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1.
K. Vopel  G. Arlt 《Marine Ecology》1995,16(3):217-231
Abstract. The fauna — including macrofauna, meiofauna, and large ciliates — of floating cyanobacterial mats in a brackish shallow-water area was studied by analysing six 20 cm2 pieces of mat. Although these microbial aggregations were scarcely 1 cm thick, their total meiofauna abundance was about five times as high as in the uppermost 4 cm of the adjacent sediment. The mat fauna was dominated by harpacticoids, although large ciliates, rotifers, nematodes, and oligochaetes were also markedly more abundant than in the sediment. All species occurring in the mats were members of the surrounding sediment fauna. Out of the 47 species found, only a few, among them predominantly the harpacticoid, Mesochra lilljeborgi B oeck , 1864, and the nematode Daptonema setosum ( bütschli , 1874), accounted for the majority of the individual abundance in the mats. Both are regularly found in sulphidic biotopes near Hiddensee. As SEM micrographs revealed, the oligochaete Paranais litoralis (O. F. M üller , 1788) and the harpacticoid Cletocamptus confluens (Schmeil, 1894) were apparently optimal substrates for dense lawns of cyanobacteria. This indicates possible close interactions between the meiofauna and these microbiota. The frequent predation of histophagous ciliates on nematodes and harpacticoids, which were probably weakened by oxygen deficiency and/or high sulphide concentrations, were not only a sign of a generally neglected pathway in the food chain, but also impressively emphasized the huge variety of interactions taking place between meio- and microfauna within this specific benthic microcosm. Because of their floating character, the mats can play an important role in the dispersal of benthic fauna.  相似文献   

2.
虾池小型底栖动物的数量研究   总被引:2,自引:0,他引:2  
提出1987年5月至10月在黄岛养虾池对虾生长周期内对小型底栖动物数量逐月调查。指出:小型底栖动物总平均密度为1092.4inds·10cm-2,自由生活海洋线虫和底栖桡足类是主要类群,其总平均密度分别为466.9和457.9inds·10cm-2。89.7%的小型底栖动物分布在沉积物表层2cm内。结果指明小型底栖动物被对虾捕食,并提出了捕食模式。  相似文献   

3.
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   

4.
Biomass and respiration (oxygen consumption) of bacteria, microfauna, and meiofauna were measured in coarse sand sediment from Brown's Bank (172 m) off Nova Scotia, Canada. Community biomass, excluding macrofauna, had a median value of 35 mg C m−2, dominated by bacteria (51%), microfauna (25%), and a minor meiofauna component (2·5%). Protozoan microfauna were mostly microflagellates (colourless cryptomonads). The experimental design allowed partitioning of benthic metabolism without using subtraction from whole community rates. Addition-removal experiments with fauna separated into size categories were used to construct a respiration-biomass regression for all taxa. Respiration rates for faunal groups were then calculated from their biomass in the natural sediment. Total microbial and meiofaunal community respiration had a median rate of 0·55 ml O2 m−2 h−1 which was partitioned into median proportions of bacteria (50%) microflagellates (27%), and metazoan meiofauna (4%). Correlations among faunal biomass values from incubated vials of sediment suggested that bacteria were important prey for protozoans. With added biomass of meiofauna, protozoans also became a potentially important source of prey. The results demonstrated the significance of microflagellate protozoans in these sediments and their metabolic and trophic importance relative to meiofauna and even bacteria.  相似文献   

5.
I am deeply honored to have been awarded the 1988 Okada Prize of the Oceanographical Society of Japan. The present paper reviews my previous works regarding the ecology of deep-sea meiobenthos in the western Pacific area. The outline cen be summarized as follows:
1)  On the basis of multivariate analyses, it was found that the rate of the organic-matter flux to the sea bed and the amount of the interstitial space within the sediment are the main factors regulating the abundance of meiofauna in the deep sea.
2)  Two indices were proposed to characterize the vertical distribution of meiofauna in the sediment profile,i.e. their maximum depth in the sediment and the degree of their concentration in the surface layer of the sediment. The index of maximum depth was closely related to the oxygen concentration in the interstitial water. On the other hand, the index of degree of concentration in the surface of the sediment tended to be higher where the supply of food seemed lower.
3)  Some taxonomically important species were found from the axis of the Izu-Ogasawara Trench. They arePliciloricus hadalis, the first species of the newest phylum Loricifera from the Pacific area, from the hadal deep sea and the fine clay sediment, andOccultammina profunda, the first infaunal species of Xenophyophorea, a group of rhizopod Protozoa.
4)  The vertical distribution ofOccultammina profunda coincided well with the unusual distribution of210Pb in the sediment profile. The organisms concentrated as high as 500 dpm g–1 of210Pb in their stercomare and granellare. The steady state model confirmed that the species made the peculiar subsurface peak of210Pb in the sediment.
5)  The depth in the sediment profile where the distinct peak of MnO2 can be seen showed strong correlation with the vertical distribution of meiofauna. This relationship suggests that oxygen concentration in the interstitial water regulates the structure of the characteristic three layers of the calcareous ooze in the deep sea. This idea was proven by the vertical distribution of free oxygen in the sediment calculated on the basis of respiration rate of deep-sea meiofauna measured using the cartesian diver technique.
6)  Radio-isotope techniques used to measure the rates at which particulated organic matter was ingested and dissolved organic matter was absorbed, suggested that deep-sea meiofauna obtained a significant fraction of their energy by absorption.
7)  The work carried out so far has revealed the important role of meiofauna in the benthic ecosystem, and emphasized the necessity for intensive research from various points of views on these microscopic organisms.
  相似文献   

