Phytoplankton community characteristics in the coastal waters of the southeastern Arabian Sea

Remote sensing applications are important in the fisheries sector and efforts were on to improve the predictions of potential fishing zones using ocean color. The present study was aimed to investigate the phytoplankton dynamics and their absorption properties in the coastal waters of the southeastern Arabian Sea in different seasons during the year 2010 to 2011. The region exhibited 73 genera of phytoplankton from 19 orders and 41 families. The numerical abundance of phytoplankton varied from 14.235×103 to 55.075×106 cells/L. Centric diatoms dominated in the region and the largest family identified was Thalassiosiraceae with main genera as Skeletonema spp., Planktionella spp. and Thalassiosira spp. Annual variations in abundance of phytoplankton showed a typical one-peak cycle, with the highest recorded during premonsoon season and the lowest during monsoon season. The species diversity index of phytoplankton exhibited low diversity during monsoon season. Phytoplankton with pigments Chlorophyll a, Chlorophyll b, Chlorophyll c, peridinin, diadinoxanthin, fucoxanthin, β-carotene and phycoerythrobilin dominated in these waters. The knowledge on phytoplankton dynamics in coastal waters of the southeastern Arabian Sea forms a key parameter in bio-optical models of pigments and productivity and for the interpretation of remotely sensed ocean color data.     

Methane in coastal and offshore waters of the Arabian Sea

Measurements of methane (CH₄) made during two surveys in the eastern and central Arabian Sea in April–May, 1996, and August–September, 1997, corresponding to late Spring Intermonsoon (SI) and Southwest Monsoon (SWM) seasons, respectively, revealed high spatial and temporal variability in surface saturation (110–2521%). The highest values were observed during the SWM in the inner shelf where coastal upwelling combined with freshwater runoff to produce very strong near-surface stratification. These values might result to a large extent from CH₄ inputs from coastal wetlands through seasonal runoff as abnormally high saturations (up to ∼13,000%) were recorded in the estuarine surface water. In situ production of CH₄, favoured by very high biological production in conjunction with the prevalence of suboxic conditions in the upwelled water, could be the other major CH₄ source. In comparison, sedimentary inputs of CH₄ seemed to be of lesser importance in spite of previously-reported occurrence of gas-charged sediments in this region.Methane profiles in the open central Arabian Sea showed two maxima. The more pronounced deeper maximum, occurring at 150–200 m depth, was similar to the feature seen elsewhere in the oceans, but was probably intensified here due to an acute oxygen deficiency. It showed some correlation with the subsurface particle maximum characteristic of the denitrifying layer. The dominant mechanism of its formation might be in situ production within particles rather than advection from the continental shelf as concluded by previous workers. The less pronounced and previously unreported shallower maximum, occurring in the well-oxygenated upper 50 m of the water column, was more dynamic probably as a result of variability of the balance between CH₄ production due to biological activity and its losses through microbial oxidation and air–sea exchange.     

东海西南近岸海域污损生物群落特征

于2013年12月~2014年11月在东海西南近岸海域进行污损生物周年挂板试验,全年共记录污损生物10门49科69属84种,群落组成以近岸暖水种为主,为典型的亚热带内湾型群落,附着盛期为4–9月,夏季污损生物的附着强度最高。固定生活类型的悬浮物食者是该近岸海域污损生物群落的附着主体,网纹藤壶（Amphibalanus reticulatus）是最主要的优势种和代表种,其它优势种还有长鳃麦杆虫（Caprella equilibra）、中胚花筒螅（Ectopleura crocea）、太平洋侧花海葵（Anthopleura nigrescens）、今岛柄涡虫（Stylochus ijimai）、克氏无襟毛虫（Spirobranchus kraussii）、近江牡蛎（Crassostrea rivularis）、翡翠贻贝（Perna viridis）、廉形叶钩虾（Jassa falcata）、强壮板钩虾（Stenothoe valida）、光辉圆扇蟹（Sphaerozius nitidus）和大室别藻苔虫（Biflustra grandicella）等。污损生物群落个体间因附着空间和食物竞争而存在着相互依存或互相制约的关系,又依照对环境因子的适应性而存在着一定的时空分布规律。温度是决定污损生物地理分布的最主要环境因素,物种的温度属性是不同气候带污损生物群落组成差异的本质体现,污损生物的种类数、附着期和附着量与水温有着密切的关系;另外,盐度、水流、光、水产养殖等自然环境或人为因素也是影响污损生物附着的重要影响因子。     

