Seasonal changes in the vertical distribution and community structure of Antarctic macrozooplankton and micronekton

The macrozooplankton and micronekton community of the Lazarev Sea (Southern Ocean) was investigated at 3 depth layers during austral summer, autumn and winter: (1) the surface layer (0–2 m); (2) the epipelagic layer (0–200 m); and (3) the deep layer (0–3000 m). Altogether, 132 species were identified. Species composition changed with depth from a euphausiid-dominated community in the surface layer, via a siphonophore-dominated community in the epipelagic layer, to a chaetognath-dominated community in the deep layer. The surface layer community predominantly changed along gradients of surface water temperature and sea ice parameters, whereas the epipelagic community mainly changed along hydrographical gradients. Although representing only 1% of the depth range of the epipelagic layer, mean per-area macrofauna densities in the surface layer ranged at 8% of corresponding epipelagic densities in summer, 6% in autumn, and 24% in winter. Seasonal shifts of these proportional densities in abundant species indicated different strategies in the use of the surface layer, including both hibernal downward and hibernal upward shift in the vertical distribution, as well as year-round surface layer use by Antarctic krill. These findings imply that the surface layer, especially when it is ice-covered, is an important functional node of the pelagic ecosystem that has been underestimated by conventional depth-integrated sampling in the past. The exposure of this key habitat to climate-driven forces most likely adds to the known susceptibility of Antarctic pelagic ecosystems to temperature rise and changing sea ice conditions.     

Variation in mesozooplankton community structure in the Japan/East Sea (1991–1999) with possible influence of the ENSO scale climatic variability

Seasonal and interannual change in mesozooplankton community structure in the offshore Tsushima Current area of the Japan/East Sea was studied in relation to climatic events and temporal variability of the upper water column environment from 1991 to 1999. We observed a clear seasonal succession in zooplankton community structure from a cold-water copepod-dominated community in winter and spring to a gelatinous, carnivorous and warm-water copepod-dominated community in summer and autumn. The mean abundance (inds. m⁻³) of the spring community was 3–4-fold higher than that of the other season. The spring community structure varied considerably between years: the community characterized by the summer–autumn type zooplankton assemblage appeared in 1991–1993 and 1998, while the community characterized by high abundance of cold-water copepods appeared in the mid 1990s. Time series profiles of water density and nutrients showed the thickness of the surface warm Tsushima Current and the cold subsurface water increased and decreased, respectively, limiting nutrient supply to the surface water in 1992 and 1998. These results suggest that a thick, warm surface layer might reduce the reproductive success and survival ratio of the cold-water copepods both directly and indirectly, by hindering their upward migration to the surface where food is available, and by limiting phytoplankton growth due to nutrient depletion, respectively. A Monsoon Index (MOI) showed weaker winter wind stress in 1992 and 1998, which might have attenuated formation of the cold subsurface layer in the northern Japan/East Sea and been responsible for surface warming of the study area. Since 1992 and 1998 were El Niño years, this study revealed that ENSO related climatic variability on an interannual time scale considerably influenced the lower trophic level ecosystem in the Japan/East Sea.     

基于O2/Ar比值估算海洋混合层群落净生产力的研究进展

群落净生产力(NCP)是海洋混合层中光合作用和群落呼吸作用的差值,代表了从表层海水向深层海洋输送的最大有机质量,是衡量生物活动对上层海洋碳循环影响的有效指标。海洋混合层的溶解氧浓度主要受物理过程和生物过程控制,而惰性气体氩(Ar)的分布主要受物理过程以及温度和盐度对溶解度的影响,由于O2和Ar具有相似的物理特性,因此氧氩比值(O2/Ar)消除了物理过程对海水中溶解氧的影响,其偏离平衡值的量(ΔO 2/Ar)可表征生物过饱和氧,并可据此估算群落净生产力。随着质谱技术的发展,连续走航测定O2/Ar比值技术得到广泛应用并可以获得高时空分辨率NCP分布,因此成为估算海洋混合层NCP的重要方法。本文介绍了基于O2/Ar比值法估算群落净生产力的原理,综述了用O2/Ar比值法估算海洋混合层中群落净生产力的研究进展,探讨了估算模型中存在的不足及解决办法,并对其未来发展方向做了展望。     

Benthic macrofauna in a shallow water carbonate sediment: major bioturbators at the Dry Tortugas

 Functional group analysis was used to determine the major bioturbators in the Dry Tortugas, Florida Keys. The surface community is dominated by surface deposit feeding polychaetes and burrowing bivalves capable of mixing the top 0–4 cm of the sediment on time scales of days to weeks. Bioturbation by the Notomastus sp. and Callianassa sp. deep community effectively removes primary sedimentary structures. Their fossilized burrow structures may be geologically important in this system. Surface microtopography is controlled by stabilizing and destabilizing forces that determine the potential for surface resuspension and sediment transport in the Dry Tortugas.     

