Late Cretaceous palynology and paleoclimate change:Evidence from the SK1(South) core,Songliao Basin,NE China

Cretaceous climate was warmer than today.The Songliao Basin contains one of the most important Late Cretaceous non-marine deposits in China for the research of the paleoenvironment and paleoclimate.This research is based on core samples from the SK1(S)borehole.The strata sampled are the upper part of the Quantou Formation to member 2 of the Nenjiang Formation,where spores,pollen,dinoflagellates,and other microfossils are abundantly preserved.Based on analysis of the spores and pollen fossils from the core samples,the following six fossil assemblage zones have been recognized in ascending order:The Cicatricosisporites-Cyathidites-Pinuspollenites,Schizaeoisporites-Cyathidites-Classopollis,Cyathidites-Schizaeoisporites,Schizaeoisporites-Cyathidites-Proteacidites,Proteacidites-Cyathidites-Dictyotriletes,and the Lythraites-Callistipollenites-Schizaeoisporites zones.The six fossil zones range from the late Cenomanian to early Campanian.The Late Cretaceous dinoflagellate cysts in the Songliao Basin are of high abundance and low diversity.Specific phytoplankton types reflect salinity changes of the Songliao Lake.Paleoecology of the dinoflagellates suggests that sediments of members 2 and 3 of the Yaojia Formation(K2y2+3)were deposited in a freshwater environment,whereas members 2 and 3 of the Qingshankou Formation(K2q2+3)and members 1 and 2 of the Nenjiang Formation(K2n1+2)were deposited in freshwater to brackish water environments.Combined with the paleoecology of dinoflagellates and the palynomorph biozones,valuable information of the paleoclimate was provided.The quantitative analyses of spores and pollen fossils,such as vegetation type,climate type,and humidity type,diversity and dominance,indicate a relatively sub-humid,mid-subtropical paleoclimate,with slight climatic fluctuation and/or temporal change.     

Temporal population dynamics of dinoflagellate Prorocentrum minimum in a semi-enclosed mariculture pond and its relationship to environmental factors and protozoan grazers

The ecological processes and interrelationships between protists,either autotrophic or heterotrophic,and environmental factors in mariculture ponds are largely unknown.This study investigated the temporal dynamics of potentially harmful dinoflagellate,Prorocentrum minimum (Pavillard) Schiller,and its relationship to physico-chemical factors and protozoan grazers over a complete cycle in a semi-enclosed shrimp-farming pond near Qingdao,Northern China.P.minimum occurred frequently in low numbers from June to ...     

2005年春夏季东海赤潮过程中营养盐作用初探

自20世纪90年代以来,我国进入赤潮高发期,近岸海域赤潮的发生频率、波及范围和危害程度呈逐年上升趋势.受长江径流等陆源输入影响,东海海域形成了其特有的富营养环境,目前已经成为我国赤潮发生最严重的区域之一.该海域赤潮暴发呈现出发生时间不断提前、持续时间不断加长、发生面积不断扩大、有毒有害藻类逐渐增加的特点[1-2].据统计,自2000年以来,我国沿岸海域共发生赤潮约480次,累计面积超过104000km2.其中,仅在东海海域发生赤潮的次数就占全国记录总数的60%,发生面积更是达到了70%以上[3],其发生频率和规模均远远高于我国其他3个海区.     

孢囊及其与赤潮爆发关系的研究进展

某些藻类(特别是甲藻),在不适宜生长的恶劣环境条件下能形成休眠孢囊。孢囊下沉到海底,以渡过不良的生存条件。一旦环境条件适宜,孢囊就大量萌发形成浮游细胞和优势群体,从而诱导赤潮的形成。简述了当前国际上对孢囊研究的最新进展,从孢囊和营养细胞相互转化的角度探索了孢囊与赤潮形成的关系,以及分子生物学技术在赤潮生物及其孢囊的定性、定量及赤潮发生监测中的应用。     

湄洲湾海域甲藻孢囊的时空分布初步调查

为了解湄洲湾海域表层沉积物中甲藻孢囊的时空分布特征,于2018年5月(春)、8月(夏)、11月(秋)和2019年2月(冬)采集湄洲湾海域7个站位表层沉积物样品,进行甲藻孢囊分析,共鉴定出甲藻孢囊6大类42种和2种未知种。异养型甲藻孢囊种类数和丰度均高于自养型甲藻孢囊,其中又以原多甲藻类孢囊的种类和丰度最高。季节间差异不明显:种类数介于34～38种之间,丰度则在397.8～569.5 cysts/g之间变化,全年平均丰度448.0 cysts/g。工业区附近的站位种类数和丰度均低于养殖区附近的站位和对照点。优势种高达16种,原多甲藻类占绝对优势,但全部优势种优势度均不大。多样性指数、丰富度指数和均匀度指数均较高,全年的平均值分别为3.45、1.55和0.92。与历史资料对比,新发现19种孢囊,但丰度相差不大。另需注意的是,在湄洲湾海域共发现6种有毒甲藻孢囊,虽然全年丰度均不高,但仍有暴发有毒赤潮的危险,需引起重视。     

