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1.
A quantitative study of metazoan meiofauna was carried out on bathyal sediments (305, 562, 830 and 1210 m) along a transect within and beneath the oxygen minimum zone (OMZ) in the southeastern Pacific off Callao, Peru (12°S). Meiobenthos densities ranged from 1517 (upper slope, middle of OMZ) to 440–548 ind. 10 cm−2 (lower slope stations, beneath the OMZ). Nematodes were the numerically dominant meiofaunal taxon at every station, followed by copepods and nauplii. Increasing bottom-water oxygen concentration and decreasing organic matter availability downslope were correlated with observed changes in meiofaunal abundance. The 300-m site, located in the middle of the OMZ, differed significantly in meiofaunal abundance, dominance, and in vertical distribution pattern from the deeper sites. At 305 m, nematodes amounted to over 99% of total meiofauna; about 70% of nematodes were found in the 2–5 cm interval. At the deeper sites, about 50% were restricted to the top 1 cm. The importance of copepods and nauplii increased consistently with depth, reaching ∼12% of the total meiofauna at the deepest site. The observation of high nematode abundances at oxygen concentrations <0.02 ml l−1 supports the hypothesis that densities are enhanced by an indirect positive effect of low oxygen involving (a) reduction of predators and competitors and (b) preservation of organic matter leading to high food availability and quality. Food input and quality, represented here by chloroplastic pigment equivalents (CPE) and sedimentary labile organic compounds (protein, carbohydrates and lipids), were strongly, positively correlated with nematode abundance. By way of contrast, oxygen exhibited a strong negative correlation, overriding food availability, with abundance of other meiofauna such as copepods and nauplii. These taxa were absent at the 300-m site. The high correlation of labile organic matter (C-LOM, sum of carbon contents in lipids, proteins and carbohydrates) with CPE (Pearson's r=0.99, p<0.01) suggests that most of the sedimentary organic material sampled was of phytodetrital origin. The fraction of sediment organic carbon potentially available to benthic heterotrophs, measured as C-LOM/Total organic carbon, was on average 17% at all stations. Thus, a residual, refractory fraction, constitutes the major portion of organic matter at the studied bathyal sites.  相似文献   

2.
Quantitative information on the abundance and biomass of metazoan meiofauna was obtained from samples collected at 15 deep-sea stations in the Eastern Mediterranean Sea (533–2400m). Meiofaunal abundance was compared to bacterial biomass and other environmental factors such as the total sedimentary organic matter content, the concentrations of the main biochemical classes of organic compounds (i.e. proteins, carbohydrates and lipids) and to ATP. To estimate the sedimentation potential of primary organic matter, sediment bound chloroplastic pigment equivalents (CPE) were assayed. Meiofaunal density was very low ranging from 4 ind.10cm−2 (Station A4, 1658m depth) to 290 ind.10cm−2 (Station A12, 636m depth). Nematodes were the numerically dominant taxon (68% of total meiofauna) and were usually confined to the top 6cm of the sediments. Total meiofaunal biomass ranged from 2.78μgC 10cm−2 (Station A4) to 598.34μgC 10cm−2 (Station 15A). There was a significant decrease in the density of metazoan meiofauna with water depth. Bacterial biomass largely dominated the total biomass (as the sum of bacterial and meiofaunal biomass) with an average of 73.2% and accounted for 35.8% of the living biomass (as ATP carbon) whereas meiofaunal biomass accounted only for 6.56%. Bacterial biomass was significantly related to the DNA concentrations of the sediment. A significant correlation between ATP concentration and CPE content was also found. No correlations were found between meiofauna, ATP and CPE, or between meiofauna and bacterial parameters. The significant relationship between meiofaunal density and the ratio of labile organic matter/total organic matter indicates that deep-sea meiofauna inhabiting an extremely oligotrophic environment (such as the Eastern Mediterranean) may be more nutritionally dependent upon the quality than on the quantity of sedimentary organic matter.  相似文献   