Genetic diversity and its seasonal variation of Jiaozhou Bay phytoplankton determined by rbcL gene sequencing

1 IntroductionRibulose-1, 5-bisphosphatecarboxylase/oxyge-nase(RubisCO)isthem ostim portantenzymeforpho-tobiosynthesis. Itcatalyzesboth thereduction ofCO2and the oxygenolysisofribulose-1, 5-bisphosphate.Asthemostabundantproteinonearth (Ellis, 1979),RubisC…     

胶州湾浮游植物遗传多样性及其季节变化研究

分别于春、夏、秋三季提取了胶州湾浮游生物总DNA,用PCR方法扩增了浮游植物核酮糖1,5-二磷酸羧化/氧化酶大亚基(rbcL)基因片段,构建了三季节rbcL基因片段质粒文库.随机从各文库中选择约50个克隆,测定了这些克隆的序列.以氨基酸序列相同为标准,共获得59个分类操作单元(OTUs),其中春季特有的21个,夏季特有的13个,秋季特有的23个.有两个OTUs为春、夏季表层海水共有.基于OTU丰度计算的香农氏指数能反映遗传多样性水平.胶州湾春、夏、秋三季的香农氏指数分别为2.69,2.44和2.76,表明秋季胶州湾浮游植物遗传多样性最丰富.春、夏、秋三季浮游植物群落组成差异显著.除夏秋季有两个OTUs相同外,其他OTUs在季节间完全不同.表层海水浮游植物群落结构是动态的,随时间、空间的不同而变化.     

Phytoplankton community structure in Otsuchi Bay,northeastern Japan,after the 2011 off the Pacific coast of Tohoku Earthquake and tsunami

The tsunami caused by the 2011 off the Pacific coast of Tohoku Earthquake seriously damaged the Pacific coast of northeastern Japan. In addition to its direct disturbance, a tsunami can indirectly affect coastal pelagic ecosystems via topographical and environmental changes. We investigated seasonal changes in the phytoplankton community structure in Otsuchi Bay, northeastern Japan, from May 2011, which was 2 months after the tsunami, to May 2013. The phytoplankton species composition in May 2011 was similar to that observed in May 2012 and 2013. The present results are consistent with the dominant species and water-mass indicator species of phytoplankton in past records. These results suggest that there was no serious effect of the tsunami on the phytoplankton community in Otsuchi Bay. Community analysis revealed that two distinct seasonal communities appeared in each year of the study period. The spring–summer community was characterized by warm-water Chaetoceros species, and dinoflagellates appeared from May to September. The fall–winter community was characterized by cold neritic diatoms, which appeared from November to March. The succession from the spring–summer community to the fall–winter community took place within a particular water mass, and the fall–winter community appeared in both the surface water and the Oyashio water mass, suggesting that water-mass exchange is not the only factor that determines the phytoplankton community structure in Otsuchi Bay.     

大亚湾夏季浮游群落生产代谢特征及其影响因素*

2017年8月对大亚湾海域浮游群落初级生产、群落呼吸代谢及其平衡特征进行了研究, 并分析了其潜在环境影响因素以及对沿岸生态系统功能与健康的指示作用。研究结果表明, 大亚湾夏季海水表层呈自养状态, 而底层呈异养状态, 群落总初级生产力(gross primary productivity, GPP)、呼吸代谢速率(community respiration, CR)与净生产力(net commutnitiy production, NCP)在表层分别为1335.36±910.12、597.86±403.30和737.50±608.22mg C·m^-3·d^-1; 在底层分别为43.65±37.05、216.25±147.28和-160.27±137.01mg C·m^-3·d^-1。海湾整体呈自养状态, 水柱平均NCP为233.41±248.88mg C·m^-3·d^-1; 部分沿岸水域存在异养状态。1~200μm粒级浮游生物是GPP和CR的主要贡献者。相关性分析和主成分分析显示, NCP在表层受GPP和CR共同调控, 且与浮游植物生物量和营养盐正相关; 而在底层主要受CR影响, 且与盐度正相关。大亚湾夏季群落生产代谢平衡存在明显的水平和垂向变化, NCP的区域差异与潜在波动性对该海湾生态系统稳定性及健康状况有重要的指示作用。     