Geographical distribution of red and green Noctiluca scintillans

The dinoflagellate Noctiluca scintillans is one of the most important and abundant red tide organisms and it is distributed world-wide. It occurs in two forms. Red Noctiluca is heterotrophic and fills the role of one of the microzooplankton grazers in the foodweb. In contrast, green Noctiluca contains a photosynthetic symbiont Pedinomonas noctilucae (a prasinophyte), but it also feeds on other plankton when the food supply is abundant. In this review, we document the global distribution of these two forms and include the first maps of their global distribution. Red Noctiluca occurs widely in the temperate to sub-tropical coastal regions of the world. It occurs over a wide temperature range of about 10°C to 25°C and at higher salinities (generally not in estuaries). It is particularly abundant in high productivity areas such as upwelling or eutrophic areas where diatoms dominate since they are its preferred food source. Green Noctiluca is much more restricted to a temperature range of 25°C-30°C and mainly occurs in tropical waters of Southeast Asia, Bay of Bengal (east coast of India), in the eastern, western and northern Arabian Sea, the Red Sea, and recently it has become very abundant in the Gulf of Oman. Red and green Noctiluca do overlap in their distribution in the eastern, northern and western Arabian Sea with a seasonal shift from green Noctiluca in the cooler winter convective mixing, higher productivity season, to red Noctiluca in the more oligotrophic warmer summer season.     

Diversity and geographical distribution of resting stages of eukaryotic algae in the surface sediments from the southern Chinese coastline based on metabarcoding partial 18S rDNA sequences

Surface sediment samples were collected from sixteen sites of the southern Chinese coastline in this study. Diversity of eukaryotic microalgae was examined using high-throughput sequencing of 18S rDNA to understand the community structure and geological distribution of microalgal resting stages. A total of 218 operational taxonomic units (OTUs) were detected for eukaryotic algae, and only 75 OTUs (34.40%) were detected into species level. The algal communities were composed of sixty-four genera belonged to twelve classes of four phyla. Dinoflagellates were the most abundant and diversified group, which accounted for the average of 56.26% and 53.70% DNA reads and OTUs, respectively. Dinoflagellates were dominated by Protoperidinium, Euduboscquella, Amylax, and Paragymnodinium. Chaetoceros, Thalassiosira, and Skeletonema were abundant in diatoms, while Pedospumella and Paraphysomonas in Chrysophyceae were the most abundant genera due to their massive occurrence in some particular sites. The high abundance of Protoperidinium sequences suggested the high nutrient levels in the southern Chinese coastline. Nineteen of the detected OTUs were assigned to harmful and/or bloom-forming microalgae. The wide occurrence of the toxic dinoflagellate Azadinium poporum and high abundance of Alexandrium pacificum in some particular sites suggested the potential risk of human poisoning.     

2000—2018 年福建近岸海域赤潮分布特征

收集2000—2018 年福建近岸海域224 次赤潮事件资料,通过综合分析结果表明：2000—2018 年福建近岸海域赤潮发现数量和面积分别占全国的17.3%和6.1%。2015—2018 年相对于2000—2004、2005—2009、2010—2014 年赤潮年均发现数量和面积有明显下降。赤潮发现月份和空间特征明显,5—6 月为高发期;宁德、福州、平潭、厦门、泉州海域是赤潮高发区;4 个时间段比较宁德和厦门海域年均发现赤潮数量下降明显,平潭海域略微下降,泉州海域增加。由甲藻门生物引发的赤潮数量、面积和损失均最高,诱发赤潮的生物类群存在南北差异,有毒赤潮占总赤潮数量的14.3%。根据提出的赤潮等级划分标准,福建近岸海域以小型赤潮为主。建议在宁德至平潭近岸海域、泉州近岸海域加强赤潮立体化监测系统的建设,5—6 月为监测的关键时期。     

中国沿海贪食共生藻的形态、超微结构和分子特征

共生藻属( Symbiodinium)主要指一类与无脊椎动物或原生生物共生的甲藻,是热带和亚热带海洋生态系统常见物种.本研究从中国沿海和一艘停靠在厦门港的货轮压舱水中分离出了4株贪食共生藻(Symbiodinium voratum).贪食共生藻运动细胞较小(长9.7±1.3 μm,宽8.7±0.9 μm) ,能够产生不...     

Dinoflagellate cyst biostratigraphy of the Upper Miocene Deurne Sands (Diest Formation) of northern Belgium,southern North Sea Basin

Diverse and well‐preserved palynomorph assemblages recovered from the Deurne Sands, a local member of the Upper Miocene Diest Formation near Antwerp, allow the recognition of dinoflagellate cyst biozones defined in the North Atlantic realm (East Coast, USA) and the North Sea region (Nieder Ochtenhausen well, northern Germany). Based on the dinoflagellate cyst assemblages and the calcareous microfossils, the deposition of the Deurne Sands took place at some time during middle to late Tortonian (Late Miocene). These sands can be correlated biostratigraphically with the Dessel Sands in the Campine area of northern Belgium. This correlation demonstrates the existence of two separate and contemporary depositional areas in northern Belgium during early Late Miocene times. Copyright © 2002 John Wiley & Sons, Ltd.