北部湾北部生态系统结构与功能研究Ⅰ.浮游动物种类组成及其时空变化

根据北部湾“908专项”于2006-2007年4个季节的调查数据,分析了北部湾北部浮游动物的种类组成及影响种数时空变化的环境因素。研究结果表明,北部湾北部浮游动物共计鉴定370种,隶属于8个门,19个类群。水螅水母类和桡足类是优势类群。种数变化呈如下从大至小的顺序为夏季、秋季、春季、冬季的单峰型季节性特征。种数平面分布与水深变化有关,种类数随水深的增加而增多。广温广盐类群和近岸低盐类群在该海域占据主导地位,与少数的河口类群及大洋类群形成北部湾北部特有的浮游动物群落组成结构。该海域在春季出现的暖温带种类由粤西沿岸经琼州海峡过道水带入本调查区。影响种数的环境因素呈季节性变化。地形特征、海流与水团的消长及浮游植物的生长与繁殖是影响浮游动物群落组成和水平分布推移的重要因素。     

2000年秋季渤海的网采浮游植物群落

研究了2000年秋季覆盖渤海60个测站的网采浮游植物物种及其群落特征,共发现浮游植物3门35属64种(不包括未定名物种).物种主要以硅藻为主,但甲藻在群落中的比重也很明显,在个别站位上会成为优势类群.优势种主要为偏心圆筛藻、三角角藻、浮动弯角藻等,其中的偏心圆筛藻、浮动弯角藻、布氏双尾藻、梭状角藻和叉状角藻是秋季渤海浮游植物的关键种.细胞丰度的平面分布由浮游硅藻的分布决定,其高值区分布在渤海中北部、渤海湾南部和渤海海峡南部.浮游甲藻在渤海湾北部存在高值区.由于渤海环流的影响在渤海中北部存在浮游植物群落的交错区,此区物种丰富度高、多样性水平高和细胞丰度高.秋季渤海浮游植物群落物种丰富度、Shannon-Wiener多样性指数和均匀度的高值区在渤海中部,但整个秋季浮游植物群落的多样性程度是较低的.     

Gulf of Mexico hydrocarbon seep communities: VI. Patterns in community structure and habitat

Communities of chemosynthetic fauna that depend on seeping oil and gas have been found in the Gulf of Mexico at approximately 45 sites between 88°W and 95°W and between the 350 and 2,200 m isobaths. Investigations suggest that the number of sites and the range of occurrence will increase with additional exploration. The dominant fauna consist of species within four groups: tube worms, seep mussels, epibenthic clams, and infaunal clams. These species co-occur to some degree, but tend to form assemblages dominated by a single group. Community development is closely coupled to the geological and geochemical processes of seepage.     

Cold seeps of the deep Gulf of Mexico: Community structure and biogeographic comparisons to Atlantic equatorial belt seep communities

Quantitative collections of tubeworm- and mussel-associated communities were obtained from 3 cold seep sites in the deep Gulf of Mexico: in Atwater Valley at 1890 m depth, in Alaminos Canyon at 2200 m depth, and from the Florida Escarpment at 3300 m depth. A total of 50 taxa of macro- and megafauna were collected including 2 species of siboglinid tubeworms and 3 species of bathymodiolin mussels. In general, the highest degree of similarity was between communities collected from the same site. Most of the dominant families at the well-characterized upper Louisiana slope seep sites of the Gulf of Mexico were present at the deep sites as well; however, there was little overlap at the species level between the upper and lower slope communities. One major difference in community structure between the upper and lower slope seeps was the dominance of the ophiuroid Ophioctenella acies in the deeper communities. The transition between upper and lower slope communities appears to occur between 1300 and 1700 m based on the number of shared species with the Barbados seeps at either end of this depth range. Seep communities of the deep Gulf of Mexico were more similar to the Barbados Accretionary Prism seep communities than they were to either the upper slope Gulf of Mexico or Blake Ridge communities based on numbers of shared species and Bray–Curtis similarity values among sites. The presence of shared species among these sites suggests that there is ongoing or recent exchange among these areas. An analysis of bathymodioline mussel phylogeography that includes new collections from the west coast of Africa is presented. This analysis also suggests recent exchange across the Atlantic equatorial belt from the Gulf of Mexico to the seeps of the West Nigerian margin.     

