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1.
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2.
This study aims to explore the distribution of meiofaunal abundance in relation to environmental factors in the Beibu Gulf,a natural semi-enclosed part of the South China Sea,surrounded by China and Vietnam.Meiofauna and ten benthic environmental factors were determined at 27 sampling stations in the Beibu Gulf in four surveys during 2006-2007.The results show a clear geographical trend in meiofaunal abundance,water depth,salinity and clay content.The meiofaunal abundance and the clay content decreased,whereas the water depth and the salinity increased from the north to the south of the Gulf.The percentage of meiofaunal abundance in the 0-2 cm layer increased,whereas in the 2-5 cm and 5-10 cm layers it decreased from the north to the south of the Gulf.Correlation analysis show significant negative correlations between meiofaunal abundance and water depth,benthic temperature,salinity and pH,but significant positive correlations between meiofaunal abundance and dissolved oxygen,chlorophyll a and clay content.  相似文献   

3.
The results of meiobenthic surveys undertaken in 1991, 1999, and 2005 off the Caucasian coasts of the Black Sea are presented. During the period of 1991 to 1999, the number of free-living nematodes increased significantly at all the sampling stations. The mean nematode abundance values grew from 85 ind./10 cm2 in 1991 to 1167 ind./10 cm2 in 1999. Proportionally, the total metazoan meiofauna density increased from 171 to 1283 ind./10 cm2. The abundance of other meiofaunal groups including harpacticoid copepods did not change significantly. As a result of these changes, the ratio of nematodes to copepods (the nematodes-copepods index) increased from 2.5: 1 in 1991 to 26: 1 in 1999 and to 70: 1 in 2005. The number of foraminifers increased twofold. In 1991, they were found only at five stations out of 25. In 1999, foraminifers were presented at all ten stations with a mean density of 212 ind./10 cm2. Such changes in the meiobenthic communities could have resulted from cascade transformations of the ecosystem leading to among other changes to a decline in the macrobenthos biomass and the release of nonutilized organic matter in the bottom ecosystems. The differences in the procedures of the sampling and the samples’ processing in the different years may be responsible for the 20–30% variation in the assessment of the meiobenthos’ number.  相似文献   

4.
东海北部小型底栖动物群落对径流及黑潮暖流入侵的响应   总被引：1，自引：1，他引：0  
为探究小型底栖动物群落在东海北部及其临近海域的分布规律,及其对环境因子的响应,于2016年9月和12月,对研究海域共计20个站位的小型底栖动物和环境因子进行了取样调查。调查结果显示,研究海域内共鉴定出小型底栖动物类群16个,其中海洋线虫为绝对优势类群,其他优势类群主要包括桡足类、动吻类和多毛类。9月航次小型底栖动物平均丰度为(1 758±759)个/（10 cm2）,线虫占95.6%;平均生物量为(1 216.4±464.7) μg/(10 cm2)(干重),线虫占55.26%。12月航次平均丰度为(2 011±1 471)个/(10 cm2),线虫占95.6%;平均生物量为(1 143.0±755.0)μg/(10 cm2)(干重),线虫占67.28%。聚类分析结果显示,小型底栖动物群落主要可以划分为近岸和外海两个组,其中近岸组小型底栖动物丰度显著高于外海站位。但在各断面分布上,绝大多数站位小型底栖动物丰度最高值均出现在60 m等深线附近,并且该水深处站位的温度和盐度数值均表现出黑潮水的特征。黑潮近岸分支对东海陆架入侵是导致小型底栖动物分布差异的重要原因,小型底栖动物在60 m等深线附近具有的高丰度值可作为其对黑潮入侵的响应。推测,黑潮入侵所导致的水体初级生产力增加以及黑潮水所携带的溶氧可能是导致该深度处小型底栖动物丰度增加的主要原因。  相似文献   