6.
Two major size classes of the sediment community, meiofauna and macrofauna, and four classes of lipid compounds, fatty acids, alkanes, alcohols and sterols, were investigated using multicorer and USNEL boxcorer samples, collected during six cruises over a two year period (September 1996 to September–October 1998), at the Porcupine Abyssal Plain ( 48° 50′N 16° 30′W, 4850 m depth) within the framework of the MAST 3 BENGAL project. This site was known to be subject to seasonality in the input of organic matter to the seafloor. Results are given for each faunal size class in terms of taxonomic structure at the level of phylum, class or order, depending on the taxon, and for the dominant faunal components in terms of density and vertical distribution. For each lipid compound class, results are given in concentration and vertical distribution. The taxonomic structure of each size class did not change within the study period. Total meiofaunal and macrofaunal densities were particularly high, probably reflecting the high quantity and quality of organic matter inputs to the site. The dominant components of the two size classes presented different temporal patterns in their responses to changes in their environment. Populations of meiofaunal species, a foraminiferan and an opheliid polychaete, which inhabit the surface or sub-surface of sediment and feed on phytodetritus, responded with a rapid increase in abundance to a pulse of organic input in summer 1996. The macrofaunal polychaetes showed a lagged response to the same event by slowly increasing in density. Other components of the sediment community, that can live deeper in the sediment, moved down the sediment column, in response to 1) the impoverishment and bioturbation of the surface layer, and 2) the downward mixing of organic matter in the sediment by larger organisms. In this study, different temporal patterns were demonstrated for the first time in different size classes of the sediment community, and in the biological and environmental parameters that were studied simultaneously.  相似文献   

7.
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   

8.
Significant spatial heterogeneity in the abundance and composition of meiofaunal and nematode assemblages was described inside the Genoa-Voltri harbour (Genoa, Italy) in relation to variation in the main environmental variables. In harbour sediments characterized by low Eh values and high organic matter concentrations, total meiofauna abundance was lower (948 ± 919 ind 10 cm−2), nematode individual biomass was higher (0.17 ± 0.07 μg C), kinorhynchs and tanaids were completely absent, and the nematode assemblage was dominated by the genera Terschellingia, Sabatieria (pulchra group) and Paracomesoma. In contrast, in sediment characterized by lower levels of organic pollution, meiofaunal abundance was higher (1085 ± 737 ind 10 cm−2), nematode individual biomass was lower (0.11 ± 0.04 μg C), kinorhynchs and tanaids were present and the nematodes were dominated by the genera Desmodora, Daptonema, Anticoma and Halalaimus.Environmental disturbance as assessed by the analysis of meiofaunal and nematode assemblages and sediment environmental variables changed significantly over a scale hundreds of meters, but did not follow a gradient from the inner to the outer harbour. Analysis of nematode assemblages is proposed as a useful tool for the identification of environmental risk areas which may assist in the development of good planning, monitoring programmes and better management of harbour ecosystems.  相似文献   

9.
On the ecology of meiofauna in an organically polluted estuarine mudflat   总被引:1,自引:0,他引:1  
The structure, distribution and seasonal changes of the benthic meiofauna in an organically polluted, tidal, brackish-water mudflat in the Ems-Dollart estuary were analysed. Towards the outfall of polluted fresh water, macrofauna disappeared, numbers of meiofauna increased but the diversity of the meiofauna decreased. In the area surrounding the outfall the numbers and biomass of nematodes and oligochaetes increased rapidly in spring and remained high until autumn (c. 13 × 106 individuals m−2; c. 2gCm−2). The benthic fauna comprised small numbers of species, dominated by a few fast-growing diatom-feeding nematodes (Eudiplogaster pararmatus and Dichromadora geophila) and oligochaetes (Amphichaeta sannio and Paranais litoralis). Eudiplogaster pararmatus exhibits brood care and it tolerates low salinities. Dichromadora geophila which is oviparous, behaved similarly regarding tolerances, life cycle and feeding but this species was less successful than Eudiplogaster in colonizing the mudflats near the outfall. The success of the two naidid oligochaete species results from their method of reproduction by means of binary fission.Most organisms fed on benthic diatoms. In spite of intensive mineralization in the mudflat, only one bacteria-feeding organism was found in abundance (the nematode Leptolaimus papilliger). The absence of macrofaunal organisms, e.g. Nereis diversicolor, is probably also responsible for the development of high densities of meiofauna in the upper sediment layers of the mudflats in the vicinity of the outfall.The heavy load of organic waste entering the Dollart reduced the diversity within the benthic ecosystem, but nevertheless a simple system remained, based on the recurrent reoxidation of the sediment surface.  相似文献   

10.
Meiobenthos were sampled from 17 stations in the abyssal deep-sea system of the central Pacific centered around 14°N, 130°W at depths 4960–5154m, during the Nixo 47 R/V Jean Charcot cruise. Meiofaunal density range from 45–89 ind. 10cm2. Predominant taxa are nematodes (84–100%) and copepods (0–10%). Rotifera, Polychaeta, and Acarina also occur. Nematodes are uniformly distributed spatially with 45 species or so; Monhysteridae is the dominant taxon, and Syringolaimus sp. (Ironidae) co-occurs faithfully. Low biomass (0.4–70.6μg 10cm2) are attributed to supposed dwarfism of metazoan meiofauna and very high proportion (60–80%) of juveniles and pre-adult forms. The majority of protozoans and metazoans are detritus- or deposit-feeders; in addition symbiotic associations, coprophagy and gardening activities are frequent. In such an oligotrophic environment, low food supply may limit meiofaunal abundance, biomass and maturation, and to a lesser extent species richness.  相似文献   

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