Distributions of Calanus spp. and other mesozooplankton in the Labrador Sea in relation to hydrography in spring and summer (1995-2000)     

E.J.H Head  L.R HarrisI Yashayaev 《Progress in Oceanography》2003,59(1):1-30

We collected mesozooplankton samples in the upper 100 m in spring or early summer each year between 1995 and 2000 along a section from Hamilton Bank (Labrador) to Cape Desolation (Greenland), and along additional sections in spring 1997 and early summer 1995. The North Atlantic waters of the central basin were characterised by the presence of the copepods Calanus finmarchicus, Euchaeta norvegica and Scolecithrocella minor and euphausiids. Calanus glacialis, Calanus hyperboreus and Pseudocalanus spp. were associated with the Arctic waters over the shelves. Amongst the other enumerated groups larvaceans were concentrated over the shelves and around the margins. Amphipods, pteropods and the copepods Oithona spp. and Oncaea spp. showed no definable relationships with water masses or bathymetry, while the diel migrant ostracods and chaetognaths were confined to deep water. Metrida longa, also a strong diel migrant, and Microcalanus spp., a mainly deep water species and possible diel migrant, were both sometimes quite abundant on the shelves as well as in the central basin, consistent with their likely Arctic origins.Analysis of community structure along the section across the Labrador Sea indicated that stations could be grouped into five different zones corresponding to: the Labrador Shelf; the Labrador Slope; the western and central Labrador Sea; the eastern Labrador Sea and Greenland Slope; and, the Greenland Shelf. The boundaries between zones varied spatially between years, but community composition was relatively consistent within a given zone and a given season (spring versus early summer). The relationship between community composition and water masses was not entirely straightforward. For example, Labrador Shelf water was generally confined to the shelf, but in spring 2000 when it also dominated the adjacent slope zone, the community in the Labrador Slope zone was similar to those found in other years. Conversely, in spring 1997, when Arctic organisms were unusually abundant in the Labrador Slope zone, there was no increased contribution of shelf water. In addition, North Atlantic organisms were often found on the shelves when no slope or central basin water was present.Although other organisms were sometimes very abundant, the mesozooplankton preserved dry weight biomass was dominated everywhere by the three species of Calanus, which together always accounted for ≥70%. One species, C. finmarchicus, comprised >60% of the total mesozooplankton biomass and >80% of the abundance of large copepods in spring and summer throughout the central Labrador Sea. In western and central regions of the central basin average C. finmarchicus biomass was ca 4 g dry weight m⁻² and average abundance, ca 17?000 m⁻² over both seasons. Highest levels (ca 7 g dry weight m⁻², >100?000 m⁻²) occurred in the northern Labrador Sea in spring and in eastern and southwest regions in early summer. C. hyperboreus contributed ca 20% of the total mesozooplankton biomass in the central basin in spring and <5% in early summer, while C. glacialis accounted for <1%. Over the shelves, C. hyperboreus contributed a maximum of 54% and 3.6 g dry weight m⁻², and C. glacialis, a maximum of 29% and 1 g dry weight m⁻², to the total mesozooplankton biomass.  相似文献   

水体溶解无机氮对角毛藻胞内活性氮组分的影响     

黄丽东  吴瑜端 《台湾海峡》1991,(2)

本文研究了水体中不同形式溶解无机氮(NH_4~+,NO_3~-,NH_4~++NO_3~-)及其含量对牟氏角毛藻和钙质角毛藻胞内活性氮组分(NH_4~+,NO_3~-,AA,Pr,RNA及DNA)的影响。结果表明:角毛藻胞内无机氮储量的大小体现了水体中无机氮的营养水平;培养角毛藻采用混合无机氮比之单一无机氮,其胞内AA和Pr含量较高,AA/Pr值可定量标志水体无机氮的营养水平及藻类本身氮的营养状况;RNA/DNA值是藻类生长增殖状况的指标之一。  相似文献   