5.
An experiment was performed to determine the effect of injected CO2 on the deep-sea (3200 m) meiofaunal community in the Monterey Canyon. Approximately 20 L of liquid CO2 was added to each of three cylindrical corrals (PVC rings pushed into the seabed) that were arranged in a triangular array 10 m on a side. After a 30-day period, sediment cores were collected within an area exposed to the dissolution plume emanating from the CO2 pools and from a reference site approximately 40 m away; cores were also collected from within two of the CO2 corrals. Sediment cores were sectioned into 0–5, 5–10, and 10–20 mm layers. Abundances of major groups (harpacticoid copepods, nematodes, nauplii, kinorhynchs, polychaetes, and total meiofauna) were determined for each layer. CO2 exposure did not significantly influence the abundances or vertical distributions of any of the major taxa. However, other evidence suggests that abundance alone did not accurately reflect the effect of CO2 on meiofauna. We argue that slow decomposition rates of meiofaunal carcasses can mask adverse effects of CO2 and that longer experiments and/or careful examination of meiofaunal condition are needed to accurately evaluate CO2 effects on deep-sea meiofaunal communities. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

6.
Deep-sea benthic communities and their structural and functional characteristics are regulated by surface water processes. Our study focused on the impact of changes in water depth and food supplies on small-sized metazoan bottom-fauna (meiobenthos) along a bathymetric transect (1200–5500 m) in the western Fram Strait. The samples were collected every summer season from 2005 to 2009 within the scope of the HAUSGARTEN monitoring program. In comparison to other polar regions, the large inflow of organic matter to the sea floor translates into relatively high meiofaunal densities in this region. Densities along the bathymetric gradient range from approximately 2400 ind. 10 cm-2 at 1200 m to approximately 300 ind. 10 cm-2 at 4000 m. Differences in meiofaunal distribution among sediment layers (i.e., vertical profile) were stronger than among stations (i.e., bathymetric gradient). At all the stations meiofaunal densities and number of taxa were the highest in the surface sediment layer (0–1 cm), and these decreased with increasing sediment depth (down to 4–5 cm). However, the shape of the decreasing pattern differed significantly among stations. Meiofaunal densities and taxonomic richness decreased gradually with increasing sediment depth at the shallower stations with higher food availability. At deeper stations, where the availability of organic matter is generally lower, meiofaunal densities decreased sharply to minor proportions at sediment depths already at 2–3 cm. Nematodes were the most abundant organisms (60–98%) in all the sediment layers. The environmental factors best correlated to the vertical patterns of the meiofaunal community were sediment-bound chloroplastic pigments that indicate phytodetrital matter.  相似文献   

7.
Metazoan meiofaunal abundance, total biomass, nematode size and the richness of taxa were investigated along bathymetric gradients (from the shelf break down to ca. 5000-m depth) in six submarine canyons and on five adjacent open slopes of three deep-sea regions. The investigated areas were distributed along >2500 km, on the Portuguese to the Catalan and South Adriatic margins. The Portuguese and Catalan margins displayed the highest abundances, biomass and richness of taxa, while the lowest values were observed in the Central Mediterranean Sea. The comparison between canyons and the nearby open slopes showed the lack of significant differences in terms of meiofaunal abundance and biomass at any sampling depth. In most canyons and on most slopes, meiofaunal variables did not display consistent bathymetric patterns. Conversely, we found that the different topographic features were apparently responsible for significant differences in the abundance and distribution of the rare meiofaunal taxa (i.e. taxa accounting for <1% of total meiofaunal abundance). Several taxa belonging to the temporary meiofauna, such as larvae/juveniles of Priapulida, Holothuroidea, Ascidiacea and Cnidaria, were encountered exclusively on open slopes, while others (including the Tanaidacea and Echinodea larvae) were found exclusively in canyons sediments. Results reported here indicate that, at large spatial scales, differences in deep-sea meiofaunal abundance and biomass are not only controlled by the available food sources, but also by the region or habitat specific topographic features, which apparently play a key role in the distribution of rare benthic taxa.  相似文献   