Foraminifera from the continental slope off Cape Hatteras, North Carolina

The recent benthic meiofaunal foraminiferal assemblage from the continental slope (590-2 003 m) off Cape Hatteras, North Carolina exhibits high species richness and evenness, moderate diversity values, and lacks numerically dominant species. The preserved planktic assemblage has relatively low species richness, high evenness, low diversity, and a few numerically dominant species. Approximately 9% of the benthic species are those that typically live within continental shelf depth ranges. The benthic assemblage abundances and diversities do not follow depth patterns or geophysical characteristics. No biogeographic boundary can be described within the study area for meiofaunal foraminifera. Oxygen limitation does not appear to be a factor affecting the benthos of the North Carolina continental slope based upon the community structure of the benthic foraminifera, if total assemblage is assumed to reflect the recently living community. The high carbonate content of sediments in the area may be explained by foraminiferal tests. Within the study area, the foraminiferal assemblages are uniform, and probably reflect relative consistency of primary environmental variables as well as dynamic downslope transport and high influx of material from the water column in the vicinity where the Gulf Stream and the Western Boundary Undercurrent cross.     

Contrasting changes between the northern and southern Gulf of St. Lawrence ecosystems associated with the collapse of groundfish stocks

In order to have a global view of ecosystem changes associated with the collapse of groundfish species in the Gulf of St. Lawrence during the early 1990s, Ecopath mass-balance models were constructed incorporating uncertainty in the input data. These models covered two ecosystems (northern and southern Gulf of St. Lawrence; NAFO divisions 4RS and 4T), and two time periods (before the collapse, in the mid-1980s, and after it, in the mid-1990s). Our analyses revealed that the ecosystem structure shifted dramatically from one previously dominated by piscivorous groundfish and small-bodied forage species during the mid-1980s to one now dominated only by small-bodied pelagic species during the mid-1990s in both southern and northern Gulf. The species structure in the northern Gulf versus southern Gulf was different, which may explain why these two ecosystems did not recover the same way from the collapse in the early 1990s. Productivity declined in the northern Gulf after the collapse but increased in the southern Gulf. The collapse of groundfish stocks resulted in declines in the mean trophic level of the landings in both the northern and the southern Gulf. Even though fishing mortality was then intentionally reduced, this part of the total mortality was taken up by predation. The temporal changes in the internal structure of both ecosystems are reflected in their overall emergent properties.     

Distribution of macroalgae and seaweed in the Azov Sea,Kerch Strait,and Taman Bay

The analysis of the macroalgae distribution along the salinity gradient in the Azov Sea, the Kerch strait, and Taman Bay during the summer allowed finding two macroalgae complexes. The first complex (brackish) is formed by algae belonging to the Enteromorpha, Cladophora, Rhizoclonium, and Chaetomorpha genera in the Taganrog Gulf. The second complex (marine) with dominating algae belonging to the Enteromorpha, Chaetomorpha, Ceramium, and Polysiphonia inhabits the littoral part of the Azov Sea itself, the Kerch Strait, and Taman Bay. The saprobe analysis of the flora showed that the majority of macroalgae species inhabiting the Azov Sea are represented by meso- and polysaprobes and a small number of oligosaprobe species inhabit the Kerch Strait. The biggest species diversity of macroalgae was noted in the southwestern part of the sea; the value of Shannon’s index was 0.65 in the Taganrog Gulf, 1.04 in the Azov Sea, 1.38 in Taman Bay. The leading role in the littoral communities of Taganrog Gulf belongs to aquatic flowering plants with Potamogeton perfoliatus being dominant; as the salinity increases, the share of such species as P. pectinatus, Zostera marina, Z. noltii, Ruppia maritime, and Zannichellia major starts to increase.     

Distribution et écologie des Méduses (Cnidaria) du golfe de Tunis (Méditerranée sud occidentale)

The Medusae of Tunis Gulf (25 species) are qualitatively the third zooplanktonic group after Tintinnids and Copepods. Anthomedusae (eight species), Trachymedusae (five species) and Leptomedusae (four species) represent the major part among the 20 species of Hydromedusae identified during our study (December 1993–November 1995). However, the Limnomedusae (two species) and the Narcomedusae (one species) are poorly represented. In the Bay of Tunis, Obelia spp., the most common and dominant species, command the quantitative fluctuations of Hydromedusae and reach exceptionally the density of 25 800 ind. m^–3. Within the Scyphomedusae (five species), Pelagia noctiluca is the most common species which outbreaks in winter and autumn. Tunis Gulf seems to be composed of two jellyfish communities; the first one is composed of endogenous species showing a constant period of blooming like Olindias, Cladonema, Aurelia, Cotylorhiza and Rhizostoma and sometimes permanent like Obelia spp. and Clytia spp.; the second is represented by exogenous species considered as “visitors” like Velella, Sminthea or Pelagia whose presence on the coast is dependent on local and particular winds and currents.     

