2004-2005年青岛前海定点54周次浮游植物群落结构特征

2004年12月10日至2005年12月10日在青岛前海定点调查54周次的浮游植物群落特征.共检出浮游植物3门76属197种.其中硅藻在物种数和细胞数量上都占有优势,但在春末夏初时期,甲藻的生长也较为活跃.物种主要以温带近岸种和广布性种为主,主要优势种为中肋骨条藻(Skeletonema costatum)、柔弱几内亚藻(Guinardia delicatula)、扭链角毛藻(Chaetoceros tortissimus)、尖刺伪菱形藻(Pseudonitzschia pungens)和大洋角管藻(Cerataulina pelagica),其中前4种藻是青岛附近海域浮游植物的关键种.浮游植物细胞丰度的变化呈"双周期型",第1次高峰期出现在1月下旬至3月中旬,浮游植物细胞丰度较高;第2次高峰期出现在7月中旬至8月中旬.2次低谷期分别出现在5月下旬和11月下旬.浮游植物细胞丰度与温度有较强的相关性,与营养盐相关性不明显.     

2006年冬季北黄海网采浮游植物群落结构2006年冬季北黄海网采浮游植物群落结构

根据2006年12月30日—至2007年1月17日北黄海的调查资料,对该海域浮游植物的种类组成、优势种、丰度及其分布和多样性等基本状况进行了分析。本次调查共鉴定浮游植物4门68属131种,主要以温带近岸和广布性种为主,其中硅藻有53属113种,占总种数的86.3%,甲藻有11属16种,占总种数的12.2%。浮游植物丰度平均值为88.89×104个/m3,硅藻丰度平均值为86.58×104个/m3,甲藻丰度平均值为2.28×104个/m3,硅藻丰度分布趋势决定了浮游植物丰度的分布趋势。辽宁南岸是浮游植物密集区,山东半岛北岸其次,而北黄海中部是浮游植物的稀疏区。优势种为：短角弯角藻（Eucampia zodiacus）、具槽帕拉藻（Paralia sulcata）、尖刺拟菱形藻（Pseudonitzschia pungens）、密连角毛藻（Chaetoceros densus）、柔弱角毛藻（Chaetoceros debilis）、刚毛根管藻（Rhizosolenia setigera）。浮游植物群落ShannonWeiner物种多样性指数平均值为1.80,Peilou均匀度指数平均值为0.42。与1959年1月相比,2007年1月北黄海浮游植物丰度由15000×104个/m3降为88.89×104个/m3,下降了近41%,硅藻丰度由148.00×104个/m3降为86.58×104个/m3,而甲藻丰度由1.25×104个/m3上升为2.28×104个/m3,占浮游植物丰度的比例由0.8%上升为2.5%。主要优势种及优势属也发生了一定程度的变化,但浮游植物群落结构仍以硅藻为主、甲藻其次,浮游植物丰度总的分布格局变化不明显。     

南黄海浮游植物初级生产力粒级结构与碳流途径分析

根据2006年夏季与冬季南黄海真光层内浮游植物初级生产速率的实测数据,对比研究了两种差异显著的水动力条件下,不同粒级浮游植物初级生产力水平、时空分布特征及其环境调控机制,并探讨了真光层生源碳可能的碳流途径。研究结果表明,南黄海夏季总初级生产力(碳)平均为30.69 mg/(m2·h),高值区位于调查海域南部长江冲淡水影响区,冬季总初级生产力低于夏季,平均水平为21.73 mg/(m2·h),高值区北迁至海州湾附近;夏季不同粒径浮游植物对总初级生产的贡献率由高到低的顺序为小型(42.8%)、微型(29.6%)、微微型(27.6%),冬季的为微微型(41.2%)、微型(36.5%)、小型(22.3%);真光层初级生产力与环境因子的相关分析表明,水动力条件(混合与层化)引起的营养盐来源和光照的变化是初级生产力分布的主要控制因素;用生态比值法对南黄海碳流途径的分析表明,微食物环在冬夏两季碳流途径中均占有重要地位,从总体上看,南黄海浮游生态系统的碳输出潜力较弱。     

Management strategies to optimise sustainable clam (Tapes philippinarum) harvests in Barbamarco Lagoon,Italy

Barbamarco Lagoon is a small lagoon adjoining the Northern Adriatic Sea and is the site of a commercially valuable clam (Tapes philippinarum) fishery. A three-dimensional (3D) coupled hydrodynamic–ecological model was applied to the lagoon with the objective of assessing impacts on clam food supply, commercial harvests and water quality of different clam rearing strategies, lagoon morphologies and flow regimes. Harvest and net growth to seeding ratios, total harvest value, clearance efficiencies and clam satiety were used to quantify the commercial success of different management strategies, while bottom dissolved oxygen concentrations were used as an indicator of ecosystem health. Increasing exchange with the Northern Adriatic Sea or increasing freshwater inputs into the lagoon improved clam food supply and increased both harvest production and ecosystem health in model simulations of the system. Results indicated that the high spatial and temporal variability of clam production and water quality responses must be considered for a holistic assessment of the outcomes of strategies in the context of ecological and production carrying capacity.     