8.
The ecological aspect of meiofaunal communities in Can Gio mangrove forest, Ho Chi Minh city, Vietnam has not been investigated before. The composition, distribution, density and biodiversity of meiofaunal communities were studied along an intertidal transect at the Khe Nhan mudflat. Each time, three replicate samples were collected in four stations along a transect following the water line from low tide level up to the mangrove forest edge. In total, 18 meiofaunal taxa were found with the dominant taxa belonging to Nematoda, Copepoda, Sarcomastigophora and Polychaeta. The densities of meiofauna ranged from 1156 inds/10 cm2 to 2082 inds/10 cm2. The increase in densities from the mangrove forest edge towards the low water line was significant. Along the mudflat transect, the biodiversity (expressed by different indices) was relatively high at different taxonomic levels but did not vary significantly along the mudflat except for taxa richness. Eighty nematode genera belonging to 24 families with Comesomatidae having the highest abundance 33.8 % were found.Theristus andNeochromadora decreased in densities from the lower water line towards the mangrove forest edge, whileParacomesoma andHopperia are typical and more abundant at the middle of the mudflat.Halalaimus increased from high on the mudflat to the low water line.  相似文献   

9.
Meiofauna and macrofauna communities and several sediment characteristics were compared between a slope situated far from the coast (Goban Spur) and two transects across the Iberian Margin with steep slopes and close to the shore. The northern Galician transect (off La Coruña) was situated in an area subjected to wind-induced upwelling events. The western Galician transect was also subjected to upwelling, was additionally influenced by outflows of water rich in organic matter from the Rías Bajas. This transect also included the Galicia Bank. Macrofauna density decreased exponentially from the shelf edge (154 m) to the abyssal plain (4951 m) and different communities occurred on the shelf, the upper- and lower slope and on the abyssal plain. Apart from two extremely low-density stations on the Iberian Margin, there were no significant differences in the meiofauna between the Goban Spur and the Iberian Margin. Along the La Coruña-transect a station where meiofaunal densities were low occurred at a depth of 1522 m, where the sediment was characterised by having a high median-grain size, ripple structures, a low Corg and total N content. There were relatively high numbers of macrofaunal filter-feeders but low numbers of crustaceans, indicating a high current velocity regime. On top of the Galicia Bank (˜770 m) the sediment consisted mainly of shells of pelagic foraminifers, and had low contents of Corg and N. The macrofauna was dominated by filter-feeding and carnivorous taxa. At both these stations meiofauna densities were low. Meiofauna densities and community structure differed between the Goban Spur and the Iberian Margin. Meiofauna densities on the Galician shelf were more than double those on the Goban Spur shelf. The two deep stations on the La Coruña transect and the deepest station on the Galicia Bank transect all contained meiofaunal densities that were higher than found at similar depths off the Goban Spur. The meiofaunal densities were inversely correlated with %CaCO3 content and, excluding the shelf stations, were positively correlated with both %Corg and total N at the Iberian Margin. Neither upwelling nor the enriched outflows from the rias affected the macrofauna, but meiofaunal densities were greatly enhanced.  相似文献   

10.
The present study focuses on horizontal spatial variability of benthic macrofauna associated with Patella ferruginea. Thirty-six samples collected at 12 transects belonging to 4 midlittoral sites along the rocky Tunisian coastline, were examined. A total of 44 species belonging to 5 taxa were found. Multivariate analysis applied on gathered data did not show a horizontal spatial variability at small scale (between transects), but at large scale, between sites as well as sectors. Thus, three groups of communities were identified (GI: Korbous and El Haouaria; GIIa: Zembra Island and GIIb: Kelibia). The distribution of species abundance within these groups revealed that crustaceans were the most abundant taxon, due to the overwhelming dominance of Chthamalus stellatus. This substratum appeared to create favourable micro-habitats for the installation of molluscs including gastropods. Regarding the low diversity index (H') and evenness (J), they seemed to reflect a disturbance and a demographic unbalance within these communities. The heterogeneity of substrate surface, created by C. stellatus specimens appeared to be caused by various complex interactions established between the key components of these communities in particular suspension feeders, predators, herbivorous molluscs and macroalgae. Thus, the dynamic status of each of these communities is the result of these complex interactions.  相似文献   

