Shallow lake trophic status linked to late Holocene climate and human impacts   总被引：1，自引：1，他引：0  

Matthew N. Waters  Michael F. Piehler  Antonio B. Rodriguez  Joseph M. Smoak  Thomas S. Bianchi 《Journal of Paleolimnology》2009,42(1):51-64

Lake Mattamuskeet, North Carolina, USA is a large (162 km²) and shallow (mean depth = 1 m) coastal lake, which was significantly modified to support agricultural activities following European settlement in 1850. Paleolimnological proxies measured on a 400-cm sediment core collected from Lake Mattamuskeet reveal shifts in organic matter input and primary producer community structure in response to climatic and human impacts on the lake during the late Holocene. Stratigraphic changes in organic matter content, nutrients, metals, lignin phenols and photosynthetic pigments were used to divide the sediment core into three intervals. Interval I includes sediment deposited between A.D. 360–1584 and indicates a clear-water, sand-bottom state with low algal abundance. In addition, the lake catchment area experienced two significant fires during this interval that were recorded as charcoal layers in the core around A.D. 360 and A.D. 1435 (calibrated ¹⁴C AMS dates). Trophic structure changed with the onset of Interval II (A.D. 1584–1860) when total algal abundance increased, and the primary producer community was comprised primarily of diatoms, chrysophytes, cryptophytes and cyanobacteria. During this interval there was also an increase in terrestrial organic material input into the lake as well as a shift in plant type from woody gymnosperms to non-woody angiosperms as determined from lignin data. Sediment deposited in Lake Mattamuskeet following European settlement (Interval III, A.D. 1860-present) suggests a dramatic increase in organic-matter deposition, metals, primary-producer abundance and the onset of cyanobacterial dominance. Sedimentary evidence indicates that shallow-water primary producers can respond rapidly to climate change and human development.  相似文献   

Estuarine phytoplankton dynamics and shift of limiting factors: A study in the Changjiang (Yangtze River) Estuary and adjacent area   总被引：5，自引：0，他引：5  

Zhuo-Yi Zhu  Wai-Man Ng  Su-Mei Liu  Jing Zhang  Jay-Chung Chen  Ying Wu 《Estuarine, Coastal and Shelf Science》2009,84(3):393

Environmental factors in estuaries are highly variable in terms of both spatial and temporal dimensions and hence phytoplankton biomass, as well as community structure, is dynamic. Two cruises were carried out in the Changjiang (Yangtze River) Estuary and adjacent area in spring and summer. The result of CHEMTAX calculation suggests that in spring diatoms and chlorophytes contribute equally to phytoplankton biomass, while phytoplankton community structure is mainly composed of diatoms in summer. We encountered blooms in summer with chlorophyll a (CHLa) over 10 μg l⁻¹ off the Changjiang Estuary and they were mainly caused by diatoms (>90%). Based on the HPLC analysis of samples collected, phytoplankton pigments mainly concentrated beyond the front between 122.5°E and 123°E where nutrients and turbidity were best balanced. Euphotic depth (Z_eu, calculated from Secchi disk depth) to surface mixed layer depth (Z_mix) ratio (i.e. Z_eu/Z_mix) were comparable in spring (average value 1.2) and the ratio increased to 5.2 in summer. Variation of the ratio indicates an apparent shift of light and physical conditions from spring to summer. Correspondingly, CHLa was positively related to Z_eu/Z_mix ratio (r² = 0.83) in spring, indicating the light limitation over the whole investigation area. On the other hand, the relationship of CHLa and Z_eu/Z_mix ratio became unclear when Z_eu/Z_mix ratio >3 in summer. This is probably due to the combination of both light limitation before the front and nutrient limitation beyond the front. In addition, evidence was found that light condition can impact the diagnostic pigments in the Changjiang Estuary.  相似文献   

