冷泉区底栖有孔虫研究进展

海底冷泉区是海洋能源和生物资源同时富集的一类特殊区域。底栖有孔虫群落及其地球化学组成是海底冷泉区发育的重要指示标志之一。海底冷泉区的底栖有孔虫及其碳同位素研究,对于探讨冷泉演化、评估古冷泉甲烷排放对全球气候变化的影响有重要的研究意义。综述了全球一些主要冷泉区的底栖有孔虫研究方法及其进展,对比了各冷泉区底栖有孔虫群落结构的主要特征及地域差异,评述了冷泉区底栖有孔虫的碳同位素记录特征、影响因素及其对冷泉活动的潜在指示意义,最后提出了南海北部冷泉活动区底栖有孔虫方面的研究展望。     

化石群落与层序地层的耦合关系研究——以塔里木盆地西部中新生代有孔虫群落与层序地层关系研究为例

本文研究的是大陆边缘海以底栖有孔虫为主的化石群落与层序地层的关系。海平面变化是控制化石群落演替和识别划分层序的主要因素。化石群落在一个完整海水进退旋回中呈机会种群落、平衡种群落、终极种群落演替变化,在化石丰度、多样度、均衡度、成壳类型等方面分异显著,与层序地层的三级层序的海进体系域、凝缩期沉积、高位体系域具有密切的耦合关系。化石群落的演替变化是对海洋环境变迁的能动反映。因此,化石群落的研究可以帮助识别和优化层序、沉积体系域和层序界面,从而为层序地层的准确识别划分提供新的思路。     

化石群落与层序地层的耦合关系研究——以塔里木盆地西部中新生代有孔群落与层序地层关系研究为例

本文研究的是大陆边缘海以底栖有孔虫为主的化石群落与层序地层的关系。海平面变化是控制化石群落演替和识别划分层序的主要因素。化石群落在一个完整海水进退诈回中呈机会种群落、平衡种群落、终极种群落演替变化,在化石丰度、多样度、均衡度、成壳类型等方面分异显著,与层序地层的三级层序的海进体系域、凝缩期沉积、高位体系域具有密切的耦合关系。化石群落的替变化是对海洋环境变迁的能动反映。因此,化石群落的研究可以帮助识别和优化层序、沉积体系域和层序界面,从而为层序地层的准确识别划分提供新的思路。     

华北地台区东部晚古生代小有孔虫动物群发育特征

本文研究了华北地台区东部辽宁、山东、山西、河南和安徽太原组地层中的小有孔虫37属127种,进行了群落分析。从沉积学角度,华北的石炭——二叠系可大致划分5个沉积体系,其中的潮坪—海湾体系和滨岸浅海体系,构成了小有孔虫繁衍发育的主要场所。从群落的角度讲,这也就是华北地台晚石炭世至早二叠小有孔虫动物群的两大生态底域位置,分别称为局限海湾生态域G和正常浅海生态域SH。自晚石炭世至早二叠世,局限海湾生态域先后孕育了小有孔虫群落G-Ia-G-M;正常浅海生态域先后孕育了小有孔虫群落SH-Ia—SH-V。群落组成受生态与演化双重因素控制,正成分描述时,参考了前人资料,建议并使用了如下术语:（1）特征分子,包括窄时分子和窄相分子;（2）遍布分子,包括广时分子和广相分子;（3）递变分子,包括异地分子或孑遗分子;（4）优势分子。本文还分析了华北地区晚石炭世至早二叠世小有孔虫演化的5个阶段。     

南海神狐海域有孔虫与高饱和度水合物的储存关系

通过对神狐海域沉积物组分与水合物成藏关系的研究, 得到SH7B孔含水合物层(155~177 m)有孔虫丰度以及有孔虫壳体微结构与水合物饱和度的关系.结果表明, 有孔虫丰度与水合物饱和度有良好的对应关系, 有孔虫丰度高, 水合物饱和度也高; 反之亦然.有孔虫丰度与水合物饱和度二者的相关系数为0.72, 说明有孔虫与水合物的分布和富集有关.扫描电镜研究表明, 有孔虫成岩作用不明显, 有孔虫为有效孔隙, 有孔虫独特的壳体结构增加了沉积物的孔隙空间, 有利于水合物的储存和富集.大部分有孔虫壳体大小相当于砂粒级, 它的存在一方面增加沉积物粗组分砂的含量, 另一方面增加沉积物的孔隙度.沉积物中生物组分——有孔虫, 是南海神狐海域水合物富集的重要因素之一.      

