渤海海域渐新世孢粉、藻类及介形类生态与环境——以曹妃甸5-5构造为例

曹妃甸5-5构造A探井15块岩心和23包岩屑样中含丰富的孢粉、藻类、疑源类以及介形类化石,包括Meliaceoidites-Quercoidites和Ulmipollenitesundulosus-Piceaepollenites2个孢粉组合,Sentusidinium-LeiosphaeridiaCleistosphaeridiumminor,Dictyotidium-Rugasphaera,Gonyaulacysta-Palaeoperidinium 3个藻类、疑源类组合,以及Phacocypris huiminensis, Dongyingia gracilinflexicostata-Chinocythere subtriangulata 2个介形类组合。根据微体古生物、岩矿和地球化学检测结果分析:该构造中沙河街组一段上亚段至东营组二段下亚段为连续沉积。沙河街组一段沉积时期湖岸形成生物礁或滩。东营组三段沉积初期发生短暂海水影响并带来适应咸水藻类,同时陆源淡水快速注入,造成淡水藻类与咸水-半咸水藻类汇聚共生,最终形成滨浅湖—半深湖。环境由炎热潮湿的亚热带气候转变为温暖干燥的温带气...     

松辽盆地晚白垩世介形类古生态学

通过化石组合和岩性指标分析松辽盆地上白垩统自下而上青山口组—姚家组—嫩江组一段介形类的古生态学。青山口组盐度具有偏咸性、微咸性到半咸性的变化,32个介形类种以栖居于温暖湿润气候带的浅湖微咸水类型占绝对优势,水体清澈安静,有机质丰富,底质为泥等细粒沉积物(个别的为粉砂沉积物),宜于介形类动物群生长且有利于壳体完好保存;其次为生活于半咸水的深湖—半深湖类型,底质为泥。姚家组—嫩江组一段见23个介形类种,栖居于温暖半湿润气候带,以半咸水的深湖、半深湖—浅湖区的类型为主,多泥底,偶见粉砂质底;其次为微咸水的浅湖—三角洲前缘型,泥或粉砂质底;仅3个种生活于温暖湿润的粉砂质底淡水浅湖区。温暖湿润的淡水三角洲分流平原带则难以产出介形类化石。     

吉林延吉盆地早白垩世沟鞭藻类及其它藻类

本文研究吉林省延吉盆地下白垩统2个组中沟鞭藻类及其它藻类组合。其中铜佛寺组二段是延吉盆地下白垩统产沟鞭藻最丰富的层位。Vesperopsis cf．zhaodongensis-Vesperopsis tongfosiensis组合指示的地质时代可能为Hauterivian—Barremian期,代表了淡水-微咸水(偏淡水)的沉积环境,而Filisphaeridium-Sentusidinium组合的时代属于Barremian—Aptian早期,指示的水体环境为淡水-微咸水(偏微咸水)。文中描述了1新种,对Vesperopsis yanjiensis Mao,Wan et Qiao,1999进行了修订。     

松辽盆地阿尔必期微体浮游植物新属种

该文描述了松辽盆地中白垩世阿尔必期泉头组三段的微体浮游植物化石1新属7新种,隶属于微咸水沟鞭藻类2属5新种(含4新亚种),淡水绿藻1属1种和疑源类1新属1新种。并对沟鞭藻 Ngktericysta Bint,1986进行了修订。     

内蒙古二连盆地早白垩世微体浮游藻类

记述了二连盆地东北部早白垩世微体浮游藻类16属28种,分属于沟鞭藻类8属15种,含3新种：Fromeacirculatasp.nov,Nyktericystatrigonasp.nov.,Paucibucinapylophorasp.nov,绿藻3属6种,疑源类4属6种,含2新种：Porusphaeraerenensissn．nov,P．pylophorasp．nov,及黄藻1属1种。可将它们划分为2个组合：赛汉塔拉组三段的Parabohaidina－Fromea-Nyktericysta-Vesperopsis组合（即组合1）和哈达图组的Porusphaeraerenensis组合（即组合2）。较详细地讨论了它们的沉积环境和含沟鞭藻类层段的地质时代,认为赛汉塔拉组三段和哈达图组的时代为早白垩世中晚期,其中赛汉塔拉组三段可能为Barremian期;两个浮游藻类组合反映了较复杂的非海相流积环境,以为鞭藻类占优势的第一组合反映在赛三段沉积时是以半咸水一微咸水为主的湖相环境,以疑源类和绿藻占优势的第二组合反映哈达图组是以淡水为主的湖相沉积。     

