寒武纪丝状蓝细菌生物膜主导和诱发的巨型鲕粒:以河南新安县石井剖面苗岭统徐庄组为例

多样化的产出环境和30×108年的分布历史表明,鲕粒成因一直是一个谜一样的沉积学难题,争论的关键问题是其究竟是有机(微生物)成因还是无机成因.来自于华北地台寒武系苗岭统徐庄组鲕粒滩相灰岩顶部的方解石巨鲕表现出同心状、放射—同心状和泥晶质的沉积组构,在鲕粒核心和鲕粒皮层中保存着精美的葛万菌(Girvanella)化石所主...     

绿潮迁移过程中环境要素与浒苔藻体生物学特征的相关性分析

浒苔(Ulva prolifera)引起的大规模绿潮起源于黄海南部,在向北迁移过程中生物量迅速扩增,在海州湾附近(35°N左右)迅速增加达到峰值.在绿潮漂浮迁移过程中,海水表层温度、溶解无机氮(dissolved inorganic nitrogen,DIN)和磷酸盐(PO43--P)变化显著.本文以迁移过程中的浒苔为...     

Photosynthetic response of floating Ulva prolifera to diurnal changes of in-situ environments on the sea surface

During yellow sea green tide outbreak, the thalli of Ulva prolifera drifted more than 350 km on the sea surface from off shore of Jiangsu Province to Qingdao city, where they were exposed to complex changes of local environments. The purpose of this study is to investigate the response of the thalli to diurnal changes of environments on the sea surface, and a sea surface environment simulator (SSES) was designed to simulate the natural environment of floating U . prolifera mat. A control experiment is designed in the laboratory, which was processed under suitable conditions (20°C for temperature, 72 μmol photons/(m 2 ·s) for light intensity and 30 for salinity), and an in-situ research was conducted to study the photosynthetic responses of floating U . prolifera to diurnal changes of environments. The results show that the photosynthetic efficiency of the thalli decreased gradually with time, and decreased rapidly after 14:00 local time (LT). After exposed to the environment on the sea surface for 6 h, the photosynthetic activity of the thalli decreased significantly. Furthermore, physiological-level and molecular-level experiments revealed that non-photochemical quenching (NPQ), cyclic electron flow (CEF) and energy redistribution between PSI and PSII all played an important role in the strong photosynthetic plasticity of U . prolifera . NPQ is the most important photoprotective responses to environmental changes before 12:00 LT. The results also confirmed that the CEF and energy redistribution between PSI and PSII are the main synergistic eff ects for the thalli to adapt to the environmental changes when the process NPQ cannot work. And the result can further reveal the reason why U . prolifera can adapt to the living condition of long distance drift on the sea surface. The findings of this research could provide a theoretical basis for explaining outbreaks of the green tide and instructing the management of the problem.     

春季季风间期赤道东印度洋浮游植物光合生理特征

Phytoplankton physiologies are dynamic and have sensitive responses to the ambient environment. In this paper,we examine photosynthetic physiologies of phytoplankton communities with Phyto-PAM in the eastern equatorial Indian Ocean during the spring inter-monsoon. Environmental parameters were measured to investigate the coupling between phytoplankton photosynthetic physiologies and their habitats. During the cruise, the water column was highly stratified. The mixed layer extended to about 75 m and was characterized by high temperature(28°C) and low nutrient level. The F_v/F_m values and chlorophyll a(Chl a) concentrations were lower at the surface, as consequences of nutrient depletion and photo-inhibition. Subsurface Chl a maximum(SCM) occurred between 75 and 100 m, and had the highest F_v/F_m values. The formation of SCM was a balance between nutrient availability and light limitation. The SCM may contribute significantly to pelagic food web and primary production in the water column. Phytoplankton in different layers encountered different light, trophic and hydrographic dynamics and evolved distinct photosynthetic characteristics. Despite of co-limitation of nutrient limitation and photo-inhibition, phytoplankton in the surface layer showed their acclimation to high irradiance, had lower light utilization efficiencies(α: 0.061±0.032) and could exploit a wide range of light irradiance. Whereas, phytoplankton in the SCM layers presented the highest light utilization efficiencies(α:0.146±0.48), which guaranteed higher photosynthetic capacities under low light level. These results provide insights into phytoplankton photo-adaption strategies in this less explored region.     

