渤海线虫群落的多样性及中性模型分析

对渤海的黄河口水下三角洲、莱州湾和渤海中部共9个站位的海洋线虫群落的多样性进行了研究.用于比较的海域和站位还包括1995年胶州湾的95B2站和1988年湄州湾的A01站.以上11个站位共鉴定出自由生活海洋线虫154种,分属于107属29个科.使用种丰度(SR),香农-维弗指数(H′)和均衡度(J)用来比较不同生境的生物多样性.不同生境和站位的生物多样性水平由高到低依次为渤海中部(9761、DA18、DA19和DA20,SR=8.60±0.84,H′=4.94±0.23)、莱州湾(9762、DA2和DA4,SR=6.48士0.40,H′=3.95±3.0)和黄河口水下三角洲(E9和E11,SR=4.18±0.56,H′=3.60±0.24).线虫生物多样性与海水的盐度和沉积物的异质性指数(h)呈显著的负相关(P≤0.01).Caswell 中性模型分析指明,大部分研究站位的"V"值为"-2～+2",说明未受到显著外界因子的扰动.渤海中部的9761站的"V"值为2.054,暗示环境稳定性的增强,而莱州湾的DA4站"V"值为-2.624指明受到外界环境因子的显著影响,可能与黄河口输送大量的物质有关.     

福建海坛岛长江澳沙滩自由生活海洋线虫群落研究

于2013—2014年间在海坛岛长江澳沙滩采样,对小型底栖动物的类群组成、丰度及分布,自由生活海洋线虫(简称海洋线虫)群落的优势属、摄食类型、年龄结构及性比、物种多样性等方面进行研究。结果表明:小型底栖动物年平均丰度为(810.87±696.75)个/10 cm~2。在鉴定出的16个类群中,海洋线虫的丰度占小型底栖动物总丰度的52.36%,其次为腹毛虫,占21.14%。海洋线虫的年平均丰度为(424.54±400.23)个/10 cm~2,季节变化总趋势为夏季((783.45±336.45)个/10 cm~2)春季((600.67±309.42)个/10 cm~2)秋季((298.26±424.57)个/10 cm~2)冬季((113.05±95.79)个/10 cm~2)。4个季度共鉴定出海洋线虫105种或分类实体,隶属于75个属,26个科。4个季度数量百分比超过5%的优势海洋线虫属有10个,分别是Axonolaimus、Theristus、Metachromadora、Mesacanthion、Rhynchonema、Epacanthion、Microlaimus、Viscosia、Lauratonema和Enoploides,不同季度的优势属存在差异。CLUSTER聚类表明,春、夏、秋季各潮带海洋线虫群落较为相似,与冬季差异较大。海洋线虫4种摄食类型年平均丰度百分比由高到低的顺序是1B (32.19%) 2A (31.32%) 2B (31.12%) 1A (5.37%);春夏季以2A和1B为主导,秋冬季以2B和1B为主导。海洋线虫群落的物种多样性最高值出现在秋季(d=8.45,H′=3.36),最低在冬季(d=7.36,H′=2.92),春季与夏季的多样性相当;周年幼体的数量所占比例为45.47%,成体中雌雄个体比例为1.10∶1。     

黄海海水中酵母菌的种类

<正> 酵母菌是海洋中常见的微生物种类之一,各大海洋中均有报道(Kohlmeyer & Kohlmeyer,1979),作者等人曾对中国海中渤海海水、渤海沿岸不同基物和黄海海水中酵母菌种类作了报道(周与良等,1990;1991;Zhou et al.,1990)。本文报道从1983年开始对黄海海水中酵母资源三次调查的结果。三次采样从27个站位共采集了69个水样,分离到474株菌,第一次是在1983年4月,水温7—9℃,5个站位采集水样10个,第二次在1986年8月,水温23—25℃,16个站位采样41个;第三次在1988年8     

天津海域底栖线虫群落结构的多元统计分析

应用多元统计分析方法(等级聚类分析和非度量多维标度)研究了天津近岸海域的底栖线虫群落结构情况.结果表明,等级聚类分析和非度量多维标度分析的结果具有很好的一致性.15个取样站位的线虫群落存在差异,根据线虫种类组成和丰度不同,调查站位可以分为4组.中南部近岸海域多数站位的线虫种类组成相似,深水区域的底栖线虫种类变化最大,而北部湾顶海域的线虫组成近似,但与其他站位相差较大.     

