Protist diversity in suboxic and sulfidic waters of the Black Sea

The oxic-anoxic transition zone of the Black Sea comprises a large suboxic zone as well as anoxic and sulfidic waters. While the prokaryotes and biogeochemical cycles that characterize this zone have been frequently studied, little is known about the diversity or ecology of its microbial eukaryotes. Here, we present the first broad qualitative report of the protist species composition in the Black Sea redoxcline using molecular tools. Fingerprint analysis from the whole redoxcline revealed a complex community structure of metabolically active protists with distinct shifts along the redox gradient. Additionally, 18S rRNA gene clone libraries were used to compare protist species composition of suboxic and sulfidic water layers. Among the ciliates, sequences related to Pleuronema and Strombidium were dominant in both water layers whereas sequences affiliated with anaerobic plagiopylids and Cyclidium were detected only in the sulfidic zone. Among the flagellates, mainly stramenopiles (mostly bicosoecids and chrysophytes) occurred throughout the redoxcline. In the sulfidic zone we found stramenopile sequences but also euglenozoans, jakobids and choanoflagellates that were related to clonal sequences from other anoxic marine habitats, thus indicating the existence of globally distributed groups of anoxic flagellates. Higher species diversity in the sulfidic zone and about twice as many novel sequence types of ciliates and stramenopiles compared with the suboxic layer emphasizes the importance of anoxic, sulfidic waters as habitat for high protist diversity although the function of these organisms is yet unknown.     

Species diversity of heterotrophic flagellates in White Sea littoral sites

The species diversity and distribution of benthic heterotrophic flagellates in sediment samples from along the salinity gradient in the Chernaya River Estuary and from Velikaya Salma Strait (Kandalaksha Bay, the White Sea) were investigated during August 2004. One hundred and six taxa have been identified by means of phase and interference contrast light microscopy and transmission electron microscopy. The majority of observed flagellates were bacterivores. The species diversity of the following groups: choanoflagellates, euglenids, kinetoplastids, bicosoecids, chrysomonads, thaumatomonads and flagellates Incertae sedis was the highest. Ancyromonas sigmoides and Petalomonas pusilla were the most common species. The species richness was lowest in the brackish water estuarine part with salinity levels between 5 per thousand and 8 per thousand. The distribution of heterotrophic flagellates conforms to the so-called "rule of critical salinity", possessing, apparently, the same universal character for organisms of different size levels. Heterotrophic flagellate communities in these littoral sites were highly heterogeneous. The curve of "cumulative species number vs. sampling effort" is well fitted by equation S=21.17N(0.50) and unsaturated, which indicates that more intensive investigations of the heterotrophic flagellates in the White Sea should be expected to reveal more species.     

Influence of the period of existence of a biotope on the formation of the species structure of a marine psammophilous ciliate community

The community structure of psammophile (interstitial) ciliates was studied in three areas of the silty sand intertidal zone of the White Sea, the background (a natural community formed under conditions of high siltation) and two experimental areas (the first, unsilted sandy “island” formed in the autumn of 2006, was originally uninhabited and the second was a similar island formed in the autumn of 2008). The experimental biotopes were more aerated and less silted than the background. The principle difference of experimental sites was the duration of their existence. Despite the remaining biotope differences between the background and first experimental site after 3 years of the experiment, the communities were of the same structural pattern. The second experimental biotope, which existing for a short time period, had considerable biotopic similarity to the first experimental one, but significantly differed from it and from the background in the course of succession and structural pattern of the formed community. It was shown that quantitatively and qualitatively (by density and number of species) the community of ciliates formed rather quickly during the first seasonal cycle of development in the new created biotope. However, one annual cycle is not sufficient for the formation of a community species structure, including the species ratio reflecting its niche structure.     

Yeasts of the White Sea intertidal zone and description of Glaciozyma litorale sp. nov.

The intertidal yeast communities inhabiting various environments in the territories of the White Sea Biological Station “Kartesh” (WSBS ZIN RAS) and the N.A. Pertsov White Sea Biological Station (WSBS MSU) were studied. A total of 31 yeast species were isolated using a conventional plating technique and identified using molecular methods. The yeast community of the White Sea intertidal zone consists of members that are typical for marine substrates, ubiquist species that are common in water and in low-temperature terrestrial environments, and a group of species that was isolated from marine substrates for the first time. The most diverse yeast communities formed on the surface of marine algae and in silt. Metschnikowia zobellii, which is a typical inhabitant of northern seas, was the most abundant yeast on algae from both biological stations. A new basidiomycetous yeast species, which was described in this work as Glaciozyma litorale sp. nov., dominated in the silt samples. The type strain of this new species is K94b^T (=KBP 4246^T = VKPM Y-3850^T = PYCC 6252^T = CBS 12957^T = DSM 28204^T); MycoBank registration number is MB 805475.     