松辽盆地南部上白垩统嫩江组两种新的沟鞭藻囊孢

本文描述了松辽盆地南部嫩江组三、四段２各新的沟鞭藻类化石,即Ｎｅｎｊｉａｎｇｅｌｌａ ｇｒａｎｕｌａｔａ ｇｅｎ．ｅｔ ｓｐ．ｎｏｖ．和Ｖａｌｅｎｓｉｅｌｌａ ｄｉｃｔｙｏｐｈｏｒａ ｓｐ．ｎｏｖ．。这两种代表较开阔的微咸水－淡水湖相沉积环境,是识别嫩江组三、四段的主要樗在地层划分对比与恢复古沉积环境中有重要的应用价值。     

福建敖江口表层沉积硅藻空间分布特征

为探讨福建敖江口表层沉积硅藻空间分布特征,2019年7月对敖江口进行表层沉积硅藻的采样调查,并研究了硅藻与环境因子的关系。结果表明,从13个站点共检出硅藻114种,隶属于39属。硅藻丰度具有从河口向外海先减少后增加的变化特征。聚类分析表明,主要硅藻属种可划分为淡水种组合带和半咸水-咸水种组合带。典型对应分析（CCA）表明,表层海水温度和盐度是影响硅藻分布的主要环境变量。河口区盐度相对较低,主要分布淡水种双面曲壳藻、优美曲壳藻和颗粒沟链藻;外海区北部盐度相对较高,主要分布咸水种流水双菱藻;外海区南部盐度相对较低,主要分布淡水种优美曲壳藻和颗粒沟链藻;滩涂的沉积物较粗,主要分布优美曲壳藻。此外,河口区和外海区南部可能存在一定的水体污染。     

红树林下中国新记录的四种硅藻

报道了来自福建和深圳红树林下中国首次记录的4种硅藻,即瓜形桥弯藻Cymbella cucumisA．Schmidt、拟优美舟形藻Mzvicula elegantoides Hustedt、侧偏舟形藻N platyventris Meister和柔弱舟形藻N tenera Hustedt,同时描述了每个种类的细胞形态特征和生态分布特点。作者认为淡水硅藻瓜形桥弯藻C．cucumis在半咸水和海水的环境中也有分布（盐度〉15）,应属于淡水和半咸水种。     

松辽盆地梨树断陷早白垩世微体古生物、沉积环境以及控油意义

根据松辽盆地梨树断陷早白垩世地层中孢粉百分含量的纵向变化特征,建立了自下而上各层组的孢粉组合。通过分析孢粉、藻类以及介形类的古环境指示特征,恢复了梨树断陷地层的气温带、古植被、干湿度以及湖水古盐度。沙河子组沉积时期为温暖潮湿的中亚热带气候,古植被为针叶林和灌草丛,湖水为淡水、微咸水;营城组沉积时期为南亚热带气候,古植被为针叶林和灌草丛,湖水同样为淡水、微咸水;到了登娄库组沉积时期,气候变得炎热干旱,为热带气候,古植被为针叶林,湖水则变为半咸水。本文的研究结果可以有效指示地层的划分与对比以及沉积环境的分析。同时,结合盆地发育讨论了古气候变化的控油意义,古气候的变化控制着烃源岩和储层的发育与分布。     

龙凤山藻在澄江早寒武世生物群中的发现

主要报道了产自云南昆明海口耳材村早寒武世筇竹寺组玉案山段澄江生物群中可能为漂浮生长的宏观藻类化石-心型龙凤山藻（新种）（Longfengshania cordata sp.nov.)和中华豆芽藻（新属、新种）（lantulaformis sinensis gen.et sp.nov)。这些化石的发现进一步显示了澄江生物群种物多样性,为揭示该生物群爆发性演化提供了新的证据。通过对龙凤山藻属亲缘关系的深入比较研究,进一步证明该类化石应归属宏观藻类以及它们遗传上的稳定性、演化上的保守性和环境上的适应性。     

河南东濮地区晚始新世至渐新世轮藻植物群及其古环境探讨

东濮地区晚始新世沙河段组四段上部至三段轮藻植物群生存于含钙量高的咸化型水体中,它们的横向分布反映了湖盆中部存在着一个ＮＮＥ向的隆起地带。早渐新世沙河街组二段轮藻植物群生长于含钙量低的淡水水体中,它们的横向分布反映了湖盆中部古地形自南向北高低相间。晚渐新世东营组轮藻植物群生存于含钙量低的淡水水体中,它们的横向分布反映了湖盆的古地势较为平坦。     

