The Impact of Some Environmental Factors on the Distribution of the Benthic Ostracod Species from of Safaga Island, Red Sea, Egypt

The benthic ostracods of Red Sea of Egypt have received little attention in ecological studies. Temperature, depth, salinity, dissolved oxygen, pH, conductivity, and other environmental variables all have an impact on benthic ostracods. This study aimed to determine the influence of environmental parameters on the distribution of benthic ostracods by determining the similarity and dissimilarity between the eight collection sites, investigating the regional distribution form by accomplished Multidimensional Scaling (MDS), and recognizing the percentage of the influence of each species on the resemblances and variances within the clusters formed by SIMPER analysis, determining the relationships between depth and other factors by Spearman’s rank correlation coefficient. A total of 43 ostracod species had been identified. According to the frequency index, a single species was rare, six were common and the remaining species (36) were dominant. Seven ostracods species were found across all sites and Cytherelloidea sp. was found in two. The abundance and richness of ostracod species were correlated positively with water temperature, dissolved oxygen, organic matter, salinity, and calcium carbonate. The cold water is preferred by the ostracods Cylindroleberis vix and Prionotoleberis lux and the warm water is favored by podocopid ostracods. The findings of this study will aid in the identification of ostracod species, as well as understanding the characteristics and ecological variables in this zone of the Red Sea in Egypt. The current investigation is an attempt to shed the light on the features of ostracods that live on the east side of Safaga Island.

Analysis on the indicator species and ecological groups of pelagic ostracods in the East China Sea

Ecological adaptation and ecological groups of pelagic ostracods were examined in the East China Sea （23°30′-33°00′N, 118°30′ -128°00′E）, in relation to temperature and salinity. The data were collected in four surveys conducted from 1997 to 2000. The density, yield density, or negative exponent models were used to determine the optimal temperature and salinity of water for the thriving growth of pelagic ostracods. Thereafter, ecological groups and potential distribution patterns of pelagic ostracods were determined based on the predicted parameters such as optimal temperature and salinity, consulting the geographic distribution. The analytical results indicate that, among the numerical dominant pelagic ostracods in the East China Sea （ECS）, Euconchoecia aculeata, E. elongata, E. chierchiae, E. maimai, and Cypridina dentata, etc. are offshore subtropical water species. These species are widely distributed in the area, and they can be brought by the warm current to north offshore during spring and winter. The predicated optimal temperature （OT） and optimal salinity （OS） for Paraconchoecia decipiens, P. echinata, P. spini- fera, P. oblonga, Conchoecia magna and Porroeciaporrecta are all greater than 25℃ and 34 separately. These species are mainly distributed in the waters of the Kuroshio, the Taiwan Warm Current, and the Taiwan Strait, and therefore are designated as ocean- ic tropical water species. On the other hand, Pseudoconchoecia concerttrica is considered as offshore subtropical water species based on its geographical distribution although its OT is 19℃. The other species, though their OSs are approximately 34 and with OTs ranging from 20° to 25℃, are considered as offshore subtropical water species because they were found to be widely distributed from the South China Sea to the East China Sea.

Ostracod Biostratigraphy of the Late Cretaceous Qingshankou Formation in the Songliao Basin

An ostracod biostratigraphic study was performed on 425 samples from the composite geological section constructed by using cores taken from five selected wells drilled in the Late Cretaceous Qingshankou Formation in the Songliao basin. A total of 19 ostracod zones are established in the formation, of which 3 are newly established and 3 are revised. The 19 ostracod zones are described in detail. This study provides a basis for the detailed stratigraphic division and correlation of the Qingshankou Formation and the Gaotaizi oil reservoir in the oilfield in the Songliao basin.

Ostracod assemblages and their environmental significance from the lake core of the Nam Co on the Tibetan Plateau 8.4 kaBP

A 332-cm long lacustrine core was drilled in the Nam Co in the central-southern part of the Tibetan Plateau. From the core, 15 species of ostracods （Crustacea： Ostracoda）, which belong to 6 genera have been identified. According to the variations of the ostracod assemblages and the ostracods ecological features, which are sensitive to the changing environment, three main stages can be distinguished as follows： Stage Ⅰ was from 8400 to 6800 a BP, during which the climate was cold-humid, and the lake depth changed from shallow to deep. Stage Ⅱ was from 6400 to 2500 a BP, during which the climate changed from warm-humid to cold-humid, and then to cold-dry. The lake depth gradually became deep. The shifting of climate, from wet-cold to dry-cold during this period, had constructed the basis of present environment in the Nam Co. Stage Ⅲ was from 2500 a BP to the present, which showed a trait of lake depth increasing. At the earlier period of this stage, the climate kept as cold-dry as that in the former stage, but the salinity of the lake increased. At the later period of this stage, the degree of cold-dry was enhanced, and the activities of land surface runoff tended to be weakened. Our research also found that the peak values of ostracods with black shell was coherent with the maximum production of the ostracods, and agreed with the increasing sedimentary water dynamics. This indicated that the ostracods with black shell was simulta- neous with the high prolificacy of ostracod, and transported from other places. The abun- dance of Candonajuvenile shells reflected the high mortality of that kind of ostracods under an unfavorable condition. This was probably a result of the rapid change of water dynamics of sedimentary environment.

