Nannoplankton extinction and origination across the Paleocene-Eocene Thermal Maximum

The Paleocene-Eocene Thermal Maximum (PETM, approximately 55 million years ago) was an interval of global warming and ocean acidification attributed to rapid release and oxidation of buried carbon. We show that the onset of the PETM coincided with a prominent increase in the origination and extinction of calcareous phytoplankton. Yet major perturbation of the surface-water saturation state across the PETM was not detrimental to the survival of most calcareous nannoplankton taxa and did not impart a calcification or ecological bias to the pattern of evolutionary turnover. Instead, the rate of environmental change appears to have driven turnover, preferentially affecting rare taxa living close to their viable limits.     

The North Atlantic spring phytoplankton bloom and Sverdrup's critical depth hypothesis

More than 50 years ago, Harald Sverdrup developed a simple model for the necessary conditions leading to the spring bloom of phytoplankton. Although this model has been used extensively across a variety of aquatic ecosystems, its application requires knowledge of community compensation irradiance (IC), the light level where photosynthetic and ecosystem community loss processes balance. However, reported IC values have varied by an order of magnitude. Here, IC estimates are determined using satellite and hydrographic data sets consistent with the assumptions in Sverdrup's 1953 critical depth hypothesis. Retrieved values of IC are approximately uniform throughout much of the North Atlantic with a mean value of 1.3 mol photons meter-2 day-1. These community-based IC determinations are roughly twice typical values found for phytoplankton alone indicating that phytoplankton account for approximately one-half of community ecosystem losses. This work also suggests that important aspects of heterotrophic community dynamics can be assessed using satellite observations.     

Biogeochemical evidence for dinoflagellate ancestors in the early cambrian

Dinoflagellates are single-celled organisms that reflect the ecological conditions in modern oceans and lakes. Ultrastructural data and molecular phylogeny suggest that they originated in the Neoproterozoic, yet dinoflagellate ancestors are classified only to the Middle Triassic ( approximately 240 million years ago). Examination of dinoflagellate-specific biological markers (dinosteranes and 4alpha-methyl-24-ethylcholestane) in concentrated microfossils with known morphology identified ancient dinoflagellate ancestors from the Early Cambrian ( approximately 520 million years ago).     

农村污染河道生态修复中浮游植物的群落特征

以沸石和生态浮床构建丁型潜坝,结合曝气及边坡湿地等措施在直湖港支流朱家浜(太湖北部)实施生态修复工程。从浮游植物群落的角度,考察生态修复工程对农村污染河道的修复效果。结果显示:(1)生态修复改变了浮游植物的群落结构及演替方向,硅藻门、绿藻门、甲藻门的部分种类取代了蓝藻门、隐藻门的优势地位;(2)生态工程显著抑制了浮游植物群落的现存量,修复期间浮游植物总生物量均小于6 mg·L-1;(3)生态修复过程中浮游植物的生物多样性维持在相对较高的水平(Shannon-Wiener指数平均值为2.32)。结合生态修复工程对水质的净化效率及浮游植物现存量与水体营养盐水平之间的相关性分析可知,生态修复工程对水体营养盐的有效去除是浮游植物群落特征发生变化的主要因素之一。     

Archean rocks in antarctica: 2.5-billion-year uranium-lead ages of pegmatites in enderby land

Uranium-lead isotopic data indicate that the granulite-facies Napier complex of Enderby Land, Antarctica, was cut by charnockitic pegmatites 2.5 billion years ago and by pegmatites lacking hypersthene 0.52 billion years ago. The 4-bil-lion-years lead-lead ages (whole rock) reported for the Napier complex are rejected since these leads developed in three stages. Reconstructions of Gondwanaland suggest that the Napier complex may be a continuation of the Archean granulitic terrain of southern India.     

