Spring Wetland Research Articles

Palaeoenvironmental support for long-term aquatic refugia in Australia’s Great Artesian Basin discharge springs

ABSTRACT In dryland areas, wetland refugia that provide permanent wetted habitats are important for the persistence of obligate aquatic species. Situated in Australia’s arid and semiarid regions, Great Artesian Basin discharge springs contain high biodiversity and many endemic species and are believed to provide the only permanent wetted habitat. However, conflicting information indicates that hydroperiods in these springs can be variable. The aim of this study was to use palaeoenvironmental information to assess millennial-scale variability in one large spring wetland and provide an initial assessment on the long-term presence of wetted habitat. A sediment core was collected from Big Spring at Byarri (Edgbaston Station) in central Queensland, Australia, and the sedimentary layers were analysed using radiocarbon dating, geochemistry, and palynology. An age model developed on the radiocarbon dates indicated that changes in the rate of sediment deposition are likely associated with the last glacial maximum but with no disruption in the sediment accumulation, or therefore wetland development. Variable wetland and landscape conditions over ∼43 000 years are supported by the geochemistry and palynological sedimentary records, including a change from a lacustrine to palustrine wetland and more recent changes, likely due to an anthropogenic presence in the landscape. The lack of a hiatus in available wetted habitat throughout the period of sediment development corroborates that Great Artesian Basin discharge springs represent a permanent wetted refugia in Australia’s drylands.

Assessing surface-groundwater interactions for sustaining spring wetlands of the Great Artesian Basin, Australia

The Great Artesian Basin (GAB) is one of the world’s largest actively recharging aquifers. Groundwater discharges from the GAB sustain numerous spring wetlands, which have great ecological, scientific, and socio-economic significance. However, groundwater extraction and variation over time have had an impact on the quantity and area of spring wetlands with a 38% decline in extent since 1900. A major barrier to understanding variability in surface–groundwater interactions in spring wetlands of the GAB is the lack of observational data across critical spatial and temporal scales. Satellite observations have the ability to overcome this barrier and allow the evaluation of spring wetland responses to groundwater storage (GWS) variation. We investigated how GWS, and its associated drivers such as evapotranspiration (ET), soil moisture storage (SMS), and rainfall, in the GAB, influence the extent of surface water at five spring supergroups (Eulo, Barcaldine, Flinders, Springsure, and Springvale). We used satellite observations (2002–2017) to assess ET, SMS, rainfall, the normalized difference vegetation index (NDVI) and the modified normalized difference water index (mNDWI) for observing surface–groundwater interactions. NDVI responded positively to the GWS variation over the GAB and varies from sub-basin to sub- basin, with higher correlations in the Carpentaria sub-basin and some parts of Central and Western Eromanga. GWS variations was correlated with ET, SMS, rainfall, NDVI, mNDWI and surface water level (SWL). After a strong La Niña began in 2010, we uncovered relatively higher linear relationships between different components (ET, SMS, rainfall, NDVI, mNDWI, and SWL) and GWS variation (R2 > 0.50) than before the La Niña (R2 < 0.50), with the Flinders spring supergroup being the exception. NDVI and SMS are found to be the most significant predictor variables among ET, rainfall, SWL, and mNDWI components to influence GWS. This study provides improved understanding of surface-ground water interaction in spring wetlands and the influence of different hydrological components on variation in spring wetland extent in the GAB region.

Nutritional value of Juncus acutus in the wetland of Kızılırmak delta

Juncus acutus, a wetland plant, helps improve habitats for both terrestrial and aquatic creatures and spawning grounds for fish. A variety of wetland birds use between the trunks of the juncus as a shelter. They also help prevent soil erosion due to their extensive root systems. On the other hand, it can be said that it has a negative effect on the feeding of grassland animals due to the high density in wetlands.Plant materials from Juncus acutus, which is intensively located in the Kızılırmak Delta, were taken in two different periods, in April and July. The changes in the nutrient content of the plant during the spring and summer periods were investigated and the quality features were divulged. According to the research results; It was observed that the water buffaloes in the Kızılırmak Delta were not fed with Juncus acutus for feeding purposes, the forage quality was low, but the livestock grazed a little on Juncus acutus when they first went to the wetland in early spring.