Characterization of earthquake sources in the Gulf of Alaska

Abstract

The characterization of earthquake sources in the Gulf of Alaska and the relative significance of earthquake sources for establishing seismic design inputs at a typical site for engineering purposes are discussed. Earthquake sources in the complex tectonic environment can be divided into two groups: (a) a subduction zone that underlies the entire region (maximum magnitude M = 8.5); and (b) individual thrust and strike‐slip faults associated with the plate motions (maximum magnitude M = 6 to 7.5). The sources of either group and individual earthquake events can be represented as planar surfaces for consistency with the physical process and a mathematically tractable computational scheme.

Although the area is very active seismically, the degree of activity of individual sources varies significantly. Therefore, even for sources with the same maximum earthquakes, different magnitudes may apply for a selected design return period. The area is considered to be a “seismic gap.”; No great earthquakes have occurred in nearly 80 years. Estimates based on a temporally varying seismic function such as the semi‐Markov model indicate that the probability of occurrence of a great earthquake in the near future is significantly higher than the average probability inferred from a statistical analysis of historical seismicity data of the entire region.

Separate attenuation relationships should be used for calculating ground motions due to earthquakes on the dipping subduction zone in the northern portion of the gulf. The dominant earthquake source for almost the entire Gulf of Alaska region is the subduction zone that contributes over 80 percent of the seismic exposure at a typical site. The dominant magnitude range is M_s = 6.5 to 7.5. “Gap filling”; earthquakes (M_s = 7.5 to 8.25) contribute a little over a third of the seismic exposure at a typical site. Deterministic assessments of ground motion values using the maximum earthquake on the subduction zone at the closest distance yield values significantly higher than those calculated for even 500‐year return periods. Estimated 100‐year return period accelerations in the area range from 180 to 340 cm/sec².     

A unified assessment of marine Mediterranean assemblages: a lesson from benthic hydroids

Hydroids are important components of the communities of rocky bottom shallow coastal areas. The hydrozoan fauna of the Mediterranean Sea is probably one of most investigated in the world, with lots of faunistic and biogeographical studies. However, quantitative studies using the same sampling methodology and controlled sampling effort have been restricted to areas in the Western and Central Mediterranean. We compared hydroid assemblages in four areas of the Mediterranean Sea, from the Gulf of Cádiz to the South Adriatic Sea, following the same sampling and quantification methodology. Our analysis showed the dominant Atlantic character of the assemblages of the Gulf of Cádiz and the South Alboran Sea because of the influence of the inflowing Atlantic waters. Conversely, the hydroid assemblages of the North Alboran Sea were more similar to the assemblages in the Ligurian and in the South Adriatic, and with a number of species ranking between the observed in these two Mediterranean zones. Fourteen species were identified as making the most significant contributions to characterizing the Mediterranean hydroid species pool from a quantitative point of view. These taxa include species previously named as typical components of the Mediterranean hydroid fauna as well as those only recently recorded in the region (Eudendrium moulouyensis) and invaders such as Clytia hummelincki.     

Meiobenthos under mariculture conditions of the brown seaweed <Emphasis Type="Italic">Saccharina japonica</Emphasis> in Rifovaya Bay,Peter the Great Gulf,Sea of Japan

The qualitative and quantitative compositions of free-living marine nematodes were studied in Rifovaya Bay (Peter the Great Gulf, Sea of Japan). It was found that the density distribution of nematode populations in bottom sediments of Rifovaya Bay is nonuniform. In total, 72 nematode species were found, including Oncholaimium paraolium, Viscosia epapilosa, and Monoposthia latiannulata on all types of substrates. The dominant trophic group comprised “predators” (2B) and “scrapers” (2A). It was shown that the species composition of nematodes in Rifovaya Bay is very similar to the species composition of nematodes in the other areas of Peter the Great Gulf.     

嵊泗列岛潮间带群落生态学研究 Ⅲ.岩相潮间带底栖生物的种类分布

对嵊泗列岛岩相潮间带底栖生物种类分布进行的研究表明,种类的水平分布主要受盐度及海岸开敞度的影响,从近岸到外海,随着盐度及海岸开敞度的增加,潮间带底栖生物的种类数呈增加的趋势。不同海区的优势种不同,近岸较屏蔽区以软体动物及甲壳动物占优势,外海开敞区以甲壳动物及藻类占优势,近外海较开敞区为一过渡区;种类的垂直分布主要受潮区及海岸开敞度的影响,各海区不同潮区生物种类数均为中潮区多于低潮区多于高潮区,高潮区基本上为滨螺分布带,中潮区为日本笠藤壶－藻类带,低潮区为藻类带;外海区种类的季节变化明显,近岸区种类季节变化小。所有物种中,以底栖海藻的季节变化最为明显。     

