春季海州湾临洪河口浮游植物粒级结构及环境因素

2017年4月作者对海州湾临洪河口海域16个站位的常规理化因子以及浮游植物粒级结构进行了采样和分析,结果表明:调查海域盐度和温度均值分别为35.2和11.2℃,均由近岸到外海逐渐增大;悬浮物质量浓度在3.4 mg/L～137.6 mg/L变化,均值为22.8 mg/L,由近岸到外海逐渐减少,水体逐渐清澈; pH均值为8.29,近岸低,外海高; DO均值为9.8 mg/L, COD在0.34 mg/L～6.55 mg/L变化,均值为3.42mg/L,DO和COD分布规律不明显;浮游植物粒级组成以微型与小型浮游植物为主,其叶绿素a质量浓度平均值与范围分别为1.48μg/L(0.68μg/L～3.13μg/L)、9.14μg/L(2.69μg/L～25.50μg/L),且呈现自沿岸河口向外海逐渐递减的趋势;而微微型浮游植物叶绿素a质量浓度平均值仅为0.27μg/L,且分布较不规律;小型浮游植物对浮游植物总生物量的贡献率最大,高达83.89%,微型及微微型浮游植物的贡献率分别为13.60%和2.52%;在相关性分析中,各项环境因子对小型浮游植物的分布有较大的影响,其中悬浮物、pH与小型浮游植物叶绿素a浓度表现出显著相关(P0.05),溶解氧、盐度与小型浮游植物叶绿素a质量浓度呈极显著相关(P0.01),微型、微微型浮游植物的分布与各项环境因子的相关性不明显。     

广东沿岸不同海洋功能区秋季浮游植物群落结构比较研究

2003年10月对广东沿岸浮游植物群落结构及相关环境因子进行了调查。设调查站位39个,根据营养盐数据分析表明,珠江对于陆源营养物质输入南海起着重要作用,其营养盐浓度明显高于广东沿岸其它海区。海域浮游植物隶属于62属118种(含变种和变型),其中硅藻门38属83种、甲藻门16属25种、蓝藻门3属4种、绿藻门2属2种、金藻门2属2种及针胞藻纲1属2种,硅藻在种类和生物量上均占主导地位。叶绿素a含量变化较大,测值范围为0.157～18.761mg/m3,最大值出现在珠江口水域GD089站。浮游植物的粒级结构存在明显的地域特点,珠江口及其毗邻海域以微型浮游植物为主,其他海域基本以小型浮游植物为主。     

Long-term abundance patterns of macroalgae in relation to environmental variables in the Tagus Estuary (Portugal)

Seasonal and inter-annual patterns of macroalgal abundance in a Tagus Estuary oyster reef are described. Macroalgal abundance was estimated as canopy percent cover by three permanent point intercept transects over a 7-year period. Four categories were defined, corresponding to bare substrate and three different macroalgal functional-form groups: (1) ULVA, foliose group, included Ulva spp.; (2) GRACIL, terete corticated macrophyte group, included only Gracilaria gracilis; and (3) FILAM, small (<10 cm) filamentous group, including eight species. A canonical correspondence analysis (CCA) showed that: (1) ULVA were associated with long and hot days, being usually dominant during spring and especially summer; (2) FILAM were associated with mild temperatures and relatively long days, abundant in spring but showed frequent peaks in summer; and (3) GRACIL were also favoured by spring season, although associated to lower temperature and less daylight hours than FILAM. GRACIL and FILAM were present throughout the year. On the contrary, ULVA were absent or with low cover during colder periods. A negative correlation between GRACIL and FILAM seems to indicate competition between the two categories. The applied models explained 23.3% of the temporal variance in category abundance. Rainfall negatively affected macroalgal cover, as indicated by the positive correlation between rainfall and bare substrate. Our conclusions are in agreement with previous studies that consider algae as excellent environmental integrators, even on a small scale, due to a strong link between the macroalgal communities and relevant environmental variables. It is also relevant that this study used open-access databases of environmental variables, which open up new possibilities for mining existing data resources in new ways. Due to large inter-annual variability, long-term studies are essential to understand population dynamics in estuarine phytobenthic communities.     