Hydrographical characteristics and oxygen isotopic signatures of water in a coastal environment (Mangalore) along the southeastern Arabian Sea

Coastal marine environments are important links between the continents and the open ocean. The coast off Mangalore forms part of the upwelling zone along the southeastern Arabian Sea. The temperature, salinity, density, dissolved oxygen and stable oxygen isotope ratio (δ¹⁸O) of surface waters as well as those of bottom waters off coastal Mangalore were studied every month from October 2010 to May 2011. The coastal waters were stratified in October and November due to precipitation and runoff. The region was characterised by upwelled bottom waters in October, whereas the region exhibited a temperature inversion in November. The surface and bottom waters presented almost uniform properties from December until April. The coastal waters were observed to be most dense in January and May. Comparatively cold and poorly oxygenated bottom waters during the May sampling indicated the onset of upwelling along the region. δ¹⁸O of the coastal waters successfully documented the observed variations in the hydrographical characteristics of the Mangalore coast during the monthly sampling period. We also noted that the monthly variability in the properties of the coastal waters of Mangalore was related to the hydrographical characteristics of the adjacent open ocean inferred from satellite-derived surface winds, sea surface height anomaly data and sea surface temperatures.     

Phytoplankton community structure in the Arabian Sea during and after the SW monsoon, 1994

Diatoms, dinoflagellates, coccolithophores, nanoflagellates, picophytoplankton and procaryote algae (Synechococcus spp. and prochlorophytes) were quantified by microscopy and flow cytometry, and their biomass determined, at 12 stations along a 1600 km transect across the Arabian Sea at the end of the SW monsoon in September, and during the inter-monsoon period of November/December 1994. The transect spanned contrasting oceanic conditions that varied from seasonally eutrophic, upwelling waters through mesotrophic, downwelling waters to permanently oligotrophic, stratified waters. The overall diversity of diatoms, dinoflagellates and coccolithophores along the transect was not significantly different between the SW monsoon and inter-monsoon. However, diatoms showed greatest diversity during the SW monsoon and coccolithophores were most diverse during the inter-monsoon. Integrated phytoplankton standing stocks during the SW monsoon ranged from 3 to 9 g C m^-2 in the upwelling eutrophic waters, from 3 to 5 g C m^-2 in downwelling waters, and from 1 to 2 g C m^-2 in oligotrophic waters. Similar phytoplankton standing stocks were found in oligotrophic waters during the inter-monsoon, but were ca. 40% lower compared to the SW monsoon in the more physically dynamic waters. Phytoplankton abundance and biomass was dominated by procaryote taxa. Synechococcus spp. were abundant (often >10⁸ cells l^-1) during both the SW monsoon and inter-monsoon, where the nitrate concentration was ⩾0.1 μ mol l^-1, and often dominated the phytoplankton standing stocks. Prochlorophytes were restricted to oligotrophic stratified waters during the SW monsoon period but were found at all stations along the transect during the inter-monsoon, dominating the phytoplankton standing stocks (>40%) in the oligotrophic region during this period. Of the nano- and micro-phytoplankton, only diatoms contributed significantly to phytoplankton standing stocks, and then only in near-shore upwelling waters during the SW monsoon. There were significant changes in the temporal composition of the phytoplankton community. In nearshore waters a mixed community of diatoms and Synechococcus spp. dominated during the SW monsoon. This gave way to a community dominated by Synechococcus spp. in the intermonsoon. In the downwelling zone, a Synechococcus spp. dominated community was replaced by a mixed procaryote community of Synechococcus spp. and prochlorophytes. In the oligotrophic stratified waters, the mix of procaryote algae was replaced by one dominated by prochlorophytes alone.     

