珠江口分粒级叶绿素a和初级生产力研究

珠江是我国第三大江,年径流量仅次于长江,珠江口是我国南方重要的运输通道和沿岸渔场.近20 a来,由于珠江三角洲地区经济的迅速发展,河口区的富营养化和赤潮时有发生[1,2].因此,关于该水域生态系统结构和功能的研究日益受到重视.河口区是陆海相互作用的耦合带和生产力较高的区域,开展对该水域叶绿素a和初级生产力的研究,对于阐明该生态系统的结构和功能及其诸如富营养化和赤潮等环境问题具有重要意义,对于生物资源的开发亦具实际价值.     

Burial of organic carbon in Holocene sediments of the Zhujiang (Pearl River) and Changjiang (Yangtze River) estuaries

The East Asian marginal seas are important sinks of terrigenous materials transported by large rivers. In this study two cores from the Changjiang (Yangtze River) and Zhujiang (Pearl River) estuaries and one core from the inner shelf off of Hong Kong were investigated to examine the burial of organic matter during the postglacial period and its possible links with paleoenvironmental changes. Based on a simple two end-member mixing model, the terrestrial organic matter supplied primarily from the Zhujiang and Changjiang dominates the estuarine areas while marine organic matter contributes more to the inner-mid shelf. The competing contributions of terrestrial and marine organic matter are responsible for the downcore variations of organic elemental compositions. The overall decreasing shifts of total organic carbon concentrations and total organic carbon to total nitrogen ratios in the Zhujiang estuarine sediments since 6.5 kaBP seems to support the notion that depth profiles of organic matter compositions deposited in the Zhujiang Estuary can aid in the reconstruction of monsoon history in the Holocene. Nevertheless, organic matter compositions in the Changjiang Estuary and inner shelf off of southeastern Hong Kong respond in a different and more complex way to freshwater discharges or precipitation changes (monsoon variability) in the catchments, owing to complex controls of deposition and preservation of organic matter in these estuarine and shelf environments. Caution is therefore needed in using organic elemental and isotopic compositions to decipher paleoenvironmental changes in East Asian continental shelves where intense river–sea interactions occur and sedimentary environments change drastically.     

Phosphate limitation of phytoplankton growth in the Changjiang Estuary

Laboratory experiments of bioassay with Pltaeodaetytum tricornutum, Chatoceros didymus, Chaetoreros calcitraus and Heterogtoea sp. sampled from the Changjiang Estuary in spring and summer, 1986, indicated that both N and P limit phytoplankton growth in the medium with N : P ranged between 8-30, and N limits phytoplankton production in the medium with N: P<8, while P is the limitary nutrient in the N : P>30. Generally, N : P in the Changjiang Estuary waters is 2 times higher than Redfield ratio. The bioassay experiments with high N : P water samples collected from Changjiang Estuary show that phytoplankton production is limited by P. Phytopiankton appears to give priority to the uptake of P at all periods of time. And the optimum N:P for phytoplankton growth is determined to be 18.     

Modeling photosynthesis and the growth of marine phytoplankton

The paper analyzes the most popular models of photosynthesis and growth of marine phytoplankton in the literature and demonstrates their limitations. A new approach to modeling is proposed and used to obtain new models of marine phytoplankton photosynthesis and growth. An important feature of the proposed models is their ability to describe coupled multisubstrate cyclical interactions typical of biochemical and physiological processes. As a first approximation, the mathematical models are represented by equations of nonrectangular hyperbolas. The models describe the stoichiometry of extraction of elements from the medium, whatever the degree of their limitation, an important feature in describing biogeochemical cycles of elements. This stoichiometry is governed by measurable internal parameters of an organism (substrate parameters) and can be a key cause of stoichiometric formation of elements in the ambient medium, described, for example, by the Redfield ratio. The substrate constants are fundamental characteristics of the models, which form “automatically” in the construction of model equations in arbitrary units.     

长江口羽状锋海区浮游植物的生态研究：—昼夜分布动态

本文对长江口羽状锋海区浮游植物的昼夜变动进行了初步研究，结果表明，浮游植物数量的昼夜变化明显，潮汐作用是影响数量昼夜分布变化的主导因素，同时也与该地区浮游植物的水平分布有着密切的联系。     

Effect of river plume on phytoplankton community structure in Zhujiang River estuary

To examine the phytoplankton assemblages and the effect of diluted waters on them, a research cruise was conducted from July 19 to August 7, 2015 in the Zhujian...     

