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51.
Community Structure and Dynamics of Phytoplankton in the Western Subarctic Pacific Ocean: A Synthesis 总被引:1,自引:1,他引:1
The phytoplankton community in the western subarctic Pacific (WSP) is composed mostly of pico- and nanophytoplankton. Chlorophyll
a (Chl a) in the <2 μm size fraction accounted for more than half of the total Chl a in all seasons, with higher contributions of up to 75% of the total Chl a in summer and fall. The exception is the western boundary along the Kamchatka Peninsula and Kuril Islands and the Oyashio
region where diatoms make up the majority of total Chl a during the spring bloom. Among the picophytoplankton, picoeukaryotes and Synechococcus are approximately equally abundant, but the former is more important in term of carbon biomass. Despite the lack of a clear
seasonal variation in Chl a concentration, primary productivity showed a large seasonal variation, and was lowest in winter and highest in spring. Seasonal
succession in the phytoplankton community is also evident with the abundance of diatoms peaking in May, followed by picoeukaryotes
and Synechococcus in summer. The growth of phytoplankton (especially >10 μm cell size) in the western subarctic Pacific is often limited by
iron bioavailability, and microzooplankton grazing keeps the standing stock of pico- and nano-phytoplankton low. Compared
to the other HNLC regions (the eastern equatorial Pacific, the Southern Ocean, and the eastern subarctic Pacific), iron limitation
in the Western Subarctic Gyre (WSG) may be less severe probably due to higher iron concentrations. The Oyashio region has
similar physical condition, macronutrient supply and phytoplankton species compositions to the WSG, but much higher phytoplankton
biomass and primary productivity. The difference between the Oyashio region and the WSG is also believed to be the results
of difference in iron bioavailability in both regions.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
52.
Evaluating fishery impacts using metrics of community structure 总被引:8,自引:14,他引:8
53.
雷州半岛灯楼角珊瑚礁海区的浮游植物 总被引:8,自引:2,他引:8
雷州半岛西南岸的珊瑚礁,是唯一的中国大陆沿岸现代珊瑚礁。根据2004年8月的调查资料研究分析了雷州半岛灯楼角珊瑚礁海区浮游植物的种类组成、生态类群和数量分布等,以期为珊瑚礁生态系的研究提供基础资料。结果显示:浮游植物共有108种(含变种和变型),其中硅藻门34属85种、甲藻门10属21种、蓝藻门1属2种,浮游植物的种数分布由近岸往远岸递增;浮游植物大致划分为近岸低盐类群、近海广布类群和外海高温高盐类群等3个生态类群;优势种有中肋骨条藻Skeletonemacostatum、菱形海线藻Thalassionemanitzschioides、奇异菱形藻Nitzschiaparadoxa等8种;多样性指数和均匀度平均值分别为3.448和0.655,总体分布比较均匀;浮游植物细胞总量平均值为93×104cells/m3,其中硅藻类占绝对优势,浮游植物分布不均匀,密集于灯楼角南面的A断面。 相似文献
54.
组织培养板在获取微藻种质中的应用 总被引:3,自引:0,他引:3
报道一种基于选择演替和及时显微跟踪的原理获取一次野外水样中多种微藻的方法。利用组织培养板方便的显微观测条件和适宜容积提供微藻存活的空间,在不同培养条件下,进行微藻群落演替、及时显微跟踪检测和优势种分离,可以使野外水样初期低生物量种类优势化,以利于纯系种质的获得。并通过不同演替条件获得其中出现的未鉴定或初期样品中未检出的种质,提供进一步研究的基础。该方法在获取微藻种质和种质库建设上不失为一可行技术手段。论文以一次野外采集海水样品在不同营养条件下的主要优势种类演替跟踪检测、低生物量种质优势化过程和纯系种质分离为例,说明该方法在获取微藻种质中的应用。 相似文献
55.
56.