Multiple microtektite horizons in upper eocene marine sediments: no evidence for mass extinctions

Microtektites have been recovered from three horizons in eight middle Eocene to middle Oligocene marine sediment sequences. Five of these occurrences are coeval and of latest Eocene age (37.5 to 38.0 million years ago); three are coeval and of early late Eocene age (38.5 to 39.5 million years ago); and three are of middle Oligocene age (31 to 32 million years ago). In addition, rare probable microtektites have been found in sediments with ages of about 36.0 to 36.5 million years. The microtektite horizon at 37.5 to 38.0 million years can be correlated with the North American tektite-strewn field, which has a fission track age (minimum) of 34 to 35 million years and a paleomagnetic age of 37.5 to 38.0 million years. There is no evidence for mass faunal extinctions at any of the microtektite horizons. Many of the distinct faunal changes that occurred in the middle Eocene to middle Oligocene can be related to the formation of the Antarctic ice sheet and the associated cooling phenomena and intensification of bottom currents that led to large-scale dissolution of calcium carbonate and erosion, which created areally extensive hiatuses in the deep-sea sediment records. The occurrence of microtektite horizons of several ages and the lack of evidence for faunal extinctions suggest that the effects of extraterrestrial bolide impacts may be unimportant in the biologic realm during middle Eocene to middle Oligocene time.     

海洋疏浚物对连云港局部海域生态环境的影响评价

为考察海洋疏浚物对海域生态环境的影响,2014年3月对连云港倾倒区及附近海域17个站位的水质和11个站位的沉积物以及海洋生物进行了调查采样。调查将所研究海域划分为倾倒区、倾倒外围区、养殖区,对这3个区域的水质、沉积物中污染物等指标的水平差异及浮游植物、浮游动物、底栖生物的群落现状和差异进行了分析,在此基础上全面评价了海洋疏浚物对该海域生态环境的影响。结果表明:(1)海水和沉积物中重金属含量的分布特征为倾倒区倾倒外围区养殖区,疏浚物为倾倒区重金属的重要污染源,且在扩散作用下对倾倒外围区海域有一定影响;(2)各海区间叶绿素a和浮游植物多项指标差异不大,倾倒活动对浮游植物的影响尚不明显;(3)海区间底栖动物群落组成差异性大,倾倒区底栖动物种类、密度、多样性指数等降低,表明倾倒活动可能导致环境变化从而对底栖动物产生了显著的负面作用。     

杭州湾人工潟湖夏季浮游植物群落演替与环境因子的关系

金山城市沙滩是东海杭州湾的一处人工潟湖,是上海首个滨海4A级景区,由于潟湖本身复杂的物理海洋学性质,为了确保金山城市沙滩水质优良,近年来一直在对其进行生态修复。本研究从2016至2018年,连续3年夏季对该潟湖浮游植物群落结构及其变化与环境因子之间的关系进行了调查,结果显示:2016—2018年夏季浮游植物种类不断增多,共发现浮游植物7门109种,其中硅藻门(Bacillariophyta)、蓝藻门(Cyanophyta)和绿藻门(Chlorophyta)种类较多。优势属共发现13个,优势度较大的是微囊藻属(Microcystis)、囊裸藻属(Trachelomonas)、直链藻属(Melosira)和小环藻属(Cyclotella),其中微囊藻属是夏季第一优势属,其他优势属重合度小。2016—2018年浮游植物丰度变化很大,分别为50.78×10~4～5 957.52×10~4个/L、5.35×10~4～25.67×10~4个/L和474.87×10~4～1 026.94×10~4个/L,其中微囊藻丰度最大,分别占97.88%、68.18%和77.23%。调查期间,浮游植物的多样性指数(H′)和均匀度指数(J′)先增大后减小,但总体呈上升趋势,而第一优势属优势度总体下降,说明经过生态修复,水体浮游植物群落发生正向演替,生态风险有减小趋势。RDA分析表明,总氮、总磷、铵盐、亚硝酸盐、无机磷和硅酸盐是影响浮游植物群落的重要环境因子。其中硅酸盐、亚硝酸盐、铵盐和无机磷与该潟湖的浮游植物群落相关性较大。     

谈李白《清平调》三章诗的英译

李白的《清平调》三章诗问世千多年来,注释家蜂起,各家所见不一,是三章难解亦难译的诗。作者较深入地研究了本诗,于文中提出了“花人合一”之说,并将其译成英文。本文阐述了作者这一观点:译诗者必须具有译诗的素质,诗是随着时间的不断推移、人类交际空间的不断缩小、人类相互了解的不断深化而越来越可译。     

