首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 15 毫秒
1.
The study of near‐pristine estuaries can be used as a tool for mitigation projects of harmful effects in anthropogenic eutrophic systems, since one can analyze the effect of temporal and spatial variations generated mainly by natural forces. Phytoplankton taxonomy has been used as a classical indicator to assess changes in transitional water communities, however alternative methods based on morphological, behavioral and physiological traits offer the opportunity to compare sites or moments with different taxonomic compositions. Our goal, in this context, is to evaluate phytoplankton community short‐term and seasonal variability in a near‐pristine estuary, Barra Grande estuary (Ilha Grande, RJ, Brazil), through species functional traits and thus community functional diversity. Samplings were carried out in a mooring in complete tidal cycles, seasonally during 2012. Our results showed a diverse phytoplankton community with 38 frequent and abundant taxa, marked by density variation (1.2 × 10.4–2 × 10.7 cell L?1) in depth, with abundance inversely related to tidal currents. The functional structure of the phytoplankton community measured by functional diversity (FD), varied seasonally in and across a gradient of tidal energy. A core community, mainly represented by flagellates and dinoflagellates, occurred in all observations and was highly functional (high FD), exploiting a variety of habitats. The chain‐forming diatoms were associated with high tidal energy, and occurred in higher densities during summer. Phytoplankton cell size, cell shape, and the ability to form colonies are extremely plastic traits that can be regulated by the environment, however, isolated tychopelagic diatoms were present in the study area across all seasons, with higher contributions in autumn and winter, reflecting the shallow characteristic of this system. During the winter, an exposed sandbar was formed, and the lack of connection with the ocean resulted in an abundance of riverine and brackish water taxa. In this near‐pristine estuary the densities and occurrences of HAB phytoplankton are low. Trait‐based analyses add information about community structure, which can be impacted by anthropogenic actions in urbanized coastal systems. Thus the information provided by this study regarding phytoplankton functional diversity and its relation to nutrients and hydrography in Barra Grande Estuary can be applied as a baseline model for the development of public policies.  相似文献   

2.
The West Pacific Ocean is considered as the provenance center of global marine life and has the highest species diversity of numerous marine taxa. The phytoplankton, as the primary producer at the base of the food chain,effects on climate change, fish resources as well as the entire ecosystem. However, there are few large-scale surveys covering several currents with different hydrographic characteristics. This study aimed to explore the relationships between the spatio-temporal variation in phytoplankton community structure and different water masses. A total of 630 water samples and 90 net samples of phytoplankton were collected at 45 stations in the Northwest Pacific Ocean(21.0°–42.0°N, 118.0°–156.0°E) during spring and summer 2017. A total of 281 phytoplankton taxa(5 μm) belonging to 61 genera were identified in the study area. The distribution pattern of the phytoplankton community differed significantly both spatially and temporally. The average abundances of phytoplankton in spring and summer were 797.07×10~2 cells/L and 84.94×10~2 cells/L, respectively. Whether in spring or summer, the maximum abundance always appeared in the northern transition region affected by the Oyashio Current, where nutrients were abundant and diatoms dominated the phytoplankton community;whereas the phytoplankton abundance was very low in the oligotrophic Kuroshio region, and the proportion of dinoflagellates in total abundance increased significantly. The horizontal distribution of phytoplankton abundance increased from low to high latitudes, which was consistent with the trend of nutrient distributions, but contrary to that of water temperature and salinity. In the northern area affected by the Oyashio Current, the phytoplankton abundance was mainly concentrated in the upper 30 m of water column, while the maximum abundance often occurred at depths of 50–75 m in the south-central area affected by the Kuroshio Current.Pearson correlation and redundancy analysis(RDA) showed that phytoplankton abundance was significant negatively correlated with temperature and salinity, but positively correlated with nutrient concentration. The phytoplankton community structure was mainly determined by nutrient availability, especially the N:P ratio.  相似文献   

