我国东南近岸海域表层沉积硅藻组合

对采自我国东南近岸海域18个站位78个表层沉积样品进行了硅藻鉴定分析,根据硅藻优势种和次优势种的分布特征,划分出3个组合和两个亚组合,其较好地对应分布于南海、台湾海峡和东海等3个近岸海域。统计数据表明,近岸海域表层沉积硅藻的分布受大陆入海径流的影响微乎其微,随着水深的增加,我国东南近岸海域海洋初级生产力减小,底栖种、潮间带种减少而浮游种增加;组合Ⅰ的分布表明南海东北部海域明显受黑潮流等外洋水团的影响,可应用组合Ⅱ1和组合Ⅱ2中优势种和特征种硅藻来指示水深,两亚组合面貌的差异是对冬夏两季海峡两侧受不同性质海流控制的响应;组合Ⅲ受沿岸流控制比较明显,而遭受黑潮等外洋水团的影响很弱。     

西伯利亚极地海域表层沉积硅藻分布特征及其与海洋环境变量的相关性研究

北冰洋西伯利亚陆架海是北极气候快速变化最为显著的海域之一,而沉积硅藻作为极地海洋生态系统的重要组成部分,对环境变化具有敏感的响应。对楚科奇海、东西伯利亚海和拉普捷夫海表层沉积物开展了硅藻组成鉴定,利用典型对应分析方法分析了硅藻属种与1986～2015年环境变量之间的关系。结果表明,夏季和秋季海冰密集度、表层海水盐度是影响研究区表层硅藻分布特征最主要的因素。此外,根据表层站位与环境变量的典型对应分析,可将西伯利亚极地海域划分为4个区域,分别为海冰硅藻组合带、暖水硅藻组合带、沿岸硅藻组合带和混合硅藻组合带。这些表层站位的分区与相应区域的海流模式有明显的相关性,海冰硅藻组合带仅分布于研究区北部的高纬度地区;暖水硅藻组合带位于受白令水和太平洋海水的分支——阿拉斯加沿岸水影响为主的区域;拉普捷夫海南部的沿岸硅藻组合带则受到河流径流和西伯利亚沿岸流的强烈影响;混合硅藻组合带受极地冷水、海冰覆盖、太平洋暖水和陆地径流的共同影响。     

东海表层沉积硅藻

1977年国家海洋局组织所属单位对东海大陆架进行了综合调查,采集了比较丰富的样品.有关资料报导了在东海大陆架有12种硅藻的记录,大陆坡11种,海槽区12种,如归并重复出现的种类,总计有20种硅藻.本文基本上用同一批材料对沉积硅藻的沉积问题,提出了我们的一些看法.     

Gradient responses of epilithic diatom communities in the Baltic Sea proper

Diatom communities and assemblages are widely used as indicators of ecological change in aquatic environments and for reconstructing palaeo-environments. Good calibration data sets, directly linking changes in diatom composition to environmental factors, are needed for building reliable gradient models with high indicative value. Such models have a broad applicability because most diatom species have cosmopolitan distributions. This paper presents community analyses of brackish-water diatoms living on submerged stones in four areas of the Baltic Sea proper along the Swedish coast. The communities on the stones were composed of epilithic, epiphytic, epipelic, epipsammic and occasionally some pelagic species. Altogether, 158 quantitative samples were taken at 41 sites between 23 April and 11 May, 1990, and the data set contained 300 diatom taxa belonging to 75 genera. Species data were analysed with principal components analysis (PCA) and environmental factors were fitted passively by multiple regression analysis on the ordination results. Differences in community composition could be explained by variation in salinity (which was correlated with N:P and Si:P ratios and the occurrence of macroalgae on the stones), nutrient concentrations and variation in exposure to wave action (which was correlated to the occurrence of soft bottoms around the stones, water temperature and the occurrence of sand grains and macroalgae on the stones). Separate analyses for small taxa (cell biovolume <1000 μm³), for large taxa (cell biovolume ≥1000 μm³) and for small and large diatom taxa together showed that diatoms of different size classes respond differently to environmental variation.     