番红砗磲外套膜色素提取条件优化及成分分析

以番红砗磲(Tridacna crocea)为实验对象,通过单因素对比实验对其外套膜色素的提取条件进行了优化,并利用薄层层析色谱法对色素组成进行了初步分析。结果表明:丙酮和乙醇为适宜的番红砗磲外套膜色素提取剂;使用丙酮为提取剂时,浸提时间为4 h,提取温度为25℃,料液比为1︰40。使用乙醇为提取剂时,浸提时间为4 h,提取温度为30℃,料液比为1︰200;利用薄层色谱法分离外套膜颜色为蓝色和红棕色的番红砗磲外套膜色素后发现,蓝色番红砗磲外套膜色素由9种色素组分构成,红棕色个体番红砗磲外套膜色素由10种色素组分构成。     

南海北部藻类粒级结构及色素成分对浮游植物吸收系数的影响

在珠江口、广东沿岸及南海北部三个航次生物-光学数据的基础上,研究了色素打包效应和色素成分的变化对浮游植物吸收系数的影响,结果表明,两种因素对吸收系数都有较大的贡献,但在不同的水体它们的影响程度各有不同.对网采浮游植物含量较高的珠江口和广东沿岸的水体而言,色素打包效应较强,对675 nm处比吸收系数的贡献平均分别为40%和20%;对微型浮游植物占主导地位的南海北部航次的水体,打包效应较弱,对675 nm处比吸收系数的影响平均仅为6%.采用多元线性回归的方法对吸收光谱进行分析,发现除叶绿素a之外的辅助色素对吸收系数的贡献主要表现在蓝绿光波段,三个航次440 nm波长处对总吸收的贡献平均分别为44%,43%和53%,其中对珠江口和广东沿岸航次的水体主要是光合类胡萝卜素的吸收贡献,而对南海北部航次的水体除了光合类胡萝卜素以外还要受到光保护类胡萝卜素的影响.由于河口、近岸和外海水体藻类粒级结构和辅助色素成分对浮游植物吸收系数的贡献有明显的差异,在南海北部水体建立比较精确的生物光学模型时,需考虑藻类粒级结构及色素成分对浮游植物吸收系数的影响.     

湿地植物香蒲光合特性及其影响因素分析

以湿地植物香蒲为材料,在水平潜流人工湿地处理单元中,采用便携式LI-6400光合作用测定仪测定其成熟叶片净光合速率(Pn)日变化,研究其光合生理生态特性。结果表明:香蒲叶片净光合速率(Pn)日变化呈双峰曲线,主峰(22.0μmol.m-2.s-1)出现在9:00左右,次峰(16.9μmol.m-2.s-1)出现在15:00,光合"午休"现象明显,且非气孔限制是产生光合"午休"的主要原因。用逐步多元回归方法得到净光合速率日变化与主要生理生态因子的回归方程为:yPn=0.7692+29.7059 xGs-0.7689xTr+0.014 2 xPAR(复相关系数0.9563,显著水平P=0.0001;叶片净光合速率Pn,μmol.m-2.s-1;气孔导度Gs,mol.m-2.s-1;蒸腾速率Tr,mmol.m-2.s-1;光合有效辐射PAR,μmol.m-2.s-1)。偏相关分析和通径分析的结果表明Gs、Tr和PAR与Pn的日变化显著相关,是影响香蒲Pn的主要因子,影响大小的顺序为:Gs>PAR>Tr。香蒲叶片Pn-PAR的响应曲线方程为yPn=-5×10-6 xPAR 2+0.0207 xPAR-1.3728(相关系数0.9935,显著水平p=0.000 1),光补偿点、光饱和点和表观量子效率分别为32.9μmol.m-2.s-1、147 6μmol.m-2.s-1、0.023 3 mol.mol-1;Pn-CO2的响应曲线方程为yPn=-2×10-5 w(CO2)2+0.054 9 w(CO2)-1.44 4(相关系数0.9694,显著水平p=0.000 1;w(CO2)单位为μmol.mol-1),CO2补偿点、CO2饱和点和羧化效率分别为23.7μmol.mol-1、621.4μmol.mol-1和0.0768 mol.m-2.s-1。     

Structure and photosynthetic properties of phytoplankton assemblages in a highly dynamic system, the Northern Adriatic Sea