Spatiotemporal distribution of copepod populations in the Gulf of Gdansk (southern Baltic Sea)

In the present study, we used a 3D Coupled Ecosystem Model of Baltic Sea version 1 (3D CEMBSv1) coupled with a copepod model to examine the spatiotemporal distribution of two representative copepod populations in the Gulf of Gdansk (southern Baltic Sea) including Acartia spp. and Pseudocalanus minutus elongatus. The annual cycles simulated for 2000 under realistic weather and hydrographic conditions were studied with the three-dimensional version of the coupled ecosystem-copepod model in the south-eastern Baltic Sea. The paper presents the comparison of simulated and observed copepod development at two stations in the Gulf of Gdansk. A validation of influential state variables gives confidence that the model is able to calculate reliably the stage development of dominant species in the southern Baltic Sea. The number of generations was one for P. m. elongatus and 3?C5 for Acartia spp.. A mean of five generations for the latter species per year were estimated in the coastal region and ca. three generations at the Gdansk Deep (in the open sea). Food concentration and temperature as the main factors controlling the development of the investigated copepods as well as salinity as a masking factor (i.e. salinity modifies the rate of their development) in the case of Pseudocalanus minutus elongatus are included in the present study.     

2014年冬季西太平洋雅浦海山与大洋海域大型浮游动物群落比较研究

2014年冬季对西太平洋雅浦Y3海山区和从西太平洋暖池区到黑潮源区之间的大洋海域的浮游动物进行了调查研究，分析了海山区和大洋海域大型浮游动物群落的物种组成、丰度和分布，并比较了两个海域大型浮游动物群落的差异，结合温度、盐度和叶绿素a浓度等环境因子数据，分析了海山对大型浮游动物群落的影响。结果表明，Y3海山区和大洋海域的大型浮游动物群落物种组成存在差异，二者的群落相似度系数为68.4%，两个海域的优势种/类群也不尽相同，海山区的优势种/类群是磷虾各期幼体、尖额磷虾和蛮𧊕，而大洋海域的优势种/类群分别是磷虾后期幼体、手磷虾、蛮𧊕、尖额磷虾和莹虾。大型浮游动物群落在海山区的平均丰度和最大丰度都要高于大洋海域，但海山区的生物多样性指数、均匀度指数和生物量占比都低于大洋海域，因而Y3海山对大型浮游动物群落的海山效应不明显。通过相关性分析和主成分分析结果可以看出，海山区的首要影响环境因子是盐度，而大洋海域则是温度；海山区和大洋海域的大型浮游动物丰度分别与200m层盐度和平均温度呈负相关关系，并且在两个调查海域均未发现大型浮游动物的丰度和生物量分布与叶绿素a浓度之间存在显著的相关关系。     

Meso-scale variability of coastal suprabenthic communities in the southern Tyrrhenian Sea (western Mediterranean)

Meso-scale spatial variability of coastal suprabenthic communities inhabiting muddy bottoms at 50–80 m depth in three gulfs of northern Sicily (Western Mediterranean) was here investigated. Although similar as concerns the hydrological and oceanographic conditions, the three areas, that encompass a large portion of the continental shelf (135 km), are characterized by different geo-morphological features. In addition, they are subjected to different trawl fishery pressures. The Gulf of Castellammare is a semi-enclosed bay, where the trawling activity has been banned since 1990. The Gulf of Termini Imerese and the Gulf of Sant’Agata are open areas, subjected to high trawl fishing intensity. In terms of density, gammarid amphipods showed differences among the three gulfs; in terms of biomass, cumaceans and amphipods were more abundant in the Gulf of Castellammare than in the other two areas. Multivariate analyses provided evidence for separation of suprabenthic assemblages between the Gulf of Castellammare and the other two gulfs. The Gulf of Castellammare seemed to host the most diversified and stable community according to α- and β-diversity indices. In the same way the low value of δ¹³C vs. δ¹⁵N correlation found in the gulf of Castellammare, which evidences the occurrence of several food sources, supports the idea of a higher stability in the semi-enclosed, trawl-ban area. In the other two areas δ¹³C vs. δ¹⁵N correlations were high, suggesting the existence of a pelagic source sustaining the suprabenthic communities. This is also confirmed by the lower δ¹³C concentrations found in suprabenthic species. Taking into account the homogeneous oceanographic conditions among gulfs, other factors, such as geo-morphology and trawling pressure should be involved in the observed differences among the three areas in terms of assemblage structure, diversity, and trophodynamics of suprabenthic communities.     