长江口及邻近海域小型底栖生物丰度和生物量

“东方红2号”调查船于2003年6月在长江口外(28°N°至32°N,121°E至123°E)陆架浅海水域进行了小型底栖生物的取样。研究表明,小型底栖生物的平均丰度为(1971±583.9)ind10cm-2,平均生物量为(1393±516.1)μgdwt10cm-2,平均生产量为(12543±4644.7)μgdwt10cm-2a-1。共鉴定出21个小型生物类群,其中自由生活海洋线虫为最优势的类群,占小型生物总丰度的91%和总生物量的51%。其他数量上较重要的类群还有底栖桡足类、多毛类、动吻类和双壳类等。相关分析表明,小型底栖生物的数量分布与沉积物叶绿素和脱镁叶绿酸的含量呈高度显著相关。台风前后8号站线虫群落的比较研究表明,台风后线虫群落在丰度,生物量及种类组成上均发生了一定的变化,对台风的响应较为显著。典型站位自由生活海洋线虫种类组成的分析表明,长江入海口向外线虫优势度降低,多样性增加。     

东海大陆架鱼类群落的空间结构

根据1997～2000年东海大陆架水深30～200米海域4个航次的底拖网调查资料,运用多元分析(聚类分析和非度量多维标度(NMDS))、SIMPER以及BIO-ENV方法分析了东海鱼类群落的空间格局以及与非生物环境因子之间的关系。结果表明,东海大陆架海域鱼类群落在空间上可分为3个群落类型,分别为东海近海群落、东海大陆架外缘群落以及这两个群落之间的东海大陆架混合群落。东海大陆架鱼类群落的种类组成沿着水深梯度的变化明显,每种鱼类均有一定的水深范围。不同的流系具有不同的温盐特征,影响了鱼类的分布及其洄游,从而控制了不同鱼类群落类型的种类组成。东海大陆架鱼类群落类型中,大陆架外缘群落类型各调查季节在空间分布和种类组成上相对稳定,而东海近海群落类型和东海大陆架混合群落类型在夏季融合在一起,其它季节保持各自的空间结构。同时东海陆架区只在一种群落类型中出现的鱼类相对较少,多数鱼类同时出现在两个群落类型中或3个群落类型中,但是它们相对较集中的区域明显不同,在不同群落类型中的生物量和出现频率有很大的差异,这些鱼类在其不同的生长发育阶段由于对海洋环境的不同需求,它们根据繁殖或摄食需求而在东海陆架区范围内洄游以寻找最适的海洋环境,因此对3个群落类型定义是相对的,很难严格确定一个永久的鱼类群落地理区域,以形成相互隔离的鱼类群落,而且鱼类群落之间的边界随着季节不同发生变化。     

