Identification and Characterization of Sulfur-Oxidizing Bacteria in an Artificial Wetland That Treats Wastewater From a Tannery

Wastewater from tanneries contains high concentrations of organic matter, chromium, nitrogen, and sulfur compounds. In this study, an artificial wetland is is used as the tertiary treatment in a tannery in León Gto., México. It consists of three subplots with an area of about 450 m². Two subplots were planted with Typha sp. and the third with Scirpus americanus. Geochemical analyses along the flowpath of the wetland show that contaminants were effectively attenuated. The most probable number technique was used to determine rhizospheric microbial populations involved in the sulfur cycle and suggested that there were 10⁴–10⁶ cells g^?1 sediment of sulfate-reducing bacteria and 10²–10⁵ of sulfur-oxidizing bacteria (SOB). Representatives of SOB were isolated on media containing thiosulfate. Phylogenetic analysis of 16S rRNA of SOB isolates shows that they belong to the genera Acinetobacter, Alcaligenes, Ochrobactrum, and Pseudomonas. Most of the isolates are organotrophic and can oxidize reduced sulfur compounds such as elemental sulfur or thiosulfate, accumulating thiosulfate, or tetrathionate during growth. All isolates can use reduced-sulfur compounds as their sole sulfur source and some can use nitrate as an electron acceptor to grow anaerobically. Our results illustrate the relevance of SOB in the functioning of the wetland constructed for tannery wastewater remediation.     

DISTRIBUTION OF BLUEGREEN ALGAE IN A MISSISSIPPI GULF COAST SALT MARSH1

Edaphic bluegreen algal communities were sampled from five menotypic angiosperm zones in Grvelline Bay Marsh near Ocean Spring. Mississippi. Samples and environmental data were taken on a quarterly basis from October 1976 to June 1977 beneath the following marsh angiosperms: Distichlis spicata (L.) Green, Scirpus olneyi gray, SPartina patens (Aiton) Muhl., Sp. alterniflora Loisel., and Juncus roemerianus Scheele. Communities in all five zones were dominated by Schizothrix calcicola (Ag.) Gom. (sensu Drauet) throughout the study, while the subdominant bluegreens varied according to season. The number of individuals in all zones was greatest in the summer and lowest in the winter. An examination of the structure of the five edaphic communities indicated a single, nearly homogeneous community exists over the entire surface of the marsh shaded by a angiosperm canopy. Light intensity appears to be the major factor affecting the distribution of bluegreen algae in this salt marsh.     

The faunal role in the degradation of the common intertidal salt marsh plant <Emphasis Type="Italic">Scirpus maritimus</Emphasis>

The aim of this work was to evaluate the role of different environmental conditions (oxic and anoxic), and the presence of macrofauna and/or meiofauna during the different steps of Scirpus maritimus L. decomposition/mineralization under controlled laboratory conditions. The results showed no significant differences between the anaerobic and the aerobic degradation of plant material, under the presence of bacteria or meiofauna. Nevertheless, under anoxic conditions sediment mineralization was enhanced, with an increase concentration of phosphorus and ammonium in the water phase. Concerning the presence of fauna, results show that, although bacterial activity was responsible for 70% of the S. maritimus leaves degradation, the presence of macrofauna together with meiofauna enhanced the leaves mineralization up to 90%. Moreover, the presence of macrofauna together with meiofauna significantly affected the decomposition of phosphorus and of nitrogen, as well as the leaves lesser labile structural parts, by increasing the mineralization of plant carbon, and raised the nutrient turnover within the system.The present study reinforces the functional link between fauna levels on the nutrient dynamics in salt marshes ecosystems, namely at the vegetation detritus/water column interface. Handling editor: S. M. Thomaz     

Host plant volatiles responsible for the invasion of Stenotus rubrovittatus (Heteroptera: Miridae) into paddy fields

We investigated the attractiveness of synthetic volatile blends or individual volatiles of flowering rice panicles or flowering Scirpus juncoides spikelets to the sorghum plant bug Stenotus rubrovittatus (Matsumura). None of the individual chemicals tested attracted either sex of the bug. Synthetic volatile blends of flowering rice panicles composed of geranyl acetone, β‐caryophyllene, n‐decanal, methyl salicylate, β‐elemene and n‐tridecene attracted females. The synthetic blend of volatiles was just as attractive as natural flowering rice panicles to females. Other synthetic blends did not attract the bug. We sampled headspace volatiles from flowering S. juncoides spikelets with solid‐phase microextraction and analysed them using gas chromatography–mass spectrometry. The main volatile emitted from S. juncoides was β‐caryophyllene, one of the major volatile components of flowering rice panicles. β‐Elemene was a common volatile found in flowering rice panicles and flowering S. juncoides spikelets. Therefore, we investigated the attractiveness of synthetic blends of flowering rice panicles and S. juncoides spikelets composed of β‐caryophyllene and β‐elemene. The synthetic blend of flowering S. juncoides spikelets significantly attracted males but not females. The synthetic blend of flowering rice panicles composed of β‐caryophyllene and β‐elemene did not attract either sex. These results suggest that β‐caryophyllene and β‐elemene are common active compounds responsible for attractiveness of flowering rice panicles and S. juncoides spikelets although some of the other volatile components act synergistically with these two compounds in natural plant odours.     

