Species composition, abundance distribution and diversity of planktonic Ostracoda in the Beibu Gulf, China

Four cruises of survey were carried out in the Beibu Gulf between Feb 1998 and May 1999. A total of 18 species of planktonic Ostracoda were identified, including Cypridina nana, Cypridina dentata, Cypridina acuminata, Cypridina nami, Euconchoecia aculeata, Euconchoecia elongata, Euconchoecia maima, and other taxa. Planktonic Ostracoda in the gulf were divided into three ecological types: (1) a hyposaline and warm-water group, (2) a eurythermal and eurysaline group, and (3) a hyperthermal and hysaline group. The warm water species such as Euconchoecia aculeate and Cypridina acuminate were the dominant Ostracoda species in the gulf, where the overall Ostracoda density ranged from 0.02 ind./m³ to 51.58 ind./m³ and averaged 1.22 ind./m³. The highest average value (2.73 ind./m³) was found in spring. Fuzzy evaluation measures indicated that the diversity in the gulf remained low (level of class I) during all seasons. Diversity appeared to be relatively higher in some regions in which the water mass was strongly influenced by the open sea and had complex structures. This article also discusses how the species composition, abundance and diversity of planktonic Ostracoda are influenced by environmental factors (e.g., aquatic system, water mass, water temperature and salinity) in the Beibu Gulf.     

北部湾海域浮游介形类物种组成、丰度分布及多样性

根据1998年1月～1999年5月北部湾海域4个航次生态环境综合调查资料,对北部湾海域浮游介形类进行分析研究。结果表明,北部湾渔场浮游介形类物种组成较为简单,记录有小型海萤（Cypridina nana）、齿形海萤（Cypridina dentata）、尖尾海萤（Cypridina acuminata）、纳米海萤（Cypridina nami）、针刺真浮萤（Euconchoecia aculeata）、细长真浮萤（Euconchoecia elongata）、后圆真浮萤（Euconchoecia maimai）等18种;隶属于2亚目、2科、4亚科、12属,其中有4种周年出现,9种只在特定的单一季节出现,其余5种季节性出现;夏季和冬季出现的物种数最多,达到11种;春季次之,为9种;秋季最少,只有6种。北部湾浮游介形类可以划分为3个生态类群,即低盐暖水类群、广温广盐类群和高温高盐类群,优势种群主要是近岸低盐暖水类群的针刺真浮萤和尖尾海萤。全海域栖息密度变化范围为0．02～51．58ind．／m^3,年平均1．22ind．／m^3,春季最高,达2．73ind．／m^3,在湾西北部密集有大量的针刺真浮萤;夏季此密集区逐渐向湾中部移动,纳米海萤为其密集种,栖息密度也有所降低;秋、冬季量少,但在湾南、北部各出现一个丰度相对较高的密集区,并由南北向湾中部递减。总生物量具有明显的季节性变化,平面分布趋势与栖息密度相似。生物多样性指数低,以湾口较高、湾顶较低,呈湾口向湾内西北方向递减趋势;全海域年平均多样性阈值为0．329,四季多样性水平皆为Ⅰ级,多样性程度低;多样性程度较高的区域,多出现于受外海水影响较大、水文状况变化较为复杂的海域。对浮游介形类的物种组成、丰度分布及多样性与北部湾的水系、水团、水温及盐度等环境因子的关系进行了探讨。     

北部湾近岸海域浮游动物群落结构特征及季节变化

2017年3月(枯水期)、7月(丰水期)和10月(平水期)分别对北部湾近岸海域44个站位的浮游动物进行了调查。结果共检出浮游动物251种和浮游幼体24类,其中枯水期138种(类),丰水期134种(类),平水期191种(类),分属河口低盐、近岸暖温、近岸暖水和外海暖水4个生态类群。优势种9种,其中枯水期以原生动物占绝对优势,丰水期以枝角类、桡足类和浮游幼体类占优势,平水期以十足类和浮游幼体类占优势。浮游动物丰度年均值为789.95个/m~3,呈现出枯水期(1540.19个/m~3)明显高于平水期(457.58个/m~3)和丰水期(372.08个/m~3)的季节变化特征;浮游动物生物量年均值为252.40 mg/m~3,生物量的季节变化与丰度变化不一致,平水期生物量(385.01 mg/m~3)明显高于枯水期(221.41 mg/m~3)和丰水期(150.78 mg/m~3)。多样性指数平水期最高(3.16),丰水期(2.35)次之,枯水期(2.22)最低。枯水期和丰水期北部湾近岸海域浮游动物生物量和丰度水平分布特征基本呈现自河口近岸海域向外海递增的趋势,平水期浮游动物生物量与丰度的空间分布较为均匀。浮游动物的种类组成结构以及优势种的演替对浮游动物的生物量和丰度季节变化有着重要的决定作用。径流导致的悬浮物、营养盐等的变化可能是决定北部湾近岸海域浮游动物生物量和丰度空间分布的主要因素。研究还表明与其他海湾相比,北部湾近岸海域浮游动物群落结构趋于小型化,需加大关注。     