南海西北部表层沉积硅藻的分布特征与环境分析

基于南海西北部表层沉积物中的硅藻分析,阐明表层沉积硅藻的分布特征,探讨硅藻与环境的对应关系及指示意义。结果表明,研究区内硅藻以热带—亚热带种和近岸种为主;硅藻丰度差异显著,近岸浅水区丰度相对较低,陆坡、河口和上升流区丰度整体较高;硅藻组合类型复杂。硅藻分布面貌受区域的温度、盐度、营养盐、水深、海流、底质类型等因素的控制较为明显。硅藻组合对海流和水团的影响范围具有指示意义。     

Phytoplankton assemblages in the CoOP-WEST coastal upwelling area

Elevated levels of phytoplankton were observed at the Northern California coastal upwelling ecosystem studied as part of the CoOP-WEST project during monthly summer surveys in 2000, 2001 and 2002. The high concentrations of chlorophyll were made up mostly of larger cells; the phytoplankton communities that resulted were dominated by centric diatoms. The highest chlorophyll a concentrations were observed when large diatoms or small colony-forming species dominated the assemblages. In contrast, when smaller nano-flagellates and picoplankton were dominant, total chlorophyll a concentrations were over four or five-fold lower than when diatoms were prevalent, illustrating the importance of large diatoms to total phytoplankton biomass. Each year, when chlorophyll concentrations were greatest, Chaetoceros species created a Chaetoceros-dominated system. A few other genera contributed to the upwelling diatom community, mostly the centric diatoms Asterionella, Thalassiosira, Rhizosolenia (including Guinardia and Proboscia), and the pennate Nitzschia. These diatoms have been described in other coastal upwelling ecosystems, and at this study site form a functional group that are apparently well adapted to the high-nutrient, turbulent conditions that are typical of these coastal regions.     

东海陆架晚第四纪沉积硅藻及其古海洋学意义

本文对东海陆架DG9617岩芯沉积硅藻进行了研究，共分析鉴定出97种和变种，有近10种硅藻在岩芯中连续分布，且有较高的含量，而其余种类含量极低，仅零星检出。根据该岩芯中产出硅藻种类、含量及硅藻丰度变化特征自下而上共划分出3个硅藻组合带及5个亚带。结合孢粉资料，对产出3个不同硅藻带岩芯的地层年代进行了对比研究，表明该岩芯所代表的地层年代为中－晚全新世，硅藻I组合带大致为大西洋期的沉积，硅藻Ⅱ组合带应为亚北方期的产物，而硅藻Ⅲ组合带与亚大西洋期对应。文中并对不同硅藻组合带产出时的古海洋环境进行了初步探讨。     

台湾海峡游泳动物群落的空间结构及其季节变化

The Taiwan Strait is a transition zone between the East China Sea and the South China Sea with unique hydrology and a geographical environment that creates special marine community features.To analyze the spatial structure and seasonal changes of the nekton assemblages in the Taiwan Strait,seasonal experimental trawl surveys were conducted during 2006–2007.The results showed that there were two assemblages in the area with different sets of species,and the average similarity within each group varies between 39.38% and 74.20%.By using multivariate statistical analysis and analyzing the distribution of dominant species,we found that the structures of the assemblages had obvious seasonal variation.The middle region from the Putian transect to the Xiamen transect could be considered a mixing area for the two assemblages.The analysis of the relationship between species assemblages and environmental factors indicated that temperature was the most important factor affecting the community structure in cold seasons,and 22.5°C and 17°C could be considered dividing lines for spring and winter,respectively.In warm seasons,the most important factor was water depth,but the relationship with depth was not as significant,with a correlation between 0.264 and 0.399.The seasonal changes of nekton assemblages basically reflected the dynamic currents in the Taiwan Strait.The south coastal assemblage extended to nearly the entire area of the Taiwan Strait along with a strong and intense warm current that shrinks in spring and winter when the southward intrusion of the cold Zhejiang-Fujian coastal current becomes stronger.The impact of shortterm and long-term environmental changes,such as extreme weather,global warming and human activity on nekton assemblages,had been recognized but need further research.Our study on nekton assemblages could be used as a baseline for measuring future changes.     