Benthic–pelagic coupling: a comparison of the community structure of benthic and planktonic heterotrophic protists in shallow inlets of the southern Baltic

1. The taxonomic composition, abundance and biomass of heterotrophic protists (ciliates, heterotrophic flagellates (HF), rhizopods and actinopods) in the sediment and water column of shallow inlets of the Southern Baltic was studied under a variety of environmental conditions during 1996–1997. A shallow, highly eutrophic station and a deeper, less eutrophic station were compared.
2. Community biomass ranged from 0.12 to 0.34 μg C cm?3 in the water column and from 1.5 to 105 μg C cm?3 in the sediment. Heterotrophic protists dominated zooplankton biomass at both stations (73% and 84% mean contribution), while they were of minor importance within the zoobenthos. Expressed per unit area, benthic biomass contributed a significant part (44% and 49%) to the total heterotrophic protistan community at both stations.
3. Although the methodology for counting ciliates and HF was focussed on a high taxonomic resolution, the results reveal some general trends in the distribution of heterotrophic protists: protozooplankton biomass was dominated by flagellates (80% mean biomass contribution) at the shallow station and by ciliates (73% mean biomass contribution) at the deep station. In the benthos at both stations, ciliates were the dominant protozoans, followed by the hitherto little‐studied rhizopods (25% and 35% mean biomass contribution) and flagellates.
4. The degree of benthic–pelagic coupling differed between taxonomic groups. Benthic and pelagic communities of ciliates showed little taxonomic overlap. In contrast, many heterotrophic flagellate species were found both in the benthos and in the pelagic. These benthic–pelagic species contributed significantly to the biomass of HF in the water column. The planktonic rhizopod community consisted of a subset of those species found in the benthos.
5. The abundance of benthic and pelagic protists was positively correlated at the shallow station, but taxonomic data indicate that the direct exchange between benthic and pelagic communities was only partly responsible.     

Laboratory experiments on the impact of biofilms on the plankton of a large river

1. Benthic organisms can have a strong effect on the plankton in rivers, although normally only members of the macrofauna are considered as important consumers. In the present study we conducted experiments on four different dates (in December, March, June and September) to assess the potential role of periphytic heterotrophic flagellates (HF), ciliates and rotifers in the control of potamoplankton (bacteria, algae, HF and ciliates). 2. Natural periphyton was established on the walls of circular flow channels by exposing them to river water (River Rhine, Germany). The experimental channels (with periphyton) and control channels (without periphyton) were filled with riverine water and the increase rates of planktonic bacteria, algae, HF and oligotrich ciliates were determined for the two treatments. 3. The abundance of periphytic ciliates and rotifers at the beginning of the four experiments showed large differences with low values in December and March, and high values in June and September. Dominant potential consumers of plankton were the heterotrich ciliate Stentor sp. and bdelloid rotifers. 4. The rates of increase of planktonic algae, HF and ciliates were significantly smaller in the presence of periphyton compared with those in their absence. Significant interactions between the treatment (with and without periphyton) and the time of experiment were found for the planktonic HF and algae, indicating that the impact of the periphyton varied temporarily. The planktonic groups responded differently to the periphyton with the planktonic HF showing the highest loss rate. Significant differences were also found among the loss rates of different HF groups and different diatom size classes. 5. These laboratory experiments demonstrate that periphytic ciliates and rotifers are potentially important consumers of different planktonic groups. The quantitative impact of periphyton on plankton with respect to the selective feeding needs further attention.     