秋、冬季北部湾浮游介形类群落多元分析

根据对北部湾生态环境综合调查所采集的浮游动物样品,对北部湾秋、冬季浮游介形类组成及群落结构进行了多元分析.结果表明,测区内浮游介形类种类为11种,分属于低盐暖水类群、广温广盐类群和高温高盐类群3个生态类群;海区内的平均丰度较低,其中针刺真浮萤数量最多,为海区的绝对优势种,左右着整个北部湾浮游介形类的数量.聚类分析和MDS分析表明,北部湾浮游介形类为一个结构相对稳定的群落,秋、冬季可看成是一个群落的2个亚群;对各聚类组的丰度与水温、盐度相关分析表明,水温、盐度对浮游介形类群落结构变化所产生的作用较小,但存在一定的规律性;在冬季,底层温盐对群落Ⅱ产生显著影响.     

Bathymetric distribution and diversity of deep water polychaetous annelids in the Sigsbee Basin, northwestern Gulf of Mexico

The deep water polychaete fauna is analyzed in this study particularly regarding its composition and variations with depth in the Sigsbee Basin, northwestern region of the Gulf of Mexico. Samples were taken at 10 stations along a bathymetric gradient with depth ranges from 200 to 3760 m with a USNEL (0.25 m²) corer. A total of 287 individuals were identified, from 21 families and 65 species. The most important families, both in terms of abundance and species richness, were: Paraonidae (65.4 ind./0.25 m², 9 spp.), Cirratulidae (28.93 ind./0.25 m², 7 spp.) and Spionidae (18.07 ind./0.25 m², 7 spp.). In general, density tended to decrease with depth with minima at around 2000 m, although two abundance peaks were detected at 3700 and 3760 m, making the pattern seem an inverted parabolic curve. The Shannon-Wiener diversity values varied from 0.54–0.92 at around 2000 m to 3.39 at 3620 m and 3.34 at 3760 m. These results contrast with what is already reported from the North Atlantic and the Tropical Pacific deep benthic communities, where highest diversities are found at 2000 m. Faunal changes evaluated through Beta Diversity (0.08–0.1) and the low similarity found between the stations, emphasized the high variability in the composition of the fauna in the Sigsee Basin, meaning that the faunal composition is practically different at all the sampling stations. Ten species are newly recorded for the Mexican fauna.     

Seasonal density dynamics and distribution of brachyuran crab larvae (Decapoda: Brachyura) in Amursky and Ussuriysky bays, Sea of Japan

The species composition, period of occurrence, density, and distribution of brachyuran crab larvae (Decapoda: Brachyura) in the Amursky and Ussuriysky bays (Sea of Japan) were studied in May–October 2007 and 2008. The larvae of this group were not numerous, with peak densities occurring in July at maximum water temperatures. The average brachyuran larvae density was up to 126.9 ind./m³ in Ussuriysky Bay and 68 ind./m³ in Amursky Bay; the contribution of Brachyura to all decapod larvae reached 80–90%. In Amursky Bay, the highest density of brachyuran larvae (up to 584 ind./m³) was observed along the western coast over depths to 20 m; in Ussuriysky Bay, the larval density was highest (up to 1817 ind./m³) in the shallowwater northern part and progressively decreased with depth. Larvae of 18 brachyuran species were found in plankton samples. In Amursky Bay, intertidal crab larvae of the genus Hemigrapsus dominated, Eriocheir japonica larvae were fairly numerous. Larvae of the pea crabs Pinnixa rathbuni and Tritodynamia rathbunae and zoeae of the bigtooth rock crab Glebocarcinus amphioetus were predominant in Ussuriysky Bay.     