海洋低氧环境底栖有孔虫研究进展

全球变暖和人为活动不断加剧海洋低氧环境发生的频率和范围,低氧对全球海洋底栖生物群落结构造成重大影响。底栖有孔虫能够广泛适应生存在各种海洋低氧环境中,是极少数能适应低氧环境的真核生物之一,底栖有孔虫对低氧环境的响应及适应机制研究是海洋研究领域的前沿和热点话题,至今仍存在很多谜团。本文总结了不同海洋低氧环境活体底栖有孔虫分布特征、活体底栖有孔虫对人为诱导低氧环境的响应、低氧环境下底栖有孔虫外壳化学组成特征、低氧环境下底栖有孔虫的生存机理,期望为后续推进海洋低氧环境下底栖有孔虫相关研究进一步开展提供参考和借鉴。底栖有孔虫作为古海洋环境重建的重要工具,对我们了解全球海洋低氧环境的历史演化进程具有非常重要的意义。展望未来我们需要进一步加强有孔虫细胞生理学和分子生物学对低氧环境的适应机制研究,从系统发生学上认识真核生物对低氧环境适应的历史演化进程,为利用有孔虫作为工具更好地重建和预测海洋低氧环境变化提供理论依据。     

崖19-1-1井晚第三纪浮游有孔虫深度分层及其古海洋学意义

依据ＧｅｒｔａＫｅｌｅｒ和Ｇａｓｐｅｒｉ，Ｋｅｎｎｅｔｔ有关中新世印度洋和太平洋浅层水、中层水和深层水浮游有孔虫深度分层组合的划分模式，对南海琼东南盆地崖１９－１－１井晚第三纪浮游有孔虫作了定量研究，并分析了陆架海区浮游有孔虫不同深度分层组合含量的变化与古地理环境变迁的关系。崖１９－１－１井以浅层水、中层水组合为主，深层水组合不发育，反映本区温跃层不发育，不利深层水浮游有孔虫的生存。滨海区，浮游有孔虫仅为少数几个浅层水的优势种，中层水浮游有孔虫不发育；内浅海区，浅层水浮游有孔虫占绝对优势，中层水浮游有孔虫处于次要地位，所含比例相对较小；外浅海区及陆坡半深海区，浅层水和中层水浮游有孔虫均较发育，中层水浮游有孔虫百分含量相对较高。崖１９－１－１井在上新世早中期曾出现外浅海至陆坡半深海区，为古水深最大时期     

崖19—1—1井晚第三纪浮游有孔虫深度分层及其古海洋学意义

依据Ｇｅｒｔａ Ｋｅｌｌｅｒ和Ｇａｓｐｅｒｉ，Ｋｅｎｎｅｔｉ有关中新世印度洋和太平洋浅层水、中层水和深层水浮游有孔虫深度分层组合的划分模式，对南海琼东南盆地崖１９－１－１井晚第三纪浮游有孔虫作了定量研究，并分析了陆架海区浮游有孔虫不同深度分层组合含量的变化与古地理环境变迁的关系。崖１９－１－１井以浅层水、中层水组合为主，深层水组合不发育，反映本区温跃层不发育，不利深层水浮游有孔虫的生存。滨海区，浮     

西藏岗巴晚白垩世有孔虫动物群与海平面变化

西藏南部岗巴地区上白垩统的有孔虫动物群十分丰富，经鉴定共有52属130种。根据岩性，该地区上白垩统可以划分出三个最基本的岩石地层单位：冷青热组、岗巴村口组及宗山组。依据其中有孔虫的形态结构、生态环境、系统演化及地史分布等特征，可以划分出五个主要的有孔虫动物群，Rotalipora动物群，Whiteinella-Helvetoglobotruncana动物群，Dicarinella-Marginotruncana动物群，Globotruncana-Globotuncanita动物群及Orbitoides-Omphalocyclus动物群。这五个有孔虫动物在晚白垩世相继绝灭，其绝灭与古水深有着十分密切的关系，主要是受海平面变化的影响。     