The thermal effects of cooling system of a thermal power plant on photosynthesis of marine phytoplankton

The activity of photosynthesis and the contents of chlorophylla and pheo-pigments were compared in the samples of the intake and effluent seawater of Owase-Mita Thermal Power Plant and in the seawater samples in the Yoshimi Bay before and after heat treatment. At Owase-Mita Thermal Power Plant, after passage of sea water through the cooling system chlorophylla content reduced to about a half and pheo-pigment content doubled in August with high temperature (25–27C), but the contents of chlorophylla and pheo-pigments changed little in January with low temperature (16C); whereas the depression of photosynthetic activity after passing through the cooling system was 71–77 % in August and 31–46 % in January. In the laboratory experiments, the heat treatment at 34–43C for 7–8 sec., which resulted in temperature rise of 7–8C, gave the decrease of chlorophylla and an increase of pheo-pigments in August temperature (26.5C), but a slight decrease of chlorophylla and a slight increase of pheo-pigments in November at the initial temperature of 19.2C, while in January and December the samples with low initial temperature (11.6 and 10.8C) showed almost no change in the content of pigments; the decrease in photosynthetic activity was 32 % in August sample,ca. 11 % in November sample,ca. 15% in January and almost no change in December. It is concluded that the photosynthetic carbon assimilation of marine phytoplankton is suppressed by passing through the cooling system of a thermal power plant even at lower water temperature in winter, while the content of chlorophylla is affected very little at a temperature below 20C.     

Seasonal pigment patterns of surface phytoplankton in the subtropical southern hemisphere

Pigment indices were used to characterise the seasonal succession of phytoplankton, and associated changes in chlorophyll a and accessory pigments, in subtropical waters of the three ocean basins in the southern hemisphere. Diagnostic indices revealed the dominance of small flagellates and elevated biomass during winter–spring in the Pacific, mixed flagellate–prokaryote communities and intermediate biomass during early summer in the Atlantic, and prokaryote dominance with low biomass in mid-summer in the Indian Ocean. Photo-pigment indices indicated only a small variation in the chlorophyll a proportion of total pigments across the ocean basins, but the accessory pigments varied considerably. Under low temperature and irradiance conditions, the photosynthetic carotenoids were prominent, but as temperatures and irradiance increased and nutrients declined, there was a significant increase in the proportion of photoprotective carotenoids. At high temperatures and irradiances, the photoprotective carotenoids were the largest component of the pigment pool, exceeding the proportion of chlorophyll a. These variations in phytoplankton composition, and their photoacclimation status, could be explained according to environmental changes and have implications for satellite estimations of biomass and primary production.     

Distribution and photo-physiological condition of phytoplankton in the tropical and subtropical North Pacific

To better understand the vertical distribution of phytoplankton in the tropical and subtropical North Pacific, we used fast repetition rate fluorometry to investigate the photo-physiological condition of the phytoplankton assemblage in this region between February and March 2007. Along 155°E, between the equator and 24°N, the peak of fluorescence (F _m), an indication of the deep chlorophyll maximum (DCM), was deeper than the top of the nitracline and occurred at the 2.4 ± 1.3 % (mean ± SD) light depth (relative to 0 m). The photochemical efficiency (F _v/F _m) and effective absorption cross-section of photosystem II (σ_PSII) were low at the surface but increased rapidly at depths between the top of the nitracline (40–138 m) and the DCM (70–158 m), an indication that the photo-physiological condition of the phytoplankton improved below the top of the nitracline. The depth of the maximal F _v/F _m [Z(F _v/F _{m max})] was 18–32 m deeper than the DCM and corresponded to the 0.8 ± 0.2 % light depth. The values of F _v/F _m at the Z(F _v/F _{m max}) were 20 % higher than those at the DCM and averaged 0.48 ± 0.01. These results suggest that the phytoplankton assemblage beneath the DCM had a high potential photosynthetic performance capacity and was growing by using the very low ambient light in this region.     