Particulate suspended matter concentrations in the Bahía Blanca Estuary,Argentina: Implication for the development of phytoplankton blooms

The inner zone of the Bahía Blanca Estuary is shallow, nutrient-rich and turbid. Tidal energy and water turbulence strongly affect the water column resulting in a well-mixed structure and high concentrations of suspended sediment. The phytoplankton community is mostly dominated by diatoms and the annual pattern has been characterized by a recurrent winter-early spring bloom. Here, we investigated to what extent the temporal variations of suspended particulate matter (SPM) regulate the phytoplankton blooms in the head of the estuary by light-limitation. Sampling was done on a fortnightly basis (weekly during the blooming season) at a fixed station in the inner zone of the estuary from January 2007 to February 2008. SPM concentrations and light extinction coefficients (k) in the water column were significantly correlated and showed relatively lower values during the phytoplankton maximal biomass levels. During winter, SPM and k reached values of 23.6 mg l⁻¹ and 0.17 m⁻¹ which were significantly lower than the annual means of 77.6 mg l⁻¹ and 2.94 m⁻¹, respectively. The particulate organic matter (POM) concentration was significantly correlated with the calculated phytoplankton biomass although the contribution of the latter to the total POM was rather low. Both, POM and biomass, had maximal values during winter (21.8 mg l⁻¹ and 393.5 μg C l⁻¹) and mid summer (24.3 mg l⁻¹ and 407.0 μg C l⁻¹), with cell densities up to 8 × 10⁶ cells l⁻¹ and chlorophyll a up to 24.6 μg l⁻¹. Our results suggest that the decrease of SPM concentrations in the water column with a concomitant increase in the penetration of solar radiation seems to be one of the main causes for the development of the phytoplankton winter bloom in the Bahía Blanca Estuary.     

Nutrient transport from an artificial upwelling of deep sea water

The transport of nutrient-rich, deep sea water from an artificial upwelling pipe has been simulated. A numerical model has been built within a commercial Computational Fluid Dynamics (CFD) package. The model considers the flow of the deep sea water after it is ejected from the pipe outlet in a negatively buoyant plume (densimetric Froude number = −2.6), within a stably stratified ocean environment subject to strong ocean current cross flow. Two cross-flow profiles were tested with momentum flux ratios equal to 0.92 and 3.7. The standard k-ε turbulence model has been employed and a range of turbulent Schmidt and Prandtl numbers tested. In all cases the results show that the rapid diffusion of heat and salinity at the pipe outlet causes the plume to attain neutral buoyancy very rapidly, preventing strong fountain-like behavior. At the higher momentum flux ratio fountain-like behavior is more pronounced close to the pipe outlet. The strong cross-current makes horizontal advection the dominant transport process downstream. The nutrient plume trajectory remains largely within one relatively thin stratified layer, making any ocean cross-flow profile less important. Very little unsteady behavior was observed. The results show that the nutrient is reduced to less than 2% of its inlet concentration 10 meters downstream of the inlet and this result is largely independent of turbulent Prandtl or Schmidt number. Initial results would suggest that if such an artificial upwelling were to be viable for an ocean farming project, a large number of upwelling pipes would be necessary. Further work will have to determine the minimum nutrient concentration required to sustain a viable phytoplankton population and the required spacing between upwelling pipes.     

黑潮入侵对南海东北部浮游植物群落结构的影响

To further understand the effect of Kuroshio intrusion on phytoplankton community structure in the northeastern South China Sea(NSCS, 14°–23°N, 114°–124°E), one targeted cruise was carried out from July to August, 2017. A total of 79 genera and 287 species were identified, mainly including Bacillariophyta(129 species), Pyrrophyta(150 species), Cyanophyta(4 species), Chrysophyta(3 species) and Haptophyta(1 species). The average abundance of phytoplankton was 2.14×10~3 cells/L, and Cyanobacterium was dominant species accounting for 86.84% of total phytoplankton abundance. The abundance and distribution of dominant Cyanobacterium were obviously various along the flow of the Kuroshio, indicating the Cyanobacterium was profoundly influenced by the physical process of the Kuroshio. Therefore, Cyanobacterium could be used to indicate the influence of Kuroshio intrusion. In addition, the key controlling factors of the phytoplankton community were nitrogen, silicate, phosphate and temperature, according to Canonical Correspondence Analysis. However, the variability of these chemical parameters in the study water was similarly induced by the physical process of circulations. Based on the cluster analysis, the similarity of phytoplankton community is surprisingly divided by the regional influence of the Kuroshio intrusion, which indicated Kuroshio intrusion regulates phytoplankton community in the NSCS.     