DISCOVERY OF DIATOM ASSEMBLAGES FROM DEEP-SEA BASIN IN THE SOUTH CHINA SEA AND THEIR GEOLOGICAL IMPLICATION

Of the diatoms from sediments of the South China Sea, mainly composed of planktonic species of tropical and subtropical zones, 36 genera and 86 species are identified. Based on the changes in diatom numbers and the appearance of diatom assemblages, six diatom zones are distinguished in Core V, reflecting six phases of paleoclimatc, paleo-watertemperature and paleogeography. According to the Quaternary climatic division, these zones represent hot weather and warm weather as a whole, and they are separately equal to postglacial period, the Holocene; Wurm glacial period; Riss-Wurm interglacial period; and Riss glacial period, the Late Pleistocene.     

Fossil diatom assemblages as paleoecological indicators of paleo-water environmental change in the Ulleung Basin,East Sea,Republic of Korea

The fossil diatom assemblage record from two sediment cores obtained from the Ulleung Basin, East Sea, Republic of Korea, revealed changes in the diatom assemblage zones in PG1 and PD3 core samples. The two sediment cores were δC¹⁴ dated and approximately represented the late Pleistocene–Holocene. The analysis of age zones in the PG1 core and PD3 core was assessed based on the frequency of variations, and occurrences of biostratigraphical fossil diatom species. During the Last Glacial Maximum (LGM), the sea level was lower than that at present and the Ulleung Basin became isolated from the Pacific Ocean. As a result, there would have been a limited Tsushima Warm Current (TWC) influence, and salinity would have decreased resulting in increased freshwater and coastal diatoms. The distribution pattern of diatoms presented in the cores was associated with changes in water temperature and salinity and the adding of terrigenous material brought about by the input of freshwater. Changes in the abundance of a tychopelagic diatom, Paralia sulcata, reflected the effect of the water currents. Diatom temperature (Td) values and the ratio of centric/pennate diatoms provided evidence of limited influences of the TWC and freshwater inflow. It is thought that all assemblage zones were influenced by the TWC, which had an important effect on the distribution and composition of fossil diatoms.     

Winter Distribution of Diatom Assemblages in the East China Sea

We examined the spatial distributional relationships between diatom assemblages and water types during the winter in the East China Sea. Principal component analysis was used to identify two water types and two diatom assemblages in the study area. Coastal water types along the mainland China coastline had low temperature and salinity levels, but high nitrate levels. The shelf-mixing water type in the rest of the study area had higher temperatures and salinities and lower levels of nitrate. Diatom assemblage distribution was not spatially consistent with water type. The Kuroshio assemblage had a large standing stock, distributed along the surface of the shelf break. This assemblage is likely the result of Kuroshio surface water coming into contact with nutrient-rich water in the shelf area, triggering proliferation of certain diatom species. A background assemblage with low standing stock level persisted over the entire study area in both coastal water and the shelf-mixing water types. Our results support previous research: the background assemblage is due to poor growth conditions such as the convection of water during winter; there were no significant seasonal variations in the species composition.     

Nannoplankton of the Atlantic Ocean from sediment trap samples

Calcareous nannoplankton from sediment trap samples collected at six sites in the Atlantic Ocean from 23° S to 73° N (cruise 20 of R/V Vityaz’ and cruise 33 and 34 of R/V Akademik Mstislav Keldysh). Those samples were studied with a scanning electron microscope. In the coastal and open-sea regions of the North and South Atlantic and in the subarctic region of the Norwegian Sea, the conditions are significantly different. In the shelf area of the Benguela upwelling, 11 species were recognized; some of them were agglutinated by diatoms and tintinnides or covered the surface of pellets. The Broken Spur and TAG pelagic areas of the North Atlantic contained up to 43 coccolith species. They included holococcoliths, large pelagic, and delicate easily soluble species distributed over the entire water column. The presence of coccoliths in the high-latitude area of the Norwegian Sea is related to their supply with the warmer North Atlantic waters. These assemblages are distinguished by a low species diversity and an enhancement of the coccolith solubility with the depth increase.     