Phytoplankton Community Structure Dynamics in Relation to Water Environmental Factors in Zhalong Wetland.

Phytoplankton, as the primary producer of the wetland water ecosystem's food chain, are very sensitive to environmental changes. In order to explore the significance of phytoplankton in protecting ecosystem integrity, the wetland ecosystem in Zhalong wetland, one of the most important international wetlands, was selected as the research area. For the study, 81 sampling sites were set up in the whole wetland, and phytoplankton samples and water quality environmental factors were measured in spring, summer, and autumn of 2019. The phytoplankton community structure and water environmental factors were evaluated by canonical correspondence analysis (CCA). The main research findings are as follows: a total of 292 species and variants of phytoplankton belonging to 8 phyla and 110 genera were identified within Zhalong wetland in spring, summer, and autumn 2019. The total phytoplankton abundance and biomass in summer were higher than in spring and autumn, and Cyclotella meneghiniana was the most dominant species in three seasons and three areas. The results of random forest are generally consistent with the results of CCA in spring, when the main environmental factors affecting phytoplankton were NTU and WT; the result in summer and autumn agreed with those of CCA, which awaits further study. In addition, the phytoplankton is mainly affected by WT, depth, and DO in the lake area, TP, DO, and NTU in the river area, and WT in the wetland area.

