Untitled

The functional significance of the dorsal superstructureas a greenhouse for symbionts is consideredas driving the frequent and repetitivetrend to acquire orbitoidiform shell architecture.The structural analysis for the taxonomy in thiswork resulted in validation of the genus NeumannitesRahaghi, 1976, attribution of the speciesIranites ornatus Rahaghi, 1976 to the genusSirtina and introduction of a new species Vanderbeekiacatalana.2008040175大 西 洋 东 部 热 带 现 生 底 栖 有 孔 虫 的 群 落 和 微生 境 - 不 同 生 产 力 的 作 用 结 果 = Communitiesand microhabitats of living benthic foraminiferafrom the tropical east atlantic: impact of differentproductivity regimes. ( 英 文 ). Licari L N;Schumacher S; Wenzhöfer F; Zabel M; MackensenA. Journal of Foraminiferal Research, 2003,33(1): 10-31Living (Rose Bengal stained) benthic foraminiferawere collected with a multicorer fromsix stations between 2°N and 12°S off West Africa.The foraminiferal communities in the investigatedarea reflect the direct influence of differentproductivity regimes, and are characterizedby spatially and seasonally varying upwellingactivity. At five stations, foraminiferal abundancecoincides well with the gradient of surfaceproductivity. However, at one station off theCongo River, the influence of strong fresh waterdischarge is documented. Although this stationlies directly in the center of an upwelling area,foraminiferal standing stocks are surprisinglylow. It is suggested that the Congo dischargemay induce a fractionation of the organic matterinto small and light particles of low nutritionalcontent, by contrast to the relatively fast-sinkingaggregates found in the centers of high productivityareas. Quality and quantity of the organicmatter seem to influence the distribution of microhabitatsas well. The flux of organic carbon tothe sea-floor controls the sequence of degradationof organic matter in sediment and the positionof different redox fronts. The vertical foraminiferalstratification within sediment closelyparallels the distribution of oxygen and nitrate inporewater, and reflects different nutritive strategiesand adaptation to different types of organicmatter. The epifauna and shallow infauna colonizeoxygenated sediments where labile organicmatter is available. The intermediate infauna (M.barleeanum) is linked to the zone of nitrate reductionin sediments where epifaunal and shallowinfaunal species are not competitive anymore,and must feed on bacterial biomass or onmetabolizable nutritious particles produced bybacterial degradation of more refractory organicmatter. The deep infauna shows its maximumdistribution in anoxic sediments, where no easilymetabolizable organic matter is available.2008040176凯 尔 特 海 底 栖 有 孔 虫 的 分 布 - 海 水 季 节 性 分层 作 用 的 重 要 性 = The distribution of benthicforaminifera in the Celtic sea:the significance ofseasonal stratification. ( 英 文 ). Scott G A;Scourse J D; Austin W E N. Journal of ForaminiferalResearch, 2003, 33(1): 32-61Seasonal stratification is an important phenomenonin tidally-stirred shelf seas, influencingbiological productivity, sedimentation rates, theorganic content of shelf sediments, and the climateof surrounding landmasses. Previous micropaleontologicaland stable isotopic investigationinvestigation of a Holocene sequence fromthe Celtic Sea suggests that benthic foraminiferaldistributions are linked to the physical and biologicaloceanographic characteristics associatedwith stratification. We have tested this hypothesisby analyzing the living and dead foraminiferalfaunas from surface samples collected duringacross-frontal cruises during the summers of1995 and 1996. Foraminiferal and environmentaldata for 56 samples are presented. Live and deadforaminiferal data were analyzed by factoranalysis and, along with the environmental data,canonical correspondence analysis (CCA). Fourdistinct assemblages were identified from factoranalysis of the live data: (1) a frontal assemblagecharacterized by Stainforthia fusiformis, (2) amixed water assemblage characterized by Cibicideslobatulus, Textularia bockii, Spiroplectamminawrightii, Ammonia batavus and Quinqueloculinaseminulum, (3) a stratified assemblagecharacterized by Bulimina marginata,Hyalinea balthica, Adercotryma wrighti andNonionella turgida, and (4) an eastern assemblagedominated by Bulimina gibba, Elphidiumexcavatum and Eggerelloides scaber. Factoranalysis of the dead data reproduces all groupingsexcept the frontal assemblage. These datatherefore support interpretations based on earlierstratigraphic data, and highlight the significanceof benthic foraminifera as faunal indicators ofpaleostratification in shelf seas. The distributionsalso support predicted cross-frontal transfer ofnutrients and the existence of surface convergingcirculation cells. Statistical analyses indicate thesignificance of unmeasured ecological variableswhich we speculate might be food supply, andoxygen concentration of bottom and sedimentpore waters.2008040177苏 格 兰 西 部 大 陆 架 沉 降 区 的 有 孔 虫 组 合 的 形成 = Foraminiferal assemblage formation in depositionalsinks on the continental shelf west of55