渤海小型底栖动物丰度的分布格局

在渤海的 2 2个站位 ,分 3个航次采集未受扰动的沉积物样品 ,进行了小型底栖动物类群的丰度、分布格局及其与沉积环境因子间相互关系的研究。结果表明 ,1 997年航次 ,5个站位小型底栖动物的平均丰度为 2 2 74± 1 0 3 9ind./1 0 cm2 ;1 998年和 1 999年航次 ,小型底栖动物的丰度分别为 869± 5 0 9ind./1 0 cm2和 63 2± 3 99ind./1 0 cm2 ,其中 ,小型底栖动物和自由生活海洋线虫丰度的高值主要出现在渤海中东部和海峡口的站位 ,底栖桡足类的丰度在海峡口的 A4、E5、D5站和辽东湾湾口的几个站位较高。在小型底栖动物中 ,线虫是数量上占绝对优势的类群 ,桡足类位于第 2位 ,处在第 3位的类群在两个航次中有所不同 ,在 1 998年航次 ,双壳类幼体的数量位于第 3位 ;1 999年航次 ,多毛类的数量位于第 3位。对小型底栖动物丰度与其沉积环境因子的分析表明 ,水深与小型底栖动物丰度、自由生活海洋线虫丰度和桡足类丰度的相关性为极显著 ;沉积物的中值粒径与桡足类的丰度和小型底栖动物总丰度呈负相关 ,前者为极显著 ,后者为显著 ;砂、粉砂和粘土含量影响三者的丰度变动 ,其中与桡足类丰度的相关性为极显著或显著。沉积物中的叶绿素 a、脱镁叶绿酸 a、含水量和有机质含量与三者丰度的关系不很明显。     

武汉东湖浮注重藻类物种多样性的研究

从1994年1月至1996年12月,每月定期从东糊四个常规采样站采集浮游藻类标本进行研究。经鉴定共发现260个分类单位,隶属于7个门的990个属,其中有2种为中国新记录,以1995年浮游藻类的群落结构进行分析的结果是：浮游藻类的种类数以绿藻门最多,硅藻门次之;各站基本上均以夏季种类最多,其次为秋季和春季,冬季最低;四个站中分布的种类差异不明显,各站都出现的种类数占全部种类数的39.6%;不同的站或同一个站在不同的季节其优势类群亦不同。计算了与水体营养类型有关的浮游藻类群落的两种指标－多样性指数和硅藻商。对东湖浮游灯群落结构的特征及变化与水质的关系进行了探讨,从浮游藻类群落的演替指出东湖的富营养化程度自20世纪50年代以来一直在加剧。     

长江口潮下带春季大型底栖动物的群落结构

2005年4月对长江口全区域潮下带共10个采样站位的大型底栖动物进行了调查。调查采获大型底栖动物38种,分属5个生态类型,种类数较少,河口外缘站位种类数多于口内站位。各站位大型底栖动物的平均丰度为32.9个/m2、平均生物量为5.035g/m2(湿重);与20世纪七八十年代相比,平均生物量显著降低;口外缘站位的总丰度和总生物量均高于口内站位。环境因子相关分析表明,盐度是决定长江口大型底栖动物种类分布最重要的环境因子。群落聚类、标序分析显示,春季长江口潮下带大型底栖动物群落结构空间分异明显,完全符合目前长江口支、港、槽“三级分汊”的空间格局。其中,北支的大型底栖动物以混合高盐水种类为主,而南支则以淡水和半咸水种类为主。南支的南北槽分界处内外站位的群落差异也由盐度决定,因为靠近口内的群落均受长江冲淡水影响较大;而口外站位群落则受咸淡水影响。南支的南北港分界点内外的群落差异则主要受长江来水的影响,原因在于处在港分界点以内的群落所在区域,直接受长江来水的冲刷,底质环境极不稳定;而港、槽分界点之间的群落所在区域由于河口上段的诸多明暗沙体的阻挡,水势较为稳定,所以底质环境较稳定,从而使得港、槽分界点之间的群落出现了更多的沙蚕等底质环境类型种类。     