不同季节艾比湖湿地盐角草根际nirS-型与nirK-型反硝化细菌群落组成分析

PDF HTML阅读 XML下载 导出引用 引用提醒 不同季节艾比湖湿地盐角草根际nirS-型与nirK-型反硝化细菌群落组成分析 DOI: 10.5846/stxb202011112920 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目(31160026);国家自然科学基金项目(31560040) Community composition of nirS-type and nirK-type denitrifying bacteria in rhizosphere of Salicornia europaea in the Ebinur Lake Wetland during different seasons Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:旨在了解艾比湖湿地盐生植物盐角草根际与非根际中不同类型反硝化细菌的分布及其随季节变化情况,为温带干旱地区荒漠盐化生态系统的代表-艾比湖湿地在生态植被恢复过程中,由微生物推动的土壤氮素循环过程提供数据支撑。采集了艾比湖湿地夏、秋、春三个季节的盐角草根际和非根际土壤样本,通过高通量测序技术,比较分析了nirS-型和nirK-型两种类型的反硝化细菌的多样性和群落结构特点;利用RDA (redundancy analysis)探究了土壤理化因素对反硝化细菌多样性及群落结构的影响。艾比湖湿地盐角草根际与非根际中,nirS-型和nirK-型反硝化细菌多样性最高的为秋季根际土壤样本;各土壤样本中的反硝化细菌多样性均呈现根际>非根际。盐角草各土壤样本中的nirS-型反硝化细菌在门分类水平上隶属于变形菌门(Proteobacteria),厚壁菌门(Firmicutes)和放线菌门(Actinobacteria),而nirK-型反硝化细菌在门水平上分类仅包括了Proteobacteria和Firmicutes。Proteobacteria在各土壤样本中的占比均较高;其中Gamma-Proteobacteria的盐单胞菌属(Halomonas)和假单胞菌属(Pseudomonas)是各土壤样本所共有的nirS-型反硝化菌的优势菌属,但它们在每个土壤样本中的相对丰度各有差异。Alpha-Proteobacteria的根瘤菌属(Rhizobium)是盐角草各土壤样本中较为广泛存在的nirK-型反硝化细菌。艾比湖湿地盐角草各土壤样本中的反硝化细菌群落结构存在着一定的差异。RDA结果显示含水量、有机质、全氮和铵态氮等对各土壤样本中的nirS-型反硝化细菌的多样性影响较大,含水量、有机质、全氮、碱解氮等是nirK-型反硝化细菌多样性的主要影响因素。土壤电导率、全磷、全钾、全氮和碱解氮协同影响nirS-型反硝化细菌的群落结构,有机质、速效钾、速效磷、pH和硝态氮是nirK-型反硝化细菌群落结构组成的主要影响因素。艾比湖湿地反硝化细菌呈现季节性变化,nirS-型和nirK-型反硝化细菌以不同的主要菌属,共同推进湿地反硝化作用。而对于湿地生态系统的保护,则需要进行长期而广泛的土壤状态评估和土壤反硝化微生物菌群的动态监测。 Abstract:The purpose of this study is to understand the distribution and seasonal variation of different types of denitrifying bacteria in the rhizosphere and non-rhizosphere of the saline plant Salicornia europaea in the Ebinur Lake Wetland, so as to provide data support for the process of soil nitrogen cycling driven by microorganisms in the process of vegetation restoration in the Ebinur Lake Wetland, a representative of desert salinization ecosystem in temperate arid area. In this study, the rhizosphere and non-rhizosphere soil samples of Salicornia europaea were collected from the Ebinur Lake Wetland in summer, autumn and spring. The diversity and community structure characteristics of nirS-type and nirK-type denitrifying bacteria were compared and analyzed by high-throughput sequencing. RDA(redundancy analysis) was used to explore the effects of soil physical and chemical factors on the diversity and community structure of denitrifying bacteria. Among the soil samples of Salicornia europaea in the Ebinur Lake Wetland, the highest genotype diversity of denitrifying bacteria in nirS and nirK was the autumn rhizosphere, and the diversity of denitrifying bacteria in each soil sample showed rhizosphere > non-rhizosphere. The nirS-type denitrifiers in rhizosphere and non-rhizosphere soil samples of Salicornia europaea belonged to Proteobacteria, Firmicutes and Actinobacteria, while the classification of nirK-type denitrifying bacteria only includes Proteobacteria, Firmicutes. Proteobacteria accounted for a higher proportion in each soil sample. Halomonas and Pseudomonas of gamma-Proteobacteria were the dominant genera of nirS-type denitrifiers shared by all soil samples, but the relative abundance in each soil sample was different. Rhizobium of alpha-Proteobacteria was a kind of nirK-type denitrifiers widely existing in the soil samples of Salicornia europaea. There were certain differences in the community structure of denitrifying bacteria among the soil samples of Salicornia europaea in the Ebinur Lake Wetland. The results of RDA showed that water content, organic matter, total nitrogen, and ammonium nitrogen had a great influence on the diversity of nirS-type denitrifying bacteria in soil samples, while water content, organic matter, total nitrogen and alkali hydrolyzed nitrogen were the main factors affecting the diversity of nirK-type denitrifying bacteria. Soil electrical conductivity, total phosphorus, total potassium, total nitrogen and alkali-hydrolyzable nitrogen synergistically affected the community structure of nirS-type denitrifying bacteria, while organic matter, available potassium, available phosphorus, pH and nitrate nitrogen were the main influencing factors of the community structure of nirK-type denitrifying bacteria.With the change of seasons, the diversity and community structure of nirS-type and nirK-type denitrifying bacteria in rhizosphere and non-rhizosphere of Salicornia europaea were changed. The denitrifying bacteria of the two genotypes, with different main genus, jointly promoted the denitrification of wetland. For the protection of wetland ecosystems, long-term and extensive soil state assessment and dynamic monitoring of soil denitrifying microbial flora are required. 参考文献 相似文献 引证文献

Hot, wet and rare: modelling the occupancy dynamics of the narrowly distributed Dixie Valley toad