基于胁迫梯度假说和互惠理论的海三棱藨草种群恢复技术

滨海湿地生态修复已成为阻止海岸带生态系统退化、保护生物多样性以及提供生态服务的关键措施。以长江口原生盐沼植物海三棱藨草(Scirpus mariqueter)为研究对象,选取崇明东滩新生滩涂湿地为研究区域,通过沿潮滩高程梯度的海三棱藨草植株斑块的移植实验,探究胁迫梯度假说和互惠理论(即种内的正相互作用)对长江口海三棱藨草种群恢复的指导意义。研究结果显示:(1)在一定的胁迫梯度范围内(潮滩高程2.0 m以上),增大种植斑块可以促进海三棱藨草的种内正相互作用,显著提高种植斑块的存活率和植株密度(P0.05);(2)潮滩水文动力沉积条件与潮滩高程梯度密切相关(P0.05),水文动力沉积作用对海三棱藨草定居和生长的胁迫随高程梯度下降而增强。潮滩高程2.0 m以下处强烈的水文动力条件干扰限制了生物-物理因素的正反馈作用。滨海湿地盐沼植被修复工作的成功率可以通过改进种植方式,增强种内的正相互作用得到极大的提高。研究可为开展大规模滨海湿地盐沼植被修复工程和提高生态修复效率提供科学依据和技术支持。     

崇明东滩南部盐沼植被空间分布及影响因素分析

崇明东滩南部滩面高程、土壤盐度在空间上呈明显的梯度变化规律。高程整体西高东低、北高南低, 盐度东北高、西南低, 两者共同限制着盐沼植物在空间上的分布。该文围绕崇明东滩南部主要植被类群及其空间分布, 探讨了土壤盐度、潮滩高程两大环境因子与植物种群分布的对应关系。基于2013年夏、秋季植被空间网格采样和空间插值, 分析了东滩南部植物的空间分布现状, 发现不同植物类群在高程和土壤盐度上存在极显著的差异(p < 0.01)。高程差异: 莎草科类群主要分布于高程区间2.93-4.07 m的低潮滩, 禾本科主要集中分布在高程3.13-4.31 m的中、高潮滩; 盐度差异: 海三棱藨草(Scirpus mariqueter)和互花米草(Spartina alterniflora)优势种群植被覆盖区表层30 cm的平均土壤盐度为(3.2 ± 0.6) g·kg^-1, 显著高于其他类群植物分布区的平均土壤盐度(2.0 ± 0.3) g·kg^-1 (p < 0.01)。崇明东滩湿地生态系统的关键种兼先锋种——海三棱藨草, 分布高程介于2.53-3.97 m, 而互花米草能适应海三棱藨草80%的高程区间, 两者在高程上存在竞争关系。统计数据显示, 研究区域中近90%的海三棱藨草分布在研究区东北部, 土壤盐度范围为1.6-4.5 g·kg^-1, 海三棱藨草、互花米草能较好地适应该空间内的盐度胁迫, 两种植物在此交替出现。但是在高程和土壤盐度的综合作用下, 互花米草的生长状况更好, 因此该区的海三棱藨草很可能会被互花米草逐步取代。对各类群植被分布和优势面积的研究发现, 海三棱藨草总分布面积为294 hm², 优势群落面积120 hm², 海三棱藨草仅占莎草科植物总优势面积的15.7%, 占研究区总面积的6.9%, 在6种主要植物(芦苇(Phragmites australis)、白茅(Imperata cylindrica)、互花米草、糙叶薹草(Carex scabrifolia)、藨草(Scirpus triqueter)、海三棱藨草)中比重最小, 这给保护区内海三棱藨草种群的恢复和保护带来极大的挑战。     

海三棱蔍草种群的物候与分布格局研究

海三棱藨草群落是生长在海岸带滩涂原生裸地上的原生植被,在上海地区分布面积达20多万亩。本项工作研究了上海市南汇县东海农场海堤外侧滩涂上海三棱藨草种群的物候和分布格局。根据滩涂高程以及海三棱藨草种群生长状况,可以划分成三个地带,即地带A,海三棱藨草与芦苇群落交错区;地带B,海三棱藨草种群生长最适的中潮位地带;地带C,海三棱藨草种群定居地带。由于三个地带内,生境条件不同,海三棱藨草种群的物候有明显差异。从地带A至C,海三棱藨草种群的分布格局依次为随机分布、均匀分布和随机分布或群聚分布。其空间分布格局在随时间变化的同时也在空间上改变其位置。     

