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1.
Material is collected on a meridional profile from Yenisei Bay to adjacent parts of the Kara Sea shelf. The length of the profile is 550 km; 13 to 62 m depths. A multiple corer and Niemistö corer are used as sampling tools. The meiobenthos is represented by 13 taxa. Nematodes are the most abundant taxon, and harpacticoid copepods (Harpacticoida) are subdominant. The abundance and taxonomic diversity of meiobenthos and nematodes increases from the freshwater part of Yenisei Bay towards the Kara Sea shelf. Three types of taxocene are distinguished: freshwater, brackish-water, and marine. The taxocene of the estuary is not distinguished by any specific set of species and consists of species characteristic of the nematode community both in the freshwater and marine zones. The trophic structure of the taxocene of nematodes in Yenisei Bay is dominated by nematodes with well-defined stoma and are differently armed. The estuary and shelf are dominated by selective and nonselective deposit feeders.  相似文献   

2.
The abundance and higher taxonomic composition of epizooic metazoan meiobenthic communities associated with mussel and tubeworm aggregations of hydrocarbon seeps at Green Canyon, Atwater Valley, and Alaminos Canyon in depths between 1400 and 2800?m were studied and compared to the infaunal community of non-seep sediments nearby. Epizooic meiofaunal abundances of associated meiobenthos living in tubeworm bushes and mussel beds at seeps were extremely low (usually <100?ind. 10?cm(-2)), similar to epizooic meiofauna at deep-sea hydrothermal vents, and the communities were composed primarily of nematodes, copepods, ostracods, and halacarids. In contrast, epizooic meiobenthic abundance is lower than previous studies have reported for infauna from seep sediments. Interestingly, non-seep sediments contained higher abundances and higher taxonomic diversity than epizooic seep communities, although in situ primary production is restricted to seeps.  相似文献   

3.
Deep-sea hydrothermal vents occur along the mid-ocean ridges and back-arc basins around the globe. There are very few community analyses of vent meiobenthos. The central objectives of this study were to identify and quantify for the first time the entire metazoan meiobenthic community associated with mussel aggregations of Bathymodiolus thermophilus Kenk and Wilson, 1985 from the EPR, 11°N and of Bathymodiolus puteoserpentis Cosel et al., 1994 from the Mid-Atlantic Ridge (MAR), 23°N. Using a quantitative sampling method, abundance, biomass, sex ratio, species richness, diversity, evenness, and trophic structure were studied based on three samples from each site. Meiobenthic abundance in each sample was unexpectedly low, but similar between sites. The community was composed of nematodes, copepods, ostracods, and mites, with a total of 24 species at EPR vents, and 15 species at MAR vents. While most copepod species were vent endemics within the family Dirivultidae, nematodes and harpacticoid copepods belonged to generalist genera, which occur at a variety of habitats and are not restricted to hydrothermal vents or the deep sea. The meiobenthos of hydrothermal-vent mussel beds constitutes a unique community unlike those of other sulfidic habitats, including the thiobios of shallow-water sediments and the meiobenthos of deep-sea, cold-seep sediments. The trophic structure was dominated by primary consumers, mainly deposit feeders, followed by parasites. Predatory meiofaunal species were absent.  相似文献   