Context Small population sizes and no possibility of metapopulation rescue put narrowly distributed endemic species under elevated risk of extinction from anthropogenic change. Desert spring wetlands host many endemic species that require aquatic habitat and are isolated by the surrounding xeric terrestrial habitat. Aims We sought to model the occupancy dynamics of the Dixie Valley toad (Anaxyrus williamsi), a recently described species endemic to a small desert spring wetland complex in Nevada, USA. Methods We divided the species’ range into 20 m × 20 m cells and surveyed for Dixie Valley toads at 60 cells during six primary periods from 2018 to 2021, following an occupancy study design. We analysed our survey data by using a multi-state dynamic occupancy model to estimate the probability of adult occurrence, colonisation, site survival, and larval occurrence and the relationship of each to environmental covariates. Key results The detection probabilities of adult and larval toads were affected by survey length and time of day. Adult Dixie Valley toads were widely distributed, with detections in 75% of surveyed cells at some point during the 3-year study, whereas larvae were observed only in 20% of cells during the study. Dixie Valley toad larvae were more likely to occur in cells far from spring heads with a high coverage of surface water, low emergent vegetation cover, and water temperatures between 20°C and 28°C. Adult toads were more likely to occur in cells with a greater coverage of surface water and water depth &gt;10 cm. Cells with more emergent vegetation cover and surface water were more likely to be colonised by adult toads. Conclusions Our results showed that Dixie Valley toads are highly dependent on surface water in both spring and autumn. Adults and larvae require different environmental conditions, with larvae occurring farther from spring heads and in fewer cells. Implications Disturbances to the hydrology of the desert spring wetlands in Dixie Valley could threaten the persistence of this narrowly distributed toad.

Plant species associations with alkaline environments associated with artesian spring wetlands

To describe the physico-chemical environment of artesian spring wetlands and surrounding scalds; to identify the association of plant species with these factors; and to assess the tolerance of a wetland species to an alkalinity gradient. Surface soils were sampled for chemical attributes and water depth in spring wetlands and associated scalds. Plant species were recorded in quadrats and their distribution in relation to physico-chemical attributes assessed. Comprehensive analyses of salt composition and mineralogy were conducted at scald sites. An experiment was conducted to assess the tolerance of theartesian spring wetland species Eriocaulon carsonii. The wetlands of artesian springs have circumneutral pH with low salinity. The environment around the wetlands has extremely high pH, dominated by sodium bicarbonate minerals, but have variable salinity. The plant species, many of which are endemic, have clear associations with individual habitats including the permanent pools, the fringing scalds and the terrestrial scalds without sub-surface groundwater. Eriocaulon carsonii is tolerant of neutral and alkaline waters but not highly acidic water. The permanent pools supported by artesian springs have low salinity and neutral pH. The scalded areas around springs are extremely alkaline and can have high salinity values. The chemistry of the springs described here are of the Na-carbonate type and typical of the Great Artesian Basin. The evolution of endemic wetland species may have resulted from the permanence of the pools rather than distinctive chemistry. By contrast the species of the scalds are specialised to an extreme chemical environment.

Helocrenic springs as sources of nutrient rich fine particulate organic matter in small foothill watershed.

Despite the large number of studies devoted to organic matter dynamics in fluvial ecosystems, the detrital pathways of spring headwater systems remain neglected. In particular, spring wetlands (helocrenes or seepages) might have considerable influence on downstream headwater stream systems due to the alteration of the nutrient and organic matter content of the water. In this study, we examined fine particulate organic matter (FPOM) drained from helocrenic springs to describe its downstream transport. We studied the quantity, nutrient content and physical components of FPOM gathered from the outflowing water using continuous sediment samplers. The nutrient content of local leaf litter deposits, residence time of water in the springs and concentration of dissolved nutrients in spring sources and outflows were also measured to characterize the inputs and outputs of the studied system. The results show that headwater spring wetlands represent a significant source of high-quality FPOM for downstream river networks. The estimated concentration of FPOM (<1000 μm) in the 11 investigated springs was 3.1 ± 2.5 mg.L-1. In general, the FPOM was relatively nutrient-rich (N = 19.25 ± 4.73 mg.L-1; P = 2.04 ± 0.78 mg.L-1; Ca = 9.65 ± 2.63 mg.L-1; S = 4.07 ± 1.16 mg.L-1; C = 278.68 ± 80.81 mg.L-1). The C:N and C:P ratios in the local leaf litter deposits were higher than in FPOM (41.04 ± 14.32 vs. 14.70 ± 2.46 and 591.7 ± 168.83 vs. 154,77 ± 64,73, respectively), indicating that suspended FPOM is more nutritious for consumers. A significant trend in terms of size fractions of FPOM was identified: with decreasing C:N and C:P ratios particle size decreases as well. Overall, the data suggest that the relatively small helocrenes can serve as an organic matter transformers, receiving primary particles and dissolved organic matter, transforming them and favouring their transport downstream. These biotopes may represent a substantial discontinuity of the river continuum at its origin, important for nutrient dynamics and food supply of associated biotic communities.