3.
Trends among major metazoan meiofaunal taxa were investigated based on 56 deployments of a multicorer at 10 time points over a period of 11 years (1989–1999) at the Porcupine Abyssal Plain Sustained Observatory site (PAP-SO: 48°50′N 16°30′W, 4850 m depth). This area is characterised by a strong seasonality in the deposition of organic matter to the seafloor and by the massive increase in the density of holothurian species since 1996, the so-called ‘Amperima event’. Total meiofaunal densities ranged from 346 to 1074 ind.×10 cm−2 and showed a significant increase with time when time was represented by cruises, years and the ‘Amperima period’ (1996–1999) vs. the pre-Amperima period (1989–1994). This pattern was driven mainly by the nematodes, which were the dominant taxon (∼90% of total abundance). The third most abundant group, the polychaetes, also increased significantly in abundance over the time series, while the ostracods showed a significant decrease. Most other taxa, including the second-ranked group, the copepods (harpacticoids and nauplii), did not exhibit significant temporal changes in abundance. Ordination of taxon composition showed a shift from the pre-Amperima to the Amperima periods, a trend supported by the significant correlation between the x-ordinate and time. The majority (52–75%) of meiofaunal animals inhabited the top 2 cm of the 5 cm sediment cores analysed. There were significant increases in the proportion of total meiofauna, nematodes and copepods (but not polychaetes) inhabiting the 0–1 cm layer over time (represented by cruises) and between the pre-Amperima and Amperima periods in the case of copepods and polychaetes. During the intensively sampled period (1996–1997), there were indications of seasonal changes in the vertical distribution patterns of total meiofauna and nematodes within the sediment. We discuss the potential link between temporal variations in organic matter flux to the seafloor and meiofaunal populations, considering both qualitative and quantitative changes in fluxes and how they may be linked to climate variations.  相似文献   

4.
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   

5.
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   

6.
利用 1 998年“大洋一号”调查船 DY95 - 8航次在中国多金属结核开辟区东、西两小区用多管取样器采集的沉积物样品 ,对小型底栖动物的组成、分布及其与环境因子的关系进行了研究。结果表明 :(1 )东、西两小区共有 1 6个类群的小型底栖动物 ,其中线虫类占居显著优势 ,在东、西两小区各占总栖息密度的 71 %和 6 4 %,其次为猛水蚤类和蜱螨类。 (2 )东、西两小区小型底栖动物类群平均栖息密度分别为 3 2 .47ind/1 0 cm2 和 1 8.0 5 ind/1 0 cm2 ,东小区高于西小区。小区各站位间的栖息密度平面分布差异显著。 (3 )东、西两小区小型底栖动物类群栖息密度的垂直分布趋势明显 ,由表层向底层 ,栖息密度逐渐降低。 (4)东、西两小区小型底栖动物空间分布与底质沉积物、结核覆盖率和底层流等环境因子密切相关 ,底质较硬、结核覆盖率较高以及底层流较强都不利于小型底栖动物的栖息。  相似文献   

7.
The abundance and biomass of metazoan meiofauna and their relationships with environmental factors [chloroplastic pigment equivalents (CPE) and sediment characteristics] were studied quantitatively around and within the Kuril Trench (560-7090 m) and the Ryukyu Trench (1290-7150 m), which are located in eutrophic and oligotrophic regions, respectively, of the western North Pacific. Faunal abundance and biomass, as well as the CPE content of sediments, were considerably higher in the Kuril region than in the Ryukyu region. In both cases, CPE tended to decrease with water depth, but relatively high values were found in the deepest areas, suggesting that organic matter has accumulated in both trenches. Meiofaunal abundance and biomass were lower than expected from sediment CPE values at hadal stations below 6000 m. Differences in the density and biomass of meiofauna between these two trenches appeared to reflect differences in overall ocean productivity above them. When the analysis was restricted to each region, however, no association was found between the abundance and biomass of meiofauna and food availability. Furthermore, the factors regulating the bathymetric patterns in these meiofaunal parameters appeared to differ between the two trenches.  相似文献   

8.
Sediment samples were collected in the intertidal zone of the Dagu River Estuary, Jiaozhou Bay, China in April,July and October 2010 and February 2011 for examining seasonal dynamics of meiofaunal distribution and their relationship with environmental variables. A total of ten meiofaunal taxa were identified, including free-living marine nematodes, benthic copepods, polychaetes, oligochaetes, bivalves, ostracods, cnidarians, turbellarians,tardigrades and other animals. Free-living marine nematodes were the most dominant group in both abundance and biomass. The abundances of marine nematodes were higher in winter and spring than those in summer and autumn. Most of the meiofauna distributed in the 0–2 cm sediment layer. The abundance of meiofauna in hightidal zone was lower than those in low-tidal and mid-tidal zones. Results of correlation analysis showed that Chlorophyll a was the most important factor to influence the seasonal dynamics of the abundance, biomass of meiofauna and abundances of nematodes and copepods. CLUSTER analysis divided the meiofaunal assemblages into three groups and BIOENV results indicated that salinity, concentration of organic matter, sediment sorting coefficient and sediment median diameter were the main environmental factors influencing the meiofaunal assemblages.  相似文献   

