An endemic freshwater mussel species from the Orontes River basin in Turkey and Syria represents duck mussel’s intraspecific lineage: Implications for conservation     

《Limnologica》2020

Amik Lake or, historically, Lake of Antioch, was a large freshwater body in the lower Orontes River basin (Hatay Province, Turkey) that was drained in the 1940s–1970s. Several endemic animal species were described from this lake, including the freshwater mussel Anodonta pseudodopsis Locard, 1883 (Bivalvia: Unionidae) characterized by a large rounded shell covered by a peculiar yellow or yellowish-brown periostracum. Molecular analyses of topotypes of this nominal taxon collected from the former lake’s tributaries in the Amik Plain indicate that it is an intra-specific lineage of the widespread Anodonta anatina (Linnaeus, 1758) based on the mitochondrial COI and 16S rRNA, and the nuclear 28S rRNA gene fragments. Geometric morphometric analyses using the lectotype and topotypes of Anodonta pseudodopsis support our DNA-based hypothesis on the status of this nominal taxon. A new synonymy is provided as follows: Anodonta anatina = Anodonta pseudodopsis syn. nov. The syntype of Anodonta pseudodopsis SMF 5129 “See von Antiochia” (Senckenberg Research Institute and Natural History Museum, Frankfurt, Germany) is designated here to be the lectotype of this nominal taxon. Finally, we conclude that Anodonta anatina range covers the Orontes River basin in Turkey and Syria and the Nahr al-Kabir al-Shamali River in the Latakia Governorate of Syria. This intraspecific lineage of Anodonta anatina and other freshwater mussels of the Middle East are highly threatened due to multiple anthropogenic impacts and must be a focus of international conservation efforts. The Karasu River in eastern Turkey hosts viable populations of all freshwater mussel species of the Orontes’s fauna and can be considered one of the most important water bodies for the conservation of these imperiled animals in the region.  相似文献   

Peak discharge increase in hyperconcentrated floods     

《Advances in water resources》2014

The peak of river floods usually decreases in the downstream direction unless it is compensated by freshwater inflow from tributaries. In the Yellow River (China) the opposite is regularly observed, where the peak discharge of river floods increases in the downstream direction (at a rate far exceeding the contribution from tributaries). This flood peak discharge increase is probably related to rapid morphological changes, to a modified bed friction, or to a combination of both. Yet the relative role of these processes is still poorly understood. This paper aims to analyze the relative contribution of bed erosion and friction change to the peak discharge increase, based on available data and a recently developed numerical model. Using this high-resolution, fully coupled morphodynamic model of non-capacity sediment transport, two hyperconcentrated floods characterized by downstream peak discharge increase are numerically reproduced and analyzed in detail. The results reveal that although erosion effects may contribute to the downstream discharge increase (especially in case of extreme erosion), for most cases the increase must be mainly due to a reduction in bed friction during peak discharge conditions. Additionally, based on the concept of channel storage reduction, the effects of decreasing bed friction and (very strong) bed erosion can be integrated in explaining the peak discharge increase.  相似文献   

Understanding river dune splitting through flume experiments and analysis of a dune evolution model          下载免费PDF全文

Jord J. Warmink  C. Marjolein Dohmen‐Janssen  Joost Lansink  Suleyman Naqshband  Olav J. M. van Duin  Andries J. Paarlberg  Paul Termes  Suzanne J. M. H. Hulscher 《地球表面变化过程与地形》2014,39(9):1208-1220

Forecasts of water level during river floods require accurate predictions of the evolution of river dune dimensions, because the hydraulic roughness of the main channel is largely determined by the bed morphology. River dune dimensions are controlled by processes like merging and splitting of dunes. Particularly the process of dune splitting is still poorly understood and – as a result – not yet included in operational dune evolution models. In the current paper, the process of dune splitting is investigated by carrying out laboratory experiments and by means of a sensitivity analysis using a numerical dune evolution model. In the numerical model, we introduced superimposed TRIAS ripples (i.e. triangular asymmetric stoss side‐ripples) on the stoss sides of underlying dunes as soon as these stoss sides exceed a certain critical length. Simulations with the model including dune splitting showed that predictions of equilibrium dune characteristics were significantly improved compared to the model without dune splitting. As dune splitting is implemented in a parameterized way, the computational cost remains low which means that dune evolution can be calculated on the timescale of a flood wave. Subsequently, we used this model to study the mechanism of dune splitting. Literature showed that the initiation of a strong flow separation zone behind a superimposed bedform is one of the main mechanisms behind dune splitting. The flume experiments indicated that besides its height also the lee side slope of the superimposed bedform is an important factor to determine the strength of the flow separation zone and therefore is an important aspect in dune splitting. The sensitivity analysis of the dune evolution model showed that a minimum stoss side length was required to develop a strong flow separation zone. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Revisiting the morphological method in two-dimensions to quantify bed-material transport in braided rivers     

Gilles Antoniazza  Maarten Bakker  Stuart N. Lane 《地球表面变化过程与地形》2019,44(11):2251-2267