Structure of planktonic microbial food web in a brackish stratified Siberian lake

The distribution of primary components of the microbial community (autotrophic pico- and nanoplankton, phototrophic bacteria, heterotrophic bacteria, microscopic fungi, heterotrophic flagellates, ciliates and heliozoa) in the water column of Lake Shira, a steppe brackish-water, stratified lake in Khakasia, Siberia (Russia), were assessed in midsummer. Bacterioplankton was the main component of the planktonic microbial community, accounting for 65.3 to 75.7% of the total microbial biomass. The maximum concentration of heterotrophic bacteria were recorded in the monimolimnion of the lake. Autotrophic microorganisms contributed more significantly to the total microbial biomass in the pelagic zone (20.2–26.5%) than in the littoral zone of the lake (8.7–14.9%). First of all, it is caused by development of phototrophic sulphur bacteria at the oxic-anoxic boundary. The concentrations of most aerobic phototrophic and heterotrophic microorganisms were maximal in the upper mixolimnion. Heterotrophic flagellates dominated the protozoan populations. Ciliates were minor component of the planktonic microbial community of the lake. Heterotrophic flagellates were the most diverse group of planktonic eucaryotes in the lake, which represented by 36 species. Facultative and obligate anaerobic flagellates were revealed in the monimolimnion. There were four species of Heliozoa and only three of ciliates in the lake.     

Long-term fluctuations of soft-bottom intertidal community structure affected by ice cover at two small sea bights in the Chupa Inlet (Kandalaksha Bay) of the White Sea

The effect on bottom organisms of periodic freezing of the upper layer of intertidal sediments during abnormal cold winters has been studied for a long time in seas of a moderate climatic zone. However, the effect of ice cover every year on intertidal communities in polar seas is still poorly investigated. Seasonal and long-term variation in the structure of intertidal soft-bottom communities in two small bights in the White Sea with annual ice cover was studied for over two decades. Sampling was carried out four times a year, in the hydrological spring, summer, autumn, and winter. It was found that bottom macrobenthic communities at upper and lower horizons of the intertidal distinctly differed in the studied sites. Periodic changes caused by the effect of abnormal ice conditions, including the partial removal by ice of sediment with in situ organisms, were discovered. Recovery of communities after disturbance normally took less than half a year. Communities at the lower and upper horizons of the intertidal zone were more stable than intermediate communities, which led to periodic shifts of the biological border between lower and upper intertidal assemblages.     

The Extent of Algal and Bacterial Endosymbioses in Protozoa1,2

Long neglected has been the extensive and more or less intimate association of protozoa with a wide variety of other cells, either prokaryotic or eukaryotic in nature. Yet study of such relationships can provide important information concerning certain basic aspects of cellular evolution in general. A survey is offered here of the whole range of such symbiotic associations (i.e. with species of protozoa serving as hosts) with the purposes of drawing attention to the exciting possibilities of such research and of reviewing significant findings made to date. Because of the vastness of the overall field, examples and discussion are primarily limited to consideration of the following major studies: methanogenic bacteria in certain ciliates, bacterial endosymbionts of the large freshwater amoeba Pelomyxa palustris (itself an amazing organism from an evolutionary/phylogenetic point of view), the rod-shaped bacteria found in Amoeba proteus, the “Greek-letter” prokaryotes of Paramecium species, the xenosomes (sensu stricto) of the marine scuticociliate Parauronema acutum, and the diverse algal endosymbionts of similarly diverse protozoan taxa–ciliates, flagellates, radiolarians, acantharians, and foraminifera.     

Spatial variability in structural and functional aspects of macrofauna communities and their environmental parameters in the Jade Bay (Wadden Sea Lower Saxony, southern North Sea)

Spatial distribution and functional structure of intertidal benthic macrofauna in relation to environmental variables in the Jade Bay (southern North Sea) were studied and compared with other intertidal areas of the Wadden Sea. A total of 128 stations covering the whole Jade Bay were sampled in summer 2009. A total of 114 taxa were found. Highest species numbers occurred in the subtidal areas, whereas highest mean abundances were found in the upper intertidal areas. Based on species abundance data, six significantly distinct macrofauna communities in the Jade Bay were identified and evaluated with multivariate statistics, univariate correlations and canonical correspondence analysis. Differences in these community patterns were caused by the response of the dominant species (Hydrobia ulvae, Tubificoides benedii, Pygospio elegans, Caulleriella killariensis, Scoloplos armiger, Urothoe poseidonis, Microprotopus maculatus) to prevailing environmental conditions along the gradient from the lower and exposed sandy intertidal areas via intermediate mixed sediments to the upper mudflat areas. Distribution patterns in relation to tidal zonation were best explained by variability in submergence time, Chlorophyll a (chl a) content and sediment composition (mud content), which are proxies for hydrodynamic conditions and food availability. Species inventory and species richness were comparable with other intertidal areas of the Wadden Sea, but the Jade Bay differs from these areas regarding dominant species. Differences in sediment composition and morphological characteristics (macrotidal versus mesotidal Wadden Sea areas) are discussed for comparison of regional differences.     