近海污染物对海洋浮游植物生长及生化组成影响的比较研究

威氏海链藻(Thalassiosira weissflogii)属沿海中心硅藻纲,是海洋硅藻的模式种之一。实验探讨氮营养盐(硝酸盐,N,c(N)分别为8.0,16.0,32.0,64.0μmol/L)、石油烃(0号柴油分散液,WAFs,c(WAFs)分别为0,0.1,0.5,1.0,5.0 mg/L)、抗生素(土霉素,c(OTC)分别为,0,1.0,3.0,5.0,10.0 mg/L)等3类近海常见污染物对威氏海链藻细胞生长及生化组成的影响。结果表明,3类近海常见污染物对藻生长(即藻细胞密度)、叶绿素a合成、蛋白质生成、藻细胞抗氧化能力(即超氧化物歧化酶活性)、脂质过氧化(即丙二醛含量)的影响程度分别为WAFsNOTC、NOTCWAFs、NWAFsOTC、WAFsNOTC、OTCNWAFs;影响程度的差异,揭示了近海各污染物的毒性作用机制及靶位不同。     

夏季长江口不同粒级浮游植物碱性磷酸酶活性

碱性磷酸酶活性(alkaline phosphatase activity, APA)是海洋研究中用于反映浮游植物磷限制状态的重要指标。在长江口等“氮过剩”海域,磷是控制海域初级生产力水平的主要因子,然而,磷限制的范围常常难以界定,当前对不同粒级浮游植物的磷限制效应所知甚少。该文根据2020年夏季长江口航次资料,给出了海洋表层各粒级浮游植物(Net:≥20 μm;Nano:2~20 μm;Pico:0.8~2 μm)APA、浮游细菌APA(0.2~0.8 μm)和溶解态APA(<0.2 μm)的空间分布特征,并分析了APA与环境要素间的相关性。结果显示,各粒级浮游植物APA均与无机磷酸盐浓度(dissolved inorganic phosphate, DIP)呈显著负相关,这表明DIP浓度是影响浮游植物APA分布的主要因素。在平面分布上,各粒级浮游植物APA在近口门的光限制区均较低,且呈现自口门向外逐渐升高的趋势,与DIP的分布特征相反。Net和Nano级APA[平均值分别为 (40.28±32.35) nmol/(L·h)和(52.38±34.78) nmol/(L·h)]显著高于Pico级APA[平均值为(28.43±20.23) nmol/(L·h)],这表明大粒级浮游植物可能更易受DIP下降的影响。该研究中,诱导浮游植物APA快速升高的DIP浓度为0.159 μmol/L,与近岸区磷限制经验阈值相接近。该研究揭示了夏季不同粒级浮游植物对长江口磷分布的响应特征,有助于理解长江口初级生产过程的环境调控机制。     

长江口南汇嘴潮滩短期冲淤演变及其动力机制研究

潮滩地形的冲淤演变规律可以在一定程度上反映动力作用与地貌特征之间的相互耦合机制.根据近几年在长江口南汇嘴潮间带多断面连续观测资料,探讨区域内潮间带滩地的近期冲淤演变特征及其主要影响因子.研究结果表明:(1)南汇嘴潮滩近期主要呈现淤涨态势,而且年内过程季节性差异明显;受区位差异影响,不同观测断面的潮滩冲淤演变呈现特征不尽相同,断面1冲淤变化最为显著,年最大冲淤厚度均在10cm以上;(2)在波浪、潮流的作用下,区域内沉积物很容易被掀动悬扬,而且输沙环流系统的存在有利于悬沙向浅水区输运且在该区域内沉降淤积,从而为潮滩发育提供泥沙来源;(3)受"碧利斯"台风引起的风暴潮天气影响,研究区域内潮滩出现"大冲大淤"现象,即台风强侵蚀期过后滩面高程短期内恢复明显.由此可见,潮滩短期冲淤演变特征是各种动力因素作用下的综合体现.     