2009 年夏季南海北部的浮游植物群落

根据2009 年8 月份对南海北部(18°～22°N, 110°～117°E)水域22 个采水站位的调查, 分析夏季调查区浮游植物的群落结构特征。通过Uterm?hl 方法共鉴定出浮游植物5 门60 属109 种(不包括未定种),群落组成以硅藻为主, 其次是甲藻。浮游植物生态类群以广温广布型种为主, 调查区的优势种为柔弱伪菱形藻Pseudo-nitzschia delicatissma, 菱形海线藻Thalassionema nitzschioides, 颗粒直链藻Melosiragrannulata, 尖刺伪菱形藻Pseudo-nitzschia pungens, 矮小短棘藻Detonula pumila, 原多甲藻Protoperidinium sp., 以及冰河拟星杆藻Asterionopsis glacialis。调查区细胞丰度介于0.009×10³个/L到249.930×10³个/L, 平均8.197×10³个/L。南海北部表层浮游植物细胞丰度由近岸向外海逐渐降低,高值区位于珠江口附近以及南部水域, 甲藻在广东沿岸附近出现高值。调查区浮游植物丰度在垂直方向随着水深的增加而递减。Shannon-Wiener 多样性指数和Pielou 均匀度指数在珠江口南部和广东沿岸站位出现低值区, 群落结构稳定性较差。     

石狮东部近岸海域浮游植物群落结构及其与环境因子的关系

根据2018年春、秋两季在石狮东部近岸海域进行调查所获得的数据,研究了该海域浮游植物的群落结构,并对浮游植物群落与环境因子的关系进行了相关性分析。通过春、秋两季的调查,经初步鉴定,共145种浮游植物,隶属于3门51属,种类以硅藻为主,其中硅藻122种,甲藻21种,蓝藻2种。在春季的调查中,优势种有奇异棍形藻(Bacillaria paradoxa)、密连角毛藻(Chaetoceros densus)等7种,秋季的优势种有中肋骨条藻(Skeletonema costatum)、琼氏圆筛藻(Coscinodiscus jonesianus)等5种。浮游植物细胞密度在1.81×10~4～410.65×10~4cells/m~3之间,春季明显高于秋季。春季多样性指数(H')平均值为3.24,秋季为3.31。相关性分析结果表明,影响石狮东部近岸海域浮游植物群落的主要环境因子有水温、盐度、无机氮含量和活性磷酸盐含量。     

Prey consumption by the juvenile soles, Solea solea and Solea senegalensis, in the Tagus estuary,Portugal

The soles Solea solea and Solea senegalensis are marine flatfish that use coastal and estuarine nursery grounds, which generally present high food availability, refuge from predators and favourable conditions for rapid growth. Two important nursery grounds for these species juveniles have been identified in the Tagus estuary, one in the upper part of the estuary (nursery A) and another in the south bank (nursery B). While S. solea is only present at the uppermost nursery area, S. senegalensis is present at both nurseries. Although they are among the most important predators in these nursery grounds, there are no estimates on their food consumption or on the carrying capacity of the system for soles. The Elliott and Persson [1978. The estimation of daily rates of food consumption for fish. Journal of Animal Ecology 47, 977–993] model was used to estimate food consumption of both species juveniles in both nursery areas, taking into account gastric evacuation rates (previously determined) and 24 h sampling surveys, based on beam-trawl catches carried out every 3 h, in the summer of 1995. Monthly beam trawls were performed to determine sole densities over the summer. Density estimates and daily food consumption values were used to calculate total consumption over the summer period. Sediment samples were taken for the estimation of prey densities and total biomass in the nursery areas. Daily food consumption was lower for S. solea (0.030 g wet weight d⁻¹) than for S. senegalensis (0.075 g wet weight d⁻¹). It was concluded that thermal stress may be an important factor hindering S. solea's food consumption in the warmer months. Total consumption of S. solea over the summer (90 days) was estimated to be 97 kg (wet weight). Solea senegalensis total consumption in nursery A was estimated to be 103 kg, while in nursery B it was 528 kg. Total prey biomass estimated for nursery A was 300 tonnes, while for nursery B it was 58 tonnes. This suggests that food is not a limiting factor for sole in the Tagus estuary. However it was concluded that more in-depth studies into the food consumption of other species and prey availability are needed in order to determine the carrying capacity of this system for sole juveniles.     

