Fossil mollusc-faunas: Their bearing on the Holocene evolution of the Lower Central Plain of Bangkok (Thailand)     

Mauro Pietro Negri   《Journal of Asian Earth Sciences》2009,35(6):524-544

In this work, fossil molluscan assemblages are analyzed in order to reconstruct the evolution of the Northern Gulf of Thailand during the Holocene. The marine sediments (Bangkok Clay Formation) of the Lower Central Plain of Bangkok and the coastal plain of Phetchaburi were sampled at 16 localities, obtaining fossil shells and mangrove peat whose ¹⁴C ages range from 9000 to 2000 CYBP. A statistical treatment of abundance data returned four major groups, namely the Dendostrea rosacea association (intertidal mud), the Corbula fortisulcata–Mactra luzonica association (shallow infralittoral sandy mud), the Nuculana mauritiana–Timoclea scabra association (infralittoral sand spit) and the Timoclea scabra–Arcopagia pudica association (infralittoral mud). The data allowed both a stratigraphic correlation along two transects covering all of the Holocene basin and the creation of digitalized maps showing the presumable extension of the Thai paleogulf around the apex of Flandrian transgression event (about 5500 CYBP).  相似文献   

蜑螺属Nerita几个混淆种的比较研究(腹足纲, 珍珠蜑螺目, 蜑螺科)*     

陈志云  连喜平  谭烨辉 《热带海洋学报》2018,37(3):73-79

蜑螺科 Neritidae 蜑螺属 Nerita 的一些种类形态近似, 形态鉴定上存在种类混淆、同物异名或错误鉴定等现象。作者在整理中国科学院南海海洋生物标本馆和中国科学院海洋生物标本馆历年来采集的蜑螺科标本时, 对4种隶属于蜑螺属的易混淆种进行了比较研究。通过对标本的反复对比, 分别找出了它们之间外部形态、地理分布以及生活习性方面的差异, 澄清了混淆, 确立了其分类地位: 1) 矮狮蜑螺Nerita chamaeleon Linnaeus, 1758和圆蜑螺Nerita histrio Linnaeus, 1758两者贝壳形态相近, 在我国海区分布重叠, 存在混淆以及错误鉴定的现象, 根据螺旋部以及壳面雕刻可将它们区分开, 即前者壳面螺肋光滑, 后者螺肋粗糙, 而前者螺旋部较后者高; 2) 锦蜑螺 Nerita polita Linnaeus, 1758和杂色蜑螺 Nerita litterata Gmelin, 1791两个种常被混淆在一起, 都鉴定为锦蜑螺, 前者在我国见于台湾、海南岛和西沙群岛, 后者在我国见于台湾、福建、广东、广西和西沙群岛, 其中杂色蜑螺此前在我国仅见于台湾, 本文的报道进一步完善了该种的地理分布信息。  相似文献   

Three new species of Genus Cryptonatica (Gastropoda, Naticidae) from Huanghai Sea Cold Water Mass     

ZHANG Suping  WEI Peng 《海洋学报(英文版)》2010,29(1):52-57

This report based on the results of investigations conducted in June 2007 and July 2008, respectively, on the benthic community structure and characteristic diversity of the Huanghai Sea (Yellow Sea) Cold Water Mass, as well as that in July 1959 during the national oceanic survey. The Naticidae specimens collected from Cold Water Mass in middle and northern Huanghai Sea were studied through morphological classiˉcation and the internal anatomy on radula. Three new species of Naticidae, i.e., Cryptonatica purpurfunda sp. nov., Cryptonatica sphaera sp. nov., and Cryptonatica striatica sp. nov. were identiˉed. The morphological characteristics of the new species are described, and the similarties and di?erences between the new species and similar species are compared and discussed.  相似文献   

Nassarius corniculus (Olivi, 1792) (Caenogastropoda: Nassariidae): a model of environmental complexity of Italian brackish and marine habitats     

Maria Alessandra Iannotta  Francesco Toscano  & Francesco Paolo Patti 《Marine Ecology》2009,30(1):106-115

Strong environmental selection may give rise to complex species and/or camouflage the presence of sibling species in brackish waters. The prosobranch gastropod Nassarius corniculus (Olivi, 1792) is a common scavenger widely distributed in Mediterranean brackish and marine areas. We examined the morphological and molecular features of N. corniculus populations and related these features to the environmental complexity of brackish habitats. Morphological data revealed differences in radular features between specimens collected from two Mediterranean lagoons (Lake Faro, Messina, Sicily and Lake Fusaro, Gulf of Gaeta). Analysis of with the mitochondrial marker mt 16S rRNA revealed genetic variability within the Lake Faro population but did not show the different geographic structure between the two lagoons indicated by morphological data. We also predicted the gene flow of N. corniculus by comparing populations of two marine areas (Faro Sea and Ischia).  相似文献   

Changes in the faunal composition of two thermal streams near Taupo,New Zealand     

M. James 《新西兰海洋与淡水研究杂志》2013,47(4):439-443

The distributions of macroinverte‐brates in two thermal streams near Taupo were examined and compared with observations made in 1966. The cooling of the streams associated with abstraction has altered the species composition. Odonata and Trichoptera were recorded for the first time in the lower reaches of the Waipahihi Stream whereas Ephydridae and Hydrophilidae were restricted to the upper reaches at temperatures above 33.5°C. Molluscs dominated the fauna at sites with temperatures below 33.5°C in the Waipahihi and Waipuwerawera Streams. Potamopyrgus anti‐podarum was present at sites with temperatures below 28°C.  相似文献   