3.
于2009年3月对鸭绿江河口进行了10个站的浮游植物生态调查,分析了该海域浮游植物的种类组成、优势种类、群落结构以及水平分布等特征参数.本次调查共鉴定浮游植物48种,其中硅藻种类最多,达41种,甲藻其次,为6种,金藻1种.浮游植物可划分为广温类群、暖水类群和暖温类群3个生态类群,以广温类群为主.浮游植物细胞数量平均4.67×108个/m3,细胞数量自河口向外海逐渐降低.其中,中肋骨条藻(Skeletonema costatum)占据绝对优势.浮游植物群落优势种单一且优势度较大,群落结构相对简单.相关性分析表明温度和盐度是浮游植物细胞数量的主要限制性因子.浮游植物数量受鸭绿江径流的影响较大.  相似文献   

4.
2013年4月，2014年5月，2012年6月和2015年10月在印度尼西亚北部苏拉维斯蓝碧海峡（Lembeh Strait）进行了4个航次的海洋生态调查，研究了蓝碧海峡的浮游植物种类组成，以及浮游植物群落结构的季节变化及其驱动因子。四个航次的调查中记录了5类浮游植物和416个种（类）。调查区浮游植物密度平均为2348cells/L，硅藻和甲藻种类最多。蓝藻种类最少，但丰度很高。季风转换期的4月份和10月份浮游植物丰度总量较低，东南季风期间5月份和6月份的浮游植物丰度较高。除了束毛藻（Trichodesmium）之外，常见种是浮游硅藻。浮游植物的丰度和多样性的季节性变化明显。海链藻（Thalassionema）、拟菱形藻（Pseudo-nitzschia）和蓝藻类的束毛藻对群落的不相似性贡献最大。由于蓝碧海峡南部营养盐浓度较高，南部水域的硅藻和甲藻密度稍高于海峡北部。虽然，南北两个水体中蓝藻的分布趋于均匀，但蓝碧海峡南部也有较高密度。与雅加达湾以及中国的一些海湾相比，蓝碧海峡的浮游植物丰度相当低。分析表明，SE季风期间上升流营养盐是左右浮游植物丰度月变化的重要因素。蓝碧海峡浮游生态系原始，且接近天然本底，人类活动背景噪声低，能够清晰地响应大环境的变化，是研究浮游生态系统的理想区域。  相似文献   

5.
The dynamics of phytoplankton diversity constitute crucial data in environmental monitoring, food-web studies and ecosystem modeling. Proper assessment of phytoplankton community composition requires large investments in offshore sampling and taxonomic competence because these communities can change fundamentally on a weekly scale. Cheap and high-frequent offshore phytoplankton sampling can be achieved by using ships-of-opportunity, and in the present study we used the Alg@line facilities onboard a passenger ferry during its regular route between Finland and Sweden in the northern Baltic Sea. The first aim was to test if pigment analysis, as a cheaper alternative to cell counts, can be used to detect environment-correlated variation in phytoplankton communities. It has been shown that spatial variation (salinity differences) and variation throughout one annual cycle (changes in temperature and nutrients) were strongly reflected by pigment composition. The second aim was to test if pigment analyses and cell counts detect environment-correlated variation in phytoplankton communities equally well. It has been shown that spatial and seasonal variations were reflected by pigment composition while cell counts reflected seasonal variation only. This suggests that the pigment analyses detected aspects of the phytoplankton that were neglected or misinterpreted by cell counts. It is advocated that available resources of long-term studies, such as environmental monitoring, can be used more efficiently by utilizing the high ecological resolution of pigment composition in combination with high-frequent ships-of-opportunity sampling. To assess heterotrophic and/or toxic species, such programs could also include sampling for cell counts in a complementary manner, with actually performing counts only for crucial samples (e.g. between large community changes) as indicated by multivariate statistical analysis of pigment composition. Some aspects of analyzing phytoplankton data with multivariate statistics are also discussed.  相似文献   