2006年秋季长江口及其邻近水域浮游植物群集

根据2006年11月在长江口及其邻近水域(30°30′N～32°30′N,121°E～123°30′E)39个测站采集的浮游植物水样研究了该水域浮游植物群集特征。调查区浮游植物以硅藻和甲藻为主,此外还有少量的金藻、蓝藻和绿藻。浮游植物细胞丰度介于0.13～59.69个/mL之间,平均为4.39个/mL,主要优势物种为圆海链藻Thalassiosira rotula和骨条藻Skeletonema spp.,调查区两个细胞丰度密集区分别出现在靠近口门以及外海水域。浮游植物细胞在20m层出现最大值。调查区两个典型断面的浮游植物分布特征分别由骨条藻和圆海链藻所刻画。固氮蓝藻铁氏束毛藻Trichodesmium thiebautii主要出现在调查区东部水域表层。根据浮游植物物种和细胞丰度进行聚类分析后,发现存在调查区东部与近岸2个浮游植物分区。     

Understanding spatial and temporal dynamics of key environmental characteristics in a mesotidal Atlantic estuary (Douro,NW Portugal)

Ecosystem management and decision making process are dependent of a good knowledge of ecosystem functioning. Conceptual models allow knowledge organization through representation of relationships between variables and processes, facilitating management decisions. In this study, spatial and temporal characterization of key environmental variables, as well as relationships between them, was studied aiming the design of a conceptual model of the Douro estuary. This temperate mesotidal estuary is limited upstream by a hydroelectric power dam that controls freshwater inflow and prevents the propagation of the tide upstream, which, in turn, influences water circulation and biogeochemical dynamics of the system. During one year, from December 2002 to December 2003, water column data were collected monthly at 10 stations along the estuary, during ebb and flood tides. Spatial and temporal variability of water column salinity, temperature, nutrients, phytoplankton biomass, total particulate matter (TPM), phytoplankton primary production (PP), faecal coliform bacteria (FC) and community respiration (CR) were analysed. Salinity stratification was assessed by means of the Estuary Number (Ne) and variation of this index as well as other key characteristics with river flow was analysed. Freshwater discharge controlled salinity stratification and freshwater residence time. Ne indicated that the Douro was stratified for river flows <300 m³ s⁻¹, and freshwater residence time was >1 day for the same conditions. A decaying exponential relationship between PP and river flow was found, whereas nitrate and TPM increased logarithmically and linearly, respectively, with river flow. Regarding spatial distribution, nitrate and PP decreased downstream, showing that the river was a source of nutrients and phytoplankton, while the opposite trend was found for TPM, FC, ammonium and CR. The latter increase was probably due to untreated sewage discharge in the urbanized middle and lower estuarine stretches. Reduction of nitrate coming from the watershed and of bacterial contamination in the urban stretches of this highly modified water body, according to the European Water Framework Directive, emerges as the main water quality issues for this estuarine ecosystem.     

Phytoplankton in the Beaufort and Chukchi Seas: Distribution, dynamics, and environmental forcing