中国近海玉螺科的研究 Ⅱ.窦螺亚科     

张素萍  马绣同 《海洋科学集刊》1997,(39):1-7

窦螺亚科(Sininae)隶属于软体动物、前鰓亚纲、中腹足目、玉螺科。此亚科在全世界海洋中约有50种,在国内尚无系统地研究过,仅有一些零星报道。作者根据中国科学院海洋研究所及前北京动物研究所收集的标本资料,经整理鉴定,共有11种(其中有1种未定出种名),分隶于2属,其中3种在我国为首次报道。  相似文献   

Contamination patterns and molluscan and polychaete assemblages in two Persian (Arabian) Gulf oilfields          下载免费PDF全文

Paolo G. Albano  Nadezhda Filippova  Jan Steger  Hannah Schmidbaur  Adam Tomašových  Michael Stachowitsch  Martin Zuschin 《Marine Ecology》2016,37(4):907-919

This study examined two shallow‐water, offshore oil facilities and their surroundings in the Umm Al Dalkh and Zakum oilfields [United Arab Emirates, Persian (Arabian) Gulf]. The focus was on sediment contamination levels and the detection of disturbance based on two representative invertebrate components of the benthos: molluscs and polychaetes. We tested the hypothesis that significant disturbance to the community has occurred, by examining whether distance from the platform or variation in contaminants explains among‐site variation in the composition of benthic communities. Moreover, we also tested the hypothesis that organic enrichment because of oil input has modified the feeding guild structure by examining whether the relative abundances of filter‐feeders, deposit‐feeders and omnivores are correlated with distance from the platform or with contamination by hydrocarbons. The contamination levels and their spatial distribution in the sediments differed significantly between the two fields, as did their mollusc and polychaete communities. The within‐field variability, however, was much lower: no clear structuring of contamination values and species composition and abundance was detectable in relation to distance from the oil platform. Contamination levels were low, often below detection levels or international guideline values. Variation in contaminant concentrations did not explain variation in taxonomic composition and abundance. The relative abundance of the above‐mentioned feeding guilds did not correlate with either distance from the platform or with contaminant concentrations. These patterns may reflect the long time that has elapsed since drilling (15–20 years), which appears to have allowed contaminants to disperse and degrade and assemblages to recover from the impact, if indeed such a disturbance ever occurred. In contrast to low values of barium and total petroleum hydrocarbons, associated with well drilling, some metals were at their highest concentrations beneath the central platforms. This suggests that production‐related activities (including platform cleaning and maintenance) are currently a more relevant contamination source.  相似文献   

Palaeontology and taphonomy of Late Quaternary fossil assemblages at Somersham,Cambridgeshire, England,and the problem of reworking     

Richard G. West  Karen L. Knudsen  David N. Penney  Richard. C. Preece  J. Eric Robinson 《第四纪科学杂志》1994,9(4):357-366

Assemblages of foraminifers, ostracods and molluscs from temperate Ipswichian Stage (last temperate stage) sediments and overlying cold Devensian Stage (last cold stage) sediments at Somersham in the southern Fenland of Cambridgeshire have been analysed. The Ipswichian sediments contain faunas consistent with temperate brackish water conditions under tidal influence. The Devensian assemblages were recovered from a series of sands and gravels laterally accreting in a channel cutting into Ipswichian sediments. In contrast to the Ipswichian faunas, the faunas of particular Devensian samples show a complex mixture of temperate freshwater, brackish and marine taxa. The molluscs are mainly freshwater, with few land snails; they occur together with foraminifers and ostracods. Freshwater, brackish water and marine ostracods are present with foraminifers. A sample of Devensian fine laminated sediment in the channel was analysed for pollen; only abundant pre-Quaternary spores were present, with abundant foraminifers in the same sample. The taphonomy of the assemblages and the difficulties of their interpretation in environmental terms are discussed. The importance of taphonomy in assessing environments, climate, range of taxa and dating is stressed.  相似文献   

Molluscs in Kongsfjorden (Spitsbergen, Svalbard): a species list and patterns of distribution and diversity     

Maria W&#;odarska-Kowalczuk 《Polar research》2007,26(1):48-63

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Evidence for rapid avian-mediated foraminiferal colonization of Lake Winnipegosis, Manitoba, during the Holocene Hypsithermal     

R. Timothy Patterson  W. Brian McKillop  Sid Kroker  Erik Nielsen  Eduard G. Reinhardt 《Journal of Paleolimnology》1997,18(2):131-143

A Holocene ecological succession was documented using palynological, foraminiferal, and molluscan faunas sampled from an excavated trench on the margin of Bell River Bay, Lake Winnipegosis, Manitoba. The palynological data record the known gradually isostatically-induced shift from aquatic to terrestrial conditions at the site, and clearly delineates the Holocene Hypsithermal maximal warm interval (commencing here about 5500 years BP). Concurrent with this warming the site became occupied by the extinct salt tolerant gastropod Marstonia gelida and the marine foraminifer Cribroelphidium gunteri by at least 5430 years BP. Water fowl-assisted colonization of non-marine habitats by foraminifera has previously been suggested as a dispersal mechanism for other non-marine foraminiferal occurrences. However, as this relatively warm-water foraminifer (presently found as far north as Cape Cod, MA on the Atlantic USA coast, and Vancouver, BC on the Canadian Pacific coast but also found in Canadian Maritime provinces during the Hypsithermal) did not inhabit the area either prior to or following the Hypsithermal warm interval, this occurrence indicates the efficiency with which foraminifera can utilize non-selective avian transport to colonize new non-marine and marine habitats. It may be that only a few years were required for colonization of the site to occur (2000–3000 km distant from native populations); this suggests that avian transport is a much more important foraminiferal dispersal mechanism than previously realized. The appearance of foraminifera at this site may also constrain models designed to determine the time required for hydraulically injected glacial freshwater to be flushed from normally brine producing aquifers in the region.  相似文献