长江口潮下带春季大型底栖动物的群落结构

2005年4月对长江口全区域潮下带共10个采样站位的大型底栖动物进行了调查。调查采获大型底栖动物38种，分属5个生态类型，种类数较少，河口外缘站位种类数多于口内站位。各站位大型底栖动物的平均丰度为32.9个/m²、平均生物量为5.035 g/m²(湿重)；与20世纪七八十年代相比，平均生物量显著降低；口外缘站位的总丰度和总生物量均高于口内站位。环境因子相关分析表明，盐度是决定长江口大型底栖动物种类分布最重要的环境因子。群落聚类、标序分析显示，春季长江口潮下带大型底栖动物群落结构空间分异明显，完全符合目前长江口支、港、槽“三级分汊”的空间格局。其中，北支的大型底栖动物以混合高盐水种类为主，而南支则以淡水和半咸水种类为主。南支的南北槽分界处内外站位的群落差异也由盐度决定，因为靠近口内的群落均受长江冲淡水影响较大；而口外站位群落则受咸淡水影响。南支的南北港分界点内外的群落差异则主要受长江来水的影响，原因在于处在港分界点以内的群落所在区域，直接受长江来水的冲刷，底质环境极不稳定；而港、槽分界点之间的群落所在区域由于河口上段的诸多明暗沙体的阻挡，水势较为稳定，所以底质环境较稳定，从而使得港、槽分界点之间的群落出现了更多的沙蚕等底质环境类型种类。     

近岸海洋线虫与细菌、古菌的共现性及其对碳、氮循环的影响

【目的】初步探究海洋线虫与微生物的相互作用对碳、氮循环的影响。【方法】利用16S r RNA和18S r RNA基因高通量测序方法,对33个近岸沉积物样品中细菌、古菌和真核生物的多样性进行调查;对海洋线虫与细菌、海洋线虫与古菌的共现性进行网络分析,并采用Spearman统计学方法,识别出与海洋线虫共现性呈显著相关性的微生物种类。【结果】在夏季,红树林和潮间带泥滩样品中线虫OTU平均相对丰度基本呈随深度增加而递减趋势;冬季的红树林样品中发现相类似变化规律,只有在冬季潮间带泥滩样品中线虫OTU平均相对丰度在深层较高于表层。相对丰度最高的海洋线虫隶属于单宫目(47%)、色矛目(19%)、刺嘴目(16%)和垫刃目(9%),它们与热源体古菌、深古菌、γ-和δ-变形菌等微生物有显著正/负相关关系。【结论】在香港米埔湿地沉积物中,与相对丰度最高的5种线虫显著相关的几大类微生物均在碳、氮、硫等元素循环方面起十分重要的作用,暗示海洋线虫与微生物潜在的相互作用对元素地球化学循环具有重要影响。研究结果有助于深入了解线虫在生态系统中未被揭示的生态功能,有助于更清晰地认识海洋线虫在底栖生态系统中所扮演的角色。     

Marine Nematode Taxonomy in Africa: Promising Prospects Against Scarcity of Information

From the late 19th century, Africa has faced heavy exploitation of its natural resources with increasing land/water pollution, and several described species have already become extinct or close to extinction. This could also be the case for marine nematodes, which are the most abundant and diverse benthic group in marine sediments, and play major roles in ecosystem functioning. Compared to Europe and North America, only a handful of investigations on marine nematodes have been conducted to date in Africa. This is due to the scarcity of experienced taxonomists, absence of identification guides, as well as local appropriate infrastructures. A pivotal project has started recently between nematologists from Africa (Tunisia), India, and Europe (Italy) to promote taxonomic study and biodiversity estimation of marine nematodes in the African continent. To do this, as a first step, collection of permanent slides of marine nematodes (235 nominal species and 14 new to science but not yet described) was recently established at the Faculty of Sciences of Bizerte (Tunisia). Capacity building of next generation of African taxonomists have been carried out at level of both traditional and molecular taxonomy (DNA barcoding and next-generation sequencing [NGS]), but they need to be implemented. Indeed, the integration of these two approaches appears crucial to overcome lack of information on the taxonomy, ecology, and biodiversity of marine nematodes from African coastal waters.     