枯水期钦州湾浮游植物群落结构组成与分布特征   总被引：3，自引：2，他引：3  

蓝文陆  李天深  郑新庆  施晓峰  黎明民  陆建军  李波 《海洋学报》2014,36(8):122-129

应用浮游植物特征光合色素的分析方法,研究了2011年枯水期钦州湾浮游植物的结构组成与分布特征。结果表明:枯水期含量较高的浮游植物光合色素按含量高低依次为叶绿素a、岩藻黄素、叶绿素b、青绿素和多甲藻素,其他特征光合色素的含量很低。经CHEMTAX对光合色素转化计算,枯水期普遍检出的浮游植物类群为硅藻、青绿藻和甲藻,是枯水期浮游植物的优势类群,其生物量的平均值(±标准差)分别为(2.36±2.38)μg/L、(0.87±0.53)μg/L、(0.13±0.14)μg/L,变化范围为0.18~7.45μg/L、0.10~1.80μg/L和0.02~0.60μg/L。硅藻、青绿藻和甲藻占枯水期浮游植物生物量比例的平均值(±标准差)分别为59%±21%、30%±16%、6%±4%,占比变化范围为29%~96%、1%~53%和0.4%~14%,其他藻类所占比例很低。河口和外湾靠外海域两个区域以硅藻为优势类群,内湾及外湾近岸硅藻和青绿藻共同为优势类群。河流营养盐输入量和比例的不同决定了钦州湾河口海区浮游植物群落结构的差异,大面积贝类养殖导致了内湾至外湾近岸海区硅藻比例的降低,而外湾水温的增加引起暖水性硅藻大量增长成为优势类群,在温度进一步增加和营养盐持续输入等条件下存在会发生硅藻赤潮的风险。  相似文献   

放养前后鱼塘沉积物中氮、磷、有机质、色素的变化及环境意义   总被引：1，自引：0，他引：1  

潘红玺  胡洪云 《湖泊科学》1998,10(3):39-42

通过对针塘沉积物中营养盐,有机质及色素在放养前后的测试,对比分析了在人类活动（养殖）的影响下,由于鱼塘水体快速富营养化而引起底质上述指标的变化过程,其中快速沉积环境极有利于沉积色素的保存,具有较好的环境营养状况指示意义,同时有机质,色素和营养盐之间存在着密切的相关关系,这为利用色素方法研究短时间序列环境演变,尤其是在近代人类活动影响下的环境变化提供了一定的依据。  相似文献   

云南杞麓湖沉积物记录的近现代生态环境变化及影响因子识别   总被引：1，自引：0，他引：1  

钱福明  张恺  陈光杰  尹永鑫  王教元  胡葵 《湖泊科学》2018,30(4):1109-1122

随着云南社会经济的持续发展与极端气候事件的频发,高原大中型湖泊面临着水质恶化、生态与环境功能退化的长期胁迫.为识别亚热带大型湖泊面临的主要环境压力,以杞麓湖为研究对象,在对沉积物钻孔进行物理(粒度、烧失量)、生物(色素、硅藻)等指标分析的基础上,结合现代监测和湖泊调查数据,重建了近两百年来湖泊水文条件、富营养化和环境变化的历史,并对硅藻群落结构的演化进行了驱动过程识别.沉积物粒度在1958年之前变化总体较为稳定且有较高的黏土含量;随着围湖造田等流域开发的增强,沉积物粒度组成自1960s开始频繁波动且粗颗粒组分快速增加.1981—2000年期间,随着落水洞泄水工程的修建杞麓湖的水位控制与水文调控得到加强,沉积物砂质含量降低且粒度组成变化较小;2000—2013年期间,湖泊疏浚工程的开展和区域降水的持续减少都导致了沉积物粒度组成波动较大、粗颗粒组成较高.沉积物色素记录了湖泊初级生产力的缓慢上升出现于19世纪中后期,并自1960s开始总叶绿素与蓝藻色素含量总体出现了较大幅度的增加趋势并持续至今.而在2000—2005年期间,湖泊浅水区的疏浚清淤导致了内源营养盐输入量的降低与藻类生物量的明显下降;沉积物蓝藻色素含量在1998、2008和2012—2013年左右出现明显的峰值,指示杞麓湖可能出现了较大范围的蓝藻暴发事件.统计分析结果显示,湖泊硅藻群落结构出现了多次明显转变且呈现底栖硅藻百分比长期降低的特征,水体富营养化的持续是驱动硅藻群落结构演替的主要因子,而水生植物退化、水文条件与气候变化也对硅藻群落的构建产生了重要的叠加影响.本文的沉积物分析结果表明,亚热带大型湖泊的生态治理与环境保护需要重点围绕营养盐负荷控制、水文调控优化与底栖生境恢复,并需应对全球变暖与极端气候事件产生的叠加影响.  相似文献   