黄河、长江和珠江三角洲近代沉积物的沉积化学特征

黄河、长江和珠江是我国直接入海的三条最大河流，流域面积之和占我国直接入海主要河流流域面积的90%。三大河三角洲近代沉积物的沉积化学特点是：黄河三角洲CaO含量高，而A12O3、TiO2和有机质含量均较低；长江三角洲的MgO、MnO含量略高；珠江三角洲的Fe2O3、TiO3含量高，CaO含量低。这种沉积化学特征的差别，是由于沉积化学成分受地带性的生物气候及河口地球化学环境制约的结果。     

长江口及邻近海域浮游植物现存量的上下行控制分析

利用2010—2011年度3个季节的调查资料以及广义相加模型(GAM)分析,研究了长江口及邻近海域浮游植物现存量(以叶绿素a浓度表征)的上下行控制作用。调查结果显示,在叶绿素高值区,三航次营养盐含量均比整个海区平均值偏低,且春季呈现三季节最低的磷酸盐(PO4-P)和硅酸盐(SiO3-Si)浓度(平均值分别为0.48和8.96μmol/L)以及最高的氮磷比(DIN/P为43.3),为该海域春季甲藻赤潮频发提供了有利条件。夏季叶绿素高值区的硅氮比(Si/DIN)相对整个调查区较高,而春季和秋季却相近,这与夏季藻华种类主要是硅藻相一致。春、夏两季叶绿素高值区的悬浮物浓度(TSS)在时空比较上均显著低值。浮游动物高值区分布与叶绿素高值区分布虽不完全重合,但有交叉或两者相邻。GAM模型分析结果显示,各环境因子变化对长江口及邻近海域叶绿素变化的贡献可达70%以上,且主要影响因子为盐度和营养盐,而与TSS、浮游动物生物量和温度三因子的直接相关性不显著(p0.05)。受长江冲淡水的影响,盐度与DIN、PO4-P、SiO3-Si、TSS等因子间存在显著的相关关系(p0.001),说明盐度对叶绿素变化的影响可能体现了营养盐和光照条件等因子的作用。上述研究结果表明,在长江口及邻近海域,营养盐的上行效应是浮游植物现存量的主要控制作用,而光照条件和浮游动物生物量与浮游植物现存量虽然在时空分布上存在一定的联系,但非决定性控制因素。     

The effects of spring-neap tide on the phytoplankton community development in the Jiaozhou Bay, China

The development of the phytoplankton community was studied in the Jiaozhou Bay during the spring to neap tide in August 2001, through three cruises and a 15 d continuous observation. This investigation indicates that diatom cell abundance increased sharply following the end of a spring tide, from 9 cells/cm^3 to a peak of 94 cells/cm^3. The dominant species composition and abundance show a quick species sequence from spring to neap tide, and the dominant species at the start phase is Skeletomena costatum, then changes to Chaetoceros curvisetus, finally it changes to Eucampia zodiacus. Silicate concentration increases during spring tide, as a result of nutrient replenishment from the water-sediment interface, its initial average concentration in neap tide is 1.39μmol/dm^3 and reached the peak average concentration of 8.40μmol/dm^3 in spring tide. But the nitrogen concentration dropped due to dilution by the low nitrogen seawater from the Huanghai Sea, its initial average concentration in neap tide is 67μmol/dm^3 and decreased to the average concentration of 54μmol/dm^3 in spring tide. The degree of silicon limitation was decreased and phytoplankton, especially diatoms, responds immediately after nutrient replenishment in th ewater column. Skeletonmea costatum, as one of the dominant species in the Jiaozhou Bay, shows a quicker response to nutrient availability than Eucampia zodiacus and Chaetoceros curvisetus. It is proposed that dominant species composition and water column stability synchronously determine the development of phytoplankton summer blooms in the Jiaozhou bay.     

Vertical distribution of phytoplankton biomass,production and growth in the Atlantic subtropical gyres

Ninety-four stations were sampled in the Atlantic subtropical gyres during 10 cruises carried out between 1995 and 2001, mainly in boreal spring and autumn. Chlorophyll a (Chl-a) and primary production were measured during all cruises, and phytoplankton biomass was estimated in part of them. Picoplankton (<2 μm) represented >60% of total Chl-a concentration measured at the surface, and their contribution to this variable increased with depth. Phytoplankton carbon concentrations were higher in the upper metres of the water column, whereas Chl-a showed a deep maximum (DCM). At each station, the water column was divided into the upper mixed layer (ML) and the DCM layer (DCML). The boundary between the two layers was calculated as the depth where Chl-a concentration was 50% of the maximum Chl-a concentration. On average DCML extends from 67 to 126 m depth. Carbon to Chl-a (C:Chl-a) ratios were used to estimate phytoplankton carbon content from Chl-a in order to obtain a large phytoplankton carbon dataset. Total C:Chl-a ratios averaged (±s.e.) 103±7 (n=22) in the ML and 24±4 (n=12) in the DCML and were higher in larger cells than in picoplankton. Using these ratios and primary production measurements, we derived mean specific growth rates of 0.17±0.01 d⁻¹ (n=173) in the ML and 0.20±0.01 d⁻¹ (n=165) in the DCML although the differences were not significant (t-test, p>0.05). Our results suggest a moderate contribution of the DCML (43%) to both phytoplankton biomass and primary production in the Atlantic subtropical gyres.     