CCA Inferred Environmental Implications of Common Ostracods on the Qinghai-Tibetan Plateau

103 surface sediment samples in 71 water bodies, such as lakes with different salinity, swamps, shallow puddles and rivers on the Qinghai-Tibetan Plateau （QTP）, were collected to study the ecological distribution of living ostracods and their environmental implications. Total of 12 genus and 45 species living ostracods are identified. According to the frequencies and abundance of ostracods occurrence, Limnocythere dubiosa, Limnocytherellina kunlunensis, llyocypris bradyi, Candona candida, Eucypris rischtanica and Leucocythere dilatata are the common species on the QTP, with occurrence frequency of more than 8 and abundance of more than 570 in the 71 water bodies. Among them, L. dubiosa, occurring in 28 water bodies with 2177 shells, is the most widely distributed ostracod in this research. Canonical Correspondence Analysis （CCA） indicates high correlation between species and environmental variables, suggesting that the occurrence of species is strongly related to the changes in ecological conditions of habitats. Among eight environmental factors, salinity and pH value are the most affective variables that influence the species occurrence. L. kunlunensis is positively correlated with salinity while E. rischtanica is negatively correlated with salinity. C. candida has a positive correlation with salinity, as does I. bradyi although there is not such a strong correlation. L. dubiosa displays a positive correlation with pH value. Consequently, we discuss the environmental implications of the common living ostracods on the QTP based on the CCA as well as the distribution of ostracod species in different salinity and pH values water. L. dubiosa, L. kunlunensis and E. rischtanica are euryhaline species, among which, L. dubiosa is the most adaptable species on the QTP with large occurrence in sundry salinity water and the most widely adaptive range for pH values. L. kunlunensis prefers to saline water while E. rischtanica prefers to fresh water. Both L. kunlunensis and E. rischtanica can live in water from faintly acid to alkaline, in contrast, L. dubiosa only appears in neutral and alkaline water bodies. L bradyi only occurs in fresh water and oligohaline water with a large pH tolerance range tolerance range from weakly acidic water to alkaline water weakly acidic water to alkaline water. C. Candida lives in freshwater, with pH value above eight. The six common species reach maximum abundance in alkaline water （pH 8-10） except for llyocypris bradyi.

东海浮游介形类(Ostracods)分布特征

根据1997-2000年东海（23°30’～33°00’N，118°30’～128°00E）海域四季海洋调查资料，探讨了东海浮游介形类分布特征及与环境的关系．结果表明：东海浮游介形类丰度占浮游动物总丰度的3．47％；春、夏、秋和冬四季平均丰度分别为0．70，1.72，2．57和0．90个／m^3；冬春季的短棒真浮萤（Euconchoecia chierchiae），夏季的后圆真浮萤（Euconchoecia maimai）和秋季的齿形海萤（Cypridina dentata）分别是各季的主要优势种；夏、秋季介形类总丰度与水文环境因子的线性相关性不显著，春季与表层盐度相关，冬季与表层温度相关．东海北部外海四季均有介形类高丰度区出现，但在东海北部近海长江口及其邻近舟山水域，介形类数量相对较低．在东海南部，冬春季高丰度区位于外海，夏秋季在近海．东海浮游介形类基本上是一大类较为典型的暖水性且具有集群行为的海洋浮游动物．介形类秋季高丰度区和较高丰度区的分布与太平洋褶柔鱼（Todarodes pacificus）、绿鳍马面鲀（Navodon SPptentrionalis）、鲐鯵鱼类等渔场的位置基本一致，在渔业上有重要的意义．

Ostracodes from Recent Surface Deposits in Tibet,Response to Environmental Changes

1 Introduction Ostracodes are good materials for studying palaeoenvironmental evolution because of their sensitive response to environment changes.At present,the environmental implications of ostracodes are mainly based

Distribution and Taxonomy of Shallow Marine Ostracods from the Western Coast of the Red Sea, Egypt