Dispersal and gene flow in free-living marine nematodes

Dispersal and gene flow determine connectivity among populations, and can be studied through population genetics and phylogeography. We here review the results of such a framework for free-living marine nematodes. Although field experiments have illustrated substantial dispersal in nematodes at ecological time scales, analysis of the genetic diversity illustrated the importance of priority effects, founder effects and genetic bottlenecks for population structuring between patches <1 km apart. In contrast, only little genetic structuring was observed within an estuary (<50 km), indicating that these small scale fluctuations in genetic differentiation are stabilized over deeper time scales through extensive gene flow. Interestingly, nematode species with contrasting life histories (extreme colonizers vs persisters) or with different habitat preferences (algae vs sediment) show similar, low genetic structuring. Finally, historical events have shaped the genetic pattern of marine nematodes and show that gene flow is restricted at large geographical scales. We also discuss the presence of substantial cryptic diversity in marine nematodes, and end with highlighting future important steps to further unravel nematode evolution and diversity.     

深圳河口福田泥滩海洋线虫的种类组成及季节变化

１９９７年４个季度在深圳河口福田泥滩３个取样站采到海洋线虫２８种,隶属于３目１３科２２属。优势种是微口线虫（Ｔｅｒｓｃｈｅｌｌｉｎｇｉａ ｓｐｌ．）、蚕咽线虫（Ｄａｐｔｏｎｅｍａ ｓｐ１．）、Ｍｅｔａｌｉｎｈｏｍｏｅｕｓ ｓｐ．和拟齿线虫（Ｐａｒａｄｏｎｔｏｐｈｏｒａ ｓｐ．）４种。春季海洋线虫密度最高,冬季次之,夏季第三,秋季最低。深圳河口福田泥滩的海洋线虫群落与大型底栖动物群落具有相似的特点,     

A simple technique for recovering larval ascaridoid nematodes from the flesh of marine fish

This paper describes and evaluates the efficiency of a simple technique for recovering larval ascaridoid nematodes (Anisakis simplex and Pseudoterranova decipiens) from the flesh of marine fish. The technique involves mechanical disintegration of the flesh in a domestic food processor, followed by visual inspection of diluted portions of the resulting homogenate under short-wave ultraviolet light. The nematodes, which remain intact, fluorescence brightly and are easily detected, particularly if the musculature has been frozen and thawed previously. The technique recovers a much higher proportion of the total number of nematodes than candling and slicing, is more rapid than pepsin-HCl digestion, and would therefore be suitable for large-scale surveys of ascaridoid nematodes in the flesh of marine fish.     

深圳湾福田红树林湿地小型底栖动物群落结构及海洋线虫新纪录种

于2018年冬季在福田红树林湿地设置4个采样断面进行沉积物样品采集,对小型底栖动物的类群组成、丰度及自由生活海洋线虫的优势属等进行分析。结果表明:共鉴定出4个以上的小型底栖动物类群,分别为海洋线虫、桡足类、多毛类、寡毛类和其他未鉴定类群,海洋线虫为最优势类群,占小型底栖动物丰度的97.28%;小型底栖动物平均丰度为(490.73±465.09) ind·10 cm-2;共鉴定出海洋线虫隶属于30属17科,其优势属(优势度≥5%) Paracanthonchus、Megadesmolaimus、Subsphaerolaimus、Terschellingia、Spinonema、Pseudochromadora和Pseudolella;发现新纪录种—大亚囊咽线虫Subsphaerolaimus major Nguyen&Gagarin,2009,并对其进行了测量及描述,并比较了其与模式种的主要差异。     

Isolation and characterization of Brucella from the lungworms of a harbor porpoise (Phocoena phocoena)

Adult female nematodes identified as Pseudalius inflexus were collected from the lungs of a juvenile male harbor porpoise (Phocoena phocoena) found dead on a beach in Cornwall, UK. Classic and molecular typing methods, immunologic and electron microscopy immunolabeling techniques, provided evidence of Brucella sp. infection within the uterine tissue of nematodes of this marine mammal. This finding presents further evidence to suggest parasites should be considered as a potential means of transfer of bacterial infection in marine mammals and highlights the zoonotic implications for humans exposed to marine mammals through occupation or leisure.     