6.
Phytoplankton diversity and community composition were studied along the Schelde river–estuary–coastal zone continuum during the summer of 2003. DCA analysis indicated a gradual compositional turnover of the phytoplankton community within the estuary. GAM modelling of species response curves along the estuarine gradient was used to identify taxa that had their population maximum in the river, the coastal zone or within the estuary. Taxa that had their population maximum within the estuary did not form a homogenous community but comprised species with different salinity optima and rather restricted salinity tolerances. The observed changes in community composition along the estuarine transition zone correspond more closely to an ecocline than to an ecotone model. Despite the fact that few taxa had their population maximum at or near the salinity gradient, alpha diversity did not display a minimum around the salinity gradient. This lack of a diversity minimum within the estuary was ascribed to an important contribution of taxa of riverine or coastal origin to alpha diversity within the estuary contributed. On average 55% of the alpha diversity in the estuarine samples was due to riverine or coastal taxa. Beta diversity displayed a clear maximum around the salinity gradient. For planktonic organisms which are subject to mass effects, beta diversity is probably a better indicator for the impact of the salinity gradient on diversity in estuaries than alpha diversity.  相似文献   

7.
长江口海域春季浮游植物的年际变化   总被引：2，自引：0，他引：2  
林梅  李扬 《海洋与湖沼》2017,48(2):303-311
于2014年5月在长江口海域采集海水样品,分析了浮游植物种类组成、细胞丰度、优势种等群落结构特征。共鉴定浮游植物105种,其中硅藻30属56种,甲藻19属41种,以及隶属于金藻、蓝藻等的8个种。浮游硅藻以近岸半咸水种为主,优势种类是中肋骨条藻(Skeletonema costatum);浮游甲藻以沿岸广布种为主,典型代表是东海原甲藻(Prorocentrum donghaiense)。为了更好地了解长江口海域浮游植物的年际变化趋势,本文收集整理了该海域1986—2014年间的春季数据,分析了浮游硅藻、浮游甲藻主要群落特征的年际变化,以及浮游硅藻优势种类细胞粒径的变化趋势。结果表明:(1)浮游硅藻、浮游甲藻的种类数均呈现不同程度的上升趋势,浮游甲藻的上升幅度更为明显;(2)浮游甲藻种类数在浮游植物种类数中的占有比例呈上升趋势,而浮游硅藻所占比例呈下降趋势;(3)浮游硅藻优势种类的细胞粒径呈现小型化趋势。  相似文献   

8.
2000年秋季渤海的网采浮游植物群落   总被引：19，自引：0，他引：19  
孙军  刘东艳 《海洋学报》2005,27(3):124-132
研究了2000年秋季覆盖渤海60个测站的网采浮游植物物种及其群落特征,共发现浮游植物3门35属64种(不包括未定名物种).物种主要以硅藻为主,但甲藻在群落中的比重也很明显,在个别站位上会成为优势类群.优势种主要为偏心圆筛藻、三角角藻、浮动弯角藻等,其中的偏心圆筛藻、浮动弯角藻、布氏双尾藻、梭状角藻和叉状角藻是秋季渤海浮游植物的关键种.细胞丰度的平面分布由浮游硅藻的分布决定,其高值区分布在渤海中北部、渤海湾南部和渤海海峡南部.浮游甲藻在渤海湾北部存在高值区.由于渤海环流的影响在渤海中北部存在浮游植物群落的交错区,此区物种丰富度高、多样性水平高和细胞丰度高.秋季渤海浮游植物群落物种丰富度、Shannon-Wiener多样性指数和均匀度的高值区在渤海中部,但整个秋季浮游植物群落的多样性程度是较低的.  相似文献   