A total 5849 individuals of ostracods constituting twenty species were collected from five shallow marine sites along the area from El-Quseir to Marsa Alam on the West Coast of the Red Sea. The twenty ostracod species belonging to sixteen genera and ten different families. The three genera;Loxoconcha, Neonesidea and Xestoleberis have high species diversity. Furthermore, the species Loxoconcha ghardaqensis, Xestoleberis rotunda, Paranesidea fracticorallicola, Tanella gracilis and Neonesidea schulzi were the best recognized in the collecting region. Otherwise, the distribution of the collected ostracod species in relation to environmental variables and plants were discussed in detail here. Based on this, it is concluded that, vegetation type appears to be the most important factor controlling the distribution of ostracod species in the investigated area. Also, other factors such as, water temperature, salinity, dissolved oxygen, pH and electrical conductivity play an important role. Scanning electron microscope images of valves are delivered of the recorded taxa. These fauna displays close affinities to those of the Red Sea and the Indo- Pacific region.

Ostracodes(Crustacea) Witnesses of Paleoenvironmental Changes During Permian-Triassic Boundary Events in South China and Turkey

The transition between Permian and Triassic(252.4 Ma) is marked by the most devastating extinction the biosphere ever went through.Although its cause stays unclear,it is admitted that this mass extinction originated in the conjunction of several global events: tectonic(Pangaea closing),volcanic(Siberian traps), magnetic(reversal of superchron),climatic(end of Permian glaciation) and eustatic(tecto-and ther-

Cretaceous-Eogene Ostracod Assemblages in Henan and Their Evolutionary Features

This paper studies a large number of Cretaceous-Eogene ostracod fossils in the Meso-Cenozoic Nanyang, Zhoukou, Rendian, Luoyang, Lingbao, Tantou and Kaifeng basins of Henan. Eight ostracod assemblages have been recognized. This paper discusses their geographical distribution and geological ages as well as their features and evolutional trends. Besides, it also deals with the palaeoclimate under which the various assemblages lived and the significance in petroleum exploration.

A restudy of ostracode assemblages in the surface sediments of the Huanghai Sea

Distribution pattern of ostracodes in the western part of the Huanghai Sea was re-analyzed using the occurrence data of 142 species from 175 surface sediment samples. The high values of ostracode speimen density are generally restricted to depths shallower than 40 m. The species diversity H(S) is higher in the southern part and lower in the northem part of the area studied, the trend which is correspondent to the change of water temperature in the Huanghai Sea. In the area where radial tidal sands is distributed, H(S) reaches its maximum average value.Six ostracode biofacies were delineated using Q-mode factor analysis, based on the data of 77 samples and 69 species. Their distributions are correspondent with environmental parameters such as water temperature, salinity and substrate type.Through tracing the geographical distribution of ostracode species in the Huanghai Sea and the East China Sea, it is reconfirmed that the discontinuity of species distribution between the two areas, located at around 32N, coincides with the boundary of subtropical/warm temperate zones of China seas.

Middle Jurassic—Tertiary Deposits and Ostracod—Charophyte fossil assemblages of Xining and Minhe Basins

The Xining and the Minhe Basins bordering on each other around Ledu innorthwestern China cover a wide area from the west of Lanzhou in Gansuprovince to the east of Xining in Qinghai province.In these inland basins,Meso-Cenozoic terrestrial deposits about 6000-7000 meters in thicknessand rich in mineral resources,such as coal,oi1 as well as salts,had beenaccumunated,which yield abundant organic remains comprising microfossils,such as nonmarine ostracods,charophytes,spores and pollen and macrofos-si1s including bivalves.gastropods,esthierians,fishes,reptiles and plants.

Ostracod texa first described in English

1982 Minheella,Song Qishan et al,Symposium on Petroleum Geology,4,92—93. Type species:Minheella minheensis Song et Cheng(pl.21,figs.9-12) Diagnosis:Carapace large,lateral view subelliptical,subrectangular orovate.Left valve larger than right,overlapping the latter along dorsal andventral margins.Posterior ends of two valves asymmetrical,that of leftvalve swollen or node like,pointed post-laterally.The swollen part separa-ted from the carapace margin by a shallow furrow.In some species posteriorend of right valve overlaps that of left valve.Inner lamella moderately wide.