阿拉伯海东南海域盐度收支的季节变化

采用SODA海洋同化产品的月平均资料,本文分析了阿拉伯海东南海域表层盐度的季节变化特征,发现局地海面淡水通量不能解释盐度的变化。两个典型区域的表层海水盐度收支分析表明,海洋的平流输送是造成阿拉伯海东南海域盐度冬季降低、夏季升高的主要原因,而淡水通量仅在夏季印度西侧沿岸区域造成盐度降低。冬季,东北季风环流将孟加拉湾北部的低盐水沿同纬度输送到阿拉伯海,然后向北输送,使表层海水盐度降低;夏季,西南季风环流把阿拉伯海西北部的高盐水向南、向东输送,使阿拉伯海东南海域盐度升高。受地理位置因素的影响,阿拉伯海东南海域表层盐度的变化冬季明显强于夏季。     

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。     

Assessing temporal variation of coloured dissolved organic matter in the coastal waters of South Eastern Arabian Sea

Coloured dissolved organic matter （CDOM） plays a major role in marine photochemical and biological processes and its optical properties are known to affect the underwater light penetration. This paper highlights in situ optical estimation and satellite retrieval of CDOM in deciphering its temporal variations in coastal waters of the South Eastern Arabian Sea. The study accentuated the source of CDOM as terrigenous origin during monsoon, of in situ productions during pre-monsoon and during post-monsoon of autochthonous-allocthonous origin. The matchup analysis for in situ and MODIS Aqua retrieved A_dg443 exhibited bias which decreased by incorporating the seasonal component. The study also identified degrading bloom of Noctiluca scintillans as the source for exceptionally high CDOM in the area during January and February. The study demands to incorporate seasonal components and phytoplankton abundance while assessing the performance of CDOM algorithms in optically complex coastal waters.     

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．     

2013年夏季北黄海浮游植物群集

利用Utermöhl方法,对2013年夏季取得的北黄海浮游植物样品进行鉴定分析,共鉴定出浮游植物3门60属114种(不包括未定名种),其中,硅藻42属75种,甲藻16属37种,金藻2属2种。群落组成以硅藻为主,其次是甲藻,然后是金藻。调查海区浮游植物的生态类型以温带近岸性为主,主要优势种为:小等刺硅鞭藻 Dictyocha fibula、裸甲藻 Gymnodinium sp.、螺旋环沟藻 Gyrodinium spirale、蜂腰双壁藻 Diploneis bombus 和具槽帕拉藻 Paralia sulcata。浮游植物细胞丰度介于0.037 0 × 10³ ～ 32.3 × 10³ cells·L^-1,平均值为2.04 × 10³ cells·L^-1;浮游植物细胞丰度大致从近岸到外海呈逐步降低趋势,在北黄海西部近岸的表层水体达到最高值32.3 × 10³ cells·L^-1,调查区东南部靠近外海区域也出现了丰度高值区;浮游植物垂直分布总体特征是随水深的增加而减少,由近岸向外海逐步降低。香农-威纳多样性指数在调查区西南部较高,而Pielou均匀度指数则在东部呈现高值区域。典范对应分析(CCA)显示,影响浮游植物优势种丰度分布的主要因素是营养盐,而跟盐度和温度的相关性不明显。     

Response of subsurface waters in the eastern Arabian Sea to tropical cyclones

Thermister chain data at different depths for June 1998 cyclone in the Arabian Sea at a location (69.2 E,15.5 N) which is about 60 km to the left of the cyclone track indicates subsurface warming below 60 m and inertial oscillations of temperature with a periodicity of about 2 days. The oscillations continued for ∼15 days even after the cyclone crossed the coast. The analysis of the buoy, DS1 located at the same position also suggests a stabilized southward flow after about two weeks of the cyclone crossed the coast. Analysis of the buoy data for May 1999 cyclone in the same region also indicates similar pattern. In order to investigate the effect of cyclone–ocean interaction and primarily to understand the process for the subsurface warming, 3-dimensional Princeton Ocean Model is configured for the eastern part of the Arabian Sea. The model uses high horizontal resolution of about 6 km near the coast and a terrain following sigma coordinate in the vertical with 26 levels. The study focuses on surface cooling and temperature rise in the underlying waters and explains its mechanism through upwelling and downwelling respectively. The simulations in concurrence with the observations suggest that the occurrence of subsurface warming precedes the surface cooling with a lag of ˜a day as the cyclone advances DS1. The simulations also demonstrate local temperature stratification plays an important role for cooling of the upper ocean and warming of the subsurface waters and extent of warming is directly related to the depth of the thermocline.     