渤海湾盆地南堡凹陷始新世—渐新世孢粉、藻类与地层对比

南堡凹陷是位于渤海湾盆地黄骅坳陷北部的小型构造单元。为深入研究南堡凹陷古近纪孢粉组合,采集了Gp1和Np288等七口钻井样品。经传统酸、碱处理法获得孢粉化石,并在研究区古近系地层中划分出六个孢粉亚组合:沙三段4亚段的Ephedripites-Taxodiaceaepollenites-Ulmoideipites tricostatus-Pterisisporites属于始新世鲁特期、沙三段1—3亚段的Quercoidites microhenrici-Ulmipollenites minor属于始新世中晚期、沙二段的Ephedripites-Rutaceoipollis-Meliaceoidites与沙一段的Quercoidites-Meliaceoidites属于渐新世早期、东二段与东三段的Ulmipollenites undulosus-Piceaepollenites-Tsugaepollenites与东一段的Juglandaceae-Celtispollenites属于渐新世中晚期。研究区古近纪孢粉组合与黄骅坳陷中北区及滩海地区的孢粉组合可以形成良好对比,并且研究区局部出现的沙三段4、5亚段与渤海湾盆地普遍出现的沙河街组四段上部为同一时期的产物。     

Differences in osmotolerance in freshwater and brackish water populations of Theodoxus fluviatilis (Gastropoda: Neritidae) are associated with differential protein expression

The euryhaline gastropod Theodoxus fluviatilis is found in northern Germany in freshwater or in brackish water habitats in the Baltic Sea. Previous studies have revealed that individuals from both habitats are not distinguishable by morphological characters or by sequence comparison of DNA encoding 16S RNA or cytochrome C. As reported in this study, animals collected in the two habitats differ substantially in their physiological ability to adapt to different salinities. Comparison of accumulation rates of ninhydrin-positive substances (NPS) in foot muscle upon transfer of animals to higher medium salinities revealed that brackish water animals were perfectly able to mobilize NPS, while freshwater animals had only limited ability to do so. In an attempt to explore whether this difference in physiology may be caused by genetic differentiation, we compared protein expression patterns of soluble foot muscle proteins using 2D gel electrophoresis and silver staining. Of the 40 consistently detected protein spots, 27 showed similar levels in protein expression in animals collected from freshwater or brackish water habitats, respectively. In 12 spots, however, protein concentration was higher in brackish water than in freshwater animals. In four of these spots, expression levels followed increases or decreases in medium salinities. In a different set of 4 of these 12 spots, protein levels were always higher in brackish water as compared to freshwater animals, regardless of their physiological situation (14 days in artificial pond water or in medium with a salinity of 16‰). The remaining 4 of the 12 spots had complex expression patterns. Protein levels of the remaining single spot were generally higher in freshwater animals than in brackish water animals. These expression patterns may indicate that freshwater and brackish water animals of T. fluviatilis belong to different locally adapted populations with subtle genetic differentiation.     

Upper Cretaceous paleogeography of the Central Southern Pyrenean Basins (Catalonia, Spain) from microfacies analysis and charophyte biostratigraphy

The most extensive latest Cretaceous deposits of the Pyrenees are non-marine facies traditionally called “Garumnian”, which represent the first continentalization of the Pyrenean Foreland Basins. The age and paleogeography of the basal Garumnian facies in the different parts of the Pyrenean Basin has been a matter of debate. Charophyte biostratigraphy and microfacies analysis suggest that the continentalization was diachronous in the Central Southern Pyrenean basins, i.e., between the Àger and Tremp basins, and the emersion progressed from south to north. In the Àger Basin, to the south, the first Upper Cretaceous non-marine rocks are represented by the La Maçana Formation. This unit is mainly formed by freshwater lacustrine limestones organized into hundreds of shallowing-upwards sequences ranging from deeper lacustrine facies, through marginal, well-illuminated environments dominated by characean meadows, and finishing with lakeshores dominated by clavatoracean meadows. The charophyte assemblage from the La Maçana Fm is mainly formed by Peckichara cancellata, P. sertulata, Microchara cristata, M. parazensis, Platychara caudata, and Clavator brachycerus, which belong to the Peckichara cancellata charophyte biozone (Late Campanian). In contrast, in the Tremp Basin, located to the north, the beginning of the non-marine sedimentation is organized into a few cycles of the well-known La Posa Fm. These cycles begin with brackish deposits formed by thick marls with euryhaline molluscs at the base, followed by lignite and brackish to freshwater limestones. The brackish facies are dominated by porocharaceans. The charophyte assemblage of the La Posa Formation is formed by Feistiella malladae, Peckichara sertulata, Microchara cristata, and Clavator brachycerus, which belong to the Septorella ultima charophyte biozone (Early Maastrichtian).     

