abundance was related to sediment parameters, indicating that their distribution across Otago inlets is habitat dependent. The present findings also indicate that factors other than those measured contribute to A. affinis distribution and abundance patterns in this region.  相似文献   

13.
Vertical distributions of phytoplankton biomass, compositions and size structure were investigated during the spring-intermonsoon (April 22 to 30) of 2010 along transact 10°N of the Bay of Bengal, northern Indian Ocean. Surface phytoplankton biomass (Chl a) was (0.065§0.009) μg/L, being greater than 80% of which was contributed by pico-phytoplankton (<3 μm). The Chl a concen- tration vertically increased to the maximal values at deep chlorophyll maximum (DCM) layer that shoaled eastwards from 75 to 40 m. The Chl a biomass at DCM layer generally varied between 0.2 and 0.4 μg/L, reaching the maximum of 0.56 μg/L with micro-phytoplankton cells (>20 μm) accounting for 58% and nano- (3-20 μm) or pico-cells for 15% and 27%, respectively. In particular, the cells concentration coupling well with phosphate level was observed at middle layer (75-100 m) of 87° to 89°E, dominated by micro-cells diatoms (e.g., Chaetoceros atlanticus v. neapolitana, Chaetoceros femur and Pseudonitzschia sp.) and cyanobacteria (i.e., Trichodesmium hildebrandtii), with the cells concentration reached as high as 4.0×104 and 4.3×104 cells/L. At the rest of the trans- act however, dino°agellates (e.g., Amphisdinium carterae and Prorocentrum sp.) were the dominant species, with the cells concentration varying from 0.3×103 to 6.8×103 cells/L. Our results also in- dicate that the regulation of large cells (micro-, nano-) on phytoplankton biomass merely occurred at DCM layer of the Bay.  相似文献   

14.
Dissolved organic carbon (DOC) distributions along two Atlantic Meridional Transects conducted in 2005 in the region between 47°N and 34°S showed clear latitudinal patterns. The DOC concentrations in the epipelagic zone (0–100 m) were the highest (70–90 µM) in tropical and subtropical waters with stable mixed layers, and lowest (50–55 µM) at the poleward extremities of the transects due to deep convective mixing supplying low DOC waters to the surface. A decrease in DOC occurred with depth, and lowest DOC concentrations (41–45 µM) in the 100–300 m depth range were observed in the equatorial region due to upwelling of low DOC waters. A strong relationship between DOC and AOU was observed in the σt 26–26.5 isopycnal layer which underlies the euphotic zone and outcrops at the poleward extremities of the North and South Atlantic Subtropical Gyres (NASG and SASG) in the region ventilating the thermocline waters. Our observations reveal significant north–south variability in the DOC–AOU relationship. The gradient of the relationship suggests that 52% of the AOU in the σt 26–26.5 density range was driven by DOC degradation in the NASG and 36% in the SASG, with the remainder due to the remineralisation of sinking particulate material. We assess possible causes for the greater contribution of DOC remineralisation in the NASG compared to the SASG.  相似文献   

15.
Abstract. As part of a wider study on the settlement and recruitment of Chthamalus spp. in Europe, this study investigated whether chthamalid cyprids can be separated by length on a European scale. Variation in cyprid length with latitude and temporal variation at selected localities were also examined. The lengths of cyprids collected between 1996 – 1999 on nine rocky shores in Europe are reported. Elminius modestus cyprids were found only at Roscoff, NW France and could be distinguished due to their carapace shape and length. They showed a unimodal length distribution, measuring between 450 and 625 µm, with no variation in length between the two sampling dates (1997 and 1998). Based on carapace shape and length, the remaining cyprids in the collections were identified as one of three chthamalid species, Chthamalus montagui, Chthamalus stellatus or Euraphia depressa. Bimodal length distributions of chthamalid cyprids were seen on some shores, while others had a single small‐sized modal group (representing C. montagui on Atlantic shores and/or E. depressa in the Mediterranean) separated from a few distinctly larger cyprids (C. stellatus). Metamorphs collected simultaneously with cyprid collections were identified as C. stellatus or C. montagui, except at Roscoff, where E. modestus were also found. In southern Portugal, where all metamorphs collected were C. montagui and adult C. montagui were the dominant barnacles, most cyprids measured between 350 and 550 µm long and this size distribution coincides with the distribution expected for C. montagui. Cyprids collected on these four more southerly Portuguese shores had the same modal length class (475 µm) and this remained constant between successive years at Luz and Albufeira, Algarve. The smallest (350 µm long) wild chthamalid cyprids found were from southern Portugal and Italy. In Spain, France and Ireland the smallest chthamalid cyprid was 425 µm long. The results from the present study support the hypothesis that on Atlantic shores cyprids of C. montagui can be separated from those of C. stellatus based on size, although there is some variation in cyprid length with latitude as well as temporal variation at selected localities.  相似文献   

16.
We report on the ability for luxury Fe uptake and the potential for growth utilizing intracellular Fe pools for 4 coastal centric diatom isolates and in situ phytoplankton assemblages, mainly composed of diatoms. Iron uptake of the diatom isolates and natural phytoplankton assemblages in the Oyashio region during spring blooms were prevented by adding hydroxamate siderophore desferrioxamine B (DFB). After the addition of DFB, intracellular Fe in the diatom isolates supported 2.4–4.2 cell divisions with 1.2–2.6 Chl a doublings. The intracellular Fe was primarily used for cell generation rather than Chl a production, leading to a reduction in the Chl a cell quota in the Fe-starved cells with time. The metabolic properties of the Fe-starved cells with their cell morphologies were different among species or genera. An on-deck incubation experiment also exhibited 1.9 cell divisions and 0.81 Chl a doublings of phytoplankton after the addition of DFB, also indicating the preference of cell generation over Chl a production. A decrease in the level of cellular Chl a, a main light-harvesting pigment in Fe-starved diatoms, may become a superior survival strategy to protect the cells from high irradiance that can cause photo-oxidative damages through photosynthesis. Such relatively low-Fe with high-light conditions could often occur in surface waters of the Oyashio region from spring to summer.  相似文献   