长江口及邻近海域枝角类和涟虫类生态学

根据2002～2003年长江口29°00'～32°00'N、122°00'～123°30'E海域4个季节的海洋调查,运用定量、定性方法,探讨长江口邻近海域枝角类和涟虫类总丰度的季节变化特征,以及丰度的季节差异与水团的关系,分析了种类的数量变动,并与东海外海的生态特征进行比较.结果表明,长江口及邻近海域涟虫类丰度的季节变化主要受温度的影响,而平面分布变化与盐度有关.平均丰度夏季最高(0.59 ind./m3),春季最低(0.05 ind./m3).本次调查共发现涟虫类4种,分别为三叶针尾涟虫(Diastylis tricincta)、卵圆涟虫(Bodotria ovalis)、亚洲异针尾涟虫(Dimorphostylis asiatica)和细长涟虫(Iphinoe tenera).其中,三叶针尾涟虫四季均出现,四季优势度分别为0.04、0.03、0.04和0.06;卵圆涟虫出现在夏、秋和冬季,优势度分别为0.11、0.00和0.07;亚洲异针尾涟虫和细长涟虫仅秋季出现,优势度分别为0.17和0.002.仅在夏季发现两种枝角类,分别为肥胖三角溞(Evadne tergestina)和鸟喙尖头溞(Penilia avirostris).在长江口,枝角类和涟虫类的分布特征与长江冲淡水都有一定的关系,显示出这两大类浮游动物具有咸淡水分布的特征.     

Zooplankton of Lake Kandrykul (Republic of Bashkortostan,Russia) under Conditions of Anthropogenic Eutrophication

The species diversity, abundance, and biomass of zooplankton in the pelagic and coastal zones of Lake Kandrykul were studied in 2007–2012. The community was dominated by large Cladocera. The maximum abundance of zooplankton was observed in the anomalously warm 2010. In July, the highest abundance of zooplankton (1300 thousand ind./m³) was recorded near the southern coast in stands of mare′s-tail Hippurus vulgaris; that of biomass (9 g/m³) was found near the northern shore in stands of narrow-leaved cattail Typha angustifolia. The lowest values of the number and biomass of aquatic invertebrates were observed in the pelagial (32 thousand ind./m³ and 0.1 g/m³) and along the M5 motorway stretching aside the northeastern coast (188 thousand ind./m³ and 0.5 g/m³). The Shannon index value (1.3–2.1) corresponded to the meso-eutrophic type of water bodies. In 2007, according to the Mjaemets trophicity index (E), the lake ecosystem was oligotrophic (E 0.11); in 2010–2012 it was mesotrophic (in the pelagial, E value was 0.54; in the open littoral it was 0.76) or weakly eutrophic (E values of protected littoral were 1.52). The estimates of water trophy as assessed by zooplankton are close to those assessed by the number and biomass of phytoplankton (meso-eutrophic type). The rapid eutrophication of the lake ecosystem was revealed. In 6 years the trophic status of the lake changed from oligo-mesotrophic to meso-eutrophic.     

The distribution of zooplankton and bowhead whales, <Emphasis Type="Italic">Balaena mysticetus</Emphasis> Linnaeus, 1758, in Akademiya Bay,Sea of Okhotsk

The modern pattern of distribution and feeding habits of the bowhead whale, Balaena mysticetus, in the Sea of Okhotsk are studied. The existence of a feeding aggregation of this whale species in the southwesternmost portion (apex) of Ulban Bay has been confirmed. There, the animals feed in shallow waters with depths of 3–5 m, which are only slightly larger than their body height. The quantitative composition and species structure of zooplankton at the stations that were set near feeding whales have been analyzed. In the samples taken in the immediate proximity to the feeding whales, the abundance of zooplankton reached 31409 ind./m³, with the average value of 17565 ind./m³. The lowest abundance, from 56 to 1879 ind./m³ (mean 927 ind./m³), was in the samples from western Konstantin Bay, where bowhead whales were not observed. In 16 samples collected in the immediate proximity to the feeding whales in the shallow waters of Ulban Bay, the average zooplankton biomass was 547.9 mg/m³, which is 3.9 times higher than that in the samples from waters where the whales were absent. Copepods dominated quantitatively at all the stations in Akademiya Bay. The proportion of euphausiids in the zooplankton biomass was lower than 1%, both near the feeding whales and in the absence of whales.     

