Analysis of the composition of bacterial communities in oil reservoirs from a southern offshore Brazilian basin

The aim of this study was to characterize and compare the bacterial community structure of two distinct oil samples from a petroleum field in Brazil by using both molecular, based on the construction of 16S rRNA gene libraries, and cultivation methods. Statistical comparisons of libraries based on Amplified Ribosomal DNA Restriction Analysis (ARDRA) data revealed no significant differences between the communities recovered in the non-biodegraded (NBD) and highly biodegraded oils (HBD). BlastN analysis of the 16S rRNA gene sequences representative of distinct ribotypes from both oils showed the presence of nine different bacterial genera in these samples, encompassing members of the genera Arcobacter, Halanaerobium, Marinobacter, Propionibacterium, Streptomyces, Leuconostoc, Acinetobacter, Bacillus and Streptococcus. Enrichments obtained using oil as inoculum and sole carbon source yielded bacterial isolates showing high 16S rRNA gene sequence similarity with Achromobacter xylosoxidans, Bacillus subtilis, Brevibacillus sp., Dietzia sp. and Methylobacterium sp. Comparison between the data obtained using cultivation-independent and enrichment cultures suggests that different selection of community members may occur when using distinct approaches. All the organisms found, except for Leuconostoc sp. and Streptococus sp., have been previously reported in the literature as hydrocarbon degraders and/or associated to oil field environments.     

云县罗扎河下游落叶季雨林的群落生态学研究

对罗扎河下游鲜为人知的落叶季雨林进行了群落生态学研究,结果表明:罗扎河下游落叶季雨林群落高度在15~20m之间;群落乔木层以厚皮树(Lannea coromandelica)、一担柴(Colonafloribunda)、粗糠柴(Mallotus philippensis)、毛果扁担杆(Grewia eriocarpa)、灰毛浆果楝(Cipadessa cinerascens)等树种为优势种;灌草层以刚莠竹(Microstegiumciliatum)盖度最大,其余如飞机草(Eupatoriumodoratum)、藿香蓟(Agera-tumconyzoides)、蹄盖蕨(Athyriumsp.)等种的盖度也比较大;群落中乔木和附生、藤本植物种类较少,而灌木和草本植物种类较多;多数乔木层植株胸径在5~10cm之间,大径级乔木比较少,即使群落中的优势种也主要是通过较多数量的中小径级个体体现出来。多样性指数计算表明,本落叶季雨林的生物多样性指数虽然比典型热带山地雨林为低,但大致相当于季风常绿阔叶林。     

Habitat heterogeneity and disturbance influence patterns of community temporal variability in a small temperate stream

Both habitat heterogeneity and disturbance can profoundly influence ecological systems at many levels of biological and ecological organization. However, the joint influences of heterogeneity and disturbance on temporal variability in communities have received little attention despite the intense homogenizing influence of human activity. I performed a field manipulation of substrate heterogeneity in a small New England stream, and measured changes in benthic macroinvertebrate communities for 100 days—a period that included both a severe drought and a flood. Generally, community variability decreased with increasing substrate heterogeneity. However, within sampling intervals, this relationship tended to fluctuate through time, apparently tracking changes in hydrology. At the beginning of the experiment, community temporal variability clearly decreased along a gradient of increasing substrate heterogeneity—a result consistent with an observational study performed the previous year. During the subsequent weeks, droughts and flooding created exceptionally high variability in both hydrology and benthic macroinvertebrate community structure resulting in the disappearance of this relationship. However, during the last weeks of the experiment when hydrologic conditions were relatively more stable, the negatively sloped relationship between community temporal variability and habitat heterogeneity reemerged and mimicked relationships observed both early in the experiment and in the previous year’s study. High habitat heterogeneity may promote temporal stability through several mechanisms including stabilization of resources and increased refugia from minor disturbances or predation. However, the results of this experiment suggest that severe disturbance events can create large-scale environmental variability that effectively swamps the influence of habitat heterogeneity, illustrating that a thorough understanding of community temporal variability in natural systems will necessarily consider sources of environmental variability at multiple spatial and temporal scales. Handling editor: L. M. Bini     

Morphological variation of <Emphasis Type="Italic">Keratella cochlearis</Emphasis> (Gosse) in Myanmar (Burma) in relation to zooplankton community structure