Time-series of remotely sensed distributions of phytoplankton, sea ice, surface temperature, albedo, and clouds were examined to evaluate the variability of environmental conditions and physical forcing affecting phytoplankton in the Beaufort and Chukchi Seas. Large-scale distributions of these parameters were studied for the first time using weekly and monthly composites from April 1998 to September 2002. The basic data set used in this study are phytoplankton pigment concentrations derived from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), ice concentrations obtained from the Special Sensor Microwave Imager (SSM/I) and surface temperature, cloud cover, and albedo derived from the Advanced Very High Resolution Radiometer (AVHRR). Seasonal variation of ice cover was observed to be the dominant environmental factor as the ice-edge blooms followed the retreating marginal ice zones northward. Blooms were most prominent in the southwestern Chukchi Sea, and were especially persistent immediately north of the Bering Strait in nutrient-rich Anadyr Water and in some fronts. Chlorophyll concentrations are shown to increase from a nominal value during the onset of melt in April to a maximum value in mid-spring or summer depending on location. Large interannual variability of ice cover and phytoplankton distributions was observed with the year 1998 being uniquely associated with an early season occurrence of a massive bloom. This is postulated to be caused in part by a rapid response of phytoplankton to an early retreat of the sea-ice cover in the Beaufort Sea region. Correlation analyses showed relatively high negative correlation between chlorophyll and ice concentration with the correlation being highest in May, the correlation coefficient being −0.45. 1998 was also the warmest in the 5 years globally and the sea-ice cover was least extensive in the Beaufort/Chukchi Sea region, partly because of the 1997–1998 El Niño. Strong correlations were noted between ice extent and surface temperature, the correlation coefficient being highest at −0.79 in April, during the onset of the bloom period.     

2014年春季渤海浮游植物群落结构

基于2014年春季在渤海进行的水文、化学和生物方面的综合大面调查,研究了渤海浮游植物群落的结构特征,并结合文献资料,分析影响浮游植物群落结构形成的原因。结果显示：2014年渤海春季共鉴定浮游植物3门29属50种,以硅藻为主,还有少数甲藻和金藻。其中,硅藻门中圆筛藻属的种类最多,共12种,其次为角毛藻属,共5种。浮游植物总细胞丰度介于1.08×10⁴~181.09×10⁴个/m³,平均为25.47×10⁴个/m³。硅藻与甲藻细胞丰度比值为12：1,硅藻在物种数量和细胞丰度上均占有绝对优势,为渤海浮游植物的主要类群。浮游植物优势种主要为密联角毛藻（Chaetoceros densus）、斯氏几内亚藻（Guinardia striata）、具槽帕拉藻（Paralia sulcata）和夜光藻（Noctiluca scintillans）。渤海春季浮游植物群落多样性水平较低,且分布不均。渤海中部和渤海海峡海域由于单一优势种过量繁殖导致群落稳定性较差。与历史同期资料对比,渤海海域浮游植物群落出现明显的物种演替现象,角毛藻的优势地位显著性下降,斯氏几内亚藻首次在渤海大面调查中被记录为优势种。本研究为今后渤海环境生态系统和渔业资源变动的研究提供重要基础资料和参考依据。     

珠江口及邻近水域鱼类群落结构研究

根据1986～1987年珠江口及邻近水域底拖网鱼类采样资料,运用系统聚类与排序等多元分析方法和群落多样性指数,研究该水域鱼类群落结构及其与环境因素的关系,分析结果把该水域鱼类划分为淡水、河口和沿岸3个群落,分别位于莲花山,虎门河道、珠江河口伶仃洋和珠江口浅海水域,各群落结构组成呈沿盐度梯度而成带分布的格局.淡水群落结构简单稳定,沿岸群落结构比较复杂,河口群落受水动力过程和生物活动影响最大,群落结构的季节变化较为显着.     

2010年秋季南海北部浮游植物群落结构研究

2010年10月26日-11月24日在南海北部进行了浮游植物群落结构的调查,共鉴定浮游植物4门70属204种(包括未定种12种),浮游植物以硅藻为主,其物种数为146种,其细胞丰度占总浮游植物细胞丰度的93.17%;甲藻次之,其物种数为51种,占总浮游植物细胞丰度的0.63%;金藻门3属4种及蓝藻门2属3种;蓝藻门中以红海束毛藻(Trichodesmium erythraeum)为主。调查区浮游植物的细胞丰度介于0.06×103~107.50×103 cells/L之间,平均值为5.00×103 cells/L。海南岛东北部和粤东近岸表层浮游植物丰度较高。垂直分布上,表层和25 m层的浮游植物细胞丰度较高。浮游植物主要优势种类有菱形海线藻(Thalassionema nitzschioides)、舟形藻(Navicula spp.)、中肋骨条藻(Skeletonema costatum)、旋链角毛藻(Chaetoceros curvisetus)、斯氏几内亚藻(Guinardia stolterforthii)、具槽帕拉藻(Paralia sulcata)等。调查区表层和5 m层Shannon-Wiener多样性指数平均值分别为3.14和2.83,Pielou均匀度指数平均值分别为0.73和0.77;两种指数在表层和5 m层均表现出较高的一致性。环境分析表明除硅酸盐外,浮游植物细胞丰度与其他环境因子均呈极显著性的相关性,主要受到氮元素及磷酸盐的共同限制作用。     