Bryozoans are returning home: recolonization of freshwater ecosystems inferred from phylogenetic relationships

Bryozoans are aquatic invertebrates that inhabit all types of aquatic ecosystems. They are small animals that form large colonies by asexual budding. Colonies can reach the size of several tens of centimeters, while individual units within a colony are the size of a few millimeters. Each individual within a colony works as a separate zooid and is genetically identical to each other individual within the same colony. Most freshwater species of bryozoans belong to the Phylactolaemata class, while several species that tolerate brackish water belong to the Gymnolaemata class. Tissue samples for this study were collected in the rivers of Adriatic and Danube basin and in the wetland areas in the continental part of Croatia (Europe). Freshwater and brackish taxons of bryozoans were genetically analyzed for the purpose of creating phylogenetic relationships between freshwater and brackish taxons of the Phylactolaemata and Gymnolaemata classes and determining the role of brackish species in colonizing freshwater and marine ecosystems. Phylogenetic relationships inferred on the genes for 18S rRNA, 28S rRNA, COI, and ITS2 region confirmed Phylactolaemata bryozoans as radix bryozoan group. Phylogenetic analysis proved Phylactolaemata bryozoan's close relations with taxons from Phoronida phylum as well as the separation of the Lophopodidae family from other families within the Plumatellida genus. Comparative analysis of existing knowledge about the phylogeny of bryozoans and the expansion of known evolutionary hypotheses is proposed with the model of settlement of marine and freshwater ecosystems by the bryozoans group during their evolutionary past. In this case study, brackish bryozoan taxons represent a link for this ecological phylogenetic hypothesis. Comparison of brackish bryozoan species Lophopus crystallinus and Conopeum seurati confirmed a dual colonization of freshwater ecosystems throughout evolution of this group of animals.     

Influence of changes in salinity and light intensity on growth of phytoplankton communities from the Schelde river and estuary (Belgium/The Netherlands)

In the Schelde continuum, a succession in the phytoplankton community is observed along the transition from the river to the freshwater tidal reaches of the estuary and from the freshwater to brackish reaches of the estuary. The goal of this study was to experimentally evaluate the contribution of changes in salinity and light climate to this succession. In summer 2000 and in spring 2001, phytoplankton communities from the river, the freshwater tidal reaches and the brackish reaches of the estuary were incubated under high or low light intensities and exposed to a change in salinity. HPLC analysis was used to evaluate the response of different algal groups to changes in light intensity and salinity. When incubated at a light intensity corresponding to the mean underwater light intensity of the freshwater tidal reaches, growth of phytoplankton from the river as well as from freshwater tidal reaches was significantly lower than when incubated at a light intensity corresponding to the mean underwater light intensity of the river. The phytoplankton community from the freshwater tidal reaches did not appear to be better adapted to low light intensities than the phytoplankton community from the river. Although diatoms were expected to be less sensitive to a reduction in light intensity than green algae, the opposite response was observed. Freshwater and brackish water phytoplankton were negatively affected by respectively an increase or decrease in salinity. However, the effect of salinity was not strong enough to explain the disappearance of freshwater and brackish water phytoplankton between a salinity of 0.5 and 10 psu, suggesting that other factors also play a role. In the freshwater phytoplankton communities from the river and the freshwater tidal reaches, green algae and diatoms responded in a similar way to an increase in salinity. In the brackish water phytoplankton community, fucoxanthin displayed a different response to salinity than lutein and chlorophyll a.     