A TAXONOMICAL AND ECOLOGICAL OVERVIEW OF RECENT AND HOLOCENE OSTRACODES OF THE NAM CO REGION, SOUTHERN TIBET

We present a list of living and (sub) fossil Ostracoda (Crustacea) from Holocene sediments from Lake NamCo,Southern Tibet, including descriptions, distribution and ecological data of the important taxa from the Nam Cocatchment. Species associations from lake surface sediments, sediment cores and outcrop samples consist of eight speciesincluding Candona candida ( O.F. Müller, 1776 ) , Candona xizangensis ( Huang, 1982 ) , Eucypris afghanistanensis( Hartmann, 1964) , Fabaeformiscandona danielopoli ( Yin & Martens, 1997 ) , Ilyocypris cf. mongolica ( Martens, 1991 ) ,? Leucocythere dorsotuberosa ( Huang, 1982 ) , Leucocytherella sinensis ( Huang, 1982 ) and Limnocythere inopinata ( Baird,1843). The dominant species are ? L. dorsotuberosa and L. sinensis. They show morphological variations with different degreesof ornamentation. We regard the variable noding and rib formation as intraspecific variability possibly driven byenvironmental factors. In general,the number and degree of ribs increases with water depth in ? L. dorsotuberosa. Thus,theornamentation may present a means to reconstruct(paleo) water depths. Our list is intended to serve as a taxonomical andpaleoecological primer for future paleolimnological work.

Middle Devonian ostracods from Jiwozhai patch reef(Dushan,Guizhou Province,South China):Biostratigraphic and palaeoecological implication

The Middle Devonian ostracods from the Jiwozhai patch reef in Dushan, Guizhou Province, South China were described for the first time in this study. Twenty-nine species belonging to 20 genera were identified and figured, including a new species named Wangshangkia jiwozhaiensis sp. nov. The ostracod fauna in the Jiwozhai patch reef represents a Givetian age. The ostracod assemblage belongs to the smooth-podocopid association, which is also ecologically equivalent to the Eifelian Mega-Assemblage Ⅲ. This association is indicative of shallow open-marine environments. The Jiwozhai patch reef fauna is primarily comprised of suspension feeders, including filter-feeding ostracods, corals, brachiopods and bryozoans. Ostracods from the Jiwozhai patch reef were compared to the ostracod faunas from Laurentia-Baltica at generic level, which reveals limited faunal exchanges between South China and Laurentia-Baltica during the Middle Devonian.

Global paleobiogeography of Albian—Cenomanian(mid-Cretaceous)marine ostracods

Despite their potential for providing important information for paleobiogeography,studies using ostracod assemblages compiled from global datasets have been scarce so far.In this study,the paleogeographic implications of the relationship between different ostracod assemblages are analyzed and discussed for the Albian and Cenomanian.We compiled an ostracod dataset at the genus level,with 168 genera for the Albian and 174 for the Cenomanian,to which different multivariate statistical methods of grouping were applied.The affinity between different ostracod assemblages from different regions allowed for the delineation of 30 operational geographic units(OGUs)for the Albian,and 32 OGUs for the Cenomanian,grouped in three paleobiogeographic units(PBUs;Megatethys,Persia,and Austral)and one sub-unit(PBSU;Maghreb associated to the Megatethys).The Maghreb PBSU showed minor changes between the Albian and Cenomanian.The relationship among the OGUs grouped in each PBU is related to different factors,such as eustatic sea level events,similar climatic zones,and marine current circulation patterns.A relationship was observed between the Gabon and Nigeria OGUs with the Persia PBU,which suggests a direct east—west connection between them during the Cenomanian.The affinity observed in the Austral PBU between the South American,South African,and Australian regions during the Albian can be explained by their relative geographic isolation due to the Walvis Ridge barrier.The eventual flooding of this barrier led to the relationship observed between the SE Brazilian and Bolivian regions with the Austral PBU.Finally,the data also suggested that the separation of the Indian subcontinent from the Austral PBU took place during the Cenomanian.