9.
The effects of tidal flushing on the abundance, productivity, and community structure of phytoplankton in response to eutrophication were examined every 2–3 months for more than 2 years in Tapong Bay, a tropical lagoon with only 1 tidal inlet connecting it to the sea in southern Taiwan. Water flushing time ranged from 4–12 d (8–25% d−1) in the outer region subject to fast flushing to 8–24 d (4–12% d−1) in the inner region subject to poor flushing. Chlorophyll a, cell number, and gross production (GP) rate of phytoplankton were significantly greater in the inner region than in the outer region. However, while GP rate was normalized by chlorophyll a (PB) and was expressed as photosynthetic intensity, no significant differences were detected among the study sites. These parameters exhibited a unimodal seasonal pattern across all study sites, with greater values in summer and lower values in winter. No significant differences in species richness or Shannon–Wiener diversity were detected among the study sites. Nevertheless, diversity indices were significantly higher in winter and lower in summer. Classification of phytoplankton communities showed that the grouping patterns were primarily determined by sampling time. Ordination by non-metric multidimensional scaling (MDS) revealed a clear temporal continuum of changes in species composition across all study sites, suggesting that the communities were primarily structured by time, but that it was little affected by study site. Analyses of similarities (ANOSIM) showed that phytoplankton communities sampled in winter could be separated from those in summer, but others were barely separable at all. In summer, the most frequently observed species were the diatom Skeletonema costatum and the cyanobacterium Oscillatoria sp., and these shifted to the diatoms S. costatum and Cylindrotheca closterium in winter. Our results suggest that tidal flushing is an important factor for regulating responses of phytoplankton abundance and productivity to eutrophication in tropical lagoons, but the community structure was little affected due to horizontal mixing by the tidal circulation.  相似文献   

10.
分析了2009 年春季(5 月)渤海辽东湾网采浮游植物物种组成, 丰度分布, 生物多样性指数及群落相似性。春季共鉴定出浮游植物3 门23 属32 种, 主要隶属硅藻门和甲藻门, 生态类型多为温带近岸型和广布型种类, 少部分为暖海性物种或大洋性物种。优势种有夜光藻(Noctiluca scientillans)、翼鼻状藻(Proboscia alata)、旋链角毛藻(Chaetoceros curvisetus)、巨圆筛藻(Coscinodiscus gigas)和尖刺伪菱形藻(Pseudo-nitzschia pungens)等。浮游植物在各站位的细胞丰度分布不均匀, 其平面分布呈现由沿岸海域向海湾中部海域递减的趋势。Shannon-Wiener 指数、Pielou 指数较低, 群落结构简单, 稳定性较差。聚类分析结果表明群落之间的相似性较高。  相似文献   

11.
娄恬  陆欣鑫  刘妍  范亚文 《海洋与湖沼》2023,54(4):1085-1100
浮游植物是河流生态系统能量流动与信息传递的关键环节。浮游植物及其功能性状对于水体水文条件、理化特征及气候变化敏感,因此被广泛应用于水体环境监测。拉林河流域是我国北方重要稻米基地和商品粮基地,受农业面源污染严重。然而,拉林河流域浮游植物群落演替规律尚不明确,基于不同生态属性的功能群对拉林河环境的指示意义仍不清晰。于2021年春季和夏季在拉林河流域设置23个采样点对浮游植物群落进行定性定量分析。基于浮游植物功能群(functional group,FG)、生态功能群(morpho-functional group,MFG)和形态功能群(morphology-based functional group,MBFG)分析浮游植物群落演替特征。通过冗余分析(redundancy analysis,RDA)揭示驱动浮游植物群落演替的关键环境因子。结果显示,研究期间拉林河流域浮游植物群落演替明显,划分FG功能群25个,MFG功能群24个,MBFG功能群7个。FG、MFG和MBFG功能群的演替受多种环境因素共同影响,其中水温(water temperature,WT)和总氮(total nitroge...  相似文献   