Waves in the nearshore waters of northern Arabian Sea during the summer monsoon

Waves at 15 m water depth in the northern Arabian Sea are measured during the summer monsoon for a period of 45 days and the characteristics are described. The significant wave height varied from 1.1 to 4.5 m with an average value of 2.5 m. 75% of the wave height at the measurement location is due to the swells arriving from the south-west and the remaining is due to the seas from south-west to north-west. Wave age of the measured data indicates that the waves in the nearshore waters of northern Arabian Sea during the summer monsoon are swells with young sea.     

阿拉伯海淡水输运量的季节变化特征研究

本文利用简单海洋模式同化再分析产品等资料,阐述了阿拉伯海与赤道西印度洋,阿拉伯海与阿曼湾之间淡水输运量的季节变化特征,揭示了阿拉伯海淡水输运量的基本平衡和季节变化特征。结果表明,阿拉伯海得到的淡水输运量(包括来自赤道西印度洋、河流)和失去的淡水输运量(包括降水量减蒸发量、向阿曼湾输运)基本相当。阿拉伯海通过海气交换失去的淡水(降水量减蒸发量)主要由来自赤道西印度洋(包括孟加拉湾)的淡水输运来补偿,赤道西印度洋向阿拉伯海的淡水输运对维持阿拉伯海的盐度基本平衡起到至关重要的作用。阿拉伯海的淡水输运量在1?6月和12月为负值,失去淡水;7?11月为正值,9月最大,得到淡水。阿拉伯海的净淡水输运量的季节变化特征表现为单峰现象。阿拉伯海与赤道西印度洋(9°N断面）的淡水输运量主要出现在表层至约200 m层,多年平均约为0.1×106 m3/s,向阿拉伯海输运。从10月至翌年3月,来自孟加拉湾的低盐水向阿拉伯海输运,该输运主要出现在印度半岛西南端近海约60 m层以浅区域。夏季和秋季,出现在索马里半岛东部海域的涡旋(大回旋)引起的输运(涡旋的西部低盐水向北输运,东部高盐水向南输运),不仅输运量是一年当中最大的,而且影响的深度可达约300 m。该输运从6月开始形成,8?9月最强,11月迅速减弱。阿拉伯海与阿曼湾的淡水输运量较小,其垂直分布呈现3层结构,表层至10 m层,高盐水向阿拉伯海输运;15～170 m层,低盐水向阿曼湾输运;175～400 m层,高盐水向阿拉伯海输运。阿曼湾湾口断面多年平均淡水输运量约为0.39×104 m3/s,向阿曼湾输运。     