长江口崇明东滩盐沼湿地围堤工程对底栖动物群落的影响

长江口崇明东滩盐沼湿地围堤工程是以清除入侵植物互花米草为目的而进行的生态修复工程。由于大型底栖动物可作为重要的环境指示生物,分析比较了围堤前后围堤工程内和工程外大型底栖动物群落结构及多样性的变化。结果表明,在2013年围堤工程前和2016年围堤工程后两次调查共采集到大型底栖动物29种,分别隶属于无针纲、多毛纲、腹足纲、双壳纲、甲壳纲和昆虫纲。在2013和2016年围堤外光滩生境分别采集到底栖动物21种和27种,并且所有样线都表现出物种数量增加或持平;然而在围堤内区域,两条全封闭样线(样线2和样线3)由围堤前的12种减少到围堤后的6种,而在保留进出水口的半封闭样线1围堤内由围堤前7种增加到围堤后12种。底栖动物平均密度在半封闭样线1围堤内由围堤前的(75±0)个/m²增加到围堤后的(288±111)个/m²(P=0.091),在全封闭的样线2(2013:(120±17)个/m²; 2016:(7±7)个/m²)和样线3(2013:(359±20)个/m²; 2016:(93±93...     

Distribution, species composition, and dynamics of echinoderm larvae in an area of the Tumen River Estuary and of the Far East State Marine Reserve

Species composition, distribution, and density dynamics of echinoderm larvae were determined based on four samples taken at 28 stations in the summer-autumn season of 1997 in an area adjacent to the Tumen River Estuary and to the Far East State Marine Reserve. Larvae of nine species were recorded. The larvae ofOphiura sarsi (up to 9600 ind./m³) and ofEchinocardium cordatum (2058 ind./m³) were dominant in terms of density. The echinoderm larvae mostly appeared in the upper water layer (0–15 m). The study area can be divided into two sites based on the density and species composition of echinoderm larvae: the first to the south of Furugel'ma Island, where the density and species number were low, and the second to the north of Furugel'ma Island, where these parameters had higher values.     

Soil microarthropods and macrofauna in monsoon tropical forests of Cat Tien and Bi Dup-Nui Ba National Parks,southern Vietnam

The abundance, biomass, vertical distribution, and taxonomic composition of soil invertebrates (springtails, macrofauna, and termites) were studied in forest formations differing in edaphic and climatic conditions: lowland forests dominated by Lagerstroemia spp. or Dipterocarpus spp. in the Cat Tien National Park and in a mountain pine (Pinus kesiya) forest on the Da Lat Plateau, southern Vietnam. In the lowland forests, springtails had a relatively low density (10000–12000 ind./m²), but their diversity was high (41–43 species in each forest). The density of large soil invertebrates (without ants and termites) reached 500–700 ind./m² at a biomass of approximately 30 g/m² (with earthworms accounting for up to 230 ind./m² and 19–28 g/m²). Among termites, species of the genera Macrotermes and Odontotermes were dominant. Their total biomass in some areas exceeded 15–20 g/m². In the mountain pine forest, the total biomass of soil macrofauna was approximately 11 g/m², the abundance and diversity of springtails were low (7500 ind./m², 28 species), and wood-destroying species of the genera Schedorhinotermes sp. and Coptotermes sp. dominated among termites.     

Meso- and macrozooplankton communities in the Weddell Sea,Antarctica

Summary The present paper describes composition and abundance of meso- and macrozooplankton in the epipelagic zone of the Weddell Sea and gives a systematic review of encountered species regarding results of earlier expeditions. Material was sampled from 6 February to 10 March 1983 from RV Polarstern with a RMT 1+8 m (320 and 4500 m mesh size). In agreement with topography and water mass distribution three distinct communities were defined, clearly separated by cluster analysis: The Southern Shelf Community has lowest abundances (approx. 9000 ind./1000 m³). Euphausia crystallorophias and Metridia gerlachei are predominating. Compared with the low overall abundance the number of regularly occurring species is high (55) due to many neritic forms. Herbivores and omnivores are dominating (58% and 35%). The North-eastern Shelf Community has highest abundances (about 31 000 ind./1000 m³). It is predominated by copepodites I–III of Calanus propinquus and Calanoides acutus (61%). The faunal composition is characterized by both oceanic and neritic species (64). Fine-filter feeders are prevailing (65%). The Oceanic Community has a mean abundance of approximately 23 000 ind./1000 m³, consisting of 61 species. Dominances are not as pronounced as in the shelf communities. Apart from abundant species like Calanus propinquus, Calanoides acutus, Metridia gerlachei, Oithona spp. and Oncaea spp. many typical inhabitants of the Eastwind Drift are encountered. All feeding types have about the same importance in the Oceanic Community.     