Molecular diversity of phytoplankton in the East China Sea around Jeju Island (Korea), unraveled by pyrosequencing

The East China Sea (ECS) around Jeju Island lies in a transitional region between the temperate and subtropical zones and is influenced by the Kuroshio Current. Hence, this area has been considered an important monitoring site for oceanic ecosystem changes. Herein, we assessed the community structure and diversity of the phytoplankton in the ECS around Jeju Island using small subunit ribosomal RNA pyrosequencing. We analyzed eight samples collected from the surface and at 30 m- and/or 50-m depths from two neritic and oceanic stations each from 24–30 April 2011. Comparisons of 15,498 pyrosequences identified 172 phylotypes of phytoplankton, excluding cyanobacteria, from the four surface stations. These pyrosequences were represented by dinoflagellates (29 %), stramenopiles (31 %), and chlorophytes (>39 %), with minor contributions from cryptophytes, haptophytes, and Telonemia. Phylotypes retrieved at 30- and 50-m depths were very similar to the surface samples. However, phylotype diversity and community structure varied considerably with the stations. Dominant phylotypes included Karlodinium veneficum, Ostreococcus tauri, Skeletonema marinoi, and Thalassiosira curviseriata, and many of the detected phylotypes include new records for the present study area. This study provides a valuable phylotype reference for future phytoplankton community structure and diversity studies with regard to marine environmental changes.     

First Investigation of Microbial Community Composition in the Bridge (Gadeok Channel) between the Jinhae-Masan Bay and the South Sea of Korea

Microbial community composition varies based on seasonal dynamics (summer: strongly stratified water column; autumn: weakly stratified water column; winter: vertically homogeneous water column) and vertical distributions (surface, middle, and bottom depths) in the Gadeok Channel, which is the primary passage to exchange waters and materials between the Jinhae-Masan Bay and the South Sea waters. The microbial community composition was analyzed from June to December 2016 using 16S rRNA gene sequencing. The community was dominated by the phyla Proteobacteria (45%), Bacteroidetes (18%), Cyanobacteria (15%), Verrucomicrobia (6%), and Actinobacteria (6%). Alphaproteobacteria (29%) was the most abundant microbial class, followed by Flavobacteria (15%) and Gammaproteobacteria (15%) in all samples. The composition of the microbial communities was found to vary vertically and seasonally. The orders Flavobacteriales and Stramenopiles showed opposing seasonal patterns; Flavobacteriales was more abundant in August and December while Stramenopiles showed high abundance in June and October at all depths. The genus Synechococcus reached extremely high abundance (14%) in the June surface water column, but was much less abundant in December water columns. Clustering analysis showed that there was a difference in the microbial community composition pattern between the strongly stratified season and well-mixed season. These results indicate that the seasonal dynamics of physicochemical and hydrologic conditions throughout the water column are important parameters in shaping the microbial community composition in the Gadeok Channel.     