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。     

曹妃甸近岸海域网采浮游植物群落结构特征及其与环境因子的相关性研究

为了研究浮游植物群落结构特征及与环境因子的相关性,于2014年6月和9月在曹妃甸海域布设了14个调查站位,对该海域浮游植物的群落组成、细胞丰度及群落多样性等基本特征进行了分析,并采用多维尺度分析方法对曹妃甸浮游植物群落结构做区域划分,通过冗余分析(RDA)研究了环境因子对浮游植物群落结构的影响。研究结果表明:曹妃甸海域6月和9月共鉴定出浮游植物3门28属62种,硅藻为主,生态类型以温带近岸广温广盐性种为主。6月浮游植物细胞丰度平均值为111. 31×10~4cells/m~3,主要优势种为中肋骨条藻(Skeletonema costatum)和柔弱角毛藻(Chaetoceros debilis); 9月浮游植物细胞丰度平均值为163. 01×10~4cells/m~3,主要优势种为中肋骨条藻和细弱圆筛藻(Coscinodiscus subtilis)。站位聚类分析和多维尺度分析表明,曹妃甸浮游植物种类地区划分主要分为3个区域,分别为填海东侧和西侧海域、曹妃甸填海区附近海域以及曹妃甸中部远离填海区域,且6月和9月浮游植物群落组成差异不显著(R=-0. 997,p=0. 998,n=14)。RDA结果显示6月的盐度、溶解氧(C_(DO))、温度(T)和pH值及9月的C_(DO)、活性磷酸盐(C_(PO_4~(3-)-P))、无机氮浓度(C_(DIN))和T是依次影响各自月份浮游植物群落的主要环境因子。     

Phytoplankton growth and mortality during the 1995 Northeast Monsoon and Spring Intermonsoon in the Arabian Sea

Phytoplankton growth rates and mortality rates were experimentally examined at eight stations in the Arabian Sea along the U.S. JGOFS cruise track during the 1995 Northeast Monsoon (January) and Spring Intermonsoon (March–April). Instantaneous growth rates averaged over an entire cruise were approximately twice as high during the NE Monsoon than during the Spring Intermonsoon period (overall averages of 0.84±0.29 (s.d.) versus 0.44±0.19 d⁻¹). Average herbivore grazing (mortality) rates, however, were quite similar for the two seasons (overall averages of 0.35±0.18 and 0.30±0.17 d⁻¹ for the NE Monsoon and Spring Intermonsoon, respectively). The absolute amounts of phytoplankton biomass consumed during each season also were similar (29 and 25% of standing stock consumed d⁻¹ for the January and March–April cruises, respectively), as were the geographical trends of this removal. These seasonal trends in growth and removal rates resulted in net phytoplankton growth rates that were considerably higher during the January cruise (0.48 d⁻¹) than during the March–April cruise (0.14 d⁻¹). That is, phytoplankton production was more closely balanced during the Spring Intermonsoon season (87% of daily primary production consumed) relative to the NE Monsoon season (49% of daily primary production consumed). Station-to-station variability was high for rate measurements during either cruise. Nevertheless, there was a clear onshore–offshore trend in the absolute rate of removal of phytoplankton biomass (μg chlorophyll consumed l⁻¹ d⁻¹) during both cruises. Coastal stations had removal rates that were typically 2–4 times higher than removal rates at oceanic stations.     

On the variation in calcium content of the waters of Laccadives (Arabian Sea)

The concentration of calcium was determined in the samples collected from four stations in the Laccadive Sea and from two lagoons of Kavaratti and Minicoy atolls. The calcium/chlorinity ratio for the open ocean samples was found to be 0.02168 ± 0.000015 with an average calcium concentration of 424.9 mg kg^?1. A maximum in this ratio was observed at about 200 m depth, below the salinity maximum corresponding to Arabian Sea Surface Water mass. No increase in calcium concentration or in calcium/chlorinity ratio was observed down to 1500 m depth, thereby ruling out the possibility of any calcium carbonate dissolution at these depths. Samples from Kavaratti and Minicoy lagoons gave much lower values of the Ca/Cl ratio (0.02145 ± 0.000036 and 0.02142 ± 0.000046, respectively). These low values are apparently the result of calcium utilization by the coral reefs. Using the reduction in the calcium concentration inside the lagoon, in the absence of any chemical precipitation, the annual CaCO₃ production by reef flat and lagoon on Kavaratti Atoll has been estimated as 1 · 10⁷ kg. This gives an average gross production of 1.4 kg CaCO₃ per m² per yr.     