4.
This study was carried out as part of a baseline long-term environmental project in the proposed mining areas for an environmental impact assessment of future mining in the Clarion-Clipperton Fracture Zone (CCFZ). The community structure and distributional pattern of meiobenthos were investigated in the deep-sea bottom of the Clarion-Clipperton Fracture Zone of the northeastern Pacific in July 1998, 1999, 2001, 2003 and August 2004, 2005. Twenty one meiobenthic groups were found at the stations in the study area. The most abundant meiobenthos comprised nematodes followed by benthic foraminiferans and harpacticoid copepods. The maximum density of meiobenthos was 306 ind/10 cm2 at the station located at 11°N (water depth, 4833 m), and the minimum density was 6 ind/10 cm2 at the station located at 14°N (water depth, 5037 m). Oligotrophic conditions in the CCFZ seem to directly reflect the lower standing stocks of meiobenthos in the CCFZ compared to other deep-sea plains of similar depth. The latitudinal distribution pattern of meiobenthos in the study area seemed to be related with surface water primary productivity, which was connected to the water circulation pattern of the Pacific Ocean near the Equator, diverging at 8ºN latitude and converging at 5°N. The horizontal distribution of meiobenthic organisms in the study area showed high densities at the stations within 135–136°W. The densities of meiobenthic organismas within the CCFZ were high at stations with few manganese nodules on the sediment surface at low-latitude sites. In 1998, the observed relative high values of meiobenthic abundance were at stations from 5° to 6°N. Other stations from 7° to 10°N showed no significant fluctuations during the interannual sampling periods. It is considered that the inter-annual fluctuation of meiobenthos abundance is intimately related with a regime shift that may have occurred in the north Pacific between 1998 and 1999, the El Niño period. Vertical distribution of meiobenthic organisms showed the highest individual numbers in the surface sediment layers of 0～2 cm depth and a steep decreasing trend as sediment becomes deeper at the stations of high latitude located in 16～17°N. Size distribution analyses showed that organisms that fit into the sieve mesh size of 0.063 mm were abundant.  相似文献   

5.
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   

6.
Rafael  Sarda 《Marine Ecology》1991,12(4):341-360
Abstract. The polychaete fauna of the subtidal in the médiolittoral and the infralittoral hard bottom zones of the Balearic Islands at depths from 0 to 40m contained 220 species. Five different polychaete communities could be identified by changes in abundance, species richness, species composition, diversity, and trophic structure. In the very clear waters of these islands the infralittoral zone extends to a depth of 40 m and allows us to investigate whether former proposed models of polychaete distribution can be extended to this particular situation.  相似文献   

7.
2009年4月14～16日在台湾海峡中北部海域进行了小型底栖生物调查研究.结果表明,研究海域的小型底栖生物平均丰度为21.11±16.29 ind/cm^2;平均生物量为20.97±4.96μg/cm^2（以干重记）.研究海域共鉴定出13个小型底栖生物类群,按丰度,最优势类群为自由生活海洋线虫其丰度为19.23±15.49 ind/cm^2,占小型底栖生物总丰度的91.10%,其他优势类群依次为底栖桡足类和多毛类,分别占小型底栖生物总丰度的2.77%和2.64%;分布在0～5 cm的表层沉积物内的小型底栖生物约为83.18%,线虫和底栖桡足类分布在0～2 cm的比例分别为57.66%和62.96%.小型底栖生物的生物量低于大型底栖生物,但由于其繁殖快,生命周期短,因此,其生物量约为大型底栖生物的445倍,年平均生产量约为大型底栖生物的1.39倍.  相似文献   

8.
Meiofaunal assemblages were investigated (in terms of abundance, biomass, individual size and community structure) at bathyal and hadal depths (from 1050 to 7800 m) in the Atacama Trench in the upwelling sector of the eastern South Pacific Ocean, in relation to the distribution and availability of potential food sources (phytopigments, biochemical compounds and bacterial biomass) in this highly productive region. Meiofaunal density and biomass in the Atacama Trench were one to two orders of magnitude higher than values reported in other “oligotrophic” hadal systems. The Atacama Trench presented very high concentrations of nutritionally rich organic matter at 7800-m depth and displayed characteristics typical of eutrophic systems. Surprisingly, despite a decrease in chlorophyll-a and organic matter concentrations of about 50% from bathyal to hadal depths, meiofaunal abundance in hadal sediments was 10-fold higher than at bathyal depths. As indicated by the higher protein to carbohydrate ratio observed in trench sediments, the extraordinarily high meiofaunal density reported in the Atacama Trench was more dependent upon organic matter quality than on its quantity. The trophic richness of the system was reflected by a shift of the size structure of the benthic organisms. In contrast with typical trends of deep-sea systems, the ratio of bacterial to meiofaunal biomass decreased with increasing depth and, in the Atacama Trench, meiofaunal biomass largely dominated total benthic biomass. Nematodes at 7800-m depth accounted for more than 80% of total density and about 50% of total meiofaunal biomass. In hadal sediments a clear meiofaunal dwarfism was observed: the individual body size of nematodes and other taxa was reduced by 30–40% compared to individuals collected at bathyal depths. The peculiarity of this trophic-rich system allows rejection of previous hypotheses, which explained deep-sea dwarfism by the extremely oligotrophic conditions typical of deep-sea regions.  相似文献   