Research in the 1990s showed that bed-material transport rates could be estimated at the reach scale in both one-dimension and, over small spatial scales (10s of m), in two-dimensions. The limit on the latter was the spatial scale over which it was possible to obtain distributed data on morphological change. Here, we revisit the morphological method given progress in both topographical data acquisition and hydraulic modelling. The bed-material transport needed to conserve mass is calculated in both one and two dimensions for a 1600 m × 300 m Alpine braided river “laboratory”. High-resolution topographical data were acquired by laser scanning to quantify Digital Elevation Models (DEMs), and morphological changes caused by the flushing of the water intake were derived from repeated surveys. Based on DEMs of differences, 1D bed-material transport rates were calculated using the morphological method. Then, a 2D hydraulic model was combined with a topographic correction to route sediment through the network of braided channels and to obtain a spatially variable estimate of transport in both downstream and cross-stream directions. Monte Carlo simulation was applied to the routing model parameters, allowing identification of the most probable parameter values needed to minimize negative transport. The results show that within-section spatial compensation of erosion and deposition using the 1D treatment leads to substantial local errors in transport rate estimates, to a degree related to braiding intensity. Even though the 2D application showed that a large proportion of the total transport was actually concentrated into one main channel during the studied low flow event, the proportion of transport in secondary anabranches is substantial when the river starts braiding. Investigations of the effects of DEM resolution, competent flow duration and survey frequency related to ‘travelling bedload’ and sequential erosion-deposition emphasized the critical importance of careful data collection in the application of the morphological method. © 2019 John Wiley & Sons, Ltd.  相似文献   

黄东海刺尖锥虫属(多毛纲,锥头虫科)一新种     

孙悦  隋吉星  李新正 《海洋学报(英文版)》2018,37(10):130-135

本文描述了于1959年采自中国黄海和东海锥头虫科刺尖锥虫属一新种——中国刺尖锥虫Leodamas sinensis sp.nov.。本文详细描述了该物种的形态特征及与近似种的区别，并编制了刺尖锥虫属Leodamas Kinberg，1866物种检索表。  相似文献   

基于形态学特征和DNA条形码对中国沿海银口天竺鲷属(Jaydia)分类研究     

罗植森  易木荣  刘思杓  邱康文  谷穗  颜云榕 《海洋与湖沼》2020,51(5):1246-1256

本研究针对中国沿海银口天竺鲷属鱼类分类鉴定不清晰，同种异名多，种类误鉴等分类问题，结合形态特征比较与DNA条形码技术对其分类鉴定问题进行梳理。2014—2019年间于南海北部沿海采集101尾银口天竺鲷属鱼类标本，经形态学特征鉴定为：横带银口天竺鲷Jaydia striata（Smith&Radcliffe，1912），特征为体侧有7—11褐色宽横带，腹鳍、臀鳍浅灰色；印度洋银口天竺鲷J.striatodes（Gon，1997），特征为体侧有7—11褐色宽横带，臀鳍后缘黑色；白边银口天竺鲷J.novaeguineae（Valenciennes，1832），特征为臀鳍、尾鳍最下缘为白边；黑边银口天竺鲷J.truncata（Bleeker，1855）特征为第二背鳍、臀鳍中部有一平行基底的黑色带，尾鳍后缘黑色带略宽；史密斯银口天竺鲷J.smithi Kotthaus，1970，特征为第二背鳍中部有一平行基底的黑色纵带，尾鳍后缘黑色带略细；斑鳍银口天竺鲷J.carinatus （Cuvier，1828），特征为第二背鳍最末软条基底有一大黑斑；黑鳃银口天竺鲷J.poeciloptera （Cuvier，1828），特征为臀鳍淡黄色，鳍膜间有一暗点。研究发现Apogon arafurae并不是J.truncata同种异名，学名应更正为Jaydia poeciloptera。基于线粒体COI基因K2P遗传距离显示，J.striata、J.smithi、J.truncata种内遗传距离大于2%。构建NJ系统发育树发现红海、阿拉伯海和北部湾的J.smithi分成2个单系支。结合NJ树分析发现，J.smithi和J.poeciloptera均出现错误鉴定，认为GenBank上传的序列（MH085808、JQ681491）存在误鉴，实为J.poeciloptera。  相似文献   

长江口扁担沙动力地貌变化过程研究   总被引：1，自引：0，他引：1  

何钰滢  戴志军  楼亚颖  王杰 《海洋学报》2020,42(5):104-116

河口浅滩不仅为人类提供宝贵湿地资源，而且是调控河势演变的重要因素。研究河口浅滩动力地貌演变规律对航道整治、湿地生态开发及岸堤防护等具有重要价值。本文利用最近150多年的长江口历史海图资料、实测水深与水文泥沙数据，分析长江口南支最大的浅滩—扁担沙动力地貌演变格局及其变化机制。结果表明:(1) 1860?2016年期间，扁担沙反复历经淤积?冲刷?淤积，浅滩由最初水下阴滩发育出露而形成纺锤状沙体，随后演变为细长扁担状，沙尾切滩成爪状沙体，下扁担沙则伴随爪状缝隙被不断填充而淤长；(2)自1954年洪水到目前，扁担沙?2 m、?5 m等深线包络的面积与体积整体上均呈现增长态势，其中面积年均增长率分别为0.88 km2/a和0.81 km2/a，体积年均增长率分别为1.3×106 m3/a和5×106 m3/a；扁担沙浅滩在不同时期冲淤变化不同，其中1998年出现大幅度冲刷，平均冲刷厚度达到1.4 m；(3)扁担沙体积变化和长江入海泥沙的增减无直接联系，但与入海径流量的变化密切相关；(4)白茆沙“南强北弱”的河势、南北港分流工程以及东风西沙水库的建立导致扁担沙向北推移。  相似文献   