11.
The metazoan meiofauna in the Chukchi Sea were collected from seven shallow water stations(depths ranging 46 to 52 m) and five deep sea stations(depths ranging between 393 and 2 300 m) during the 4th Chinese National Arctic Research Expedition in 2010. The results showed that abundance of meiofauna was higher in shallow water sediments(average of 2 445 ind./(10 cm2)) than in deep sea sediments(407.06 ind./(10 cm2)). A UNIANOVA test for difference between the two different regions was highly significant(F=101.15, p0.01). Nematodes were numerically dominant, representing(96.6±4.6)% of the total meiofaunal abundance at the shallow water stations and(98.90±1.42)% at deep sea stations. The number of higher taxonomic groups and abundance of meiofauna were higher at Stas CC1, CC4, and R06 near the Bering Strait and the continent, than at the rest of the shallow water and deep sea stations. The primary factors causing the differences were concentrations of nutrients P and Si of bottom seawater(R=0.831, p0.003), followed by depth(R=-0.655, p0.05) and sand fractions of sediments(R=0.632, p 0.05). The numbers of meiofauna on the 65 μm and 32 μm sieves were significantly higher than those on the rest of the screens. Differences in numbers of meiofauna retained on screens with different mesh openings were highly significant among all sampling stations(F=31.60, p0.01). The highest numbers of individuals on screens with 32 μm mesh openings were found at deep sea stations. The number of meiofauna in the top 0–1, 1–2, and 2–4 cm segments constituted 84.4% of the total and was significantly higher than those in the bottom 4–6 and 6–10 cm segments(F=15, p0.01).  相似文献   

12.
Faunistic data from a newly designed camera-epibenthic sledge (C-EBS) are presented. These were collected during the joint Russian–German expedition SoJaBio (Sea of Japan Biodiversity Studies) on board the R.V. Akademik Lavrentyev from four transects (A–D) between 460 and 3660 m depth. In total, 244,531 macro- and megafaunal individuals were sampled with the classes Malacostraca (80,851 individuals), Polychaeta (36,253 ind.) and Ophiuroidea (34,004 ind.) being most abundant. Within the Malacostraca, Peracarida (75,716 ind.) were most abundant and within these, the Isopoda were the dominant taxon (27,931 ind.), followed by Amphipoda (21,403 ind.), Cumacea (13,971 ind.) and Tanaidacea (10,830 ind.). Mysidacea (1581 ind.) were least frequent. Bivalvia, Amphipoda, Cumacea and Mysidacea as well as inbenthic meiofaunal Nematoda occurred in higher numbers at the shallower stations and their numbers decreased with increasing depth. Polychaeta, Isopoda, and Tanaidacea, on the contrary, increased in abundance with increasing depth. Only one isopod species was sampled at abyssal depths in the Sea of Japan but at very high abundance: Eurycope spinifrons Gurjanova, 1933 (Asellota: Munnopsidae). Echinoderms occurred frequently at the shallower slope stations. Ophiuroids were dominating, followed by holothurians, and echinoids and asteroids which occurred in lower numbers and primarily at the shallower stations of transects A and B. Only 2163 individual anthozoans were recorded and these were mostly confined to the lower slope. The technical design of a new C-EBS is described. Next to temperature-insulated epi- and suprabenthic samplers, it is equipped with still and video cameras, which deliver information on seabed topography and megafaunal occurrence. Furthermore, Aanderaa CTD and SEAGUARD RCM allow for collection of physical parameters, such as near bottom oxygen composition, temperature and conductivity.  相似文献   

13.
Previous studies at the Isla Vista oil seep have suggested that meiofauna, particularly nematodes, might be an important factor in explaining macrofaunal enrichment by making bacterial biomass available to the benthic food web. To explore this possibility, we analyzed meiofaunal abundance and microalgal pigments inside and just outside of bacterial mats at this natural oil seep.The bacterial mats occur where crude oil and natural gas are actively seeping out of the sediment; cores from within the mats contained a great deal of crude oil (up to 50 %). Meiofaunal abundances were the same in and out of the bacterial mats (averaging 1·-9 × 106 individuals m-2). However, dramatic changes in community structure were noticed. Harpacticoids made up 19 % of the fauna outside the mats but only 1 % inside. Pigment concentrations were also the same in both sites with phaeophytin dominating chlorophyll (120 compared to 29.8 mg m-2). The variance of both microalgal pigments and meiofauna was much greater inside than outside, suggesting that the bacterial mats are a more heterogeneous environment.Although the effect of crude oil toxicity is not clear, the high abundances of microbial and meiofaunal biomass support the hypothesis of benthic enrichment via microbes and meiofauna.  相似文献   