Keratella cochlearis was present in 27 of 35 water bodies sampled in Myanmar, and was the most abundant rotifer in 10. Measurements of lorica length and posterior spine length from 20 localities showed that posterior spine length varied both with lorica length and with the composition of the crustacean zooplankton. Long spines were associated with dominance by Heliodiaptomus. The shortest spines were found in samples dominated by cladocerans or cyclopoid copepods. Posterior spine length was positively correlated with the number of diaptomid copepods. Forms without posterior spines were found in 17 localities. The lorica lengths of these spineless forms were generally similar to those of co-occurring spined forms (r = 0.68), but in a few samples the loricas of the spineless forms were significantly larger. These larger forms are similar to the ‘aspina’ forms recently recognised in the River Thames in England. These samples were dominated by cladocerans or cyclopoid copepods. In one locality spineless forms were found without spined forms. The crustacean zooplankton in this locality was also dominated by cladocerans. Guest editors: S. S. S. Sarma, R. D. Gulati, R. L. Wallace, S. Nandini, H. J. Dumont & R. Rico-Martínez Advances in Rotifer Research     

Local structuring factors of invertebrate communities in ephemeral freshwater rock pools and the influence of more permanent water bodies in the region

We used three isolated clusters of small ephemeral rock pools on a sandstone flat in Utah to test the importance of local structuring processes on aquatic invertebrate communities. In the three clusters we characterized all ephemeral rock pools (total: 27) for their morphometry, and monitored their water quality, hydrology and community assemblage during a full hydrocycle. In each cluster we also sampled a set of more permanent interconnected freshwater systems positioned in a wash, draining the water from each cluster of rock pools. This design allowed additional testing for the potential role of more permanent water bodies in the region as source populations for the active dispersers and the effect on the community structure in the rock pools. Species richness and community composition in the rock pools correlated with level of permanence and the ammonia concentration. The length of the rock pool inundation cycle shaped community structure, most probably by inhibiting colonization by some taxa (e.g. tadpoles and insect larvae) through developmental constraints. The gradient in ammonia concentrations probably reflects differences in primary production. The more permanent water bodies in each wash differed both environmentally and in community composition from the connected set of rock pools. A limited set of active dispersers was observed in the rock pools. Our findings indicate that aquatic invertebrate communities in the ephemeral rock pools are mainly structured through habitat permanence, possibly linked with biotic interactions and primary production. Handling editor: S. I. Dodson     

Biodiversity conservation in cocoa production landscapes: an overview

Cocoa agroforests that retain a floristically diverse and structurally complex shade canopy have the potential to harbour significant levels of biodiversity, yet few studies have documented the plant and animal species occurring within these systems or within landscapes dominated by cocoa production. In this special issue, we bring together nine studies from Latin America, Africa and Asia that document the contribution of cocoa agroforestry systems to biodiversity conservation, and explore how the design, management and location of these systems within the broader landscape influence their value as habitats, resources and biological corridors. Tree diversity within the cocoa production systems is variable, depending on management, cultural differences, location and farm history, among other factors. Animal diversity is typically highest in those cocoa agroforests that have high plant diversity, structurally complex canopies, and abundant surrounding forest cover. In general, both plant and animal diversity within cocoa agroforests is greater than those of other agricultural land uses, but lower than in the original forest habitat. There are several emerging threats to biodiversity conservation within cocoa production landscapes, including the loss of remaining forest cover, the simplification of cocoa shade canopies and the conversion of cocoa agroforestry systems to other agricultural land uses with lower biodiversity value. To counter these threats and conserve biodiversity over the long-term, land management should focus on conserving native forest habitat within cocoa production landscapes, maintaining or restoring floristically diverse and structurally complex shade canopies within cocoa agroforests, and retaining other types of on-farm tree cover to enhance landscape connectivity and habitat availability.     

Tracking the effects of one century of habitat loss and fragmentation on calcareous grassland butterfly communities

Habitat loss and fragmentation are known to reduce patch sizes and increase their isolation, consequently leading to modifications in species richness and community structure. Calcareous grasslands are among the richest ecosystems in Europe for insect species. About 10% (1,150 ha) of the total area of a calcareous ridge region (Calestienne, Belgium) and its butterfly community was analysed over a timeframe of about 100 years. Since 1905 to present day (2005), the Calestienne region has undergone both calcareous grassland loss and fragmentation: not only did calcareous grassland size decrease and isolation increase, but also, the number of calcareous grassland patches within the landscape increased until 1965, and subsequently decreased, clearly reflecting the effects of fragmentation. These processes have had a profound effect on the butterfly community: extinction and rarefaction affected significantly more often specialist species, which means that generalist species are more and more overrepresented. This ecological drift, i.e. the replacement of specialists by generalists in species assemblages is likely to be a general effect of habitat loss and fragmentation on natural communities.     