三种织纹螺性畸变的发展过程与雄性结构效应     

施华宏  黄长江  于秀娟  朱四喜  张瑜斌 《海洋科学》2004,28(9):36-41

从2000年3月到2002年10月对中国沿海海产腹足类性畸变的大范围调查过程中．在广东省汕头港、湛江港和厦门港分别采集到西格织纹螺(Nassarius siquijorensis)、胆形织纹螺(Nassarius thersites)和节织纹螺(Nassarius hepaticus)等3个种，解剖观察发现3种织纹螺的雌性个体都发生了性畸变现象。根据织纹螺性畸变的发展过程，对目前的性畸变发展划分体系作了新的修改和补充。通过对比性畸变个体与正常雄性个体的特征．探讨了雄性个体结构特征在性畸变过程中的效应。  相似文献   

无机砷As(V)对牟氏角毛藻(Chaetoceros mulleri)生长、叶绿素a含量及抗氧化活力的影响     

李斌  陈亚男  齐占会  白艳艳  徐东  马元庆  张娟  李焕军  孙珊  何鑫  张昀昌 《海洋与湖沼》2016,47(2):455-459

研究了无机砷As(V)胁迫对牟氏角毛藻(Chaetoceros mulleri)培育水体中磷酸盐含量、藻细胞密度、叶绿素a含量及其抗氧化活性的影响,As(V)浓度梯度为0、7.3、10.2、23.9、45.2和114.0μg/L(分别记为Ctr和V1—V5),取样时间为2、3、5、7、14和21 d。结果表明,试验条件下适当浓度As(V)暴露会促进牟氏角毛藻对磷酸盐的吸收速度,而较低浓度暴露时则反之。所有处理组中仅V2组在14d时藻细胞密度增至最大值71×104ind./m L,其它处理组在整个试验期间藻细胞密度变化均不显著(P0.01)。2 d时各组藻细胞叶绿素a含量均显著降低,且均显著低于对照;5 d时V5组显著升高(达102.16μg/108cell),而其它处理组却仍明显低于其初始值;21 d时,除V1组外各处理组均明显高于对照(50.63μg/10~8cell)。在As(V)暴露2 d时,处理组GSH含量均明显低于对照(3.23μg/10~8cell)(P0.01),且随着As(V)暴露浓度的升高呈先升高后逐渐降低的趋势。As(V)暴露对牟氏角毛藻GSH含量具有显著的抑制作用。谷胱甘肽还原酶活性随着As(V)浓度升高基本呈降低趋势。As(V)胁迫可能会抑制牟氏角毛藻的光合作用和抗氧化活性,长期暴露还会对其生长繁殖造成影响。  相似文献   

柽柳灌丛热量收支特性与蒸散研究   总被引：5，自引：1，他引：5  

张小由  龚家栋  周茂先  司建华 《高原气象》2004,23(2):228-232

Bowen能量平衡法是广泛用于测定各种低矮植物蒸散的常用方法。本文将改进的波文比—能量观测系统用于测定灌木柽柳群落的测定，通过6～9月对感热通量、潜热通量、土壤热通量等的测定，计算出额济纳地区柽柳灌丛(6～9月)的蒸散量为335．31mm；在8月潜热通量占能量支出量的62．85％，感热通量占32．85％，土壤热通量占4．44％。在日变化中，潜热在上午大于感热，下午感热交换大于潜热。  相似文献   

Using species distribution modelling to predict future distributions of phytoplankton: Case study using species important for the biological pump          下载免费PDF全文

Lasse Ørsted Jensen  Erik Askov Mousing  Katherine Richardson 《Marine Ecology》2017,38(3)

Some phytoplankton species have been predicted to contribute more to the biological pump than others. In this study, we examine the potential of species distribution modelling (SDM) for describing current and predicting future global distributions of two phytoplankton species: the diatom Chaetoceros diadema and the coccolithophore Emiliania huxleyi. Species distribution models (SDMs) were constructed using species data from the Ocean Biogeographic Information System and environmental layers from the Coupled Model Intercomparison Project Phase 5. The resulting distributions were evaluated by comparing predicted distributions with those found via a literature survey. The developed SDMs were then applied to predict future changes in the distributions of these species using environmental conditions based on the Intergovernmental Panel on Climate Change's Representative Concentration Pathways scenario 8.5 climate scenario, predicted for the year 2100. The model predicts that the total ocean area covered by C. diadema and E. huxleyi will decline under the examined climate scenario by 8% and 16%, respectively. Furthermore, the future ranges above depths >1,000 m are predicted to decline by 28% for C. diadema. As the biological pump is most active in deep ocean waters, this projected decrease in range in the deeper regions of the ocean may have implications for carbon sequestration, particularly for the diatom species. We conclude that SDM appears to be a robust tool for examining phytoplankton distributions. If the predicted changes in ranges of these two species under future ocean conditions are realised, this may result in a reduced contribution of these two phytoplankton species to carbon sequestration via the biological pump.  相似文献   