9.
Temporal changes in the vertical distribution of metazoan meiofaunal groups were examined at a bathyal site (depth 1450 m) in Sagami Bay from December 1996 to August 1998. Among major meiofaunal groups, the vertical distributions of copepods (adults and copepodites), and kinorhynchs changed seasonally and they concentrated in the shallower part in the sediment profile when CPE concentrations were higher. Seasonal changes in the vertical distributions of ovigerous females and nauplii of copepods were not related to CPE concentrations, but related to that of total copepods. On the other hand, nematodes, ostracods, and polychaetes did not show seasonal migrations. These results suggest that there is a difference in the response to the sedimentation of organic matter between metazoan meiofaunal taxa.  相似文献   

10.
Large nematodes form an important component of deep‐sea macrofaunal assemblages, but are often considered to be part of the meiobenthos and are rarely studied. We analysed the standing stocks, diversity, and functional group and genus‐level composition of macrofaunal nematodes at lower bathyal depths (3,500 m water depth) in the Whittard Canyon system (NE Atlantic) and on the adjacent continental slope. Five replicate sample sets were obtained using a Megacorer, at four locations (three canyon branches, one slope). Sediment samples were processed on a 500‐μm mesh to provide both nematode and polychaete data from the same samples. The dominant nematode genera included Paramesacanthion, Metacylicolaimus, Cylicolaimus and Phanodermopsis. Nematode standing stocks (density and biomass) increased significantly from slope to canyon locations. Similarly, nematode dominance increased substantially (and diversity decreased) from slope to canyon locations. Nematode feeding groups and tail shape groups also appeared to exhibit common trends across study locations. Nematode genus‐level faunal composition varied significantly between slope and canyon locations. We describe and discuss the broadly similar trends detected in the matching polychaete data, noting some differences in the polychaete density and diversity responses. We suggest that the similar trends in macrofaunal nematode and polychaete ecology across our four study locations reflect responses to both changing sedimentology and food availability.  相似文献   

11.
北黄海小型底栖生物丰度和生物量时空分布特征   总被引：1，自引：0，他引：1  
分别于2006年7月和2007年1,4和10月在北黄海陆架浅海水域进行小型底栖生物调查.结果表明,4个航次的小型底栖生物平均丰度分别为(1 099±634),(664±495),(1 601±837)和(524±378) ind·10 cm-2;平均生物量分别为(1 446.34±764.66),(428.63±294.84),(1 580.53±1 041.23)和(793.50±475.83) μg·dwt·10 cm-2.共鉴定出18个小型底栖生物类群,按丰度,自由生活海洋线虫为最优势类群,4个航次的优势度分别为72%,90%,85%和74%,其他优势类群依次是桡足类、多毛类、动吻类和介形类;按生物量依次是线虫、桡足类、多毛类、介形类和双壳类.97%的小型底栖生物分布在0～5 cm的表层沉积物内,线虫和桡足类分布在0～2 cm沉积物的比例分别为86%和87%.二因素方差分析(two-way ANOVA)表明:小型底栖生物丰度和生物量在由4个航次所代表的春、夏、秋、冬各季节之间存在显著差异(春、夏高于秋、冬),在4个航次的5个相同取样站位之间也有显著差异.小型底栖生物的丰度和生物量与水深和底盐呈负相关性.北黄海冷水团对小型底栖生物丰度和生物量时空分布有一定的影响.  相似文献   