Paleoceanography of the Late Cretaceous (Maastrichtian) Western Interior Seaway of North America: evidence from Sr and O isotopes

Well-preserved fossils of the Late Cretaceous Western Interior Seaway (WIS) of North America have been analyzed for Sr concentration and Sr and O isotopes in order to decipher paleosalinities and paleotemperatures. The samples are from four biofacies within the Seaway (late Maastrichtian): offshore Interior (Pierre Shale), nearshore Interior (Fox Hills Formation), brackish (reduced salinity; Fox Hills Formation) and freshwater (Hell Creek Formation). Samples were also obtained from the Severn Formation of Maryland (considered to be representative of the open ocean). All biofacies (except the freshwater) are demonstrably within the Jeletzkytes nebrascensis ammonite zone (<1 Ma duration). The ⁸⁷Sr/⁸⁶Sr ratios show significant and systematic decreases from marine (mean±1 S.D.=0.707839±0.000024) to brackish facies (mean±1 S.D.=0.707677±0.000036), consistent with dilution by freshwater with a lower ⁸⁷Sr/⁸⁶Sr ratio than seawater. Such variation disallows using the ⁸⁷Sr/⁸⁶Sr ratios of fossil shell material to assign ages to fossils from the Late Cretaceous WIS without knowledge of the salinity in which the organism grew. The Sr isotope ratios for scaphitid ammonites within a single biofacies are similar to each other and different from those for scaphites in other biofacies, implying that these organisms are restricted in their distribution during life. The ⁸⁷Sr/⁸⁶Sr values of freshwater unionid mussels range widely and are not compatible with the freshwater endmember ⁸⁷Sr/⁸⁶Sr ratio required by the trend in ⁸⁷Sr/⁸⁶Sr vs. biofacies established from the other samples. Paleosalinities for the biofacies are estimated to range from 35‰ in the open marine to a minimum of 20‰ in the brackish, based on the presence of cephalopods in all four facies and the known salinity tolerance of modern cephalopods. Producing reasonable ⁸⁷Sr/⁸⁶Sr values for the freshwater endmember of a ⁸⁷Sr/⁸⁶Sr vs. 1/[Sr] plot requires a Sr concentration 0.2-0.5 that of seawater for the dominant freshwater input to the WIS. Such high Sr concentrations (relative to seawater) are not observed in modern rivers, and we suggest that the brackish environment in the WIS arose through the mixing of freshwater and seawater in a nearshore aquifer system. Reactions of the solution with aquifer solids in this ‘subterranean estuary’ [Moore, Mar. Chem. 65 (1999) 111-125] produced brackish water with the Sr concentration and isotopic composition recorded in the brackish biofacies. δ¹⁸O values of the fossils show decreases from the marine to brackish biofacies consistent with increasing temperatures (from ∼13 to 23°C) or, if temperatures were relatively constant, to a decrease in the δ¹⁸O of the water in which the shell formed. The latter interpretation is consistent with less-than-fully marine salinities in the nearshore biofacies, but both changes in temperature and the isotopic composition of the water may have occurred in this environment.     

Survival and behavioral characteristics of amphidromous goby larvae of Sicyopterus japonicus (Tanaka, 1909) during their downstream migration

To understand the ecology and environmental tolerances of newly hatched larvae of the amphidromous fish Sicyopterus japonicus during their downstream migration, the salinity tolerance of eggs, 0-15 day old larvae, and adults, and the temperature tolerance, specific gravity and phototaxis of hatched larvae were examined. Tolerances of adults were measured as survival after a 24 h challenge in freshwater (FW), brackish water (1/3 SW) and seawater (SW). The survival rate of adult S. japonicus was 100% in FW and 1/3 SW, while none survived in SW. Hatching success of eggs (30 eggs each) was significantly higher in FW (mean: 73%) and 1/3 SW (73%) than in SW (19%). Tolerance of newly hatched larvae to salinity and temperature was investigated in different combinations of salinities (FW, 1/3 SW and SW) and temperatures (18, 23 and 28 °C). Larval survival was significantly different in each salinity and temperature. Survival rate was significantly higher in 1/3 SW than in FW and higher in SW than in FW at 23 °C and 28 °C. At the latter part of the experiment, there was no survival in FW and at 28 °C. Survival was higher in lower temperatures, but larval development did not occur in FW. Specific gravity of newly hatched larvae was 1.036 at 28 °C and 1.034 at 23 °C. When exposed to a light source on one side of an aquarium, larval distribution was not affected. Our results indicated larval S. japonicus are more adapted to brackish water and seawater than freshwater, while the adults and eggs are more adapted to freshwater and brackish water than seawater. This is consistent with their amphidromous life history with growth and spawning occurring in freshwater and the larval stage utilizing marine habitats.