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1.
2009年1月在南海北部海域的5个站位,采用稀释法和显微分析技术研究了浮游植物生长率及微型浮游动物对浮游植物的摄食压力,同时测定了微型浮游动物的丰度及类群组成.结果表明:南海北部微型浮游动物类群主要以无壳纤毛虫为主,南海北部微型浮游动物类群细胞丰度为33～529个/dm3.南海北部浮游植物生长率为0.45～1.83 d-1,微型浮游动物摄食率为0.44～1.76 d-1,摄食压力占浮游植物现存量的42.6%～82.8%,占初级生产力的97.3%～225.1%.近岸区摄食压力比陆架区高,表明冬季南海近岸区微型浮游动物摄食能够有效的控制浮游植物的生长,而陆架区浮游植物生长率大于摄食率,浮游植物存在着现存量的积累,微型浮游动物并不能完全控制浮游植物的生长.  相似文献   

2.
2005年7月在台湾海峡南部4个站位应用“稀释法”结合高效液相色谱(HPLC)色素分析技术研究了不同色素类群浮游植物的生长率及微型浮游动物对其的摄食死亡率.结果表明,不同色素类群浮游植物的生长率(k)和摄食死亡率(g)分别为0.52～ 1.34 d-1和0.25 ～ 1.10 d-1,微型浮游动物对不同色素类群浮游植物的现存量和初级生产力的摄食压力分别为22％～ 66％和40％～ 151％.通过比较不同类群浮游植物的g/k值,发现颗粒较大的浮游植物(硅藻和甲藻)的净生长率要大于那些微型藻类(蓝细菌、隐藻和定鞭金藻等)的净生长率,说明本次研究中微型藻类更易受到微型浮游动物的摄食控制.  相似文献   

3.
根据2005年8月和11月的调查资料,利用现场稀释法,以叶绿素a为检测对象,分别对三亚湾海区夏秋两季微型浮游动物的摄食情况进行研究。结果表明,夏秋两季浮游植物瞬时生长率(k)分别为0.9~1.32/d和1.81~3.30/d,而微型浮游动物的摄食率(g)则为0.85~1.79/d和1.29~2.57/d。对浮游植物现存量和初级生产力的摄食压力分别是,夏季为57.26%~83.30%和78.13%~140.38%,秋季为72.47%~92.35%和86.65%~97.90%。秋季微型浮游动物以微型浮游植物为其主要食物来源,其摄食率和对初级生产力的摄食压力最高,平均分别为1.09/d和107.98%;微型浮游植物的瞬时生长率也是最高的,平均为0.94/d,为浮游植物群体的主要组成部分。在三亚湾夏秋两季可把微型浮游动物作为控制浮游植物生长的重要影响因子之一,同时与秋季相比,夏季微型浮游动物在物质循环和能量流动方面起到更显著的作用。  相似文献   

4.
南海北部秋季微型浮游动物摄食和种类组成的初步研究   总被引：4，自引：0，他引：4  
2004年9月到10月间在南海北部海区对微型浮游动物的种类组成进行了调查,同期运用现场稀释法,以叶绿素a为监测对象,估计了该海区内微型浮游动物摄食率和摄食压力的水平。结果表明,南海北部海区纤毛虫群体中以多膜纲寡毛目为主,有16种,其中寡毛亚目纤毛虫4种,砂壳亚目纤毛虫11种。各站纤毛虫丰度比较低,在9~102ind/m3之间。浮游植物瞬时增长率(k)在0.03/d~2.13/d之间;微型浮游动物的摄食率(g)在0.01/d~1.06/d之间。微型浮游动物对浮游植物现存量的摄食压力(Pi)在0.089%~65.23%之间,对初级生产力的摄食压力(Pp)在33.63%~86.04%之间。微型浮游动物的摄食水平主要受其丰度的影响,同时微型浮游动物对浮游植物现存量和初级生产力的摄食压力显示,在南海北部海区微型浮游动物在初级生产力传递方面具有重要的科学意义和研究价值。  相似文献   

5.
于2005年3月对黄海海域的7个站位应用稀释法研究了浮游植物的生长率和微型浮游动物对浮游植物的摄食压力。结果表明：实验期间,微型浮游动物生长速率范围在0．34～0．95d-1,浮游植物摄食速率范围在0．44～0．94d-1。微型浮游动物对浮游植物的现存量和初级生产力的摄食压力分别为47．76％～63．80％和61．50...  相似文献   