Evaluating the Effectiveness of Fencing to Manage Feral Animal Impacts on High Conservation Value Artesian Spring Wetland Communities of Currawinya National Park

Evaluating the Effectiveness of Fencing to Manage Feral Animal Impacts on High Conservation Value Artesian Spring Wetland Communities of Currawinya National Park

Springwater provenance and flowpath evaluation in Blue Lake, Bonneville basin, Utah

Water in Utah and Nevada is important for agriculture, municipal use, solute transport, and ecosystem preservation. Large spring wetland systems occur on the playa margin of the Bonneville basin, including Blue Lake, 15 km south of the Bonneville Salt Flats on the Utah-Nevada state border. Large spring systems have historically been studied as water budgets don't apparently balance from direct mountain front recharge (Nelson and Mayo, 2014; Gardner and Heilweil, 2014; and others). Blue Lake is no exception; prior studies here have suggested discharge rates 0.04 - 0.05 km3/yr (Louderback and Rhode, 2009), greater than expected for modelled recharge in the surrounding mountain range (0.03 km3/yr). Three hypothesized recharge mechanisms for Blue Lake are tested: mountain-front recharge, interbasinal groundwater flow, and infiltration from historic Lake Bonneville. Remote sensing suggests that a conservative estimate of Blue Lake discharge constitutes 50-64% of modelled mountain-front recharge (Flint et al., 2011). Major ions, δ18O, δ2H, dissolved gases (14C, 3He, 4He, Ne, Ar, Kr, Xe) and trace elements (Sr and 87Sr/86Sr isotopes) comprehensively constrain recharge conditions, water-rock interactions, flowpaths, and groundwater provenance of this large spring system. 14C signatures suggest that Blue Lake discharge has a transit time between 5,600 and 12,200 years, older than that of Fish Springs. Noble gas concentrations in Blue Lake water suggest an elevated recharge temperature greater than 19°C and low salinity, indicating a deep water table and high geothermal gradient in the recharge area. 87Sr/86Sr ratios of playa-margin springs are elevated from that of mid-playa groundwaters, springwaters from the adjacent mountain range, and alluvial fill groundwater from the valley directly south of Blue Lake. Playa-margin spring Sr isotope values (0.713-0.714) are most similar to direct runoff from the Deep Creek Range granodiorite outcrop (>0.713). Interbasinal groundwater flow in combination with mountain-front recharge is best supported by chemical data rather than mountain-front recharge alone or the slow discharge of regional aquifers recharged by lacustrine infiltration from Lake Bonneville.

Karstic spring wetlands of the Persepolis Basin, southwest Iran: unique sediment archives of Holocene environmental change and human impacts

Palustrine carbonates are frequently found with active and dried karstic springs in the foothills of the mountains bordering the Persepolis Basin, southwest Iran. A combination of geological conditions favours their formation, including (i) the presence of karstic limestone aquifers in the limbs of anticlines cut through by fault systems; (ii) very gentle slopes from the spring resurgence point towards the centre of the alluvial plain, creating a flat waterlogged area; and (iii) a semiarid climate with marked precipitation seasonality or significant fluctuations in water discharge and wetland water table. We suggest the term “anastomosing wetlands” or “anastomosing palustrine environments” to denote the studied karstic spring–fed carbonate wetlands, because of similarities with anastomosing river systems in aerial view. The common presence of extended anastomosing wetland carbonates in the Persepolis Basin and adjacent basins in the central and southern Zagros suggests that they can play an important role in the geological records of collision-related basin-and-range settings dominated by karstic limestones. Karstic spring wetlands are a main source of fresh water hosting a rich biodiversity, which attracts human communities, whose impact is visible in the archaeological material imbedded in the wetland stratigraphy. Fresh water availability, through these spring wetlands, partly explains why the semiarid Persepolis region was selected by successive civilizations, from Elamites to Persians until early Islamic entities, to establish regional centres throughout the period from the third millennium B.C. to the first millennium A.D. Only a few of these ecosystems have survived the intensive human activities of recent decades.