2014年夏季南海北部浮游植物群落结构

2014年8月20日-9月6日对南海北部(18°~22°N,114°~116°E)的11个站位进行了浮游植物群落结构的调查,其中2个站位为时间连续站。共鉴定出浮游植物4门68属229种(包括变种、变型及未定种),其中硅藻门43属147种,甲藻门20属75种。浮游植物平均细胞丰度为16.318×103 cells/L,硅藻的平均细胞丰度为14.653×103 cells/L,占总丰度的89.80%,硅藻的分布决定了浮游植物的分布。近岸冲淡水含有丰富的营养盐,因此近岸海域的细胞丰度高于大洋海域,垂直分布表现出先增加后降低的趋势。本次调查的优势种为铁氏束毛藻(Trichodesmium thiebautii)、中肋骨条藻(Skeletonema costatum)、拟脆杆藻(Fragilariopsis sp.)、短孢角毛藻(Chaetoceros brevis)、菱形海线藻(Thalassionema nitzschioides)、柔弱伪菱形藻(Pseudo-nitzschia delicatissima)、尖刺伪菱形藻(Pseudo-nitzschia pungens)、扁面角毛藻(Chaetoceros compressus)、洛氏角毛藻(Chaetoceros lorenzianus)以及海洋角毛藻(Chaetoceros pelagicus),各优势种的分布趋势相似,呈现出近岸高于外海的趋势。Shannon-Weiner多样性指数与Pielou均匀度指数的平均值分别为2.37和0.56。浮游植物昼夜垂直变化明显。典范对应分析结果显示浮游植物空间分布主要受总氮盐、硅酸盐、微型浮游动物与盐度的影响。根据细胞丰度进行的站位的聚类分析显示浮游植物群落明显可划分为近岸群聚与大洋群聚。     

九龙江口红树林保护区水体浮游植物群落结构及营养状态评价

于2016年1月(冬季)、4月(春季)、7月(夏季)以及10月(秋季)对九龙江口红树林保护区的浮游植物多样性组成及其时空变化进行研究.结果表明,福建九龙江口红树林保护区共采集到浮游植物5门91属138种,其中硅藻占50.00%、绿藻占31.16%、蓝藻占8.70%、甲藻和裸藻各占5.07%.主要优势种为具槽直链藻(Melosira sulcata)、中肋骨条藻(Skeletonema costatum)、条纹小环藻(Cyclotella stratia)、舟形藻(Navicula sp.)、粗针杆藻(Synedra robusta)和菱形藻(Nitzschia sp.);浮游植物细胞数量在0.82×105~4.55×105个/dm3之间,年平均数量为1.97×105个/dm3.浮游植物种类时空变化明显,而数量的空间变化较大,季节变化不太明显.Shanno-Wiener指数、Margalef丰富度指数和Pielou均匀度指数变化范围分别为2.10~3.55、1.05~3.61、0.78~0.95.多样性指数及浮游植物生物量评价结果显示,九龙江口红树林保护区的水体为中营养状态,水质较好,但仍应加强对陆源径流和养殖废水排放进入红树林的控制和管理.     