应用浮游植物监测与评价长江口水体营养状况

通过对长江河口浮游植物采样研究,应用浮游植物群落多样性指数和均匀度指数、浮游植物丰度以及生物学综合评价法对长江河口水体营养状况进行监测与评价.生物学综合评价结果显示:1999年枯水期,口门内的SX01～SX04样站表、底层水体为中营养水平,口门外近岸及近外海水域一般为贫营养水体.1999年丰水期,表、底层水质状况与枯水期不同,口门内的SX01～SX04样站水体为贫营养型,近口门、近外海水域为中营养型,近岸中部、东部表层一般达到富营养型水体,近岸底层东北部为富营养型,其余近岸水域为中营养型水体.2000年枯水期水质情况为:口门内表、底层水体为贫营养水体,近岸水域表层为中营养水体,底层为贫营养水体,近外海水域表、底层一般也为贫营养水体.     

Selective transmission of light in the ocean waters and its relation to phytoplankton photosynthesis

Occurrence of the depth differences in pigment composition and photosynthetic properties of marine phytoplankton were examined in relation to the spectral changes of light with depth. Phytoplankton were taken from various depths in the northwestern North Pacific, and their absorption spectra were determined with intact cells and in 90% acetone extract. The photosynthetic activities of phytoplankton were concurrently measured under blue, green, red and white light. The difference in absorption spectra for the surface and deeper samples was considerably small, indicating that the prevailing green or blue light in the deeper layers may have little significance for depth-variations of the pigment composition in marine phytoplankton. The depth differentiation in the shape of the light-photosynthesis curve was marked in a well stratified water column but no active response of deeper phytoplankton to green light could be confirmed. The photosynthetic efficiencies of phytoplankton for blue and green light were approximately 105–115 % and 80–90 % of white light, respectively, irrespective of sampling depth.Contribution No. 261 from Shimoda Marine Biological Station     

长江口及邻近海域浮游植物生态系统气候变化综合风险评估

近几十年来,在气候变化和人类活动的影响下,我国近岸河口海域尤其是长江口及邻近海域生态灾害频繁发生,严重影响了海洋生态系统的健康及其服务功能。本研究基于政府间气候变化专门委员会（Intergovernmental Panel on Climate Change, IPCC）气候变化风险理论框架,构建了河口浮游植物生态系统的气候变化综合风险评估指标体系,并利用IPCC 第五次耦合模式比较计划（CMIP5）地球系统模式数据,分别计算分析了在温室气体低（RCP 2.6）、中等（RCP 4.5）和高（RCP 8.5）浓度排放情景下未来不同时期（2030—2039、2050—2059、2090—2099年）长江口及邻近海域浮游植物生态的致灾因子危害性、承灾体暴露度和脆弱性及其综合风险。结果表明： RCP 2.6、4.5和8.5情景下,到21世纪中期,致灾因子危害性均有明显上升,其中RCP 4.5和8.5情景下,到21世纪末,还将大幅度增加,且以RCP 8.5情景最为显著,而RCP 2.6情景下则相反,有所下降;RCP 2.6情景下,高暴露度区域主要位于长江口附近,不同年代的变化差异较小;RCP 4.5和8.5情景下高暴露度区域明显大于RCP 2.6情景,尤其是后者到21世纪末期扩大至长江口邻近海域;脆弱性总体呈现近岸高远岸低的分布特征,且变化均较小;RCP 2.6、4.5和8.5情景下,综合风险均呈现近岸高远岸低,且有增加的趋势,但以RCP 8.5情景最为明显,并在21世纪末达到最大。