9.
为探究莱州湾和牟平近海小型底栖生物群落组成及影响因子,作者于2016年7月在这两个海域采集了沉积物样品,并结合沉积环境因子进行了小型底栖生物群落组成分析。结果表明,在莱州湾和牟平近海各仅检获了7个小型底栖生物类群,且莱州湾的小型底栖生物平均丰度和生物量均明显低于牟平近岸海域。莱州湾线虫和桡足类平均丰度分别占小型底栖生物的91.9%和6.3%,牟平近海分别占92.1%和4.2%。对两个海域小型底栖生物群落组成与环境因子进行Pearson相关性分析,结果显示:小型底栖生物丰度与底层水溶解氧含量呈显著正相关;表层小型底栖生物丰度比与沉积物中叶绿素a含量、脱镁叶绿素含量、沉积物有机质含量以及水深呈显著正相关,与中值粒径和底层水温度呈显著负相关。本研究显示,基于不同沉积物类型中的参考比值,线虫和桡足类丰度比值(N/C)可用于莱州湾和牟平近海沉积环境有机污染状况的评估。研究还发现,牟平海域的小型底栖生物丰度和生物量呈现由近岸向外海增加的异常趋势,且小型底栖生物的数量和类群多样性较十年前显著降低,显示沉积环境受到了明显干扰。  相似文献   

10.
A shallow subtidal (3 m deep) meiofaunal assemblage in Los Abrigos Bay, Tenerife, Canary Islands was sampled during May 2000-April 2001. Themain aims were to (1) find temporal variations inmeiofaunal assemblage structure and overall abundance, as well as in the most abundant meiofaunal species throughout the study period, and (2) identify environmental variables (sedimentary composition, organic matter content, and total nitrogen) that better explain meiofaunal assemblage structure during the study year. The most abundant species were the nematodes Siphonolaimus sp. 2 and Catanema sp., which represented 46.2% of the overall meiofaunal abundances and varied significantly throughout the study duration. Overall meiofaunal abundance and the most abundant taxonomic groups (nematodes, copepods, and oligochaetes) showed significant temporal variations during the study period. Nematodes overwhelmingly dominated during the study period, ranging from 78% in May to 97.34% in February. Multivariate analyses showed seasonality inmeiofaunal community structure during the study year, with the lowest abundances in May.  相似文献   

11.
Samples were taken bi-weekly for one year at a sand site and a mud site in the North Inlet Estuary, Georgetown, South Carolina, for meiofauna, their suspected microbial food (bacteria and diatoms), and associated physical factors. Linear regression techniques were used to correlate food abundance and physical factors with the density of meiofaunal taxa. At both sites diatoms positively correlated with meiofauna taxa, but bacteria did not. Physical factors were not correlated with meiofaunal or microbial abundances at the sand site. Whereas, at the mud site meiofauna and diatom abundances were positively correlated with the depth of the redox layer and inversely correlated with temperature. Peaks of meiofaunal abundance did not follow peaks of food abundance. Analysis of copepods at the species level indicated that taxa response was due to the response of the dominant species. Even though some correlations existed, this study suggests that copepod species and meiofauna at the gross taxonomic level do not respond to changes in potential food abundance. Physical factors apparently influence both meiofauna and diatoms in the same fashion. However, bacterial abundance was not positively correlated with any of the factors studied.  相似文献   

12.
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   

13.
The macrofauna and meiofauna of three oiled and three control experimental ecosystems at the Marine Ecosystems Research Laboratory (MERL) were followed for 25 weeks of semi-continuous additions of an oil-water dispersion of No. 2 fuel oil. Water column hydrocarbon levels were maintained at about 190 ppb, and after 20 weeks 109 sm/g dry weight fuel oil hydrocarbons were recorded in the top 2 cm of sediment.This simulated chronic oil pollution resulted in a highly significant decline in the number of macrofaunal and meiofaunal individuals in the experimental tanks compared with the controls. The effect was apparent on the numbers of individual macrofaunal species and on all metazoan meiofaunal groups.  相似文献   