6.
2004年7~8月在台湾海峡南部的5个站位,用稀释法研究了浮游植物的生长率,微型浮游动物对浮游植物的摄食率及其生产力.微型浮游动物主要为无壳纤毛虫,尤其是急游虫类和侠盗虫类.浮游植物的生长率为0.52~0.72/d,浮游动物的摄食率为0.45~1.33/d,相当于每天摄食浮游植物现存量的36%~74%和初级生产力的88%~141%.微型浮游动物的次级生产力(MP02)为初级生产力的28.5%~58.4%.表明微型浮游动物在台湾海峡夏季海洋生态系统的能量流动中发挥着重要的作用.  相似文献   

7.
中型浮游动物因摄食微型浮游动物,释放了微型浮游动物对浮游植物的摄食压力,这种营养级联效应会增加浮游植物丰度和降低中型浮游动物对浮游植物的摄食率,从而弱化浮游生物网营养传递过程中的下行控制作用。本研究在实验室模拟了食物链中肋骨条藻-裸甲藻-双毛纺锤水蚤的营养传递过程,发现在中肋骨条藻低生物量时,双毛纺锤水蚤偏好于选择摄食裸甲藻;高生物量时,双毛纺锤水蚤偏好选择摄食中肋骨条藻。营养传递过程中存在正的级联效应(0.018~0.12 d^-1),级联效应的大小与裸甲藻的摄食率和双毛纺锤水蚤对裸甲藻的摄食选择指数呈现显著的正相关关系。双毛纺锤水蚤对中肋骨条藻的直接摄食死亡率大于营养级联效应,从而导致中肋骨条藻生物量的降低。因此,营养级联效应对中型浮游动物摄食浮游植物的影响要弱于中型浮游动物的直接摄食作用。  相似文献   

8.
三亚湾珊瑚礁海区微型浮游动物种群组成和摄食研究   总被引：2，自引：0，他引：2  
采用现场稀释法,以叶绿素 a 为检测对象,利用 2006 年 4 月的调查资料对三亚湾珊瑚礁海区微型浮游动物的种群组成和摄食情况进行了研究.结果表明,区内微型浮游动物的组成以纤毛虫为主.微型浮游动物以 Tintinnopsis compressa, Tintinnopsis cylindrical, Tintinnidium semicilidium 三种纤毛虫为优势种,其中 Tintinnopsis 属纤毛虫是优势种群,有 38 种,占总纤毛虫种数的37.3 %.微型浮游动物的摄食率 ( g ) 在 1.28 ～ 2.37 d-1之间,平均值为 0.945 d-1;浮游植物瞬时增长率 ( k ) 为 0.26 ～ 1.44 d-1,平均值为 1.963 d-1;微型浮游动物对浮游植物现存量和初级生产力的摄食压力分别在 72.20 % ～90.65 % 和 113.31 % ～ 315.34 %,平均值分别为 84.56 % 和 177.05 %.三亚湾珊瑚礁海区内,微型浮游动物的摄食水平主要取决于水体中微型浮游动物和叶绿素a之间的相对数量关系.在控制浮游植物生长和转移浮游植物生产力方面微型浮游动物起着相当重要的作用,可以在一定程度上降低潜在的富营养化威胁.  相似文献   

9.
2005年11月16日和27日,运用稀释法和桡足类添加法,对厦门宝珠屿海域小型浮游动物及桡足类的摄食对浮游植物生长的影响进行了研究.结果表明,各粒级浮游植物的生长率均大于小型浮游动物的摄食率,小型浮游动物对总的Chla和nano-Chla具有一致的显著的摄食作用(0.51～0.78d-1),当存在螺旋环沟藻等大型的异养甲藻时,亦能摄食micro-级浮游植物.所添加的桡足类主要摄食micro-级的浮游植物,也显著摄食小型浮游动物,16日,所添加的桡足类促进nano-级浮游植物的每天生长效应达0.03ind/dm3.说明了厦门海域小型浮游动物及桡足类的摄食共同控制着浮游植物的生长,由于桡足类的杂食性,可产生一定的营养级联效应.  相似文献   