Sublittoral meiofauna with particular reference to nematodes in the southern Yellow Sea, China 总被引:6,自引:0,他引:6
Densities of major meiofaunal taxa were investigated at 34 sampling stations during six cruises by R/V Beidou to the southern Yellow Sea, China from 2000 to 2004, and the community structure of free-living marine nematodes was studied during one of the cruises in 2003. Meiofauna abundance ranged from 487.4 to 1655.3 individuals per 10 cm2. Nematodes and harpacticoid copepods were the two most dominant groups, contributing 73.8–92.8% and 3.5–18.7%, respectively, to the total meiofauna abundance. One-way ANOVA showed no significant annual fluctuation of meiofauna and nematode abundances from 2000 to 2004 in the southern Yellow Sea. However, two-way ANOVA based on six stations sampled in 4 years (2001–2004) showed that there were significant differences among the six stations and the 4 sampling years for meiofauna, nematode and copepod abundance. Correlation analysis demonstrated that meiofauna abundance was mainly linked to chloroplastic pigments. Other environmental factors could not be ruled out, however. A total of 232 free-living marine nematode species, belonging to 149 genera, 35 families and 4 orders, were identified. The dominant species in the sampling area were the following: Dorylaimopsis rabalaisi, Microlaimus sp.1, Prochromadorella sp., Promonohystera sp., Cobbia sp.1, Daptonema sp.1, Leptolaimus sp.1, Halalaimus sp.2, Aegialoalaimus sp., Chromadorita sp., Parodontophora marina, Parasphaerolaimus paradoxus, Quadricoma sp.1, Campylaimus sp.1, Halalaimus gracilis, Paramesacanthion sp.1, Paramonohystera sp.1, and Metalinhomoeus longiseta. CLUSTER and SIMPROF analyses revealed three main types of nematode community (or station groups) in the sampling area, including I: coastal community, II: transitory community between coastal and YSCWM (Yellow Sea Cold Water Mass), and III: YSCWM community. Each community was indicated by a number of dominant nematode species. Bio-Env correlation analysis between the nematode community and environmental variables showed that water depth, sediment water content, organic matter, chlorophyll a (Chl-a) and phaeophorbide a (Pha-a) were the most important factors to determine the community structure. 相似文献
57.
Influence of stratification and irradiance regime on summer phytoplankton composition in coastal and shelf seas of the British Isles 总被引:1,自引:0,他引:1
The effect of interaction between stratification and irradiance regimes on phytoplankton community structure was investigated in three shelf/coastal regions of the British Isles, each of which displayed ranges of vertical stability and light attenuation. Relationships between vertical stability, light penetration and community structure were indicated by the ordination of dominance (assessed using cell volume) of the main phytoplankton phyletic groups—diatoms, dinoflagellates and microflagellates—on a surface defined by a bulk stratification index () and water column depth, scaled by transparency (λh). Diatom- and dinoflagellate-dominated communities occupied distinctly different domains on the - λh surface, diatoms being favoured in well-mixed water columns with high values for λh and dinoflagellates dominating where stratification was strong and λh was low. Microflagellates were not abundant in any of the study areas and showed no clear ordination on the - λh surface. The domain of co-dominance of diatom and dinoflagellates on the - λh surface was narrow with small changes in the irradiance or stratification regime resulting in a switch to diatom or dinoflagellate dominance. It is suggested that loss of non-motile diatom communities in strongly stratified water columns might be a strong selective force in favour of dinoflagel-lates. However, in water columns with intermediate stratification and optical properties, the outcome of competition may be decided by physiological attributes of the two groups with respect to growth in low and fluctuating irradiances. 相似文献
58.
西门岛红树林区大型底栖动物的群落结构 总被引:20,自引:0,他引:20
浙南乐清湾西门岛红树林区是中国红树林的最北分布地,为研究该区红树林与底栖动物的生态关系,于2004年5月和8月对红树林区大型底栖动物进行现场采样,共发现大型底栖动物42种,其中软体动物20种、甲壳类11种、多毛类5种、其它类6种。平均生物量和平均栖息密度分别为74.26g/m2和340个/m2,软体动物和其它类动物分别占总生物量的43%和39%,它们的栖息密度分别占动物总栖息密度的66%和30%。红树林区底栖动物的特征种为可口革囊星虫Phascolosomaesculenta,在中潮区其生物量和栖息密度分别高达84.33g/m2和304个/m2。该红树林区底栖动物群落结构的分析结果表明:底栖动物种类与红树林发育状况呈负相关、底栖动物生物量与红树林发育状况呈正相关,红树林主分布区(中潮区)底内群落结构较低潮区简单、生物量高、物种多样性低,而无红树林的低潮区则与之相反,生物量低、种间分布均匀、多样性高。多样性指数低潮区(2.44)>中潮区(1.21)>高潮区(1.0);均匀度指数为0.30~0.73,中潮区为最低。 相似文献
59.
60.