琼东南盆地晚第三纪浮游有孔虫深度分层意义

依据Ｋｅｌｌｅ１９８５年、Ｇａｓｐｅｒｉ等１９９３年有关中新世印度洋和太平洋浅层水、中层水和深层水浮游有孔虫深度分层组合的划分模式，对南海琼东南盆地崖１３－１－４井晚第三纪浮游有孔虫作了定量研究，并分析了陆架海区浮游有孔虫不同深度分层组合含量的变化与古地理环境变迁的关系。崖１３－１－４并以浅层水、中层水组合为主，深层水组合不发育，反映该区温跃层不发育，不利于深层水浮游有孔虫的生存。滨海区，浮游有孔     

Historical Comparison of Fish Community Structure in Lower Chesapeake Bay Seagrass Habitats

Seagrass beds provide important habitat for fishes and invertebrates in many regions around the world. Accordingly, changes in seagrass coverage may affect fish communities and/or populations, given that many species utilize these habitats during vulnerable early life history stages. In lower Chesapeake Bay, seagrass distribution has contracted appreciably over recent decades due to decreased water clarity and increased water temperature; however, effects of changing vegetated habitat on fish community structure have not been well documented. We compared fish community composition data collected at similar seagrass sites from 1976–1977 and 2009–2011 to investigate potential changes in species richness, community composition, and relative abundance within these habitats. While seagrass coverage at the specific study sites did not vary considerably between time periods, contemporary species richness was lower and multivariate analysis showed that assemblages differed between the two datasets. The majority of sampled species were common to both datasets but several species were exclusive to only one dataset. For some species, relative abundances were similar between the two datasets, while for others, there were notable differences without directional uniformity. Spot (Leiostomus xanthurus) and northern pipefish (Syngnathus fuscus) were considerably less abundant in the contemporary dataset, while dusky pipefish (Syngnathus floridae) was more abundant. Observed changes in community structure may be more attributable to higher overall bay water temperature in recent years and other anthropogenic influences than to changes in seagrass coverage at our study sites.     

白云岩洞穴洞口弱光带的苔藓群落特征——以绥阳水洞为例

白云岩洞穴是喀斯特山区特有的生境之一,其洞口弱光带发育了独特的苔藓植物群落。文章以贵州绥阳县的水洞为例,探讨了白云岩洞穴洞口弱光带的苔藓群落物种组成、类型及生态分布特征。2015年4月到9月对水洞进行三次野外标本采集,共采集60个样方中的苔藓植物,记载了该洞穴典型苔藓群落47个。研究揭示:（1）该洞物种组成丰富,种类由17科34 属55 种组成,是中国已知苔藓物种最丰富的洞穴; (2)生活型单调,仅有四种类型,分别是交织型(47.27%)、矮丛集型(34.55%)、平铺型(9.09%)和高丛集型(9.09%);（3）根据生长基质不同,划分了4种苔藓群落大类型,分别是钙土苔藓群落、白云石生苔藓群落、钙华苔藓群落和水生苔藓群落,该洞钙华沉积不显著,仅有少量比例的钙华苔藓群落;（4）苔藓植物分布在从洞口到洞深37 m范围,随着光照强度从洞口至洞穴深处的变弱,苔藓群落由多物种群落变化为单一物种群落。      

甘肃宝积山盆地中侏罗世植物群特征及古生态、古气候研究

本文对甘肃宝积山盆地窑街组植物大化石进行了系统研究,经鉴定共有19属50种,结合已有的宝积山盆地中侏罗世植物化石资料,发现甘肃宝积山盆地中侏罗世植物群由27属73种组成.其中,银杏类植物10属30种,真蕨类植物5属26种,松柏类植物5属6种,楔叶类植物3属5种,苏铁类植物2属4种,裸子植物球果和种子化石2属2种.基于当前植物群组成特征,对植物化石埋藏学特性进行分析,确定植物化石主要为原地埋藏或亚原地埋藏,少数属种为异地埋藏,并通过对化石类群古生态特征进行分析,结合现生植物的生存环境,初步重建了宝积山盆地中侏罗世植物群落,划分为四个植物群落:岸边湿地楔叶类植物群落、低地蕨类苏铁类植物群落、坡地银杏类植物群落和高地松柏类植物群落.通过对植物群组成特征和植物化石叶相特征的统计分析,并与其他气候带植物群特征进行对比,推断中侏罗世时期甘肃宝积山盆地为温暖潮湿的暖温带气候.     