Preliminary study on seasonal succession and development pathway of phytoplankton community in the Bohai Sea

IThe Phytoplankton spoteS succession is a major characteristic Of PhytOPlankton behavior inthe an, and is Of major swificance tO PhytOPlankton d~cs and in coupling the PhytOPlankton cornxnunity to hasher trophic levels (Smayda, 1980). But another conception species ence that be defined by BraarUd often confUSeS with speCies sucCeSSion. Spotes su~ is thechange of speCies compeition within a given water mass resulting from changing physical,chemical and biological factors within the wa…     

海洋沉积硅藻研究进展

综述了国外近40 a海洋沉积硅藻表层组合及其在地层划分与对比、古地理环境重建、海平面升降和岸线变迁等方面的应用,以及硅藻休眠孢子化石的分类学、地层学和分子系统发育学研究的最新进展.对中国海洋沉积硅藻的研究进展作了概述,基本查明了渤海、黄海、东海、南海4大海区表层硅藻属种组成及表层硅藻组合面貌;利用硅藻组合进行了地层划分与对比、古海洋环境演变过程的研究;并将各种数理统计方法结合到硅藻分析中,使中国海洋沉积硅藻研究逐渐由定性或半定量向定量研究发展.但在利用硅藻进行古环境定量重建等方面,与国外的研究还存在一定差距.今后应加强建立现代硅藻-环境变量数据库、表层沉积生物硅的溶解、硅藻休眠孢子化石的分类学和地层学等方面的研究.     

Spatio-temporal structure of diatom assemblages in a temperate estuary. A STATICO analysis

This study examines the spatio-temporal structure of diatom assemblages in a temperate estuary (Ria de Aveiro, Western Portugal). Eighteen monthly surveys were conducted, from January 2002 to June 2003, at three sampling sites (at both high and low tide) along the estuarine salinity gradient. The relationship of diatom assemblages and environmental variables was analysed using the STATICO method, which has been designed for the simultaneous analysis of paired ecological tables. This method allowed examination of the stable part of the environment-diatom relationship, and also the variations of this relationship through time. The interstructure factor map showed that the relationship between the 11 environmental variables and the abundance of the 231 diatom species considered was strongest in the months May and September 2002 and January, February and May 2003. The stable part of the species–environment relationships mainly consisted of a combined phosphate, chlorophyll a and salinity gradient linked to a freshwater-marine species gradient. A more pronounced gradient was observed in January, February and May 2003. Diatom assemblages showed clear longitudinal patterns due to the presence of both marine and freshwater components. May and September 2002 had the least structured gradients with marine-estuarine species appearing in the freshwater side of the gradient. The most complete gradient in February 2003 could be considered, in terms of bio-ecological categories, as the most structured period of the year, with a combination of strong marine influence in the lower zone and freshwater influence in the upper. The best-structured gradients were during periods of a diatom bloom. Stable diatom assemblages (with a strong structure and a good fit between the diatoms and environment) are described and characterized. This study shows the efficiency of the STATICO analysis. The inclusion of space-time data analysis tools in ecological studies may therefore improve the knowledge of the dynamics of species–environmental assemblages.     

南海北部陆坡ZSQD196PC柱状样末次间冰期以来的古海洋学记录：氧同位素、有孔虫和硅藻

为了解南海北部陆坡末次间冰期以来的古海洋沉积环境演化特征,对研究区ZSQD196PC柱状样有孔虫、硅藻及有孔虫氧同位素资料开展了分析。依据沉积有孔虫、硅藻主要属种的百分含量、丰度及组合特征,将有孔虫划分为3个组合,分别对应于氧同位素MIS1、2、3~4期;将硅藻划分为4个组合,大致对应于MIS1~4期。MIS1期有孔虫以暖水种占优势,Pulleniatina obliquiloculata百分含量显著升高;硅藻丰度低且以热性种占优势,其中冷期出现大量沿岸种,反映相对温暖的气候条件。MIS2~4期有孔虫以冷水种占优势,温跃层种含量相对较高;硅藻丰度高且以广布种占优势,出现沿岸种含量的升高,反映较冷的气候条件。通过对比浮游有孔虫氧同位素,分析讨论了末次盛冰期、Blling—Allerd暖期和新仙女木事件在ZSQD196PC柱状样的沉积响应,揭示了末次冰期中的气候波动。     

Long-term diatom fluxes in response to oceanographic conditions at Stations AB and SA in the central subarctic Pacific and the Bering Sea, 1990–1998