Morphological and molecular evidence supports the first occurrence of two fishes,Siganus sutor(Valenciennes, 1835)and Seriolina nigrofasciata(Rüppell, 1829)(Actinopterygii:Perciformes), from marine waters of Odisha coast,Bay of Bengal,India     

Barik Tapan K.  Swain Surya N.  Sahu Bijayalaxmi  Tripathy Bibarani  Acharya Usha R. 《海洋学报(英文版)》2020,39(6):26-35

Marine ecosystems provide a wide variety of diverse habitats that frequently promote migration and ecological adaptation. The extent to which the geographic distribution of marine organism has reshaped by human activities remains underappreciated. The limitations intrinsic to morphology-based identification systems have engendered an urgent need for reliable genetic methods that enable the unequivocal recognition of fish species,particularly those that are prone to overexploitation and/or market substitution. In the present study, however, an attempt has been taken to identify two locally adapted fish species, Siganus sutor(Valenciennes, 1835) and Seriolina nigrofasciata(Rüppell, 1829) of order Perciformes, which happens to be the first record in Odisha coast,Bay of Bengal. The diagnostic characteristics of Siganus sutor are: dorsal fin XIII-10, anal fin VII-9, pectoral fin 15,pelvic fin II-3, while that of Seriolina nigrofasciata dorsal fin VI-I-35, anal fin I-17, pectoral fin 16, pelvic fin 5. All COI barcodes generated in this study were matched with reference sequences of expected species, according to morphological identification. Bayesian and likelihood phylogenetic trees were drawn based on DNA barcodes and all the specimens clustered in agreement with their taxonomic classification at the species level. The phylogeographic studies based on haplotype network and migration rates suggest that both the species were not panmitic and the high-frequency population distribution indicates successful migration. The result of this study provides an important validation of the use of DNA barcode sequences for monitoring species diversity and changes within a complex marine ecosystem.  相似文献   

A new pelagic Polyconchoecia Xiang,Chen and Du, 2018(Ostracoda:Myodocopa:Halocyprididae) from the South China Sea     

项鹏  王雨  陈瑞祥  叶又茵  王春光  陈小银  林茂 《海洋学报(英文版)》2020,39(4):73-83

Halocyprid ostracods are appreciable part of ostracods floating through virtually everywhere in marine environment.In this study,we describe a new species of genus Polyconchoecia Xiang,Chen and Du,2018,tribe Conchoeciini Chavtur and Angel,2011,family Halocyprididae Dana,1853 from the middle of the South China Sea.Polyconchoecia chenii sp.nov.is very close to P.commixtus Xiang,Chen and Du,2018.But it differs from P.commixtus by the distinctions of locations of major glands of carapace and the characteristics of appendages:more posteriorly situated left asymmetric gland of carapace,no right asymmetric gland;segmented frontal organ;the endopod 2 of the first antenna with a very small seta;a-and c-setae of the first antenna with long end joint have long end joint,the b-and d-setae have no end joint,spinose e-seta without end joint;the e-seta of the second antenna is present;teeth side is distinctive;the setal counts of the mandible,maxilla,fifth limb,and sixth limb are individual.The locations of the major glands on carapace and the characteristics of the first antenna can be the key of the new species.This work is the second discovery of the genus Polyconchoecia from the world.  相似文献   

中国海洋无脊椎动物分类学与系统演化研究进展与展望     

李新正  寇琦  王金宝  甘志彬  杨梅  龚琳  隋吉星  马林  曲寒雪  初雁凌  曾宥维  王伟娜  张祺  董栋 《海洋科学》2020,44(7):26-70

综述了我国海域无脊椎动物的分类学和系统演化研究的历史和概况，以及我国分类系统学工作者在海洋无脊椎动物分类学、区系与动物地理学、系统发育与分子系统学领域的主要工作，重点介绍了中国科学院海洋研究所的海洋无脊椎动物分类学工作。涉及类群包括原生动物、海绵动物、刺胞动物、线虫、多毛类环节动物、星虫、螠虫、软体动物、节肢动物、苔藓动物、毛颚动物、棘皮动物、半索动物等主要的无脊椎动物门类。涉及海域以我国管辖海域，特别是中国近海为主，也涉及了西太平洋、西南印度洋等深海环境的无脊椎动物类群的分类学报道。本文总结过去，展望未来，对于在我国在海洋无脊椎动物分类与系统演化研究领域成就基础上，发现薄弱环节，研讨今后本学科的发展方向，填补研究空白，赶超本领域国际前沿，都有重要借鉴意义。  相似文献