12.
The Bonnet Carré Spillway, located 28 miles northwest of New Orleans, was constructed in the early 1930s as part of an integrated flood-control system for the lower Mississippi River system. From 11 April to 8 May 2008, Mississippi River water was diverted through the spillway into the 629-square-mile Lake Pontchartrain, which is hydraulically connected to the Gulf of Mexico. On 8 April, prior to the opening of the spillway, water-quality instruments were deployed and recorded hourly measurements of water temperature, dissolved oxygen, specific conductance, pH, and nitrate. Discrete water-quality and phytoplankton (algae) samples were collected in Lake Pontchartrain from 8 April to 3 October 2008 to assess the water-quality nutrient enrichment effects of the diversion on the lake. The maximum influence of river water in the southern portion of the lake was captured with continuous (hourly) monitoring of nitrate concentrations, and field measurements such as of specific conductance during the critical period in late April to early May. By late May, the deployed instruments had recorded the arrival, peak, and decline of selected constituents associated with the freshwater influx from the Mississippi River/Bonnet Carré Spillway diversion. The continuous monitoring data showed the short-term interactions of high-nitrate, low-specific conductance river water and low-nitrate, high-specific conductance lake water. The phytoplankton community composition, as an indicator of water quality, illustrated an extended response from the river water evident even after the continuous and discrete samples indicated that the lake had returned to pre-diversion conditions. The initial phytoplankton community response to nutrient increases was related to accumulations of diatoms. During periods of low nutrient concentrations, accumulations of blue-greens occurred by July and August. As blue-green algae cell densities and biovolumes increased in the summer, so did the species richness of blue-green algae, particularly the harmful algae bloom taxa. Cell densities and biovolume of the phytoplankton lake indicator taxa Skeletonema costatum, Anabaena sp., and Cylindrospermopsis raciborskii were highest and dominated the diatom and blue-green algae communities during the period of most river water influence on the lake and immediately following the freshwater inflows. The dominance and recession of these indictor taxa reflect the dramatic changes that occurred in the phytoplankton community in response to an increase in nutrient-rich freshwater from the diversion into the lake, and not normal seasonal phytoplankton compositional differences. Water-quality data indicated a gradual reversion to pre-diversion lake conditions by June to July, but shifts in the phytoplankton composition were still evident through August 2008. Observations from this study were similar to results from previous studies of Mississippi River/Bonnet Carré Spillway diversion opening in 1997.  相似文献   

13.
多样性指数在海洋浮游植物研究中的应用   总被引：109，自引：12，他引：97  
孙军  刘东艳 《海洋学报》2004,26(1):62-75
对海洋浮游植物群落分析中常用的多样性指数进行了比较研究.对物种丰富度依赖型、丰度依赖型和实测浮游植物群落中物种丰富度、Shannon指数(以2或e为底)、Pielou均匀度指数、Simpson指数(1-D或1/D形式)、Margalef指数、Berger-Parker指数、McIntosh指数、McIntosh均匀度指数、Brillouin指数、Brillouin均匀度指数、Fisher α指数和Q统计指数等不同多样性指数计算结果进行了比较,发现不同多样性指数对浮游植物群落多样性的分析存在明显差异.对于一般情况下浮游植物群落多样性的研究,物种丰富度、Margalef指数、Fisher α指数、Shannon指数、Simpson相遇指数和Pielou指数的综合使用是较合适的,但对Margalef指数和Fisherα指数的结果要谨慎解释.并在综合应用各指数的基础上提出了浮游植物群落多样性分析的一般步骤.  相似文献   

14.
大亚湾生态监控区的浮游植物年际变化   总被引：2，自引：0，他引：2  
依据国家海洋局、国家海洋局第三海洋研究所等权威机构2004~2007年所获的数据和资料,对大亚湾生态监控区近4a长时间尺度的浮游植物群落年际变化进行分析,通过物种组成、丰度变化、优势类群演替、群落结构及赤潮灾害事件来反映生境的退化,探讨其变化的主要原因及趋势。结果表明,浮游植物群落由暖水种占绝对优势转变为广温广布种占主导地位。种类与丰度呈逐年下降的态势,浮游植物丰度的分布保持西高东低,近岸高于远岸的特征,浮游植物的高丰度与营养盐丰富及温排水有关。终年以硅藻为优势种群,优势种演替具有明显的季节与年际变化,细长翼根管藻(Rhizosolenia alataf.gracillima)是春季稳定的优势种,柔弱拟菱形藻(Pseudo-nitzschia delicatissma)是夏季稳定的优势种,春末甲藻的优势度增加明显。浮游植物群落多样性指数呈逐年下降趋势,均匀度呈逐年上升态势。浮游植物的异常增殖及过度集中导致多样性较低,种间比例不均匀,群落结构单一。赤潮季节性发生频繁,发生频率及引发种类呈上升趋势,海洋环境脆弱。  相似文献   