12.
The quantitative characteristics and spatial distribution of the meiobenthos in Baidaratskaya Bay (Kara sea) were analyzed based on data collected in 1994–2007. The extremely high density of the meiobenthos (up to 8121 ind/10 cm2, average 2318 ind/10 cm2) makes it possible to consider Baidaratskaya Bay among the most productive Arctic regions. The spatial distribution of the meiobenthos was mostly determined by the depth and sediment properties in the subtidal zone of the bay. The density of meiobenthic organisms decreased with depth, and with the increase of the small sediment fraction. The difference in the meiobenthic densities between the two coastal areas of the bay (Yamal and Jugora CAs) is also revealed. Such difference caused by the combined effects of small-scale and mesoscale factors, mainly by the grain size. Opposite changes in the meio- and macrobenthic biomass with depth is shown.  相似文献   

13.
The influence of a thick layer of oxygen-depleted water (<0.2 ml l−1) on the abundance and distribution of chaetognaths was investigated in the northeastern Arabian Sea (NEAS), a natural oxygen-deficient system in the global ocean. The species and maturity stage-wise distribution of this group were studied at five discrete depths down to 1000 m. A total of 22 species belonging to four genera were observed, and the genus Sagitta dominated, representing 60% (500-1000 m) to 89% (Mixed layer depth) of the total chaetognath population. Based on their vertical distribution limits, four groups were recognised, as follows: I: species abundant in surface water with a maximum distribution limit up to 300 m; II: species confined mainly to deeper waters (>500 m); III: species present throughout the water column (0-1000 m); and IV: species present in most layers, but with a preference for a specific depth stratum. A positive correlation (P<0.01) was observed in the abundance of chaetognaths and their main prey copepods, emphasising the strong trophic relationship between these groups. It was found that the intensely oxygen-deficient waters of the NEAS play a crucial role in the vertical distribution and abundance of chaetognath species of all four genera. This report presents information on the maturity stages and ontogenetic migration of this important planktonic group in relation to the oxygen-depleted water in the study region for the first time. The results obtained are also important for understanding the biological processes associated with a major oxygen minimum zone (OMZ) in the global ocean.  相似文献   

14.
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   

15.
The structure of the nematodes communities has been studied in the sediments on two sites located outside and under the layer ofAhnfeltia tobuchiensis (Kanno and Matsubara 1932; Makijenko 1970). Bottom sediments at the stations were represented by sands with a different degree of silting. Specific structure of nematodes at the stations was significantly different under the similar environmental conditions (water depth, dissolved oxygen saturation, salinity, temperature of the bottom layer and organic carbon content inside of the sediment). Nematodes dominated (75.7 %) in meiobenthos community under the layer of A.tobuchiensis where concentration of silt particles was 12 %. Representatives of the family Comesomatidae were dominant. Low index of species diversity and high Simpson domination index were detected in this community. Under a layer ofA. tobuchiensis with the thickness of 30 cm concentration of the silt particles was 5.39 %; nematodes density was low and made 32.1 % of the general density of meiobenthos. Species of the families Xyalidae and Monoposthiidae were dominant. Outside of A.tobuchiensis, field percentage of silt particles was minimal (3.1 %) and representatives of families Cyatholaimidae and Axonolaimidae dominated. The specific structure of nematodes in this type of the ground is characterized by high index of species diversity and low level of domination.  相似文献   

16.
A quantitative study on the community structure and biodiversity of free-living marine nematodes and their relationship with environmental factors in the northern South China Sea were carried out based...  相似文献   