两种混养方式对异枝江蓠(Gracilaria bailinae)生长性能、表面附生细菌群落及抗生素抗性基因的影响

为揭示"鱼-藻"和"鱼-虾-藻"混养对异枝江蓠(Gracilaria bailinae)生长性能、表面附生细菌群落和抗生素抗性基因(antibiotic resistance genes,ARGs)的影响,阐明异枝江蓠表面附生细菌群落与生长性能、ARGs之间的关系,利用16S rDNA高通量测序技术和Real-time qPCR技术分析了异枝江蓠表面附生细菌群落和ARGs的组成与差异,冗余分析(RDA)探讨细菌群落与生长性能、ARGs之间的关联。结果表明:(1)"鱼-虾-藻"混养会促进异枝江蓠的生长性能,增加表面附生细菌群落的多样性。(2)异枝江蓠表面附生细菌群落主要属于变形菌门、蓝藻门、浮霉菌门和拟杆菌门,不同混养方式中优势菌属组成不同,"鱼-虾-藻"混养优势菌属多样性较高。(3)"鱼-虾-藻"混养的异枝江蓠ARGs/MGEs的相对丰度大多高于"鱼-藻"混养。(4)RDA分析表明,生长性能主要与Ralstonia、Blastopirellula等显著相关,ARGs/MGEs主要与Nitrosomonas、Alteromonas、Pleurocapsa;CC-7319等显著相关。"鱼-虾-藻"混养能够增强异枝江蓠的生长性能,提高异枝江蓠表面附生细菌群落的多样性。但"鱼-虾-藻"混养能够增加异枝江蓠ARGs/MGEs的相对丰度,存在一定的生态风险。因此,在注重经济效益的同时也要关注可能存在的对人类健康的危害。研究结果将有助于海水养殖环境的优化,为大型海藻在海水养殖业中的应用与推广提供理论基础。     

Spatio-Temporal Distribution of Algal and Animal Communities in a Posidonia oceanica Meadow

Abstract. Investigations were carried out in a Posidonia oceanica meadow at Ischia (Gulf of Naples) along a depth gradient from 1 to 32 m in November 1979 and May 1981.
In these two months, different discontinuities were found at the sampling stations (1, 5, 10, 20, 30 m) at 10 m for leaf features, between 1 and 5 m for the algal community and the vagile fauna. The leaf features (length, surface, and biomass) along the transects show a delay in leaf production toward the deeper stations, below the thermocline.
The algal community shows in both seasons and in all stations a persistence of an encrusting layer, mostly represented by Corallinaceae and the brown alga Myrionema orbiculare , while at the shallowest station (1 m) the community is characterized by a more developed upright layer.
The vagile fauna of the leaf stratum, mostly represented by Polychaeta, Mollusca , and Crustacea (Peracarida and Decapoda) , shows a consistent zonation in both seasons along the transect. A superficial community at I m, characterized by a low number of species and individuals and specialized for high environmental energy levels, and a deeper community, persistent in time and more strictly related to the Posidonia oceanica meadows, are identified.
The influence of environmental factors and the importance of meadow structure for the zonation of the algal and animal communities are discussed.     

辽河口沉积物中古菌和细菌群落结构分析

本研究旨在了解辽河口表层沉积物中古菌和细菌的群落结构组成、多样性及其与环境因子之间的相关性。采用构建古菌和细菌16S rRNA基因文库的方法，应用Illumina Miseq测序技术进行序列分析。结果表明:辽河口表层沉积物中细菌多样性高于古菌多样性，近岸细菌和古菌多样性高于远岸，即河相区（0.8~7.04）细菌多样性高于混合区（13.1~20.7）和海相区（24.2~31.5）；主要古菌群落为奇古菌门（Thaumarchaeota，72.73%）和广古菌门（Euryarchaeota，25.05%），其中泉古菌门（Crenarchaeota，0.001%）只在河相区站位被发现；细菌群落组成中变形菌门（Proteobacteria，61.94%）为该河口的优势菌群，其次为拟杆菌门（Bacteroidetes，11.21%）和酸杆菌门（Acidobacteria，5.59%），其他门类如蓝藻门（Cyanobacteria，3.03%）等比例较小。与环境因子的冗余度分析表明:影响表层沉积物中古菌群落分布的主要环境因子依次为氨盐、泥、酸碱度、盐度、电导率和砂，而细菌群落的分布主要受到溶氧、泥、砂、黏土和总磷的影响。由此可见，不同环境条件下微生物的群落结构存在空间异质性，不同微生物对同一环境条件的响应亦不同。     

黄东海浮游生物群落呼吸率对碳平衡的重要性

黄东海接受长江冲淡水和黑潮带来的大量营养盐和有机物质,其碳循环对陆架海碳源汇格局至关重要.浮游生物群落呼吸是影响碳循环的重要过程.为揭示黄东海浮游生物群落呼吸率(PCR)对碳平衡的贡献,于2011年四季使用黑白瓶培养法测定黄海南部及东海北部浮游群落呼吸率和初级生产力,并同步测定温度、盐度、营养盐、叶绿素和细菌丰度等环境...     