2007年春季南海西北部陆架区海域浮游植物的群落结构

据2007年春季在南海西北部陆架区海域进行的网采浮游植物调查数据,分析了浮游植物群落的结构特征．此次共鉴定出浮游植物4门318种,其中硅藻类183种,甲藻类128种,蓝藻类5种,金藻类2种．大部分海域浮游植物种类数在40～70种之间,外海区域的种类数稍高于沿岸．浮游植物密度的变化范围为0．22×10。～3683．85×10。eells／m’,平均值（标准偏差）为97．49×10。（±437．38×10。）cel｜s／m。．其高值区主要位于粤西近岸海域,向外海呈递减趋势．调查海域硅藻类的平均密度（标准偏差）最高,为93．82×10。（±434．34×10。）cells／m’;甲藻类的次之,为3．65×10。（±9．08×10。）cells／m’．浮游植物优势种主要有拟旋链角毛藻（Chaetocerospseudocurvisetus）、细弱海链藻（Thalassiosirasubtilis）、中肋骨条藻（Skeletonemacostatum）、劳氏角毛藻（Chaetocerosloren—zianus）和菱形海线藻（Thalassionemanitzschioides）．该调查海域浮游植物多样性指数的变化范围为1．48～6．23,平均值（标准偏差）为4．70（±1．03）,其分布趋势与浮游植物密度的分布趋势大致相反．将站位依等深线划分为粤西近岸海区、琼东南近岸海区和外海海区,应用非度量多维标度（nMDS）和聚类分析法分析这3个海区的浮游植物群落结构差异,并通过ANOSIM和SIMPER进行检验．结果表明3个海区之间浮游植物群落结构具有显著性差异,且粤西近岸海区与外海海区之间差异性较高．近岸种拟旋链角毛藻和中肋骨条藻在粤西近岸海区为最主要的优势种,而外海海区优势种较多,且大部分为大洋暖水性种类．     

A comparative study of mercury contamination in the Tagus estuary (Portugal) and major French estuaries (Gironde,Loire, Rhône)

Concentrations of mercury were determined for the waters, suspended matter and sediments of the Tagus and of major French estuaries.The Tagus estuary is one of the most contaminated by mercury derived from the outfalls of a chloralkali plant and from other industrial sources. In deposited sediments the median level, 1·0 μg Hg g^?1, is twenty times higher than the natural background and Hg contents depend on the sediment grain-size, age and the distance from waste-outfalls. Suspended matter is more regularly and highly contaminated (median value: 4·5 μg Hg g^?1). In the French estuaries Hg levels in the suspended material decrease with salinity due to dilution and/or remobilization processes. In June 1982, in the Loire estuary, high values of Hg are observed in the middle estuary and attributed to urban and industrial sources.In the Tagus estuary, the general distribution of total dissolved Hg confirms the contamination: it increases seaward from 10 ng 1^?1 in the river to 80 ng 1^?1 in the estuary outlet. The dissolved Hg is almost totally organic in the river, inorganic in the middle estuary due to inorganic Hg effluents and again organic in the lower estuary. This variation is related to the dissolved organic carbon values. The dissolved Hg levels in the Loire Estuary (5–300 ng 1^?1) are much higher than in the Gironde estuary (3–6 ng 1^?1) and of the same order as those observed in the Tagus estuary.     

Parallel structure among environmental gradients and three trophic levels in a subarctic estuary