厦门海域鱼类群落分类学多样性的研究

根据厦门海域鱼类种类组成历史资料和调查资料,系统整理了厦门海域的鱼类总名录和现有名录,并应用分类学等级多样性指数和分类差异变异指数分析了厦门海域鱼类群落分类学多样性的时空变化。结果表明:厦门海域有记录鱼类共649种;现有鱼类有331种,隶属2纲22目90科181属,其中软骨鱼纲共5目9科9属15种,辐鳍鱼纲共17目81科172属316种。厦门海域鱼类总名录的等级多样性指数Δ+和分类差异变异指数Λ+分别为79.267和220.96;现有鱼类群落分类多样性指数Δ+和分类差异指数Λ+分别为77.504和245.34。分类多样性指数Δ+在冬、春季较高,秋季次之,而夏季最低;而分类差异指数Λ+夏季较高,秋季次之,冬春季较低。秋季和冬季鱼类组成的相似度最高,其次为夏季,最后为春季。与历史总名录相比,厦门海域的现有鱼类群落分类学范围较小,生态幅变窄,群落稳定性较差。     

渤海浮游植物群落结构及与环境因子的相关性分析

2011年11月25日-12月1日在渤海(37°00′-40°00′N,118°00′-121°00′E)21个站位进行了水文、化学和生物的综合调查,应用Uterm觟hl方法对调查海域的浮游植物群落进行了研究,并将群落数据与环境因子(温度、盐度和营养盐)进行了相关性分析。本次调查共发现浮游植物3门30属65种,主要由硅藻和甲藻组成,还有少量的金藻,生态类型以温带近岸性物种为主,主要优势种为:具槽帕拉藻[Paralia sulcata(Ehrenberg)Cleve]、偏心圆筛藻(Coscinodiscus excentricus Ehrenberg)、梭状角藻[Ceratium fusus(Ehrenberg)Dujardin]、相似曲舟藻(Pleurosigma affine Grunow)、星脐圆筛藻(Coscinodiscus asteromphalus Ehrenberg)和菱形藻(Nitzschia sp.)等。调查区浮游植物细胞丰度介于0.89×103~16.4×103cells/L,平均值为4.36×103cells/L。表层浮游植物细胞丰度分布主要受硅藻刻画,高值区集中在辽东湾南侧和渤海海峡西侧海域,甲藻则主要集中在调查区西部和西北部海域。细胞丰度在水体中的垂直分布为随水深增加先升高后降低。调查区浮游植物群落多样性指数和均匀度指数均在调查区中部海域较高,在外侧海域较低。与历史资料的对比发现,近30年来渤海中部海域浮游植物群落结构由早期的硅藻占绝对优势转化为硅藻和甲藻联合占优。PCA和CCA分析以及与历史资料的对比表明,渤海中部海域营养盐结构的改变可能是造成这种转化的主要原因。     

MODIS水色产品在中国黄、东海海域应用研究

An extensive study collected in situ data along the Yellow Sea(YS) and East China Sea(ECS) to assess the radiometric properties and the concentration of the water constituents derived from Moderate Resolution Imaging Spectroradiometer(MODIS). Thirteen high quality match-ups were obtained for evaluating the MODIS estimates of Rrs(λ), chlorophyll a(Chl a) and concentrations of suspended particulate sediment matter(SPM). For MODIS Rrs(λ), the mean absolute percentage difference(APD) was in the range of 20%–36%, and the highest uncertainty appeared at 412 nm, whereas the band ratio of Rrs(λ) at 488 nm compared with that at 547 nm was highly consistent, with an APD of 7%. A combination of near-infrared bands and shortwave infrared wavelengths atmosphere correction algorithm(NIR-SWIR algorithm) was applied to the MODIS data, and the estimation accuracy of Rrs were improved at most of the visible spectral bands except 645 nm, 667 nm and 678 nm. Two ocean-colour empirical algorithms for Chl a estimation were applied to the processed data, the results indicated that the accuracy of the derived Chl a values was obviously improved, the four-band algorithms outperformed the other algorithm for measured and simulated datasets, and the minimum APD was 35%. The SPM was also quantified. Two regional and two coastal SPM algorithms were modified according to the in situ data. By comparison, the modified Tassan model had a higher accuracy for the application along the YS and ECS with an APD of 21%. However, given the limited match-up dataset and the potential influence of the aerosol properties on atmosphere correction, further research is required to develop additional algorithms especially for the low Chl a coastal water.