春、夏季长江口邻近水域浮游动物优势种的生态特征

依据2000～2003年长江口邻近海域5月和8月8个航次的调查资料,对长江口浮游动物优势种的生态特征进行了研究。根据优势种出现的年份,平均丰度、优势度、聚集强度和对总丰度变化的回归贡献,确定本区优势种的重要性为真刺唇角水蚤（Labidocera euchaeta）〉中华哲水蚤（Calanus sinicus）〉背针胸刺水蚤（Centropage dorsispinatus）。太平洋纺锤水蚤（Acartia pacifica）,火腿许水蚤（Schmackeria poplesia）和虫肢歪水蚤（Tortanus vermiculus）为次要优势种。马蹄娩螺（Limacina trochiformis）是偶然出现的优势种。中华哲水蚤在春季对总丰度贡献最大。真刺唇角水蚤是8个航次唯一的优势种,种群年间变化不显著。太平洋纺锤水蚤,火腿许水蚤和虫肢歪水蚤分布范围相对狭小,火腿许水蚤和虫肢歪水蚤分布在沿岸偏淡水的水体,适合较低的温度。太平洋纺锤水蚤分布在近岸偏成水的水体,适合较高的温度。     

微藻在污水中的除磷脱氮作用

初步调查了广州海珠区污水排放区污水中微藻的组成,表明该区微藻以蓝藻门颤藻科Ｏｓｃｉｌｌａｔｏｒｉａｃｅａｅ为主,以小颤藻Ｏｓｃｉｌｌａｔｏｒｉａｔｅｎｕｉｓ、两栖颤藻Ｏ．ａｍｐｈｉｌｉａ为优势种;测定了其在污水中的除磷脱氮能力,结果表明,两优势种处理污水氮、磷的能力随微藻的生长期和污水中氮、磷浓度的不同而有较大的变化。     

夏季长江口及邻近海域水母类生态特征研究

利用2003年6月和2006年6月在长江口及邻近海域进行的两次大面调查所采集的浮游动物网采样品,对长江口及邻近海域水母类的种类组成、优势种、数量分布及生态类群等进行了探讨。结果表明:研究水域共记录水母类77种,其中水螅水母60种,管水母12种,钵水母1种,栉水母4种。优势种有:五角水母(Muggiaea atlantica),双生水母(Diphyes chamissonis),拟细浅室水母(Lensia subti-loides),四叶小舌水母(Liriope tetraphylla),两手筐水母(Solmundella bitentachlata),嵊山秀氏水母(Sugiura chengshanense)和瓜水母(Bere cucumis)等。其中水螅水母类的优势种存在较大的年际变化,2003年为嵊山秀氏水母,2006年为四叶小舌水母和两手筐水母。研究水域内水母类平面分布不均匀,2003年平均丰度为13.3个/m3,除在长江口外存在一个由河口低盐种贝氏拟线水母(Nemopsis bachei)大量聚集形成的高值区外,在舟山群岛南部还存在一个密集中心;2006年水母类丰度略有上升,平均丰度为16.0个/m3,与2003年相比,其密集中心向东北部偏移。2006年6月研究海域温、盐较2003年同期均大幅升高是造成两航次优势种类更替及水母类分布变化的主要原因。     

北部湾地形、底质特征与渔场分布的关系

北部湾作为南海北部重要水域.属于热带和亚热带半封闭海湾.湾内地形地貌以及底质特征复杂。鱼类资源丰富。北部湾渔区的划分与地形地貌、底质特征存在密切联系.为更好的了解渔业生物的生活史、空间配布以及北部湾的渔业资源特点本文进行了初步的基础研究。为北部湾的渔业资源开发提供了科学依据。     

Accumulation of periphyton biomass on artificial substrates deployed near a sewage sludge outfall in South Australia

Digested sludge from the Port Adelaide Sewage Treatment Works has been discharged into Gulf St Vincent, a marine embayment in South Australia, since 1978. The outfall was sited in seagrass meadows and four years after it began operating the dominant seagrass species were lost from an area of 365 ha. Discernible effects extended over 1900 ha and the seagrass beds in partially affected areas were characterized by unusually heavy growth of epiphytes. Artificial substrates were used to assess the accumulation of ‘epiphyte’ (periphyton) biomass in areas affected by sludge and at a control site. The greatest accumulation was recorded in the area most affected by sludge, i.e. the area from which all seagrass has been lost. It is suggested that excessive accumulation of epiphytes, resulting from the addition of sludge to the water column, may have contributed to the decline of the original seagrass beds.