We assessed spatial and temporal variability in the physical environment of a subarctic estuary, and examined concurrent patterns of chlorophyll α abundance (fluorescence), and zooplankton and forage fish community structure. Surveys were conducted in lower Cook Inlet, Alaska, during late July and early August from 1997 through 1999. Principle components analysis (PCA) revealed that spatial heterogeneity in the physical oceanographic environment of lower Cook Inlet could be modeled as three marine-estuarine gradients characterized by temperature, salinity, bottom depth, and turbidity. The gradients persisted from 1997 through 1999, and PCA explained 68% to 92% of the variance in physical oceanography for each gradient-year combination. Correlations between chlorophyll α abundance and distribution and the PCA axes were weak. Chlorophyll was reduced by turbidity, and low levels occurred in areas with high levels of suspended sediments. Detrended correspondence analysis (DCA) was used to order the sample sites based on species composition and to order the zooplankton and forage fish taxa based on similarities among sample sites for each gradient-year. Correlations between the structure of the physical environment (PCA axis 1) and zooplankton community structure (DCA axis 1) were strong (r = 0.43-0.86) in all years for the three marine-estuarine gradients, suggesting that zooplankton community composition was structured by the physical environment. The physical environment (PCA) and forage fish community structure (DCA) were weakly correlated in all years along Gradient 2, defined by halocline intensity and surface temperature and salinity, even though these physical variables were more important for defining zooplankton habitats. However, the physical environment (PCA) and forage fish community structure (DCA) were strongly correlated along the primary marine-estuarine gradient (#1) in 1997 (r = 0.87) and 1998 (r = 0.82). The correlation was poor (r = 0.32) in 1999, when fish community structure changed markedly in lower Cook Inlet. Capelin (Mallotus villosus), walleye pollock (Theragra chalcogramma), and arrowtooth flounder (Atheresthes stomias) were caught farther north than in previous years. Waters were significantly colder and more saline in 1999, a La Niña year, than in other years of the study. Interannual fluctuations in environmental conditions in lower Cook Inlet did not have substantial effects on zooplankton community structure, although abundance of individual taxa varied significantly. The abundance and distribution of chlorophyll α, zooplankton and forage fish were affected much more by spatial variability in physical oceanography than by interannual variability. Our examination of physical-biological linkages in lower Cook Inlet supports the concept of “bottom-up control,” i.e., that variability in the physical environment structures higher trophic-level communities by influencing their distribution and abundance across space.     

Zooplankton community structure in a highly turbid environment (Charente estuary,France): Spatio-temporal patterns and environmental control

Zooplankton assemblages were studied from January 2007 to January 2008 along the salinity gradient of the Charente estuary (France). A Lagrangian survey was performed monthly at five sampling stations defined by salinity (freshwater, 0.5, 5, 15 and 25) in order to collect zooplankton and measure the main environmental parameters (concentrations of suspended particulate matter, particulate organic carbon, chlorophyll a and phaeopigments). A combination of multivariate cluster analysis, species indicator index and canonical correspondence analysis was used to relate the spatio-temporal patterns of the zooplankton assemblages with environmental drivers. The estuary was divided into three different zones by means of environmental parameters while four zooplankton assemblages were identified along the salinity gradient. The Charente estuary appeared as one of the most turbid systems in Europe, with suspended particulate matter (SPM) concentration reaching 3.5 g l⁻¹ in the Maximum Turbidity Zone (MTZ). Algal heterotrophy and microphytobenthos resuspension from the wide mudflats could be responsible for the relatively high chlorophyll a concentrations measured within this MTZ. Salinity and SPM affected significantly the spatial distribution of zooplankton species while temperature and river flow seemed to control their temporal variations. From a zooplanktonic viewpoint, the highly turbid Charente estuary seemed to match an “ecotone–ecocline” model: the succession of species assemblages along the salinity gradient matched the concept of ecocline while the MTZ, which is a stressful narrow area, could be considered as an ecotone. Although such ecoclinal characteristics seemed to be a general feature of estuarine biocenoses, the ecotone could be more system-specific and biological compartment-specific.     

春季东海近岸表层浮游植物群落结构及其与环境因子的关系

采用HPLC-CHEMTAX方法分析了2008年春季东海近岸海域的表层浮游植物群落结构及其与环境因子的关系。结果表明,调查区表层浮游植物优势类群为硅藻和甲藻,对叶绿素a的平均贡献率分别为42%和32%。硅藻和甲藻均适于生长在低温、低盐和高氮磷比的环境,但硅藻水华发生在温度较低、盐度较高、氮磷比较高的长江冲淡水与外海水交汇的盐度锋面上,而甲藻水华发生在温度较高、盐度较低、氮磷比较低的冲淡水与台湾暖流交汇的温度锋面上。LOWESS回归表明,叶绿素a和甲藻分别随温度和盐度升高呈先增后降的趋势,硅藻随温度和盐度变化波动较大。叶绿素a和硅藻随氮磷比升高而递增,甲藻随氮磷比的变化波动较大。