Context‐dependent functional dispersion across similar ranges of trait space covered by intertidal rocky shore communities

Functional diversity is intimately linked with community assembly processes, but its large‐scale patterns of variation are often not well understood. Here, we investigated the spatiotemporal changes in multiple trait dimensions (“trait space”) along vertical intertidal environmental stress gradients and across a landscape scale. We predicted that the range of the trait space covered by local assemblages (i.e., functional richness) and the dispersion in trait abundances (i.e., functional dispersion) should increase from high‐ to low‐intertidal elevations, due to the decreasing influence of environmental filtering. The abundance of macrobenthic algae and invertebrates was estimated at four rocky shores spanning ca. 200 km of the coast over a 36‐month period. Functional richness and dispersion were contrasted against matrix‐swap models to remove any confounding effect of species richness on functional diversity. Random‐slope models showed that functional richness and dispersion significantly increased from high‐ to low‐intertidal heights, demonstrating that under harsh environmental conditions, the assemblages comprised similar abundances of functionally similar species (i.e., trait convergence), while that under milder conditions, the assemblages encompassed differing abundances of functionally dissimilar species (i.e., trait divergence). According to the Akaike information criteria, the relationship between local environmental stress and functional richness was persistent across sites and sampling times, while functional dispersion varied significantly. Environmental filtering therefore has persistent effects on the range of trait space covered by these assemblages, but context‐dependent effects on the abundances of trait combinations within such range. Our results further suggest that natural and/or anthropogenic factors might have significant effects on the relative abundance of functional traits, despite that no trait addition or extinction is detected.     

长江口潮间带底栖生物生态及变化趋势

基于长江口3个区域潮间带(崇明东滩、南汇边滩和嵊山岛)监测数据,对长江口区域潮间带底栖生物生态现状及变化趋势进行评价。结果表明,2019年长江口海域泥相和岩相潮间带共鉴定大型底栖生物9门57种,软体动物、甲壳类和多毛类构成主要类群。崇明东滩、南汇边滩两个泥相潮间带底栖生物平均栖息密度分别为96.4个/m~2和160.4个/m~2,平均生物量分别为68.42 g/m~2和45.71 g/m~2;嵊山岛岩相潮间带平均栖息密度和生物量分别为488.9个/m~2和763.72 g/m~2。各断面多样性、丰富度和均匀度指数分别位于1.36—3.24、0.75—2.88和0.48—0.77,泥相潮间带低潮区生物多样性优于中潮区和高潮区,岩相潮间带中潮区生物多样性最好。聚类分析可见长江口海域潮间带底栖生物分为泥相和岩相2个大组群,物种分布存在明显的分潮区现象,高潮区站位成群或与个别中潮区站位成群,低潮区站位成群或与个别中潮区站位成群,表明底质类型和潮汐是影响潮间带大型底栖生物群落结构的主要因子。近30年来,崇明东滩和南汇边滩底栖生物种类数存在一定波动,嵊山后陀湾断面生物种类数明显下降;3个区域潮间带...     

Aspects of benthic decapod diversity and distribution from rocky nearshore habitat at geographically widely dispersed sites

Relationships of diversity, distribution and abundance of benthic decapods in intertidal and shallow subtidal waters to 10 m depth are explored based on data obtained using a standardized protocol of globally-distributed samples. Results indicate that decapod species richness overall is low within the nearshore, typically ranging from one to six taxa per site (mean = 4.5). Regionally the Gulf of Alaska decapod crustacean community structure was distinguishable by depth, multivariate analysis indicating increasing change with depth, where assemblages of the high and mid tide, low tide and 1 m, and 5 and 10 m strata formed three distinct groups. Univariate analysis showed species richness increasing from the high intertidal zone to 1 m subtidally, with distinct depth preferences among the 23 species. A similar depth trend but with peak richness at 5 m was observed when all global data were combined. Analysis of latitudinal trends, confined by data limitations, was equivocal on a global scale. While significant latitudinal differences existed in community structure among ecoregions, a semi-linear trend in changing community structure from the Arctic to lower latitudes did not hold when including tropical results. Among boreal regions the Canadian Atlantic was relatively species poor compared to the Gulf of Alaska, whereas the Caribbean and Sea of Japan appeared to be species hot spots. While species poor, samples from the Canadian Atlantic were the most diverse at the higher infraordinal level. Linking 11 environmental variables available for all sites to the best fit family-based biotic pattern showed a significant relationship, with the single best explanatory variable being the level of organic pollution and the best combination overall being organic pollution and primary productivity. While data limitations restrict conclusions in a global context, results are seen as a first-cut contribution useful in generating discussion and more in-depth work in the still poorly understood field of biodiversity distribution.     