Comparison of Phytoplankton Communities Between Melt Ponds and Open Water in the Central Arctic Ocean     

ZHANG Tianzhen  ZHUANG Yanpei  JIN Haiyan  LI Ke  JI Zhongqiang  LI Yangjie  BAI Youcheng 《中国海洋大学学报(英文版)》2019,(3):573-579

Climate warming has a significant impact on the sea ice and ecosystem of the Arctic Ocean.Under the increasing numbers of melt ponds in Arctic sea ice,the phytoplankton communities associated with the ice system are changing.During the 7th Chinese National Arctic Research Expedition cruise in summer 2016,photosynthesis pigments and nutrients were analyzed,revealing differences in phytoplankton communities between melt ponds and open water in the central Arctic.Photosynthetic pigment analysis suggested that Fuco(5-91μg m^-3)and Diadino(4-21μg m^-3)were the main pigments in the open water.However,the melt ponds had high concentrations of Viola(7-30μg m^-3),Lut(4-59μg m^-3)and Chl b(11-38μg m^-3),suggesting that green algae dominated phytoplankton communities in the melt ponds.The significant differences in phytoplankton communities between melt ponds and open water might be due to the salinity difference.Moreover,green algae may play a more important role in Arctic sea ice ecosystems with the expected growing number of melt ponds in the central Arctic Ocean.  相似文献   

Selective feeding of bay scallop Argopecten irradians on phytoplankton community revealed by HPLC analysis of phytopigments in Bohai Sea,China     

JIANG Tao  WANG Longhua  ZHANG Fuchong  FANG Xiao  LU Lin  ZHANG Jihong  WANG Wei  QU Keming  CHAI Chao 《海洋湖沼学报（英文）》2019,(5):1746-1755

Understanding the feeding selectivity on phytoplankton by shellfi sh is currently a big challenge. In order to investigate the feeding behavior of bay scallop ( Argopecten irradians ) on phytoplankton, we compared its compositions of phytopigments in digestive glands with those in the surrounding seawater, and conducted fi ve consecutive investigations between July and November 2016 in a bay scallop culture area along coast of Qinghuangdao City, northwest of the Bohai Sea, China. Phytopigments in four-size fractionated phytoplankton of seawater (micro-(20-200 μm);nano(L)-[10-20 μm];nano(S)-[2.7-10 μm], and pico-[<2.7 μm]) and digestive glands of A . irradians were examined to investigate the selective feeding of A . irradians . Results show that fucoxanthin and peridinin constituted the major part of taxonomically diagnostic carotenoids (TDCs) in the micro- and nano(L)-phytoplankton in seawater. Compared with total phytoplankton biomass of seawater (TPB, sum of the four sizes), a substantial decrease of fucoxanthin proportion to total DCs in digestive glands was observed while that of peridinin, 19′-butanoyloxyfucoxanthin, alloxanthin and 19′-hexanoyloxy-fucoxanthin showed an obvious increase when those pigments were mainly confi ned to micro-sized phytoplankton (20-200 μm). However, zeaxanthin and prasinoxanthin were mainly confi ned to nano(s)- and pico-phytoplankton, of which the proportions in digestive glands were usually lower in TPB. The contribution of lutein to total DCs in digestive glands (with an average of 7.23%) increased compared with TPB of seawater (with an average of 0.63%) during all fi ve sampling times.  相似文献   