15.
黄渤海底栖纤毛虫分子多样性和生物地理学研究   总被引：3，自引：0，他引：3  
对中国渤海、北黄海和南黄海三个海域底栖纤毛虫的分子多样性与生物地理学进行了研究。从底栖真核微生物18S rDNA的焦磷酸测序数据中提取出隶属于纤毛门的序列，并在此基础上分析了纤毛虫群落的阿尔法多样性和贝塔多样性。结果表明，纤毛虫操作分类单元的丰富度在渤海比北黄海和南黄海都高，但夏冬两季无显著差异。在所有检测的环境因子中，水体深度与阿尔法多样性的相关性最强。就纤毛虫群落组成上看，总体上旋唇纲的序列及操作分类单元丰富度均占优势地位（占比分别为77.0%和66.5%）；旋唇纲主要由环毛亚纲以及未能进一步分类的类群组成。底栖纤毛虫群落结构在三个海域之间显著不同，但夏冬两季无显著差异。从各主要类群的相对比例来看，唯有侧口纲的序列比例在三个区域间呈现显著的不同。偏门特尔分析表明，相对于地理距离和环境因子而言，水体深度在调控底栖纤毛虫群落结构中扮演者更为重要的角色。本研究同时也发现，超过60%的操作分类单元未能被进一步分类到纲或目级水平，约45%的操作分类单元与GenBank数据库中已描述种类的序列相似度低于或等于97%，表明在近海沉积物中可能存在大量待发现的纤毛虫类群或物种。本研究发现底栖纤毛虫阿尔法多样性从北黄海到南黄海降低的趋势，这一点与之前基于形态学方法的调查结果相似。然而，测序数据显示旋唇纲是最主要类群，而形态学调查表明前口纲和核残迹纲是主要类群。本文也探讨了可能造成分子与形态学研究结果差异的一些潜在原因。  相似文献   

16.
研究了热带西太平洋雅浦Y3海山冬季和马里亚纳M2海山春季网采浮游植物群落结构,对调查区浮游植物的物种组成、优势种类、细胞丰度以及多样性指数进行了分析。结果表明,两个海山区共鉴定浮游植物4门50属219种,其中硅藻门30属106种,甲藻门17属112种,蓝藻门1属2种,金藻门2属3种。两个航次研究区浮游植物优势种均以链状硅藻如根管藻(Rhizosolenia)、半管藻(Hemiaulus)和角毛藻(Chaetoceros)等属的种类为主,此外太阳漂流藻(Planktoniella sol)、铁氏束毛藻(Trichodesmium thiebautii)以及部分角藻(Ceratium)物种优势度也比较明显。Y3海山区浮游植物细胞丰度介于1.60～16.61 cells/L,平均值为5.02 cells/L; M2海山区浮游植物细胞丰度介于1.36～10.20 cells/L,平均值为4.12cells/L。两个海山区浮游植物细胞丰度的分布趋势均受硅藻影响较大,甲藻细胞丰度相对较低。在属的水平上,角毛藻、根管藻、角藻和半管藻等属的细胞丰度对两个海山区浮游植物总细胞丰度的贡献较大。多样性指数方面, Y3海山区浮游植物群落香农-威纳指数H′(shannon-wiener index)介于3.95～4.69,平均值为4.30; M2海山区浮游植物群落香农-威纳指数介于3.23～4.46,平均值为3.83。两个海山区浮游植物群落多样性指数均处于较高水平,但站位间的变化不明显。目前,关于热带西太平洋海山区浮游植物群落结构的研究还非常缺乏,亟需后续研究的补充。  相似文献   

17.
Abstract. The estuarine ecosystem of the Amvrakikos Gulf, a semi-enclosed embayment of the Ionian Sea, was surveyed at 9 stations in June, 1980. Quantitative and qualitative relationships among the phytoplanktonic, zooplanktonic and benthic populations were examined and related to environmental parameters. It was found that quantitative maxima of each of the three components occurred at different stations. When stations were grouped according to a similarity index of each community, it could be shown that the stations were very similar with regard to phytoplankton and slightly less similar with regard to zooplankton. The stations differed considerably as far as the benthos is concerned. The phytoplankton also exhibited a lower species diversity (0.08-0.82 bits-indiv.-1) than the zooplankton (1.08-2.10 bits indiv.-1) and the benthos (0.85-5.06 bits indiv.-1). Differences in salinity among stations showed no significant correlation with the abundance or species diversity of phytoplankton, zooplankton or benthos.  相似文献   