Do Rapoport's rule,the mid‐domain effect or the source–sink hypotheses predict bathymetric patterns of polychaete richness on the Pacific coast of South America?

Aim We evaluated the bathymetric gradient of benthic polychaete species richness from the Chilean coast, as well as its possible underlying causes. We tested three possible hypotheses to explain the richness gradient: (1) Rapoport's effect; (2) the mid‐domain effect (MDE); and (c) the source–sink hypothesis. Location South‐eastern Pacific coast of Chile. Methods The bathymetric gradient in richness was evaluated using the reported ranges of bathymetric distribution of 498 polychaete species, from the intertidal to abyssal zone (c. 4700 m). Rapoport's effect was evaluated by examining the relationship between bathymetric mid‐point and bathymetric range extent, and species richness and depth. The MDE was tested using the Monte Carlo simulation program. The source–sink hypothesis was tested through nestedness analysis. Results Species richness shows significant exponential decay across the bathymetric gradient. The pattern is characterized by a high presence of short‐ranged species on the continental shelf area; while only a few species reach abyssal depths, and they tend to show extremely wide bathymetric ranges. Our simulation analyses showed that, in general, the pattern is robust to sampling artefacts. This pattern cannot be reproduced by the MDE, which predicts a parabolic richness gradient. Rather, results agree with the predictions of Rapoport's effect. Additionally, the data set is significantly nested at species, genus and family levels, supporting the source–sink hypothesis. Main conclusions The sharp exponential decay in benthic polychaete richness across the bathymetric gradient supports the general idea that abyssal environments should harbour fewer species than shallower zones. This pattern may be the result of colonization–extinction dynamics, characterized by abyssal assemblages acting as ‘sinks’ maintained mainly by shallower ‘sources’. The source–sink hypothesis provides a conceptual and methodological framework that may shed light on the search for general patterns of diversity across large spatial scales.     

Small mammal species richness and turnover along elevational gradient in Yulong Mountain,Yunnan, Southwest China

Understanding the species diversity patterns along elevational gradients is critical for biodiversity conservation in mountainous regions. We examined the elevational patterns of species richness and turnover, and evaluated the effects of spatial and environmental factors on nonvolant small mammals (hereafter “small mammal”) predicted a priori by alternative hypotheses (mid‐domain effect [MDE], species–area relationship [SAR], energy, environmental stability, and habitat complexity]) proposed to explain the variation of diversity. We designed a standardized sampling scheme to trap small mammals at ten elevational bands across the entire elevational gradient on Yulong Mountain, southwest China. A total of 1,808 small mammals representing 23 species were trapped. We observed the hump‐shaped distribution pattern of the overall species richness along elevational gradient. Insectivores, rodents, large‐ranged species, and endemic species richness showed the general hump‐shaped pattern but peaked at different elevations, whereas the small‐ranged species and endemic species favored the decreasing richness pattern. The MDE and the energy hypothesis were supported, whereas little support was found for the SAR, the environmental stability hypothesis, and the habitat complexity. However, the primary driver(s) for richness patterns differed among the partitioning groups, with NDVI (the normalized difference vegetation index) and MDE being the most important variables for the total richness pattern. Species turnover for all small mammal groups increased with elevation, and it supported a decrease in community similarity with elevational distance. Our results emphasized for increased conservation efforts in the higher elevation regions of the Yulong Mountain.     

Connecting domination contracts

In Black Rights/White Wrongs, Charles Mills continues his critique of contemporary American political philosophy for ignoring issues of racial oppression, and in particular for ignoring the way that liberal social contracts rest on underlying domination contracts. In this commentary, I will discuss some of the new research inspired by Mills’ account of domination contracts, including recent accounts of the “capability contract” and the “species contract”, and explore how they relate to Mills’ own work on the “racial contract”. While this new research on diverse domination contracts confirms the richness of Mills’ analysis of the social contract tradition, it may also require some revisions to his own preferred vision of how we theorize racial justice.     