The use of random amplified polymorphic DNA (RAPD) for hybrid detection in Scirpus from the river Schelde (Belgium)

Along the unique freshwater tidal zone of the river Schelde (Belgium), plants of Scirpus species occur primarily in small and fragmented populations. The majority of these are native Scirpus lacustris, S. pungens, S. triqueter, S. tabernaemontani and intermediate morphological forms. The distribution area of S. triqueter is even restricted to this tidal habitat. However, several cultivated S. tabernaemontani strains have recently been introduced. The latter species is often used to stabilize riverbanks. To determine the existing genetic diversity among these species, stems from plants from 44 different locations were subjected to random amplified polymorphic DNA (RAPD) analysis, using 22 decanucleotide primers. Data analysis of the amplified DNA fragments enabled us to unambiguously differentiate among these Scirpus taxa. Hybridization between S. triqueter and S. tabernaemontani was documented, and the studied hybrids were always genetically more similar to S. triqueter than to S. tabernaemontani . Among the introduced clones, at least two different origins could be distinguished. Several of the introduced S. tabernaemontani clones were clearly different from individuals of the same species that were native to this region. As there were different hybrid genotypes owing to different hybrid events or to introgression, this complex should be safeguarded from genetic pollution. New S. tabernaemontani genotypes with markers not previously observed in that hybrid complex of the unique tidal freshwater habitat should be avoided in replantation projects.     

Clonal performance of Scirpus yagara in multiple levels of substrate heterogeneity and submergence

荆三棱在多等级基质异质性与水淹处理下的克隆表现环境异质性可以影响克隆水生植物的表现。鲜有研究者关注两个层次的环境异质性并将其融入 对克隆植物生态学的研究中。本研究的目的是: (1)检验不同基质异质性与水淹处理是否对植物表现产生相 似效应,(2)探索克隆植物的觅食行为。本研究将荆三棱(Scirpus yagara)置于不同基质异质性与水淹处理之中。基质处理包括1个均质性基质处理(湖泥与沙等体积混合)与3个异质性基质处理(湖泥斑块与沙斑块交错构建的两斑块、四斑块与八斑块基质)。水淹处理包括：0、10和30 cm。本实验测量了克隆分株数、克隆代数、叶数、球茎数、克隆分株高度、茎长、根状茎长、克隆半径、间隔子长、间隔子厚度、总生物量、球茎生物量与单个球茎生物量等性状数据。研究结果表明,水位上升导致克隆分株数、克隆代数、叶数和球茎数显著减少,同时基质异质性造成间隔子长度与间隔子厚度的显著变化。水位与基质异质性两因子对克隆分株数、叶数和间隔子长度产生了显著的交互效应。在两斑块基质与四斑块基质中,荆三棱对湖泥斑块表现出显著的觅食行为,更多的构件被放置于湖泥斑块中。尤其在两斑块基质中,所有的构件被放置于湖泥斑块中。在八斑块基质中,荆三棱表现出双向觅食,这导致构件在不同斑块中的均匀放置。研究结果表明,荆三棱的觅食行为与斑块大小具有相关性。     

DIATOM COMMUNITY STRUCTURE: TAXONOMIC AND STATISTICAL ANALYSES OF A MISSISSIPPI SALT MARSH1

Edaphic diatoms were collected on a seasonal basis from beneath five monospecific stands of spermatophytes on Graveline Bay Marsh (Mississippi) from 14 October 1976 through 21 June 1977. Of the 119 diatom taxa encountered. only seven were restricted to a single edaphic habitat, and five of these accounted for 17.2%of the individuals comprising the community associated with Distichlis spicata (L.) Greene. The single most abundant diatom was Navicula tripunctata (Müll.) Bory, which accounted for 21.5%of all individuals counted during the study. Based on a 2-way ANOVA of species diversity (H’) and the number of taxa in a sample, edaphic diatom community diversity was highest beneath D. spicata and Spartina patens (Ait.) Muhl., lowest beneath Sp. alterniflora Loisel. and Juncus roemerianus Scheele, and somewhat intermediate for the Scirpus olneyi Gray habitat. Structural differences between selected community pairs were quantified using a similarity index (SIMI) and the values generated were exceedingly variable. A multiple regression analysis revealed that structural differences amongst edaphic diatom communities were related to differences in elevation, far red light energy, ammonia nitrogen, soil moisture, and tentatively, height of the spermatophyte canopy.