17.
Mapping surveys of coastal benthic habitat in Qeshm Island Geopark, Persian Gulf, were conducted using a combination of biological, sedimentological and echo‐sounding data. The survey area covered approximately 233 km2 in a depth range of 5–25 m, and the data were acquired from a single beam echo sounder, grab, video and still photography. Sediment and macrofauna samples were collected by grab at 76 stations and subjected to classification and ordination analyses. Two acoustic classes were identified differentiating along the near/offshore axis. Sediment texture was dominated by fine grain sizes, with five distinct sub‐sediment types. In total, 214 macrobenthic taxa were identified, of which polychaetes accounted for 60%. Other dominant groups included young sponges, nematodes, malacostracan crustacean, bivalves, ostracods and ophiuroids. Underwater videos and still photos integrated the macrofaunal and sedimentary data and revealed a range of biogenic sedimentary features such as burrows and tubes. The biological data identified six main biological assemblages showing an inshore/offshore pattern. The macrobenthic abundance did not demonstrate a significant difference with depth, although polychaetes were positively correlated with depth. The highest abundance and species richness were observed at median depths. Species distribution and diversity did not show any correlation with sediment type. A preliminary habitat mapping of the south coast of the Qeshm Island Geopark has been carried out, integrating acoustic, sediment and biological data.  相似文献   

18.
Rocas, the only atoll in the South Atlantic, is located 266 km off the northeast Brazilian coast. Spatial patterns in community structure of meiofauna, particularly nematodes, and macrofauna were examined along a transect through the sediment path from windward to leeward of the Rocas Atoll sand flat. Differences in benthic community structure between four zones of the sand flat were found to be significant and related to the major local processes of carbonate-grain transport and sedimentation. Both meiobenthic and macrobenthic assemblages were significantly more diverse and abundant within the sediment inflow zone (the initial part of the detrital path of Rocas sand flat) than in the other zones, where a clear impoverishment of benthic invertebrates occurred. This first study of the benthos of an intertidal sand flat over a reef island in the Atlantic showed that the meiofauna is numerically dominated by the nematodes Metoncholainussp. 1 (Oncholaimidae) and Epsilonema sp. 1 (Epsilonematidade), whilst the macrofauna is largely dominated by oligochaetes and large Oncholaimidae nematodes. Analysis of the species composition, trophic structure and abundance of both the meiobenthos and the macrobenthos revealed an impoverished community subjected to an intense water-movement disturbance.  相似文献   

19.
辽河口邻近海域小型底栖生物的空间分布及季节变化   总被引：2，自引：1，他引：1  
本文研究了辽河口邻近海域2013年8月、10月和2014年5月3个航次小型底栖生物的种类及其空间分布,分析了小型底栖生物丰度和生物量的季节变化。结果表明,3个航次（夏季、秋季和春季）小型底栖生物的平均丰度分别为（264±83） ind/（10 cm2）、（216±85） ind/（10 cm2）和（227±67） ind/（10 cm2）,平均生物量分别为（272±125）μg/（10 cm2）、（207±89）μg/（10 cm2）和（244±103）μg/（10 cm2）。与其他研究海域相比,辽河口小型底栖的丰度和生物量处于较低水平。共鉴定出了14个小型生物类群,按照丰度排序,线虫是最优势的类群,夏季、秋季和春季3个航次占总丰度的比例分别为94.0%、92.5%和90.8%;其他优势类群为多毛类、桡足类和双壳类。小型底栖生物量的优势类群则为多毛类（41.1%~44.0%）,高于线虫（33.8%~36.5%）,其次是双壳类（2.6%~6.7%）。水平分布的研究表明,调查海域近岸入海口小型底栖生物的丰度和生物量普遍低于近海海域,但是秋季时近岸分布与近海差距不大。垂直分布的研究表明,95.9%的小型底栖生物分布于0~5 cm的表层沉积物中。小型底栖生物的丰度和生物量在夏季时都达到高峰值。与环境因子的相关分析表明,小型底栖生物的数量分布与盐度和水深呈极显著正相关（P<0.01）,与叶绿素a呈显著正相关（P<0.05）。  相似文献   

20.
Abstract. Along the vertical cliff of Romito (Leghorn, Italy) 97 polychaete species were found from 0 to 6 m depth. Three depth related communities could be identified by trends in structural parameters (abundance, number of species, and diversity), by changes in species composition, and by the distribution of ecological and trophic groups. Such a zonation is consistent with the principal models proposed for the Méditerranean and seems mainly related to algal conditioning of the substrate.  相似文献   

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