A Study in Ultra-Ecology: Microorganisms on the Seagrass Posidonia oceanica (L.) DELILE

Abstract. Microbial colonization on the leaves of a shoot of the mediterranean seagrass Posidonia oceanica (L.) DELILE was studied using Scanning Electron Microscopy. Methods of field ecology such as transect, random plot and stratified sampling survey were applied to the microbial niveau to gain both qualitative and quantitative information on the microbial assemblage. While macro-epiphytic growth was significantly greater on the outer leaf sides, microbial colonization density was significantly higher on the inner leaf sides, both on leaf surface and epiphyte surface. Diatoms colonized the surface of incrusting algae and epiphytic animals in significantly lower numbers than the Posidonia leaf surface and were absent on erect epiphytic algae. Bacterial densities on epiphyte surfaces even exceeded values of the corresponding leaf surfaces on algal thalli near the leaf tips and on old leaves. Diatoms reach highest mean density on mature leaves and close to the leaf tips, while bacteria reach their greatest density on the oldest leaf and closer to the leaf base. Diatom density in general increases with exposure time of plant surface, while greatest bacterial density was observed at 7–10 weeks exposure. Basal leaf parts on younger leaves were dominated by rod-shaped bacteria, while distal leaf parts and old leaves were dominated by small coccoid bacteria. Surfaces of epiphytic algae were always distinctly dominated by small coccoid bacteria, and edges of thalli attracted high microbial densities. Microbial biomass (calculated from cell volumes using standard conversion factors) amounts to 2.3 g dry weight m-² in the Posidonia stand where the shoot was sampled. The observed patterns of epiphytic colonization are interpreted as the result of a complex, dynamically changing system of interactions both within the epiphytic community and between the epiphytic community, the host plant, and it's environment. A model of the organization of the epiphytic community on Posidonia leaves is presented. “Ultra-ecology” is a term introduced to denote a type of SEM research in the micro-environment which is analogous to in situ investigation in “macroscopic” ecological work.     

Influences of initial plankton biomass and mixed-layer depths on the outcome of iron-fertilization experiments

Several in situ iron-enrichment experiments have been conducted, where the response of the phytoplankton community differed. We use a marine ecosystem model to investigate the effect of iron on phytoplankton in response to different initial plankton conditions and mixed-layer depths (MLDs). Sensitivity analysis of the model results to the MLDs reveals that the modeled response to the same iron enhancement treatment differed dramatically according to the different MLDs. The magnitude of the iron-induced biogeochemical responses in the surface water, such as maximum chlorophyll, is inversely correlated with MLD, as observed. The significant decrease in maximum surface chlorophyll with MLD results from the difference in diatom concentration in the mixed layer, which is determined by vertical mixing. The modeled column-integrated chlorophyll, on the other hand, is the highest with intermediate MLD cases, suggesting difference in iron-induced biogeochemical responses between volume and area considerations. The iron-induced diatom bloom is severely restricted below the compensation depth due to both light limitation and grazing pressure, irrespective of the MLD. Sensitivity of the model to initial mesozooplankton (as grazers on diatoms) biomass shows that column-integrated biomass, net community production and export production are strongly controlled by the initial mesozooplankton biomass. Higher initial mesozooplankton biomass yields high grazing pressure on diatoms, which results in less accumulation of diatom biomass and may account for notably lower surface chlorophyll during SEEDS (Subarctic Pacific Iron Experiment for Ecosystem Dynamics Study) II than during SEEDS. The initial diatom biomass is also important to the outcome of iron enrichment but is not as crucial as the MLD and the initial mesozooplankton biomass. This modeling study suggests that not only MLD but also the initial biomass of diatoms and its principle grazers are crucial factors in the response of the phytoplankton community to iron enrichments, and should be considered in designing future iron-enrichment experiments.     

Size-Fractionated Primary Production Estimated by a Two-Phytoplankton Community Model Applicable to Ocean Color Remote Sensing

In order to estimate primary production from ocean color satellite data using the Vertical Generalized Production Model (VGPM; Behrenfeld and Falkowski, 1997), we propose a two-phytoplankton community model. This model is based on the two assumptions that changes in chlorophyll concentration result from changes of large-sized phytoplankton abundance, and chlorophyll specific productivity of phytoplankton tends to be inversely proportional to phytoplankton size. Based on the analysis of primary production data, P _opt ^B , which was one parameter in the VGPM, was modeled as a function of sea surface temperature and sea surface chlorophyll concentration. The two-phytoplankton community model incorporated into the VGPM gave good estimates in a relatively high productive area. Size-fractionated primary production was estimated by the two-phytoplankton community model, and P _opt ^B of small-sized phytoplankton was 4.5 times that of large-sized phytoplankton. This result fell into the ranges observed during field studies.     