Molecular and morphological characterization of the association between bacterial endosymbionts and the marine nematode Astomonema sp. from the Bahamas

Marine nematode worms without a mouth or functional gut are found worldwide in intertidal sandflats, deep-sea muds and methane-rich pock marks, and morphological studies show that they are associated with endosymbiotic bacteria. While it has been hypothesized that the symbionts are chemoautotrophic sulfur oxidizers, to date nothing is known about the phylogeny or function of endosymbionts from marine nematodes. In this study, we characterized the association between bacterial endosymbionts and the marine nematode Astomonema sp. from coral reef sediments in the Bahamas. Phylogenetic analysis of the host based on its 18S rRNA gene showed that Astomonema sp. is most closely related to non-symbiotic nematodes of the families Linhomoeidae and Axonolaimidae and is not closely related to marine stilbonematinid nematodes with ectosymbiotic sulfur-oxidizing bacteria. In contrast, phylogenetic analyses of the symbionts of Astomonema sp. using comparative 16S rRNA gene sequence analysis revealed that these are closely related to the stilbonematinid ectosymbionts (95-96% sequence similarity) as well as to the sulfur-oxidizing endosymbionts from gutless marine oligochaetes. The closest free-living relatives of these gammaproteobacterial symbionts are sulfur-oxidizing bacteria from the family Chromatiaceae. Transmission electron microscopy and fluorescence in situ hybridization showed that the bacterial symbionts completely fill the gut lumen of Astomonema sp., suggesting that these are their main source of nutrition. The close phylogenetic relationship of the Astomonema sp. symbionts to known sulfur-oxidizing bacteria as well as the presence of the aprA gene, typically found in sulfur-oxidizing bacteria, indicates that the Astomonema sp. symbionts use reduced sulfur compounds as an energy source to provide their hosts with nutrition.     

Freeliving nematodes from the Salton Sea

Thirteen species, or putative species, of freeliving nematodes are recorded from a variety of habitats in the hypersaline Salton Sea, the largest inland lake in California. This doubles the number of species of multicellular invertebrates known to occur in the lake. All species are referable to known marine genera, and are regarded as having a marine coastal origin. The range of taxa present is representative of the full taxonomic spread found in marine coastal habitats, suggesting that a wide range of marine nematode taxa are capable of adapting to the hypersaline conditions. The broad spectrum of feeding types present suggests that nematodes play a variety of ecological roles within the lake.     

Free-living nematodes research: State of the art,prospects, and future directions. A bibliometric analysis approach

Nematodes are among the most successful metazoans inhabiting the Earth and they are pivotal components as in terrestrial as in aquatic (both in marine and freshwater) environments providing important ecosystem services. The aim of this study was to understand major research trends and topics on free-living nematodes inhabiting soil, marine and freshwater environments and to highlight possible differences among them. To achieve this objective, a bibliometric analysis was performed using Scopus database. The indexed global scientific literature on free-living nematodes from 1912 to 2021 was explored using VOSviewer software, allowing a comprehensive overview of the topic. The analyses of co-authorship (among researchers and countries), the co-occurrence of keywords and the analysis of citation of journals were performed. Overall, free-living soil nematodes found a wider audience in high ranked journals especially when compared with freshwater nematodes. Marine nematodes stand in between them and many aspects of biodiversity research in marine ecosystems are covered by high-medium ranked journals (i.e. taxonomy, systematic, phylogeny, morphological and genetic diversity). Although, the estimation of the taxonomic diversity of the phylum Nematoda enumerated a high number of documents, an increasing attention emerged for the investigation of pollution effects (i.e. nematodes as bioindicators of environmental status) and the use of nematodes as model organisms for addressing scientific questions in line with the Eco-Evo-Devo (Ecological Evolutionary Developmental biology) approach. These fundamental themes were indirectly confirmed by the co-authorship analysis, which revealed that taking integrative approaches between taxonomy (both morphological and molecular), ecological and evolutionary aspects attracted a higher number of citations.