14.
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   

15.
Abstract

Twenty-four stations (12 each, during pre- and postdisturbance studies) 5300 to 5330 m deep between 10°01' and 10°03'S latitude and between 75°59' and 76°02'E longitude were sampled to study the effect of benthic disturbance on the distribution of meiofauna in the Central Indian Ocean. Bottom-sampling was conducted with a box corer. Total meiofauna density ranged from 35 to 45 organisms per 10 cm2 of bottom area during the predisturbance period and 21 to 32 organisms per 10 cm2 during the postdisturbance period in the test and reference sites. Differences between pre- and postdisturbance study results were statistically significant (P < 0.05). Nematoda was the most abundant meta-zoan group, on an average representing >55% of the meiofaunal population. The abundance of nematodes and harpacticoid copepods as well as total meiofauna showed marked decreases during postdisturbance sampling. Vertical distribution of meiofauna in the sediment cores revealed that 75% to 90% of the metazoan population was confined to the top 2-cm layer of the sediment. Recolonization experiments suggest that harpacticoid copepods may take more time for recolonization than the nematodes and are more sensitive to the physical disturbance. These findings suggest that nematodes and harpacticoid copepods can be used as indicator organisms in recolonization experiments.  相似文献   

16.
The effects of the disposal of copper mine tailings on the littoral meiofaunal assemblages of the Chañaral area of northern Chile were studied. Of the metals data collected, only in the case of copper was there a clear association with the tailings distribution in both the seawater and porewater samples, and it is assumed that the tailings on the beaches was the source of copper in the adjacent seawater. When compared to the reference sites, the meiofaunal assemblages at the impacted sites had significantly lower densities and taxa diversities; at the northern sites only the densities were lower. Otoplanid turbellarians were identified as characteristic of those beaches impacted by tailings. The combination of porewater copper and the amount of tailings present were identified as mostly responsible for the observed structure of the meiofaunal assemblages. It was also established that the variation in natural sediment grain size from beach to beach was not a significant factor in the observed differences in the meiofaunal assemblages. The two groups of meiofauna that proved to be most sensitive to the effects of tailings dumping were the foraminiferans and the harpacticoid copepods.  相似文献   

17.
Abstract. Quantitative information on the vertical distribution of meiofaunal abundances and biomass were obtained from samples collected at 3 bathyal stations in the Eastern Mediterranean Sea located at the same depth but characterized by different food supply. Vertical distribution patterns of nieiofauna were investigated in relation to the biochemical composition of the sediment organic matter (proteins, carbohydrates, and lipids) and compared to benthic bacterial standing stocks. No significant relationship between bacteria and meiofauna was found, whereas a significant relationship between protein and lipid concentrations and total meiofauna density was observed. These data suggest that labile organic matter. considered as material readily aVdihbk to benthic consumers, may be an important factor regulating meiofaunal abundance and vertical distribution in deep-sea sediments.  相似文献   

18.
Incubation experiments were carried out daily during a Lagrangian experiment within an upwelled filament off the Galician coast to determine the importance of microzooplankton in the diet of calanoid copepods. Despite low chlorophyll concentrations the microzooplankton formed the minor component of the diet of the copepod community (7 to 15% of carbon ingested through autotrophic and heterotrophic prey). Ingestion of ciliates was greater than that of heterotrophic dinoflagellates, which reflected a higher abundance of ciliates in the water column. Heterotrophic nanoflagellates appeared also to be consumed by the copepods, although the very small size fraction (2–5μm) was probably not grazed by the larger copepods of Calanus spp. Grazing pressure by the copepods enumerated in the net samples was not sufficient to impact significantly the microzooplankton populations (2 to 51% of daily microzooplankton production was removed). Allometric relationships of grazing on microzooplankton for a range of numerically dominant copepod species are developed from the experimental results. The grazing pressure of the whole copepod community is estimated from these relationships. By considering the total mesozooplankton community we suggest that microzooplankton growth was probably restricted by metazoan grazers.  相似文献   

19.
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   

20.
渤海底栖桡足类群落结构的研究   总被引：7，自引：0，他引：7  
渤海1998年9月航次的调查结果.小型底栖生物总平均丰度为(8688±5097)个/m2,底栖桡足类居第2位,平均丰度为(663±569)个/m2,占总数量的76%.根据77种底栖桡足类丰度所做的聚类和标序分析将渤海20个站位划分为4个组合.根据11种环境因子数据所做的聚类和主成分分析将研究海域划分为两个生境、4个亚区.对研究海域进行的分区与自然分区是基本一致的.支配研究海域底栖桡足类群落结构的主要环境因子是水深和沉积物粒度.  相似文献   

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