Die Makrofauna und ihre Verteilung im Nordost-Felswatt von Helgoland

The macrofauna and its distribution in the sheltered, rocky intertidal zone of Helgoland (North Sea) was studied at 9 vertically and/or morphologically different stations from March to September in 1984. Seasonal variations in the communities were described based on each species' conspicuousness. A total of 172 species was found. The macrofauna shows a zoned pattern, but also the different substrata, for example, affect its distribution. The number of species increases from the upper intertidal to the upper sublittoral zone from 23 to 133 species. The upper intertidal is characterized byLittorina saxatilis, Chaetogrammarus marinus andHyale nilssonii. Typical and abundant species of the middle and lower intertidal areFlustrellidra hispida, Littorina mariae/obtusata, Littorina littorea, Mytilus edulis andSpirorbis spirorbis. The upper sublittoral zone is characterized byGibbula cineraria and increasing species numbers of Bryozoa, Nemertini and Opisthobranchia. Only few species (e.g.Dynamena pumila, Laomedea flexuosa, Polydora ciliata, Fabricia sabella, Jaera albifrons, Carcinus maenas) occur in the entire intertidal zone. In comparison to other very sheltered shores in Great Britain, which are also dominated by Fucaceae, the macrofauna in the Helgoland intertidal zone lacks several littoral species, such asPatella spp.,Monodonta lineata, Gibbula umbilicalis, Littorina neritoides, Chthamalus spp., whereasLittorina littorea andGibbula cineraria are highly abundant.     

The microplankton organisms at the oxic-anoxic interface in the pelagial of the Black Sea

Abstract The semi-permanent anoxia in the deep-waters of the Black Sea supported the formation of a unique microplankton community at the oxicanoxic interface. One group of ciliates ( Pleuronema marinum, Askenasia sp., species of the families Tracheliidae, Holophryidae and Amphileptidae) inhabited the water layer just above the upper boundary of H₂S, and was spatially associated with and fed on large colorless sulphur bacteria ( Thiovulum spp.). Other ciliates (species of order Scuticociliatida) populated the upper layer of the H₂S zone. A significant part of them possessed ectosymbiotic bacteria. Since the metazoans were not found in the O₂ and H₂S boundary layer, the protist community is considered to be the main factor in utilization of chemotrophic bacterial production.     

Species richness and diversity across rocky intertidal elevation gradients in Helgoland: testing predictions from an environmental stress model

Environmental stress affects species richness and diversity in communities, but the precise form of the relationship is unclear. We tested an environmental stress model (ESM) that predicts a unimodal pattern for total richness and diversity in local communities across the full stress gradient where a regional biota can occur. In 2008, we measured richness and diversity (considering all macrobenthic species) across the entire intertidal range on three rocky shores on Helgoland Island, Germany. Intertidal elevation is known to be positively related to abiotic stress. Since Helgoland is between the northern and southern biogeographic boundaries for the cold-temperate NE Atlantic intertidal biota, it exhibits low stress levels for this biota at low elevations and high stress at high elevations because of long (>6 h) emersion times. Thus, we predicted a unimodal trend for richness and diversity across elevation. On all three shores, richness increased from high to middle elevations, but remained similar between middle and low elevations. Diversity followed the same trend on one shore and different trends (although also non-unimodal) on the other two. Evenness explained the trend differences between richness and diversity. Overall, our study yielded little support for the ESM. Reasons for richness and diversity not decreasing at low elevations may be related to influences of mostly subtidal species, Helgoland’s intertidal range, or sampling resolution. Our study also suggests that the ESM must be developed further to differentiate between richness and diversity. We offer recommendations to improve future ESM research using intertidal systems.     

中街山列岛岩相潮间带大型底栖动物的群落格局

于2006年9月和2007年7月在中街山列岛4个有居民海岛岩相潮间带设立8个断面,对大型底栖动物的群落结构进行了调查。共获得大型底栖动物34种,其中腔肠动物1种,环节动物3种,甲壳动物10种,软体动物20种。优势种有日本笠藤壶(Tetraclita japonica)、紫贻贝(Mytilus edulis)和节蝾螺(Turb articulatus)等4种。以季节和站位为因子对多样性指数进行双因素方差分析,结果表明只有夏、秋季丰富度指数(P=0.028)存在显著差异,其他指数的方差分析没有显著差异(P>0.05)。3个潮带4个岛屿共12个站位的聚类分析和MDS标序分析表明,12个群落可分为3组(Ⅰ、Ⅱ和Ⅲ组)。大型底栖动物ABC曲线分析表明底栖动物群落尚未受到干扰。