The effect of food on the determination of sex ratio in Calanus spp.: evidence from experimental studies and field data     

Irigoien  X.; Obermuller  B.; Head  R. N.; Harris  R. P.; Rey  C.; Hansen  B. W.; Hygum  B. H.; Heath  M. R.; Durbin  E. G. 《ICES Journal of Marine Science》2000,57(6):1752-1763

  相似文献   

低温贮藏罗非鱼微生物学质量变化特性和保藏期   总被引：14，自引：0，他引：14  

许钟  杨宪时  肖琳琳 《中国海洋大学学报(自然科学版)》2005,35(4):621-625

进行了罗非鱼在0,5,10,15℃贮藏过程中的微生物学质量变化特性和高品质期、货架期的研究,并对其特定腐败菌假单胞菌、细菌总数、VBN与感官评价的一致程度进行了探讨。结果表明,罗非鱼在0～15℃温度区域是淡水鱼中鲜度下降慢的鱼种,在0,5,10,15℃贮藏中,罗非鱼的高品质期分别为11,6,3和1.5d,货架期分别为20,9.5,5和2.5d。高品质期和货架期终点的假单胞菌数平均为(6.27±0.23)Log10cfu·g-1和(7.70±0.11)Log10cfu·g-1,显示了假单胞菌计数与罗非鱼的感官鲜度及保藏期具有较可靠的一致性。高品质期和货架期终点的细菌总数平均为(6.84±0.60)Log10cfu·g-1和(8.08±0.41)Log10cfu·g-1,VBN值平均为(11.8±1.38)mg·100-1·g-1和(20.1±1.66)mg·100-1·g-1,均无显著差异(P>0.05),表明细菌总数和VBN作为罗非鱼低温贮藏的鲜度指标与感官鲜度评价有较好的一致性。  相似文献   

应用热脉冲技术对胡杨和柽柳树干液流的研究   总被引：38，自引：2，他引：36  

张小由  龚家栋  周茂先  司建华 《冰川冻土》2003,25(5):585-590

应用热脉冲技术对干旱区胡杨(Populus euphrtaicr)和柽柳(Tamaris spp.)树干液流速度进行了研究.结果表明:在正常生长状态下,胡杨树干单位面积液流通量为0 34L·cm^-2·d^-1,柽柳为0 15L·cm^-2·d^-1.树液流速的日变化表现出多峰形特征,在午后有短暂液流急速减小的现象,而晚上植物为了补充体内水分亏缺,保持一定的树液流量.随着胸径的增大,茎流速率和茎流量也随之增大.在生长季节胸径21cm和15cm的胡杨日平均耗水量23.3L和19.25L;基径5cm和4cm的柽柳日平均耗水量0.62L和0.37L.在生长季节(5～10月)胡杨总蒸腾量为3419.4L,柽柳仅为63.9L.  相似文献   

纤细角毛藻的光生物反应器培养     

田治立  王长海 《海洋通报》2005,24(1):35-40

采用正交实验的方法,在光生物反应器中对纤细角毛藻 Chaetoceros gracilis的生长进行了研究,结果表明:光照强度、通气率对藻体细胞的生长具有显著的影响,在通气培养条件下,当培养密度较高时,纤细角毛藻细胞不仅能耐受超高光照强度的照射,而且还可以获得很高的生长速度。本实验条件下, -1 7经过 5 d的培养,细胞的比生长速率﹑生物量产量和细胞密度分别达到了 0.74 d ﹑1.13 g/L和 8.1×10 /mL的较高水平。  相似文献