14.
Rapa (27°36′ S, 144°20′ W) is a small (~40 km2) volcanic island isolated in the Southern Austral Archipelago, where direct anthropogenic stressors are extremely limited. Here, we present the results of the first quantitative survey of coral community structure across habitats and depths around the island. Despite its geographical isolation in the depauperate South Central Pacific, its small size and unfavourable environmental conditions (competition with macroalgae, low sea surface temperatures, reduced reef accretion), the diversity of scleractinian corals at Rapa is particularly high (112 species from 32 genera, including 37 species of Acropora) in comparison to other French Polynesian islands and subtropical Pacific locations. Our results indicate that the abundance (>100 colonies per 10 m2 recorded at nine of the 17 sampling stations) and cover (>40% at four stations) of corals are relatively high for a marginal reef location. Strong spatial heterogeneity was found, with high variation in diversity, abundance, cover and community composition among stations. Variation in community composition was related to habitat types, with distinct assemblages among fringing reefs within bays, reef formations at bay entrances, and those on the submerged platform surrounding the island. On the platform, a depth gradient was detected, with generic richness, abundance and cover generally greater at deeper stations (18–20 m depth) compared with medium‐depth (10–12 m) and shallow (1–3 m) stations. A gradient was also recorded along bays, with increasing coral diversity and abundance from the bay heads to the bay entrances. The coral community at Rapa was characterized by the presence of several taxa not found in other French Polynesian archipelagos and the rarity of others that are common and abundant in the Society and the Tuamotu islands. Another distinctive feature of reef communities at Rapa is the high cover and dominance of macroalgae, particularly in the shallower parts of the surrounding platform, which probably explains the lower densities of coral colonies recorded there. These characteristics of the diversity and biogeographical composition of coral assemblages at Rapa provide considerable ecological grounds for its conservation.  相似文献   

15.
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16.
珊瑚藻是珊瑚礁生态系统中重要的功能性群体。2010年通过水肺潜水分析了三亚珊瑚礁区的珊瑚藻种类组成和丰度, 以及群落空间特征与环境因子的关系。共鉴定出3科10属25种珊瑚藻, 其中珊瑚藻科占优势地位。三亚珊瑚礁区的珊瑚藻优势种分别为叉节藻Amphiroa ephedraea、拟中叶藻Mesophyllum simulans、串胞新角石藻Neogoniolithon fosliei、中叶藻M. mesomorphum、圆锥呼叶藻Pneophyllum conicum、孔石藻Porolithon onkodes和布氏水石藻Hydrolithon boergesenii。基于多元统计的分析结果, 将调查采样站位分为近岸型和离岸型2个主要集群, 其中近岸型的珊瑚藻种类以浊度、沉积速率(0~63μm)和悬浮物耐受种类为主, 离岸型则以光依赖-沉积物敏感种类为主。以珊瑚藻种类组成和丰度为基础的群落相似性分析结果表明, 其空间变异处于显著性水平。生物与非生物变量的相关分析结果表明, 最佳两变量组合(浊度和盐度)显著影响三亚珊瑚礁区2种类型调查站位中的珊瑚藻集合。在同一个研究站位, 因受干扰程度不同, 深水处的珊瑚藻的覆盖率比浅水处高。分析结果表明, 在三亚独特的珊瑚礁区中, 自然或人为的物理干扰因素都对调节珊瑚藻群落结构非常重要。  相似文献   

17.
Abundance of deep-sea meiobenthos off Sanriku, Northeastern Japan was studied quantitatively using sediment samples collected by box corers or an Okean grab. Sampling stations were established along a line transect which covered areas from off the mouth of Otsuchi Bay to the abyssal plain of the western Pacific crossing over the Japan Trench (water depths from 120 m to 7460 m). Abundance of meiobenthos decreased linearly with water depth down to 1503 m and became constant at stations deeper than 4130 m. Nematodes predominated over the other taxonomic groups at all stations. An equation to estimate meiofaunal abundance from several sediment characteristics, which was previously proposed by the first author based on data from tropical and subtropical regions of the western Pacific, was applied to the present boreal area. At one station where the Okean grab was used, the estimated value was 4.7 times more than the observed one. Except for the station, however, observed values fell within the confident range of estimated values. The estimated values were always higher than the observed ones at boxcorer stations, whereasvice versa at Okean-grab stations. These results suggested that keen attention is necessary in selecting sampling gear for ecological studies of deep-sea meiobenthos.  相似文献   