Ostracod Assemblages in Relation to Littoral Plant Communities of a Shallow Lake (Lake Świdwie,Poland)

The aims of this study included: specifying values of ecological parameters and Ostracoda species characteristic for different types of plant habitats occurring in lake systems, determining the impact of mud presence on the taxonomic structure and density of the ostracods, tracing seasonal changes in the structures of Ostracoda assemblages identifying the species typical of particular seasons. Various types of rushes and underwater meadows were taken into consideration as lake microhabitats. The research was conducted in the shallow Lake Œwidwie (NW Poland). Multivariate (constrained) ordination methods were used to analyse the relationships between species composition and environmental variables. In the lake and its margins 31 species of the Ostracoda were identified. The development of water vegetation during the vegetation season was conducive to growth in ostracod density. The accessibility of mud in plant habitats had a favourable effect on the general density of ostracods. Species which preferred a high mud content in their habitats included: Cypria ophtalmica, C. exsculpta and Physocypria kraepelini. Species typically encountered in underwater meadow habitats were: Cyclocypris ovum and Cypridopsis vidua. Underwater meadows of charophyte were characterized by the highest ostracod density in the whole lake system, with the average of 7860 ind. m^–2 and the maximum of 17 470 ind. m^–2. Species typically encountered in rush habitats included Notodromas monacha, Dolerocypris fasciata and Metacypris cordata. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The seasonal dynamics and distribution of burrowing shrimp larvae of the infraorders Gebiidea and Axiidea in Amursky and Ussuriysky Bays,the Sea of Japan

The species composition, period of occurrence, density, and distribution of the larvae of burrowing shrimp of the infraorders Gebiidea and Axiidea in Amursky and Ussuriysky bays (Sea of Japan) were studied in May–October 2008. Larvae of eight species of this group were found in plankton samples. The period of occurrence of larvae in the bays was longest in Upogebia major and Nihonotrypaea petalura (4 and 3 months, respectively). Zoeae of the rest of the species occurred in the plankton for no more than 2 months, indicating a single larval hatching during the reproductive season. The average density of gebiidean and axiidean larvae was low and reached the highest values (4 ind./m³) in June in Amursky Bay and in July in Ussuriysky Bay; their contribution to the total density of decapod larvae was not above 18%. In general, larvae of the family Upogebiidae dominated in Amursky Bay and larvae of the Callianassidae were predominant in Ussuriysky Bay. The zoeae of U. major (up to 37 ind./m³) and Nihonotrypaea makarovi (up to 46 ind./m³) were most numerous. Larvae of the family Axiidae were recorded only in very low numbers in both bays.     

广西北部湾茅尾海夏冬季浮游细菌群落结构及其影响因子

海洋浮游细菌在生物地球化学循环过程中具有不可替代的作用。为解析广西北部湾茅尾海夏冬季浮游细菌群落结构及其关键环境影响因子,于2017年6月(夏季)和2017年12月(冬季)在该海域设置7个站点,采集0.5m处表层海水样品,利用16S核糖体RNA (16S rRNA)基因高通量测序技术,分析茅尾海浮游细菌群落结构与多样性。结果表明：茅尾海海域浮游细菌隶属于11个门、36个纲、86个目、188个科和506个属;主要浮游细菌类群为变形菌门(Proteobacteria, 52.47%)、厚壁菌门(Firmicutes, 17.34%)、放线菌门(Actinobacteria, 16.39%)、拟杆菌门(Bacteroidetes, 7.54%)和蓝细菌门(Cyanobacteria, 5.38%),共占浮游细菌总丰度的99.12%。北部湾茅尾海夏季浮游细菌群落Chao 1指数和Richness指数均显著(P<0.05)高于冬季。主坐标分析(PCoA)和相似性分析(ANOSIM)结果表明,不同季节浮游细菌群落结构存在极显著差异(R=0.586,P<0.001)。在目分类水平上进行组...     

Abundance,dynamics and succession of planktonic rotifers in Lake Biel,Switzerland

Twenty species of planktonic rotifers were important in Lake Biel during 1978. Eight species were present throughout the year, four species occurred only in spring and eight species in summer or autumn. Rotifer numbers attained two major maxima, one in May (19.3 10⁶ ind. m^?2) and one in August (16.5 10⁶ ind. m^?2). Predominant genera were Synchaeta, Polyarthra, Conochilus, Asplanchna and Keratella. Within the genus Synchaeta a succession of different species was observed.     