Cretaceous-Paleocene Foraminiferal Communities from the Western Tarim Basin and Their Environmental Significance

Foraminifera is one of the most important fossil faunas of the marineCretaceous and Paleocene in the Western Tarim Basin,which can be divided into9 communities.This paper deals mainly with the changes of environmentsin which the foraminiferal communities existed,especially with the changesof temperature and salinity revealed by analyses of test composition and traceelements in the tests,and by statistic studies of species density,richness,diversity,equitability and dominance.     

Spatial differences in macroinvertebrate communities in intertidal seagrass habitats and unvegetated sediment in three New Zealand estuaries

This study investigated macroinvertebrate community composition in seagrass beds at a range of spatial scales, with an emphasis on the transition between vegetated and unvegetated sediment. At four intertidal sites in three New Zealand estuaries (Whangamata, Wharekawa, and Whangapoua Harbours), a large continuous bed of seagrass (Zostera capricorni) was selected with adjacent unvegetated sediment. Macroinvertebrate community composition and biomass, as well as sediment characteristics, were determined at sampling locations 1 and 50 m inside seagrass beds, and 1, 10, and 50 m outside seagrass beds. Analysis of univariate measures of community composition (total abundance, number of species, and diversity) and total biomass indicated significant differences among sites and sampling locations, but contrary to many previous studies these measures were not higher inside than outside the seagrass beds. Multivariate analysis indicated that sites with high seagrass biomass supported a similar community composition. The remaining sampling locations were clustered by site, but there were also significant differences in community composition among sampling locations within a site. There were distinctive communities at the edge of seagrass beds at sites with high seagrass biomass, and evidence that the effects of seagrass beds may extend into the unvegetated sediment. At the low seagrass biomass site there was no evidence of any edge effects, although community composition differed inside and outside the bed. Differences in community composition were driven primarily by small changes in the relative abundance of the dominant taxa. At high seagrass biomass sites the absence of deep-burrowing polychaetes and low numbers of bivalves suggests that one possible mechanism underlying the observed variation in community composition was inhibition by the dense root-rhizome mat. The results of this study emphasize the need to consider the linkages between habitats in heterogeneous estuarine landscapes and how those linkages vary among sites, if the structure and functioning of macroinvertebrate communities in seagrass habitats are to be understood.     

甘肃窑街中侏罗世植物群特征及古生态研究

本文对产于甘肃窑街中侏罗统窑街组地层的植物大化石进行了系统的研究,发现甘肃窑街中侏罗世植物群由31属63种组成。其中,银杏类植物7属23种,真蕨类植物7属14种,松柏类植物7属11种,苏铁类植物5属10种,楔叶类植物4属4种,分类位置不明化石1属1种。在研究植物群组成特征的基础上,通过对植物化石埋藏类型与化石类群生态学的分析,重建了古植物群落,总结了窑街植物群的古生态特征,并划分出四个群落,即划分为近岸湿地群落、山间低地—缓坡群落、山间高地群落、旱生群落等四个群落。根据植物群的整体特征、植物类群之间的比例关系、特征分子及其古生态特征及孢粉植物群特征,推断甘肃窑街盆地中侏罗世古气候为温暖潮湿的亚热带气候。Brachyphyllum及茨康目植物化石的存在,表明甘肃窑街中侏罗世气候环境存在季节性变化。     

Effects of Pleistocene environmental changes on the distribution and community structure of the mammalian fauna of Mexico

Biological communities in Mexico experienced profound changes in species composition and structure as a consequence of the environmental fluctuations during the Pleistocene. Based on the recent and fossil Mexican mammal checklists, we determine the distribution, composition, diversity, and community structure of late Pleistocene mammalian faunas, and analyze extinction patterns and response of individual species to environmental changes. We conclude that (1) differential extinctions occurred at family, genus, and species level, with a major impact on species heavier than 100 kg, including the extinction all proboscideans and several ruminants; (2) Pleistocene mammal communities in Mexico were more diverse than recent ones; and (3) the current assemblages of species are relatively young. Furthermore, Pleistocene relicts support the presence of biogeographic corridors; important refugia existed as well as centers of speciation in isolated regions. We identified seven corridors: eastern USA–Sierra Madre Oriental corridor, Rocky Mountains–Sierra Madre Occidental corridor, Central United States–Northern Mexico corridor, Transvolcanic Belt–Sierra Madre del Sur corridor, western USA–Baja California corridor, Tamaulipas–Central America gulf lowlands corridor, and Sonora–Central America Pacific lowlands corridor. Our study suggests that present mammalian assemblages are very different than the ones in the late Pleistocene.     