18.
2007年春季在渤海湾天津潮下带采集小型底栖生物样品,分析沉积物中自由生活线虫的垂直分布情况。多元统计分析结果表明,底栖线虫的垂直分布和沉积物深度有关。在较深的5～10cm层,线虫群落与其上层次的差异较大:0～2cm层和5～10cm层差异极显著(P=0.001),2～5cm层和5～10cm层间差异显著(P=0.016)。不同站点间底层的线虫群落差异明显。而沉积物0～2cm层和2～5cm间的线虫群落差异不明显(P=0.541)。列出了SIMPER分析中16种明显影响表层-底层群落的线虫,13种明显影响中层-底层间群落比较的线虫。在研究和比较线虫群落时,应该考虑取样深度的影响。  相似文献   

19.
The across shore variability and trophodynamics of meiofauna were studied in a microtidal beach of the Thyrrenian Sea (NW Mediterranean). Two sites were sampled at Collelungo beach (Maremma Park, Italy) subjected to different regimes of sediment erosion and deposition. At each site, four levels were sampled in November 2002 and May 2003 along a transect from the supralittoral zone to the surf zone. Sediment cores were taken down to a depth of 10 cm and meiofaunal abundance and community structure were analyzed and related to the principal trophic resources (quantity and quality of organic matter, chlorophyll a, bacteria density and biomass).Meiofaunal abundance ranged between 14 ind. 10 cm−2 and 716 ind. 10 cm−2 in the top 0–10 cm of sediment. Abundance was lower in the surface (0–2 cm) than in the deeper (5–10 cm) sediment layers but no significant differences were found between the two sites.Multivariate BIOENV analysis showed that dryness, grain size (related to physical processes) and bacterial biomass, were the main variables explaining meiofauna distribution in these beaches. Meiofaunal densities and number of taxa were always higher at the swash level, while lower abundances were observed at the dry sampling level (+5 m). This across shore trend was also observed for the quality of the organic matter (PRT/CHO) and bacterial densities. Nematode assemblage structure at the swash sampling level showed a dominance of non-selective deposit feeders (1B), with Xyalidae as the dominant family (56%), followed by Thoracostomopsidae (14%) and Selachnematidae (12%).According to the findings, physical and biological variables at the swash level create optimal living conditions for the meiobenthos, making the swash a key area within the beach ecosystem, with potential implications within basic and applied ecological studies.  相似文献   

20.
The primary focus of this paper is to better understand carbon burial on the Louisiana continental margin using spatial scales that covered various shelf depositional areas far-field and near-field (sediment and organic carbon inputs relative to river mouth proximity) and covering a variety of sedimentation rates. Box-cores samples were collected in July 2003; cores were collected along two depositional transects extending westward and southward from the Southwest Pass (SW Pass). A key difference between the two transects sampled in this study was the greater occurrence of mobile muds derived from spillover from shallower regions along the westward 50 m isobaths. The dominant mechanism for mixing in the surface active zone (SAZ) on the inner Louisiana shelf was due to physical, not biological, forces. Burial efficiencies for organic carbon (57.2–91.5%) and total nitrogen (44.2–86.9%) ranged widely across all shelf stations. Lower burial efficiencies for bulk organic carbon, total nitrogen, and pigment biomarkers were associated with mobile muds west of Southwest Pass. Chlorophyll a concentrations were significantly higher than pheopigments at depth at the Mississippi River and Southwest Pass stations, making up 40.4 and 77.4% of total pigment concentrations in the (SAZ) and 46.2 and 63.2% in the accumulation zone (AZ), respectively. These results are in agreement with earlier plant pigment studies which showed that a large fraction of the phytodetritus delivered to the inner shelf was derived from coastal and river diatoms. The amount of lignin preserved with depth decreased with increasing residence time in the SAZ and diagenetic zone (DZ) along the canyon transect but not along the western transect. Trends for lignin concentration followed previously identified surface sediment trends indicating overall lower burial of refractory terrestrial material at depth with greater distance offshore.  相似文献   

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