17.
Abstract. Two new species of the sponge genus Ulosa were found living in symbiosis with a chroococcacean cyanophyte (cyanobacterium) in shallow Caribbean coral reefs off Belize (Central America). Ulosa funicularis is a stringy green sponge (styles: 157 × 2.5 μm, mean dimensions); U. arenosa is a thickly encrusting, shaggy, brownish-greenish mottled species with sandy ectosome (styles: 175 × 3.6 μm). The endosymbiotic algae make up 50% of the cellular sponge tissue. The algal cells are light green, spherical, 5–9 μm in diameter, and divide by median constriction. Electron microscopy shows that cell walls are fully developed but that thylakoids are unusual for their inflated sacs, which are in communication with the nucleoplasmic regions. Although the pigment composition is typical for the Cyanophyta, the phycobiliproteins occur in considerably  相似文献   

18.
The Strait of Malacca (SoM), the world’s busiest sea-route, is increasingly polluted as the rapid development of world trades, affecting phytoplankton primary productivity therein. The variations of surface phytoplankton biomass, size-structure and carbon fixation were investigated across the SoM during the spring period (May 4 to 9, 2011). Chlorophyll a concentration increased from 0.12 μg/L at the northwest entrance of the SoM to a maximal 0.63 μg/L at narrowest section, and decreased to 0.10 μg/L at the southeast entrance. Photosynthetic carbon fixation by phytoplankton coincided well with Chl a biomass, and increased from 10.8 to 22.3 μg C/(L d), then decreased to 9.21 μg C/(L d); while the carbon fixation rate showed an inverse pattern to the changes of Chl a, and decreased from 87.1 to 35.5 μg C/(μg Chl a d) and increased thereafter to 95.3 μg C/(μg Chla·d). Picophytoplankton cells (<3 μm) contributed to more than 60% and 50% of the total Chl a and carbon fixation at both the entry waters; while the contributions of pico-cells decreased sharply to the minimum of 18.3% and 27.5% at the narrowest part of the SoM. In particular, our results showed that the silicate concentration positively regulated Chl a biomass and carbon fixation, reflecting that the higher silicate favoured the growth of phytoplankton and thus led to higher primary production in this strait.  相似文献   

19.
The excitation spectra of chlorophyll (Chl) fluorescence can be used to differentiate phytoplankton populations at phylum level in vivo and in situ within a few minutes.The investigated phytoplankton divisions (Dinophyta,Bacillariophyta,Chrysophyta,Cyanophyta,Cryptophyta,Chlorophyta) are each characterized by a specific composition of photosynthetic antenna pigments and,consequently,by a specific excitation spectrum of the Chl fluorescence.Norm excitation spectra (emission of 680 nm and excitation of 400–600 nm) of every division were obtained from several species per division by a F4500 fluorescence spectrophotometer.Fisher’s linear discriminant analysis of the norm spectra shows that the divisions could be discriminated.The discrimination method,established by multivariate linear regression and weighted least squares,was used to differentiate the phytoplankton samples cultured in the laboratory and samples collected from the Jiaozhao Bay at division level.The correctly discriminated samples were more than 94% for single algal species ones,more than 84% for simulatively mixed ones,more than 83% for real mixed ones and 100% for samples collected from the Jiaozhou Bay for the dominant species.The method for phytoplankton differentiation described here can be applied to routine checking by fluorescence spectrophotometer,and benefit the monitoring and supervision tasks related to phytoplankton populations in the marine environments.  相似文献   

20.
2010年秋季南海北部浮游植物群落结构研究   总被引:5,自引:0,他引:5       下载免费PDF全文
2010年10月26日-11月24日在南海北部进行了浮游植物群落结构的调查,共鉴定浮游植物4门70属204种(包括未定种12种),浮游植物以硅藻为主,其物种数为146种,其细胞丰度占总浮游植物细胞丰度的93.17%;甲藻次之,其物种数为51种,占总浮游植物细胞丰度的0.63%;金藻门3属4种及蓝藻门2属3种;蓝藻门中以红海束毛藻(Trichodesmium erythraeum)为主。调查区浮游植物的细胞丰度介于0.06×103~107.50×103 cells/L之间,平均值为5.00×103 cells/L。海南岛东北部和粤东近岸表层浮游植物丰度较高。垂直分布上,表层和25 m层的浮游植物细胞丰度较高。浮游植物主要优势种类有菱形海线藻(Thalassionema nitzschioides)、舟形藻(Navicula spp.)、中肋骨条藻(Skeletonema costatum)、旋链角毛藻(Chaetoceros curvisetus)、斯氏几内亚藻(Guinardia stolterforthii)、具槽帕拉藻(Paralia sulcata)等。调查区表层和5 m层Shannon-Wiener多样性指数平均值分别为3.14和2.83,Pielou均匀度指数平均值分别为0.73和0.77;两种指数在表层和5 m层均表现出较高的一致性。环境分析表明除硅酸盐外,浮游植物细胞丰度与其他环境因子均呈极显著性的相关性,主要受到氮元素及磷酸盐的共同限制作用。  相似文献   

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