防污林土壤养分效益的初步分析——以包头西郊全巴图地区为例

本文对工业污染区防污林建设过程中土壤养分进行分析对比，结果显示：通过６年的综合改造，增加了土壤的有机质、速效Ｎ、Ｐ、Ｋ的含量，表明在恢复土壤养分功能方面，防污林体系的综合建设有利于生态平衡     

Ages for the Middle Stone Age of southern Africa: implications for human behavior and dispersal

The expansion of modern human populations in Africa 80,000 to 60,000 years ago and their initial exodus out of Africa have been tentatively linked to two phases of technological and behavioral innovation within the Middle Stone Age of southern Africa-the Still Bay and Howieson's Poort industries-that are associated with early evidence for symbols and personal ornaments. Establishing the correct sequence of events, however, has been hampered by inadequate chronologies. We report ages for nine sites from varied climatic and ecological zones across southern Africa that show that both industries were short-lived (5000 years or less), separated by about 7000 years, and coeval with genetic estimates of population expansion and exit times. Comparison with climatic records shows that these bursts of innovative behavior cannot be explained by environmental factors alone.     

Climatic implications of an 8000-year hydrogen isotope time series from bristlecone pine trees

Tree rings from three dendrochronologically dated bristlecone pines were analyzed for stable hydrogen isotopic composition. These trees give a continuous time series from 8000 years ago to the present that indicates the presence of a postglacial climate optimum 6800 years ago and a continuous cooling since then. The qualitative agreement between this record and records from other sources, such as ice cores, pollen, and treeline fluctuations, indicates that these climate changes were global. This record can serve as a reference for other climate indicators throughout the past 8000 years.     

Proterozoic ocean chemistry and evolution: a bioinorganic bridge?

Recent data imply that for much of the Proterozoic Eon (2500 to 543 million years ago), Earth's oceans were moderately oxic at the surface and sulfidic at depth. Under these conditions, biologically important trace metals would have been scarce in most marine environments, potentially restricting the nitrogen cycle, affecting primary productivity, and limiting the ecological distribution of eukaryotic algae. Oceanic redox conditions and their bioinorganic consequences may thus help to explain observed patterns of Proterozoic evolution.     

不同类型水库浮游植物密度与环境因子灰关联分析

[目的]探究影响红枫湖水库（支流宽谷型）和乌江渡水库（干流峡谷型）的浮游植物密度的主要环境因素及其影响强弱顺序,为合理开发利用这2座不同类型水库水资源提供理论依据。[方法]于2005年枯水期、丰水期和平水期对上述2座水库进行浮游植物群落特征的生态调查和水质理化指标测定,应用灰关联分析方法进行数据分析,在水温、pH值、透明度、溶解氧等7项环境因素中找出影响浮游植物密度的主要因素。[结果]红枫湖水库和乌江渡水库的关联度均大于0.500,各理化因子对浮游植物密度影响大小的顺序,红枫湖水库为：透明度〉化学耗氧量〉水温〉pH值〉总氮〉溶解氧〉总磷;乌江渡水库为：溶解氧〉水温〉pH值〉总氮〉化学耗氧量〉透明度〉总磷。[结论]该7项环境因子对2座水库浮游植物密度均有很大影响,但最主要的影响因子不同,其中透明度是影响红枫湖水库浮游植物密度的首要因子,其次为化学耗氧量、水温;乌江渡水库则依次以溶解氧、水温、pH值为主要影响因子。     

营养盐加富和鱼类添加对浮游植物群落演替和多样性的影响

浮游植物是水体生态系统敞水区最重要的初级生产者,其组成与多样性反映了群落的结构类型和存在状态。通过围隔实验,模拟水库春季发生的营养盐加富和鱼类放养的干扰,分析在这两种干扰下的浮游植物群落演替过程中优势种和稀有种的变化,并通过以丰度与生物量为变量的香农和辛普森多样性指数的计算,分析浮游植物群落演替过程中的多样性变化特征。结果表明,营养盐加富干扰下的浮游植物群落的优势种变化和演替更为明显,营养盐加富与鱼类添加对浮游植物群落多样性变化的影响符合中度干扰理论。在优势种优势度变化较大的浮游植物群落演替过程中,多样性指数与浮游植物生物量有较高的负相关性。在浮游植物群落演替过程中,香农和辛普森多样性指数的变化趋势基本一致,采用丰度与生物量为变量的两种多样性指数的计算结果对实验系统中浮游植物群落多样性的分析结果没有明显的影响。     