Mass Mortality in the Gulf of Trieste: The Course of Community Destruction

Abstract. Over a period of two weeks in September, 1983 a high biomass macroepifauna community characteristic of a greater part of the Gulf of Trieste suffered mass mortality. The affected area is estimated to cover several hundred km2. Within 2–3 days all sponges and the brittle star Ophiothrix quinquemaculata, which together make up over 60 % of the community biomass, were dead. Benthic fish, mostly gobiids, were already affected on the first day and littered the bottom in great numbers. Concurrently the complete spectrum of macroinfauna species including (in order of emergence) holothurians, burrowing shrimp, echinoids, polychaetes, sipunculids and bivalves appeared on the sediment surface. Within one week sea stars and all remaining ophiurids had died. At this time hermit crabs were found lying dead next to their shells. Several anemones survived into the last week, although many showed signs of severe stress and lay on the surface with exposed pedal discs. Oxygen deficiency is the apparent immediate cause of this phenomenon and several possible factors leading to anoxic conditions in the Gulf are discussed. This ecological catastrophy provides evidence that the affected community, considered to have achieved relative stability by developing a strategy effectively dampening the effect of physical oscillations, has a distinct tolerance limit to stress. The Gulf of Trieste, among the most productive areas in the Mediterranean Sea, must be considered as sensitive; September is a particularly critical month.     

渤海沉积物中细菌群落结构和基因丰度的空间分布特征

This study investigated differences in the community structure and environmental responses of the bacterial community in sediments of the Bohai Sea.Illumina high-throughput sequencing technology and real-time PCR were used to assay the bacterial 16S rRNA genes in the surface sediments of 13 sampling stations in the Bohai Sea.The results showed that sediments at the majority of the 13 sampling stations were contaminated by heavy metal mercury.The main phyla of bacteria recorded included Proteobacteria(52.92%),Bacteroidetes(11.76%),Planctomycetes(7.39%),Acidobacteria(6.53%)and Chloroflexi(4.97%).The genus with the highest relative abundance was Desulfobulbus(4.99%),which was the dominant genus at most sampling stations,followed by Lutimonas and Halioglobus.The main factors influencing bacterial community structure were total organic carbon,followed by depth and total phosphorus.The content of lead,cadmium,chromium,copper and zinc had a consistent effect on community structure.Arsenic showed a negative correlation with bacterial community structure in most samples,while the impact of mercury on community structure was not significant.The bacterial community in sediment samples from the Bohai Sea was rich in diversity and displayed an increase in diversity from high to low latitudes.The data indicated that the Bohai Sea had abundant microbial resources and was rich in bacteria with the potential to metabolize many types of pollutants.     

北黄海微表层细菌丰度与可培养细菌群落结构分析

为分析海洋微表层这一特殊生境中的细菌类群,于2010—2011年4个航次对北黄海微表层和次表层海水中的总菌丰度、可培养细菌丰度和群落结构进行了分析。采用流式细胞仪测定总菌丰度,平板计数法测定可培养细菌丰度,PCR-16SrDNA分析可培养细菌的群落结构。结果表明,调查海域微表层海水总菌均值为1.76×106 cell/mL,次表层海水总菌均值为1.07×106 cell/mL。可培养细菌丰度范围是1.00×102~1.70×106 CFU/mL,微表层和次表层可培养细菌所占总菌数量的百分比分别为13.05%和0.45%。微表层对总菌的富集因子(EF)均值为2.02,可培养细菌的EF均值为74.16。PCR-16SrDNA序列分析结果表明,该海域可培养细菌分属变形菌门(Proteobacteria)(94.34%)、厚壁菌门(Firmicutes)(1.89%)、拟杆菌门(Bacteroidetes)(1.89%)和放线菌门(Actinobacteria)(1.89%)4个类群。本研究初步发现,微表层对细菌具有较强的聚集作用,尤其对可培养细菌聚集作用更为明显。微表层中可培养细菌的群落结构与次表层有所不同,其种类丰富,来源和功能多样。由此可见,微表层独特的生境成就了其独特的微生物类群,其生态功能有待于进一步研究。