The photosynthetic properties of phytoplankton populations as related to physical–chemical variations on small temporal and spatial scales and to phytoplankton size structure and pigment spectra were investigated in the Northern Adriatic Sea off the Po River delta in late winter 1997. Large diatoms (fucoxanthin) dominated the phytoplankton in the coastal area whereas small phytoflagellates (mainly 19′-hexanoyloxyfucoxanthin, chlorophyll b, 19′-butanoyloxyfucoxanthin) occurred outside the front. The front was defined by the steep gradient in density in the surface layer separating low-salinity coastal waters from the offshore waters.Physical features of the area strongly influenced phytoplankton biomass distributions, composition and size structure. After high volumes of Po River discharge several gyres and meanders occurred in the area off the river delta in February. Decreasing river discharge and the subsequent disappearance of the gyres and the spreading dilution of the river plume was observed in March. The dynamic circulation of February resulted in high photosynthetic capacity of the abundant phytoplankton population (>3.40 mg m⁻³). In March, the slow circulation and an upper low-salinity water layer, segregated from the deeper layers, resulted in lack of renewal of this water mass. The huge phytoplankton biomass, up to 15.77 mg chl a m⁻³, became nutrient depleted and showed low photosynthetic capacity. In February, an exceptionally high P_max^B, 20.11 mg C (mg chl a)⁻¹ h⁻¹ was recorded in the Po River plume area and average P_max^B was three-fold in February as compared to the March recordings, 10.50 mg C (mg chl a)⁻¹ h⁻¹ and 3.22 mg C (mg chl a)⁻¹ h⁻¹, respectively.The extreme variability and values of phytoplankton biomass in the innermost plume area was not always reflected in primary production. Modeling of circulation patterns and water mass resilience in the area will help to predict phytoplankton response and biomass distributions. In the frontal area, despite a considerable variability in environmental conditions, our findings have shown that the phytoplankton assemblages will compensate for nutrient depression and hydrographic constraints, by means of size and taxonomic composition and, as a result, the variability in the photosynthetic capacity was much less pronounced than that observed for other parameters.     

Phytoplankton dynamics associated with the monsoon in the Sulu Sea as revealed by pigment signature

Phytoplankton dynamics during the northeast monsoon was investigated in the Sulu Sea from algal pigment analysis. We visited the Sulu Sea in February 2000, a mid period of the northeast monsoon, and in November and December 2002, the beginning of the northeast monsoon. SeaWiFS images showed generally low concentrations of surface chlorophyll a (Chl a) during the southwest monsoon and higher concentrations with several peaks during the northeast monsoon. In the beginning of the northeast monsoon, subsurface chlorophyll maxima (SCM) occurred, where vertical variation in class-specific composition as estimated from pigment signatures was prominent. Prochlorococcus, cyanobacteria, prymnesiophytes and crysophytes were important groups above the SCM, and the contribution of cyanobacteria to Chl a became much lower at and below the SCM. Contributions of chlorophytes and prasinophytes to Chl a generally showed maxima near the SCM. This distribution was accompanied by vertical changes in the concentration of photoprotective pigments relative to photosynthetic accessory pigments. During the mid northeast monsoon, the upward supply of nutrients was probably enhanced at some stations due to vertical mixing, and as a consequence diatoms dominated in the upper 100 m water column of these stations, and other eukaryotic flagellates including prymnesiophytes, chrysophytes and cryptophytes were secondary major components of the community. The elevation of Chl a concentration and changes in phytoplankton community during the northeast monsoon likely influence the variation in biological production at higher trophic levels in the Sulu Sea.     

用多层感知器模型由吸收光谱反演浮游植物色素

浮游植物吸收光谱已逐渐成为高光谱水色遥感的可获取参量。文章采用了多层感知器模型, 由珠江口担杆群岛附近水体的浮游植物吸收光谱进行了色素浓度的反演, 感知器的输入量是浮游植物吸收光谱, 输出量分别对应叶绿素a、叶绿素b、叶绿素c、光保护类胡萝卜素和非光保护类胡萝卜素五大类主要色素的浓度。分析结果表明, 叶绿素a和叶绿素c估算结果的平均相对偏差比较低, 在测试数据集中两者的偏差分别为19.06%和15.90%; 光保护类胡萝卜素和非光保护类胡萝卜素的估算浓度的相对偏差比较高, 对于测试数据而言, 分别为37.62%和36.96%; 叶绿素b浓度在测试数据集中的估算相对偏差约为27.47%。五大类色素在测试数据集和训练数据集的估算偏差比较接近, 已训练好的多层感知器可用于担杆岛水体中色素信息的反演。同时, 此色素反演方法也为遥感监测水体浮游植物种群动态提供了重要的手段。