Long-term monitoring of diatom fluxes during 1990–1998 was conducted at Station AB in the Bering Sea and Station SA in the central subarctic Pacific in order to decipher the relationships between sinking diatom and the upper water mass environments. The total diatom flux at Station AB was generally twice as high as that at Station SA. The dominant species in the sinking flora was primarily Neodenticula seminae at both stations, which was a significant contributor to organic carbon flux. The flora at Station AB was represented by relatively abundant coastal taxa including Chaetoceros resting spores. These results suggest more favorable conditions for diatom production at Station AB compared with those at Station SA. The possible influences of oligotrophic and temperate water masses were discerned from the positive SST anomaly and the occurrence of a few specimens of temperate species. The cumulative annual fluxes of total diatoms at Stations AB and SA are apparently related to the variation in the mean annual depth of mixed layer. At Station SA, annual mean of total diatom flux showed a negative correlation with the Pacific Decadal Oscillation (PDO) Index, which suggests a significant relationship between surface water turbidity and diatom production. At Station AB, the annual change of coastal diatom flux was correlated with the PDO and the winter value of the Arctic Oscillation, which may suggest a significant influence of Alaskan Stream waters via the Aleutian Islands and intensity of surface water mixing.     

Population dynamics of phytoplankton, heterotrophic bacteria, and viruses during the spring bloom in the western subarctic Pacific

We characterized the community composition of phytoplankton in the western subarctic Pacific from the pre-bloom to the decline phase of the spring bloom with special reference to decreases in the silicic acid concentration in surface waters as an index for diatom bloom development. Furthermore, responses of heterotrophic bacteria and viruses to the spring bloom were also concomitantly investigated. Under pre-bloom conditions when nutrients were abundant but the surface mixed layer depth was relatively deep, chlorophyll (Chl) a concentrations were consistently low and green algae (chlorophytes and prasinophytes), cryptophytes, and diatoms were predominant in the phytoplankton assemblages as estimated by algal pigment signatures. Together with the shallowing of the mixed layer depth and the decrease in silicic acid concentration, diatoms bloomed remarkably in the Oyashio region, though the magnitude of the bloom in the Kuroshio-Oyashio transition (hereafter Transition) region was relatively small. A total of 77 diatom species were identified, with the bloom-forming diatoms mainly consisting of Thalassiosira, Chaetoceros, and Fragilariopsis species. It has become evident that the carotenoid fucoxanthin can serve as a strong indicator of the diatom carbon biomass during the spring diatom bloom. Differences in the species richness of diatoms among stations generally enabled us to separate the Oyashio bloom stations from the Transition and the Oyashio pre-bloom stations. Relatively high values of the Shannon-Wiener index for the diatom species were also maintained during the Oyashio bloom, indicating that a wide variety of species then shared dominance. In the decline phase of the Oyashio bloom when surface nutrient concentrations decreased, senescent diatom cells increased, as inferred from the levels of chlorophyllide a. Although the cell density of heterotrophic bacteria changed little with the development of the diatom bloom, viral abundance increased toward the end of the bloom, suggesting an increased likelihood of mortality among organisms including diatoms resulting from viral infection. This is the first report on the microbial trophodynamics, including viruses, during the spring diatom bloom in the western subarctic Pacific.     

我国典型潮间带底栖硅藻群落空间分布特征

底栖硅藻是河口、泥质海滩生态系统的重要生物类群,其数量与分布变化直接或间接地影响到多种海洋生物的饵料供给、海鸟的生存与迁徙。通过对我国从南到北14个典型潮间带表层沉积物中底栖硅藻的分析,共鉴定出硅藻153种,其物种多样性（Shannon-Weaver 指数范围:1.61~4.39）与生物量（范围:0.09×103 ~ 10×103个/g,干质量）在空间上存在显著差异;聚类分析与相似性分析检验（r=0.738,P=0.1%< 0.01）表明,14个调查区域的硅藻群落在空间上可分为4个大的组合,分别对应着渤、黄、东、南海4个区域,吻合了我国近海浮游植物的地理分布特征。与环境因素的相关性分析表明,底栖硅藻群落的物种多样性与生物量受沉积物类型与盐度的影响显著,泥质区域更有利于硅藻的保存,而生物多样性在泥砂质低盐区域相对较高。此外,底栖硅藻生物量与表层沉积物中TOC含量表现出显著正相关性;δ13C数值的空间变化范围为-25‰~-20‰,指示了有机质陆海混合的特征,其中,涧河河口、黄河口、大沽河口、苏北浅滩区域,δ13C数值明显偏正,表明底栖硅藻可能是这些区域沉积物中有机碳的重要贡献者。