Managed flooding can augment the benefits of natural flooding for native wetland vegetation

Managed flooding is increasingly being used to maintain and restore the ecological values of floodplain wetlands. However, evidence for its effectiveness is sometimes inconsistent and water available for environmental purposes often limited. We experimentally inundated a floodplain wetland (or “billabong”) in late spring by pumping water from its adjacent creek, aiming to promote the native wetland flora and suppress terrestrial exotics. Vegetation was surveyed before (spring) and after (late summer) the managed flood in the experimental billabong and in three control billabongs. Floodplain water levels were continuously monitored. Wet conditions caused two of the control billabongs to also flood, but to a lesser extent than the experimental billabong. We therefore assessed vegetation changes relative to flooding duration. With increasing flooding duration, the cover of wetland vegetation (amphibious and aquatic species) increased and the cover of terrestrial and exotic vegetation decreased, with these effects largest in the deliberately flooded billabong. Flooding durations greater than 20 days generally resulted in increased cover of wetland plants and restricted the growth of terrestrial plants. Reinstatement of more appropriate flooding regimes can thus promote native wetland plants, while suppressing terrestrial exotic species. Our study also provides evidence for the use of modest water allocations to augment the benefits of natural flooding in the maintenance and restoration of native wetland plant communities.

Too Cold, Too Wet, Too Bright, or Just Right? Environmental Predictors of Snake Movement and Activity

Movement and activity patterns are fundamental to the basic ecology of any organism and can be influenced by a variety of environmental factors. For snakes, which are notable for being secretive and difficult to study, environmental influences on movement are often obscure. Here, we investigate environmental drivers of terrestrial activity for 23 snake species from a temperate community in the Atlantic Coastal Plain region of South Carolina, USA. Activity was strongly seasonal, with primarily fossorial species showing unimodal activity peaks in summer, whereas several aquatic species showed increased terrestrial movements to and from a wetland in both spring and fall. After controlling for seasonal activity, temperature and precipitation had consistent effects on snake movement, with activity of snakes increasing with temperature and decreasing with precipitation. The influence of moon illumination was more ambiguous but may have a weak, negative effect on snake activity. These environmental factors likel...

Effects of Water Regime on Spring Wetland Landscape Evolution in Poyang Lake between 2000 and 2010

Water regime was one of the most important driving factors in the formation of wetland landscape and the growth and distribution pattern of wetland vegetation. Currently, research on the relationship between wetland landscape and water regime was mostly focused in autumns and winters in Poyang Lake, and lack of research in springs. Based on the nine high-resolution spring remote sensing images during 2000–2010, the classification characteristics of wetland landscape and spatial distribution pattern of vegetation and their succession trends in Poyang Lake were studied through quantitative interpretation technology and multivariate statistical analysis. Combined with water level fluctuations characteristics of the five monitoring hydrological stations (i.e., Hukou, Xingzi, Duzhan, Tangyin and Kangshan) at the Poyang Lake, the inter-annual and intra-annual water level variations of Poyang Lake were analyzed. The study was aimed to investigate the quantitative effects of water regime on the spring wetland landscape and spatial distribution pattern of vegetation and their succession trends in Poyang Lake. The results showed that: (1) the maximum scope of water levels of the five monitoring stations varied from 8.5 m to 13.57 m, and the water level of Poyang lake showed a downward trend, declining at an average rate of 0.16 m per year during 2000–2010; (2) the total area of the 10 types of the landscapes did not change significantly, which was always maintained at about 3026 km 2 and the total area of vegetation coverage showed increasing trend during 2000–2010 in Poyang Lake, with a maximum area in 2008 and a minimum area in 2010; (3) The water level change was consistent with the area of the lake water, and was inconsistent with the areas of the mudflat, vegetation and land-water transition zone. The highest linear fitting degree with water level was the area of the land-water transition zone, followed by the lake water and vegetation. The results were helpful to further explore the eco-hydrology process and its trend at Poyang Lake wetland, a scientific reference for the maintenance of stable ecosystem functions of the seasonal freshwater lake wetland.