中全新世福建沿海地区海平面波动:基于NDQK5岩芯介形类化石记录

福建沿海地区第四系较为发育,是研究晚更新世以来相对海平面变化的理想区域。本文以福建宁德NDQK5岩芯中产出的高分辨率介形类化石为研究对象,结合加速器质谱法(accelerator mass spectrometry,AMS)14C和光释光测年技术建立岩芯年代框架,重建了中全新世期间福建沿海地区的相对海平面变化。结果显示,NDQK5岩芯中的介形类化石记录主要分布于4~17.1 m段,对应年代约为8.2~6.9 ka BP。岩芯内共计识别出海相介形类23属26种,根据优势种以及特征种的相对丰度变化特征可将岩芯内的介形类动物群划分为3个组合:①介形类组合A以Bicornucythere bisanensis和Sinocytheridea impressa为主,代表潮下带环境;②介形类组合B以Sinocytheridea impressa和Neomonoceratina delicata为优势种,指示近岸内陆架的沉积环境;③介形类组合C以Sinocytheridea impressa和Loxoconcha ocellifera为主,代表潮间带的沉积环境。基于介形类组合的分布特征,本文推断福建沿海地区海平面约在8.2~7.4 ka BP期间持续上升,并在约7.9~7.4 ka BP区间达到最高;7.4~7.0 ka BP期间海平面下降,随后再次上升。因此,介形类化石记录指示福建沿海地区在全新世高海平面背景下依然存在相对海平面的次一级波动。同时,结合已有福建沿海地区海平面变化驱动机制的研究结果,本研究推断8.2~7 ka BP期间福建沿海地区的海平面变化可能主要受控于冰盖融水;7 ka BP后该地区的海平面波动可能受控于“冰川-水均衡调整”作用。

Constraints of authigenic carbonates on trace elements (Sr,Mg) of lacustrine ostracod shells in paleoenviron-ment reconstruction and its mechanism

Molar ratios of Mg/Ca and Sr/Ca were measured in two species of ostracod shells preserved in the upper core (15–55 m) of the Hequing Basin in Yunnan Province, southwest China. By correlating the molar ratios between Mg/Ca and Sr/Ca and comparing them with Sr concentrations of the sediments, we suggested that: (1) the molar Mg/Ca and Sr/Ca ratio variations in respective ostracod primo reflected the changes in its ambient water composition and ecology; (2) the molar Sr/Ca ratios responded better to the salinity change linearly than Mg/Ca without aragonite precipitation in the system, and otherwise there was no linear relation between them; and (3) the molar Sr/Ca ratios were mainly controlled by salinity and authigenic carbonate precipitation, whereas the molar Mg/Ca ratios were related to both salinity and temperature. In fact, the rate of ostracod growth owing to temperature controls the fluctuation of Mg/Ca in shells. Here, more attentions should be paid to the constraint of authigenic mineral precipitation processes on the trace elements in ostracod shells and to the correlation between these trace elements in biogenic carbonates and compositions of the sediments in systems and in future in vitro experiments.

Ostracod fauna across the Permian-Triassic boundary at Chongyang, Hubei Province, and its implication for the process of the mass extinction

Thirty species of 10 ostracod genera were identified from 440 fossil specimens isolated through the hot acetolysis of the rock samples collected across the Permian-Triassic boundary at Chongyang section. Twenty species of 6 genera are found to occur in the limestone of Changxing Formation, and 11 species of 7 genera above the main faunal mass extinction horizon. The os-tracod assemblages identified at the Chongyang section are obviously different from those previously reported in the contem-poraneous microbialites in Guangxi and Chongqing regions, not only in the ostracod components but also in the abundance of filter-feeding ostracods relative to the deposit-feeding ostracods, an indicator of the oxygen level of the seawater. This spatial difference in ostracod assemblages might reflect the diversity of oceanic environmental conditions after the end-Permian mass extinction. Ostracods disappear at 200 cm below and near the main mass extinction horizon, and on the top of the microbialites, respectively, showing an episodic and gradual collapse process at the Chongyang section. The carbon isotope composition is found to appear at 200 cm below the main mass extinction horizon, indicating the initial deterioration of oceanic environment. Fluctuation of the carbon isotope composition is obviously related with the episodic evolution of ostracod species, but not with the abundance of ostracods.

First record of ostracods from the Upper Ordovician red-coloured marine sandstones of the Tierekeawati Formation in Tarim Basin, NW China: implications on palaeoenvironment and palaeobiogeography

Ostracods are described for the first time from the red-coloured marine sandstones of Arisu section(Arisu red beds)of the Upper Ordovician Tierekeawati Formation in Kalpin area of northwestern Tarim Basin, Xinjiang Uygur Autonomous Region(Xinjiang), Northwest China. Twenty-two species belonging to thirteen genera are described and figured. The ostracod fauna suggests a probable Sandbian–Katian age for these beds. The palaeoecological assemblage of ostracod fauna implies the deposition in a nearshore-offshore environment during a regression when the Arisu red beds of the Tierekeawati Formation were laid down in the Tarim Basin. Many cosmopolitan and provincial genera were present in diversified ostracod fauna of the Arisu red beds, suggesting the possible biogeographic relationships among the Tarim, Tibet, and South China plates, as well as Europe and North America continents during the Late Ordovician. Ostracods experienced faunal exchanges between Laurentia and the Tarim Plate during the Late Ordovician Period.