海洋浮游植物薄层的研究进展

浮游植物薄层是指位于水体次表层、厚度从几厘米到几米的高丰度浮游植物分布层。与大洋相比,在河口、海湾和近海的浮游植物薄层往往分布浅、强度大,具有明显的时空变化。浮游植物薄层的形成和维持不仅受到层化、楔入、剪切等物理过程的调控,也与浮游植物的生长、聚集及浮游动物的差异化捕食等生物生态学过程有关,目前围绕浮游植物薄层的形成机制已提出了趋旋俘获等假说。浮游植物薄层对其生长、繁殖、防御等具有重要意义,有的浮游植物薄层聚集了大量的有毒有害藻,与有害藻华的发生关系密切。深入研究浮游植物薄层的成因,将为阐明有害藻华的发生机制和有效监测提供重要依据。     

人工鱼礁建设对海洋浮游植物群落变化的影响

本研究关注了浮游植物群落对人工鱼礁建设后短期内的响应,浮游植物群落特征季节变化及其与环境因子之间的相互关系。基于小黑山岛海域 2013—2016 年 12 个航次的现场调查,共鉴定出 75 种浮游植物,硅藻是该海域最主要的浮游植 物类型;研究区域内叶绿素 a 浓度范围为 0.22 ~ 9.46 ug/L,Shannon 多样性指数 （log2） （H''） 范围为 0.76 ~ 3.06,Pielou 均匀度指数 （J''） 范围为 0.28 ~ 0.77。鱼礁建设前后海水环境因子变化较小,且礁区内外差异不显著,鱼礁建设后变化主要有3 点。Pb 和 Hg 浓度有所降低,符合一类海水水质标准的航次及站位增多。于叶绿素 a 浓度、H''和 J''均有所下降,礁区内外叶绿素 a 浓度无明显差别,且礁区的 H''和 J''高于非礁区。盂优势种有一定的变化,但礁区内外无明显差别,具槽直链藻是该海域全年性的优势种。典范对应分析 （CCA） 表明影响站位和各浮游植物在分析图中分布的最主要因素不是人工鱼礁建设而是季节变化。浮游植物群落主要受溶解氧、NO3-N、水温、悬浮物和 As 影响,其中 As 浓度虽然优于国家一类海水水质标准,但仍对浮游植物群落的分布影响显著。     

Variability of nutrients and phytoplankton primary production in a shallow macrotidal coastal ecosystem (Arcachon Bay,France)

Seasonal and spatial variations of phytoplankton primary production were studied using a high frequency sampling strategy in the external (ENW) and internal (INW) part of Arcachon Bay, during 2002 and 2003. In order to better assess the availability of nutrients and their relationship with phytoplankton primary production, nutrient variability was studied in relation to environmental conditions and phytoplankton production. During winter, when primary production rates were the lowest, nutrient concentrations were maximal but did not show excessive levels compared to highly urbanised areas. Seasonal and spatial variations of nutrient concentrations (especially DIN-nitrate + nitrite + ammonium- and Si) were largely influenced by Leyre River loads coupled with high tidal exchange with the Atlantic Ocean creating a nutrient gradient between the INW and ENW. By February, diatom growth leads to an early severe nutrient depletion in the entire bay. Examination of nutrient ratios showed that the potential limiting nutrient during spring was P in 2003, and Si in 2002. During summer 2003, N and Si concentrations reached their lowest values, and nutrient ratios revealed a N-deficient environment, more pronounced in the INW. The high Si:N ratios during this period might be explained by (1) important N-uptake by all autotroph communities and (2) benthic-pelagic coupling with high Si regeneration. This study shows that nutrient levels in Arcachon Bay seem to play an important role in the control of phytoplankton primary production rates during the productive period and explain their spatial, seasonal and inter-annual variability. Our estimates of annual integrated phytoplankton primary production (103 g C m⁻² y⁻¹) place this bay within the low to moderate phytoplankton primary production systems.