10.
大亚湾中型浮游动物群落结构和植食性   总被引：2，自引：0，他引：2  
本文以中型浮游动物成体为研究对象,通过在大亚湾实验站附近一个采样点连续两年的野外调查和现场摄食实验,分析大亚湾近岸富营养化海域中型浮游动物的群落特征,及其对浮游植物的选择摄食特性。结果表明:2015—2017年实验站附近中型浮游动物的总丰度在冬季达到最高,其次为春、秋和夏季;其优势种大多是滤食性桡足类,如锥形宽水蚤(Temora turbinata)、中华哲水蚤(Calanus sinicus)等,中型浮游动物的摄食特性与优势种摄食行为有很大的相关性。中型浮游动物群落更偏好于粒径较大的小型浮游植物(20—200μm),而对微型(2—20μm)或超微型浮游植物(0.7—2μm)的摄食影响较小,甚至会因为选择性摄食对这两种类型的浮游植物的生长有间接促进作用。且中型浮游动物的摄食选择性具有明显的季节性,除每个季节均倾向于摄食甲藻和青绿藻。除此之外,在春季偏好于定鞭藻和隐藻,夏季偏好于定鞭藻和绿藻,秋季偏好于硅藻、隐藻和聚球藻。尽管硅藻的生物量在调查期间平均约占总浮游植物类群的50%,但是中型浮游动物并不主动摄食硅藻,而更偏爱生物量低但营养较高的甲藻。总体上,中型浮游动物虽然对浮游植物有一定的摄食,但其植食性较弱,不能对浮游植物的生物量进行有效控制。  相似文献   

11.
The source and significance of two nutrients, nitrogen and phosphorous, were investigated by a modified dilution method performed on seawater samples from the Jiaozhou Bay, in autumn 2004. This modified dilution method accounted for the phytoplankton growth rate, microzooplankton grazing mortality rate, the internal and external nutrient pools, as well as nutrient supplied through remineralization by microzooplankton. The results indicated that the phytoplankton net growth rate increased in turn from inside the bay, to outside the bay, to in the Xiaogang Harbor. The phytoplankton maximum growth rates and microzooplankton grazing mortality rates were 1.14 and 0.92 d-1 outside the bay, 0.42 and 0.32 d-1 inside the bay and 0.98 and 0.62 d-1 in the harbor respectively. Outside the bay, the remineralized nitrogen (Kr=24.49) had heavy influence on the growth of the phytoplankton. Inside the bay, the remineralized phosphorus(Kr=3.49) strongly affected the phytoplankton growth. In the harbor, the remineralized phosphorus (Kr=3.73) was in larger demand by phytoplankton growth. The results demonstrated that the different nutrients pools supplied for phytoplankton growth were greatly in accordance with the phytoplankton community structure, microzooplankton grazing mortality rates and environmental conditions. It is revealed that nutrient remineralization is much more important for the phytoplankton growth in the Jiaozhou Bay than previously believed.  相似文献   

12.
Phytoplankton group-specific growth and microzooplankton grazing were determined seasonally using the dilution technique with high-performance liquid chromatography （HPLC） in the Xiamen Bay, a subtropical bay in southeast China, between May 2003 and February 2004. The results showed that growth rates of phytoplankton ranged from 0.71 to 2.2 d^-1 with the highest value occurred in the inner bay in May. Mierozooplankton grazing rates ranged from 0.5 to 3.1 d^-1 with the highest value occurred in the inner bay in August. Microzooplankton grazing impact ranged from 39% to 95% on total phytoplankton Chl a biomass, and 65% to 181% on primary production. The growth and grazing rates of each phytoplankton group varied, the highest growth rate （up to 3.3 d^-1 ） was recorded for diatoms in August, while the maximum grazing rate （ up to 2.1 d ^-1 ） was recorded for chlorophytes in February in the inner bay. Among main phytoplankton groups, grazing pressure of microzooplankton ranged from 10% to 83% on Chl a biomass, and from 14% to 151% on primary production. The highest grazing pressure on biomass was observed for cryptophytes （83%） in August, while the maximum grazing pressure on primary production was observed for eyanobacteria （up to 151% ） in December in the inner bay. Net growth rates of larger phytoplanktons （diatoms and dinoflagellates） were higher than those of smaller groups （ prasinophytes, chlorophytes and cyanobacteria）. Relative preference index showed that microzooplankton grazed preferentially on prasinophytes and avoided to harvest diatoms in cold seasons （December and February）.  相似文献   

13.
Introduction The growth of phytoplankton, which is the main primary producer in the ocean, is always limited by some nutrients such as nitrogen and phosphorus. This limitation has spacial variation, and even in the same area, the nitrogen and phosphorus limitation has seasonal alternation [1]. There are many ways to determine the nutrient limitation of phytoplankton growth. Among them, the enrichment bioassay is the closest to the natural condition and is accepted by many scholars [2-7]. In r…  相似文献   