The Cambrian conundrum: early divergence and later ecological success in the early history of animals

Diverse bilaterian clades emerged apparently within a few million years during the early Cambrian, and various environmental, developmental, and ecological causes have been proposed to explain this abrupt appearance. A compilation of the patterns of fossil and molecular diversification, comparative developmental data, and information on ecological feeding strategies indicate that the major animal clades diverged many tens of millions of years before their first appearance in the fossil record, demonstrating a macroevolutionary lag between the establishment of their developmental toolkits during the Cryogenian [(850 to 635 million years ago (Ma)], and the later ecological success of metazoans during the Ediacaran (635 to 541 Ma) and Cambrian (541 to 488 Ma) periods. We argue that this diversification involved new forms of developmental regulation, as well as innovations in networks of ecological interaction within the context of permissive environmental circumstances.     

白洋淀湿地生态现状评价及保护对策

依据实地调查资料,对白洋淀湿地生态现状进行评价,为湿地生态系统的修复和利用提供基础。评价内容包括水质水量、浮游植物、水生植物、浮游动物、鱼类及鸟类。结果表明:白洋淀水量是影响其水质和生物种群的重要因素;与历史资料比较,白洋淀湿地水量减少、水体污染严重、生物多样性下降;由于近年来的生态补水,白洋淀生态系统得到一定程度的恢复。提出白洋淀湿地生态保护对策:建立稳定的生态补水机制,加大污染源治理力度,建设湿地生态系统恢复工程。     

上海青草沙水库生态护坡区浮游植物的群落结构

2017年上海青草沙水库建设了生态护坡,为探究其对水体浮游植物群落结构的影响,于2018年逐月对该水库生态护坡区和库内对照区的浮游植物群落进行调查比较。共鉴定出生态护坡区浮游植物201种,库内对照区194种,两区域物种达中等相似,且种类组成均为绿藻-硅藻-蓝藻型。生态护坡区和库内对照区优势种以蓝藻门和硅藻门为主,且基本相同,优势度较大的优势种为隐球藻属未定种(Aphanocapsa sp.)、湖泊伪鱼腥藻(Pseudanabaena limnetica)、小环藻属未定种(Cyclotella sp.)和模糊沟链藻(Aulacoseira ambigua)。生态护坡区浮游植物群落密度、生物量年均值依次为(578.46±455.30)×10⁴ cells/L、(1.55±1.03)mg/L,库内对照区依次为(663.46±588.67)×10⁴ cells/L、(1.61±0.98)mg/L,两区域浮游植物现存量无显著差异(P>0.05)。主坐标PCOA分析表明生态护坡区和库内对照区浮游植物群落结构差异不显著(P>0.05)。上述结果...     

陵水湾春秋两季浮游植物群落结构及水质调查

于2019年春、秋两季笔者分别对陵水湾近岸海域浮游植物的种类、群落结构、多样性指数和水质进行调查.结果表明:春、秋两季分别鉴定出浮游植物6门81种和3门53种,均以硅藻居多.春、秋两季优势种各不相同,但均为7种.春、秋两季浮游植物平均细胞密度分别为8.56×103个·m-3和22.81×103个·m-3.春季该海域浮游...     

生态整合与文明发展

探讨了快速发展中“不平衡、不协调、不可持续”问题的生态学成因,总结了社会-经济-自然复合生态系统概念提出30年来理论和方法的研究进展,阐述了生态整合的内涵、方法和将生态文明融入经济、政治、文化和社会建设的各方面和全过程的科学基础、系统方法和整合技术,指出新时期生态学的研究对象正从组分到关系、从物质到信息、从结构到功能、从学苑到社会转型;生态学的研究方法正从测量向测序、寻优向寻适的方向演化.提出社会小康、生态中和、科学大智是生态文明新时代美丽中国的新形象.