海南岛西北沿岸海域浮游桡足类的分布及群落特征

为了解昌江沿岸海域生态系统的现状, 探讨海域环境因素对浮游动物的生存环境造成的影响。本文根据2008年11月至2009年7月在海南西部昌江沿岸水域21个测站、4个季度月调查所获的浮游桡足类样品数据, 对该海域浮游桡足类群落结构、分布、季节变化及影响因素进行了分析。本调查共鉴定出桡足类44种, 隶属4目17科24属, 其中秋季25种, 冬季23种, 春季22种, 夏季23种。本次调查共发现优势种6种, 分别是微刺哲水蚤(Canthocalanus pauper)、亚强次真哲水蚤(Subeucalanus subcrassus)、锥形宽水蚤(Temora turbinata)、刺尾纺锤水蚤(Acartia spinicauda)、椭形长足水蚤(Calanopia elliptica)和精致真刺水蚤(Euchaeta concinna), 优势种以近岸暖水种居多。浮游桡足类丰度季节变化明显: 冬季最高, 达409 ind./m³; 秋季次之, 为144 ind./m³, 春季为55 ind./m³, 夏季最低仅为17 ind./m³。其丰度的平面分布显示: 秋、冬季节分别在海区中部和南部形成明显密集区, 春、夏季节则大致呈现由外海向近岸逐渐递减的趋势。浮游桡足类的多样性指数(H')表现为夏季>春季>秋季>冬季, 春、夏季的均匀度指数(J')明显高于秋、冬季。本调查反映出该海区的桡足类群落具有热带—亚热带区系特征, 种类组成季节更替明显, 桡足类种群受海域水温和硅藻的影响明显, 受盐度影响不明显。     

Changes in pelagic Polychaete assemblages along the California current system

The composition, abundance, species richness and structural changes of the planktonic polychaete assemblages were analysed along a latitudinal transect in the California Current System (California, U.S.A. and Baja California, Mexico). The biological (species and abundance) and physical (temperature and salinity) data were analysed using Principal Component Analysis (PCA). The principal water masses in the survey area were determined. Twenty-four holoplanktonic species belonging to families Alciopidae, Iospilidae, Lopadorhynchidae, Tomopteridae and Typhloscolecidae were identified. Three clear species assemblages were discerned in the PCA results: 1. A `north group' (from Oregon-California border to San Francisco), with relatively high species richness (11) and the highest mean abundance (121 ind. per 500 m<sup>3</sup>) was characterised by Tomopteris septentrionalis, T. planktonis, Plotohelmis tenuis, and Travisiopis lobifera. California Current Water and Subtropical Central Water were present in the area occupied by this assemblage. 2. A `south group' (from off Bahía Magdalena to Cabo San Lucas), with the highest species richness (16), but low mean abundance (37.8 ind. per 500 m³); it included tropical affinity species, such Lopadorhynchus henseni, Tomopteris nationalis, and Travisiopsis dubia. In concordance Surface Equatorial Water was identified in this region. 3. A `transition group' (between the north and south regions) recorded the lowest mean abundance (2.3 ind. per 500 m³) and species richness (9). Only the California Current Water was detected in this area. The spatial pattern of species richness found along of this transect, was at least, partially due to the planktonic productivity distribution in the epipelagic region and the influence of several water masses coming from different directions.     

Spatial Subtidal Macrobenthic Distribution in Relation to Abiotic Conditions in the Lima Estuary, NW of Portugal

During the summer of 2002, sampling was carried out in the Lima estuary in order to compare the pattern of the macrobenthic community’s distribution in relation to physical and chemical variables. A total of 54 macrobenthic taxa were identified. Abundance, biomass and specific diversity varied among the twenty stations. Abundance ranged from 212 to 9856 ind./m², with an average of 1581 ind./m². Abra alba presented the highest density corresponding to 39.1% of the total specimens gathered, followed by Hediste diversicolor with 31.5%. Biomass ranged from 0.12 to 264.62 g AFDW/m², with an average of 17.58 g AFDW/m². Cerastoderma edule and A. alba were the species with a clear predominance in the total biomass, contributing 75.3 and 13.8%, respectively. The multivariate techniques used revealed a macrobenthic community with five distinct groups, particularly related to the sedimentological characteristics and salinity. These results demonstrated significant differences in macrobenthic assemblage’s composition along an estuarine gradient. For the first time the presence of the nonindigenous invasive species Corbicula fluminea was described in this estuary.