18.
本研究于2015年在黑龙江省镜泊湖选取7个典型采样点,对镜泊湖春、夏两季间浮游生物群落结构的演替及其与环境因子关系进行分析。在调查期间共鉴定浮游植物152个分类单位,浮游动物38个分类单位,种类组成上浮游植物主要以绿藻门和硅藻门藻类为主,浮游动物以轮虫和原生动物为主。研究期间浮游生物优势种主要包括:河生集星藻(Actinastrumfluviatile(Schroed.)Fott)、梅尼小环藻(Cyclotella meneghiniana Kütz.)、谷皮菱形藻(Nitzschia palea (Kütz.) W.Smith)、前节晶囊轮虫(Asplanchna priodonta)、螺形龟甲轮虫(Keratella cochlearis)和瓶砂壳虫(Difflugia urceolata)。在研究期间水温、pH、电导率、和总氮在春、夏两季之间变化明显(P0.05或P0.01)。春、夏两季的浮游生物丰度呈现明显下降趋势(P0.05)。Spearman相关分析揭示镜泊湖水体浮游生物丰度与水温和电导率极其显著相关(P0.01)。冗余分析(RDA)表明,水温和电导率是驱动镜泊湖水体浮游生物群落生态分布的主要环境因子。与近10余年间镜泊湖相关研究对比发现,镜泊湖水体浮游植物群落结构较为稳定,浮游动物优势类群略有改变。综合营养状态指数评价表明镜泊湖水体为中营养状态,与前期研究结果相似,说明水体目前无进一步恶化的趋势。  相似文献   

19.
本文分析了1999?2017年大亚湾夏季浮游植物群落结构的长期变化及其与环境因子的关系,结果显示,大亚湾海域海水温度呈显著下降趋势,盐度呈显著上升趋势;溶解无机氮浓度出现较大幅度提升,2008?2017年间大亚湾溶解无机氮浓度平均值比1999?2007年提升了72.73%;大亚湾浮游植物种类数变化趋势不明显,主要优势种没有发生明显变化,柔弱伪菱形藻（Pseudonitzschia delicatissima）为区域第一优势种,其次为中肋骨条藻（Skeletonema costatum）;浮游植物总丰度、硅藻丰度、甲藻丰度以及主要种类中的柔弱伪菱形藻、中肋骨条藻和叉角藻（Ceratium furca）丰度均呈现显著上升趋势;浮游植物生物多样性指数（H′）和均匀度（J）均呈下降趋势。人类活动所引起的溶解无机氮浓度大幅升高以及外海水入侵加强所引起的海水温度降低和盐度上升导致了浮游植物丰度的上升、优势种的单一化和生物多样性指数的下降。  相似文献   

20.
Long-term changes of phytoplankton community by water sampling method in Xiagu Sea waters of Xiamen, China, were investigated in this study. Species composition of the phytoplankton community in these waters changed greatly since the 1950s. The numbers of Dinophyta species increased significantly, although Bacillariophyta species are generally dominant. The succession of dominant species in phytoplankton community is obvious:large-size dominant species such as Biddulphia sinensis of the 1950s were gradually replaced by small-size ones such as Cyclotella striata and Nitzschia closterium, and species that still maintain dominant such as Skeletonema costatum are also small ones, leading the whole phytoplankton community of smaller size. Cell density of phytoplankton community increased greatly, among which cell density of the most dominant species Skeletonema costatum have been increasing in exponent function. Margalef index of phytoplankton community decreased, indicating decline of biodiversity of the community, and dominant character of Skeletonema costatum increased. Generally, the structure of the entire phytoplankton community is becoming more and more singular and unstable, which makes the occurrence of red tides more frequent. The succession in the phytoplankton community is related to the long-term changes in marine environment, influenced by human activities and global climate changes, especially the increases of nutrient content.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号