Interannual and long-term variation in the nearshore fish community of the mesohaline Hudson River estuary

The detection of long-term shifts in species composition and spatial structuring of aquatic communities may be obscured by high levels of interannual variation. Estuarine fish communities are likely to exhibit high levels of variation owing to the influence of riverine forcing and the importance of anadromous and transient species, whose abundances may not be locally controlled. We describe patterns of interannual variation and long-term shifts in the nearshore fish community of the mesohaline Hudson River estuary based on 21 yr of beach seine sampling conducted annually between late August and mid November. Of the 60 species encountered, the most abundant were Atlantic silversides (Menidia menidia), striped bass (Morone saxatilis), white perch (Morone americana), American shad (Alosa sapidissima), and blueback herring (Alosa aestivalis). Relationships between annual community composition and seasonal flow and temperature regimes were examined with canonical correspondence analysis. Annual variation was most closely correlated with river flows in the 3-mo period preceding fish sampling, indicating a persistent effect of environmental conditions on community structure. Despite significant interannual variation in composition, longer-term trends in community structure were observed. These included declines in catch rates of freshwater and estuarine species and a dramatic increase in the catch of Atlantic silversides, an annual marine species. Associated with these changes were declines in community diversity and increased compositional variation. These results indicate that analyses of temporal changes in community structure need to account for the multiple time scales under which forcing factors and community composition vary.     

Plankton in the Norwegian-Greenland Sea: from living communities to sediment assemblages —an actualistic approach

A synoptic study is carried out to reconstruct the development of the plankton community in the late Quaternary in the Norwegian-Greenland Sea. It comprises quantitative analyses of coccolithophores, dinoflagellate cysts, diatoms and radiolarians. An actualistic approach is applied to evaluate the different fossil records of these plankton groups. The preliminary results of the current investigation are reported here.The composition and distribution of living communities of coccolithophores are presented as an example. A close relationship between the distribution of regional groups and surface water masses is observed. Seasonal vertical fluxes of coccolithophores and radiolarians through the water column show similar patterns within different years. However, diatoms are highly variable, both in absolute fluxes and species composition. The differentiation of sporadic and periodic processes is evident only after several years of observation. During settling and sedimentation biotic and abiotic processes such as grazing, dissolution and lateral transport alter the assemblages.Investigation of death assemblages in surface sediments reveals that in spite of these alteration processes the abundance and species distribution are related to surface water masses. Higher abundances and diversities are usually found in sediments underlying the warm Norwegian Current. Concentrations decrease to the north-west towards the cold polar water masses.The sediment assemblages of all groups are strongly altered relicts of former living communities. They are characterized by distinct changes in species composition and absolute abundances related to palaeo-oceanographic development. Their variation through the sedimentary record is used to distinguish four ecostratigraphic units during the late Weichselian and Holocene.     

Shallow water agglutinated foraminiferal response to Late Cretaceous–Early Paleocene sea-level changes in the Dakhla Oasis,Western Desert,Egypt

The Late Cretaceous (Maastrichtian) to early Paleocene (Thanetian) shallow water (<100 m) agglutinated foraminifera from a section at Dakhla Oasis (Western Desert, Egypt) were analyzed for their assemblage, species and genera distribution, diversity, depositional environment, community structure and palaeobathymetry with respect to regional tectonics, climate and global eustasy. Data suggest an equitable benthic environment with low species dominance deposited in a brackish littoral and/or marsh setting. Sea level curves using characteristic benthic foraminiferal species, genera and assemblages corroborate quantitatively generated estimate and statistical analysis. Data suggests that in the absence of or of an impoverished benthic foraminiferal fauna, a high resolution agglutinated foraminiferal dataset can be as good a predictor of the benthic community structure and environment, as its calcareous counterpart, at least for shallow settings (<100 m). Present data also provides a good window in better understanding the distribution and interrelationship between the three dominant genera, Haplophragmoides, Trochammina and Ammobaculites. Faunal changes at boundaries (Cretaceous/Paleogene, Danian/Selandian and Selandian/Thanetian) are also evaluated.