14.
The Sea of Okhotsk is one of the most productive marine basins in the world ocean and plays an important role in transport of organic carbon and iron to the western subarctic Pacific. We report the first measurements of phytoplankton growth and microzooplankton grazing rates in the Sea of Okhotsk, in late summer of 2006. The study area can be divided into two areas: nutrient-sufficient waters on the continental shelf along the east coast of Sakhalin Island and in the vicinity of Bussol Strait, and surface nutrient-depleted waters beyond the shelf break and in the vicinity of Sakhalin Bay. Phytoplankton growth rate in the studied area was strongly affected by nutrient availability, with high phytoplankton growth rate (0.55±0.14 d?1) in the nutrient-replete region and severely depressed growth (0.03±0.05 d?1) in the nutrient-depleted region. On the other hand, microzooplankton grazing rates in both the nutrient-replete and nutrient-depleted regions were approximately the same (0.26±0.20 d?1 vs. 0.27±0.24 d?1). Consequently, microzooplankton grazing consumed <50% of the phytoplankton growth in nutrient-rich waters but >3 times the phytoplankton growth in nutrient-depleted waters. Phytoplankton physiological condition as measured by the maximum photochemical quantum efficiency (Fv/Fm) of algal photosystem II (PS II) showed a general trend in agreement with the in situ growth rate of phytoplankton. In contrast to the phytoplankton community, picophytoplankton, especially the cyanobacteria Synechococcus, showed no nutrient effect on their growth, and the growth and mortality rates were well balanced, suggesting that they have a low nutrient requirement and their biomass was controlled principally by microzooplankton grazing.  相似文献   

15.
Dilution experiments were conducted to investigate microzooplankton grazing impact on phytoplankton of different taxonomic groups and size fractions (< 5, 5–20, 20–200 μm) during spring and summer bloom periods at two different sites (inner Tolo Harbour and Tolo Channel) in the Tolo Harbour area, the northeastern coastal area of Hong Kong. Experiments combined with HPLC pigment analysis in three phytoplankton size fractions measured pigment and size specific phytoplankton growth rates and microzooplankton grazing rates. Pigment-specific phytoplankton growth rates ranged between 0.08 and 3.53 d− 1, while specific grazing rates of microzooplankton ranged between 0.07 and 2.82 d− 1. Highest specific rates of phytoplankton growth and microzooplankton grazing were both measured in fucoxanthin in 5–20 μm size fraction in inner Tolo Harbour in summer, which coincided with the occurrence of diatom bloom. Results showed significant correlations between phytoplankton growth and microzooplankton grazing rates. Microzooplankton placed high grazing pressure on phytoplankton community. High microzooplankton grazing impact on alloxanthin (2.63–5.13) suggested strong selection toward cryptophytes. Our results provided no evidence for size selective grazing on phytoplankton by microzooplankton.  相似文献   

16.
Microplankton abundances and phytoplankton mortality rates were determined at six stations during four cruises spanning three seasons in the Ross Sea polynya, Antarctica (early spring, Oct.–Nov. 1996; mid-late summer, Jan.–Feb. 1997; fall, Apr. 1997; mid-late spring, Nov.–Dec. 1997). Rates of microzooplankton herbivory were measured using a modified dilution technique, as well as by examining the rate of disappearance of phytoplankton (chlorophyll) in samples incubated in the dark (i.e. grazing in the absence of phytoplankton growth). Strong seasonal cycles of phytoplankton and microzooplankton abundance were observed during the study. Microzooplankton abundance varied by more than three orders of magnitude during the four cruises, and was positively correlated with phytoplankton biomass over the entire data set. Nevertheless, microzooplankton grazing was insufficient to impact significantly phytoplankton standing stocks during most of the experiments performed in this perenially cold environment. Only thirteen out of a total of 51 experiments yielded phytoplankton mortality rates that were significantly different from zero. The highest mortality rate observed in this study (0.26 d−1) was modest compared with maximal rates that have been observed in temperate and tropical ecosystems. Results from twenty experiments examining the rate of decrease of phytoplankton biomass during incubations in the dark agreed quite well with the results of the dilution experiments performed at the same time. The range of mortality rates for the dark incubations was −0.09–0.06 d−1, and the average was essentially zero (−0.01 d−1). That is, chlorophyll concentration was virtually unchanged in samples incubated in the dark for 3 d. A number of factors appeared to contribute to the very low rates of microbial herbivory observed, including low water temperature, and the size and taxonomic composition of the phytoplankton assemblage. Based on our results we conclude that the seasonal, massive phytoplankton blooms observed in the Ross Sea are due, in part, to low rates of removal by microbial herbivores.  相似文献   