The effects of fire on communities,guilds and species of breeding birds in burnt and control pinewoods in central Italy

Breeding bird communities in burnt and unburnt residual pinewoods were studied over 3 years by line-transect method, following a catastrophic fire event in Castelfusano (Rome, Central Italy; July 2000). We applied bootstrap procedures to evaluate whether the observed data were true or just produced by chance, and then examined the emerging patterns at three levels: community, guild and species levels. At the community level, fire acted on breeding bird communities by altering especially the total abundance patterns: the species abundance decreased in the burnt pinewood compared to the residual one, but other parameters were not significantly affected by fire. As a consequence of fire, the destruction and structural simplification of the canopy and shrubby component, as well as the increase of edge habitat and patchiness at landscape scale, induced a turnover in species between pinewoods. Species turnover was higher at the burnt than at the residual pinewoods, during all the 3 years of study. At the guild level, the forest species decreased strongly in terms of richness and abundance in the burnt pinewoods, contrary to the edge and open habitat species which increased in terms of richness, abundance and evenness. Edge species showed the highest turnover in burnt pinewood during the whole period of study. At species level, after an a priori subdivision (based on bibliographic search) of the various species in two ecological guilds (forest versus edge species), it was found that an a posteriori statistical analysis confirmed the expected trend, i.e. that the species which decreased significantly in burnt pinewood were essentially the forest species, whereas the species which increased were essentially the edge/open habitat ones. Overall, in order to investigate the effects of fire catastrophes on birds, the guild approach seems more exhaustive than the taxonomic community approach, where intrinsic confounding trends are present.     

Distribution of cephalopods in the upper epipelagic northwestern Bering Sea in autumn

In the northwestern Bering Sea in autumn, the epipelagic cephalopod community was represented by the boreal fauna, and was found to be composed of three families and nine species of the order Teuthida: Gonatidae (Berryteuthis magister, Boreoteuthis borealis, Gonatopsis japonicus, Gonatus madokai, Gonatus kamtschaticus, Gonatus onyx, and Gonatus pyros), Chiroteuthidae (Chiroteuthis calyx) and Onychoteuthidae (Onychoteuthis borealijaponica). Two pelagic gonatid species (B. borealis and G. kamtschaticus) dominated the cephalopod community in the upper 50 m. The distribution patterns of B. borealis and G. onyx were associated with diel vertical migrations of these squid. The distribution of two distinct size groups of G. kamtschaticus suggested ontogenetic migration of larger squid to deeper layers, and adds to previous data suggesting that this species may be a heterogeneous assemblage. Demersal B. magister rarely occurred in the surface waters. The occurrence of maturing O. borealijaponica in the southern marine area indicated that these were occasional seasonal migrants from the ocean. The occurrence of juvenile C. calyx suggested that these squid may conduct vertical forage migrations from deep waters to the surface layers.     

主要医院感染病原菌与社区感染株耐药性比较

目的比较主要医院感染(HAI)病原菌与社区感染(CAI)株的耐药性,指导合理使用抗菌药物。方法收集永康市第一人民医院2003年1月至2006年6月所有标本中分离的主要HAI菌及其CAI株,分别统计其药物敏感试验。采用美国Dade Behring Microscan Walkaway 40全自动细菌鉴定及药敏测试仪及其配套药敏鉴定板测定MIC值。全国医院感染监测网软件和χ2统计分析。结果主要HAI菌为前4种革兰阳性(G )菌依次是金黄色葡萄球菌、表皮葡萄球菌、屎肠球菌、溶血葡萄球菌,前5种革兰阴性(G-)菌依次是大肠埃希菌、肺炎克雷伯菌、鲍曼不动杆菌、铜绿假单胞菌、阴沟肠杆菌。HAI株耐药率普遍高于CAI株,不同的细菌耐药率各具特点。不论HAI株还是CAI株,G 菌对万古霉素的耐药率最低,G-菌对亚胺培南的耐药率均较低,且两者耐药率差异均无显著性。金黄色葡萄球菌、大肠埃希菌、肺炎克雷伯菌、鲍曼不动杆菌4种HAI株对大多数抗菌药物的耐药率明显高于CAI株,其余5种细菌HAI株仅对少数抗菌药物的耐药率高于CAI株。结论HAI菌株耐药性比CAI菌株强,临床应区分感染性质合理使用抗菌药物,有针对性控制感染,从而减少抗菌药物的滥用和细菌耐药性的产生。