不同紫外波段对中肋骨条藻光合生理特性的影响     

朱镕军  高嘉钰  吴亚平  徐军田 《海洋科学》2020,44(11):45-51

人类活动导致臭氧层变薄和混合层变浅,迫使混合层的浮游植物暴露在更高的紫外辐射下。实验以中肋骨条藻（Skeletonema costatum）为研究对象,在自然光照条件下,通过在暗盒上方覆盖不同的截止型滤光板,获得不同波段紫外辐射,探讨不同紫外波段对其生理特性的影响。本实验通过在室外培养,模拟赤潮爆发状态,对中肋骨条藻进行7种不同紫外波段的处理（分别使用280、300、320、340、360、380、400 nm截止型滤光板）。实验结果表明：紫外辐射会显著抑制中肋骨条藻的光合固碳速率,随着紫外波段逐步被滤除,光合固碳速率越来越高;>280 nm和>300 nm波段下的比生长率显著低于>400 nm波段处理;280 nm~300 nm波段紫外对叶绿素a有显著的漂白效应,同时也会显著减少类胡萝卜素的含量;这表明紫外辐射对中肋骨条藻的抑制效应主要是紫外辐射B导致的,而紫外辐射A的作用不显著。在估测浮游植物海洋初级生产力的过程中,紫外辐射的作用往往被忽视。  相似文献   

Distribution and vertical dynamics of planktonic communities at Sofala Bank, Mozambique     

M.C. Leal  C. S  S. Nordez  V. Brotas  J. Paula 《Estuarine, Coastal and Shelf Science》2009,84(4):605-616

Coastal ecosystem processes are largely influenced by the interaction of different factors operating at various temporal and spatial scales, specifically those responsible for primary production patterns that modulate zooplankton and subsequent trophic levels. Hydrological processes, such as tidal cycles and coastal currents, nutrients availability, phytoplankton groups (studied through algal pigment signatures analysed by HPLC), and zooplankton abundance and distribution were investigated at the Sofala Bank (Mozambique), with special emphasis on their horizontal distribution and vertical dynamics (48 h). Horizontal distribution has shown inshore–offshore gradients in all analysed parameters, as well as inshore waters intrusion probably related to Zambezi River delta runoff. Tidal currents were responsible for major hydrological vertical variations and for horizontal and vertical advection of phytoplankton biomass in the surface and deepest layers, respectively. Nutrient concentrations were typical from oligotrophic regions, and nutrient ratios were strongly influenced by depleted nitrate + nitrite concentrations, indicating low estuarine discharges typical from the dry season. The very low N:P ratio obtained suggests strong nitrogen limitation to phytoplankton communities, supporting the low phytoplankton abundance observed. Both phytoplankton pigments and zooplankton were found mainly near the bottom (40 m depth), despite the latter displayed vertical migrations triggered by light variations. Phytoplankton community was dominated by microflagellates, specifically prymnesiophyceans, and behaved as a whole, except Cyanobacteria that displayed vertical distribution movements different from other phytoplankton groups, being mainly concentrated at mid-water column depths (10–20 m). This investigation enhances physico-chemical phenomena and their importance determining the planktonic communities vertical dynamics at Sofala Bank, a tropical coastal ecosystem of the Western Indian Ocean where planktonic dynamics are still poorly described and understood.  相似文献   

Characteristics of phytoplankton community structure during and after a bloom of the dinoflagellate Scrippsiella trochoidea by HPLC pigment analysis     

Chun-kwan Wong  Chong-kim Wong 《中国海洋大学学报(英文版)》2009,8(2):141-149

A bloom of the dinoflagellate Scrippsiella trochoidea was detected for the first time in inner Tolo Harbor, Hong Kong in 2 000. Water samples were collected at eight stations along a transect passing through a red tide patch for microscopic analysis of phytoplankton composition and high-performance liquid chromatography (HPLC) analysis of phytoplankton pigments. During the bloom, the density of dinoflagellates was 1.1×10⁶ cells L⁻¹ within the patch and 8.6×10⁵ cells L⁻¹ outside the patch where the phytoplankton community was dominated by diatoms. After the bloom the S. trochoidea began to decrease in density and was replaced by diatoms as the dominating bloom-causing organisms at all stations, and the density of dinoflagellates at most stations was less than 1.0 × 10⁶ cells L⁻¹. The status of S. trochoidea as the causative species of the bloom was indicated by the presence of peridinin, the marker pigment for dinoflagellates. The shift from dinoflagellates to diatoms was marked by the decline of peridinin and the prevalence of fucoxanthin. Phytoplankton pigment markers also revealed the presence of other minor phytoplankton assemblages such as cryptomonads and blue-green algal.  相似文献