17.
Phytoplankton growth and microzooplankton grazing were studied during the 2007 spring bloom in Central Yellow Sea. The surveyed stations were divided to pre-bloom phase (Chl a concentration less than 2 μg L−1), and bloom phase (Chl a concentration greater than 2 μg L−1). Shipboard dilution incubation experiments were carried out at 19 stations to determine the phytoplankton specific growth rates and the specific grazing rates of microzooplankton on phytoplankton. Diatoms dominated in the phytoplankton community in surface waters at most stations. For microzooplankton, Myrionecta rubra and tintinnids were dominant, and heterotrophic dinoflagellate was also important in the community. Phytoplankton-specific growth rates, with an average of 0.60±0.19 d−1, were higher at pre-bloom stations (average 0.62±0.17 d−1), and lower at the bloom stations (average 0.59±0.21 d−1), but the difference of growth rates between bloom and pre-bloom stations was not statistically significant (t test, p=0.77). The phytoplankton mortality rate by microzooplankton grazing averaged 0.41±0.23 d−1 at pre-bloom stations, and 0.58±0.31 d−1 during the blooms. In contrast to the growth rates, the statistic difference of grazing rates between bloom and pre-bloom stations was significant (after removal of outliers, t test, p=0.04), indicating the importance of the top-down control in the phytoplankton bloom processes. Average potential grazing efficiency on primary productivity was 66% at pre-bloom stations and 98% at bloom stations, respectively. Based on our results, the biomass maximum phase (bloom phase) was not the maximum growth rate phase. Both phytoplankton specific growth rate and net growth rate were higher in the pre-bloom phase than during the bloom phase. Microzooplankton grazing mortality rate was positively correlated with phytoplankton growth rate during both phases, but growth and grazing were highly coupled during the booming phase. There was no correlation between phytoplankton growth rate and cell size during the blooms, but they were positive correlated during the pre-bloom phase. Our results indicate that microzooplankton grazing is an important process controlling the growth of phytoplankton in spring bloom period in the Central Yellow Sea, particularly in the “blooming” phase.  相似文献   

18.
Phytoplankton growth rates and mortality rates were experimentally examined at 21 stations during the 2017 spring intermonsoon(April to early May) in the northern and central South China Sea(SCS) using the dilution technique, with emphasis on a comparison between the northern and central SCS areas which had different environmental factors. There had been higher temperature but lower nutrients and chlorophyll a concentrations in the central SCS than those in the northern SCS. The mean rates of phytoplankton growth(μ_0) and microzooplankton grazing(m) were(0.88±0.33) d~(–1) and(0.55±0.22) d~(–1) in the central SCS, and both higher than those in the northern SCS with the values of μ_0((0.81±0.16) d~(–1)) and m((0.30±0.09) d~(–1)), respectively.Phytoplankton growth and microzooplankton grazing rates were significantly coupled in both areas. The microzooplankton grazing impact(m/μ_0) on phytoplankton was also higher in the central SCS(0.63±0.12) than that in the northern SCS(0.37±0.06). The microzooplankton abundance was significantly correlated with temperature in the surface. Temperature might more effectively promote the microzooplankton grazing rate than phytoplankton growth rate, which might contribute to higher m and m/μ_0 in the central SCS. Compared with temperature, nutrients mainly affected the growth rate of phytoplankton. In the nutrient enrichment treatment,the phytoplankton growth rate(μn) was higher than μ_0 in the central SCS, suggesting phytoplankton growth in the central SCS was nutrient limited. The ratio of μ_0/μn was significantly correlated with nutrients concentrations in the both areas, indicating the limitation of nutrients was related to the concentrations of background nutrients in the study stations.  相似文献   

19.
1 Introduction Phytoplankton has been considered as a dom inantprim ary producer in m arine ecosystem s, starting them arine food chain (N ing and V aulot.,2003;Sun etal.,2001; Zhu et al., 2000; N ing and V aulot, 1992). A l-though potentialfates ofphytoplankton include advec-tion,verticalm ixing,sinking and m ortality due to virallysis and grazing (B anse,1994),m ortality due to graz-ing,especially by m icrozooplankton,is generally con- μm m esh to 25-L carboys, then transpo…  相似文献   

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