Study of Biodiversity of Macrobenthos in Shadegan Wetland in Spring and Summer 2015 with Emphasis on Dominant Species

Study of Biodiversity of Macrobenthos in Shadegan Wetland in Spring and Summer 2015 with Emphasis on Dominant Species

Iningainema pulvinus gen nov., sp nov. (Cyanobacteria, Scytonemataceae) a new nodularin producer from Edgbaston Reserve, north-eastern Australia

A new nodularin producing benthic cyanobacterium Iningainema pulvinus gen nov., sp nov. was isolated from a freshwater ambient spring wetland in tropical, north-eastern Australia and characterised using combined morphological and phylogenetic attributes. It formed conspicuous irregularly spherical to discoid, blue-green to olive-green cyanobacterial colonies across the substratum of shallow pools. Morphologically Iningainema is most similar to Scytonematopsis Kiseleva and Scytonema Agardh ex Bornet & Flahault. All three genera have isopolar filaments enveloped by a firm, often layered and coloured sheath; false branching is typically geminate, less commonly singly. Phylogenetic analyses using partial 16S rRNA sequences of three clones of Iningainema pulvinus strain ES0614 showed that it formed a well-supported monophyletic clade. All three clones were 99.7–99.9% similar, however they shared less than 93.9% nucleotide similarity with other cyanobacterial sequences including putatively related taxa within the Scytonemataceae. Amplification of a fragment of the ndaF gene involved in nodularin biosynthesis from Iningainema pulvinus confirmed that it has this genetic determinant. Consistent with these results, analysis of two extracts from strain ES0614 by HPLC–MS/MS confirmed the presence of nodularin at concentrations of 796 and 1096μgg−1 dry weight. This is the third genus of cyanobacteria shown to produce the cyanotoxin nodularin and the first report of nodularin synthesis from the cyanobacterial family Scytonemataceae. These new findings may have implications for the aquatic biota at Edgbaston Reserve, a spring complex which has been identified as a priority conservation area in the central Australian arid and semiarid zones, based on patterns of endemicity.

Diversity of ammonia-oxidizing bacteria in relation to soil environment in Ebinur Lake Wetland

ABSTRACTAmmonia oxidation is the first and rate-limiting step of nitrification and is carried out by ammonia-oxidizing bacteria (AOB). Ebinur Lake Wetland, the most representative temperate arid zone wetland ecosystem in China, is the centre of oasis and desertification of the northern slope of Tianshan conjugate. Soil samples were collected from three sites (Tamarix ramosissima, Halocnemum strobilaceum and Phragmites australis) and different soil layers (0–5, 5–15, 15–25 and 25–35 cm) in this wetland in spring, summer and autumn and were used to characterize the diversity of AOB based on the ammonia monooxygenase (amoA) gene. Polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) and bivariate correlation analysis were used to analyse the relationship between the diversity of AOB and soil environment factors. The PCR-DGGE indicated that the diversity of AOB was high in the entire sample and the Shannon diversity index varied from 1.369 to 2.471. The phylogenetic analysis showed that the amoA fragments were grouped into Nitrosospira sp. and Nitrosomonas sp. Most amoA gene sequences fell within the Nitrosospira sp. cluster, and only a few sequences were clustered with Nitrosomonas sp., indicating that Nitrosospira sp. may be more adaptable than Nitrosomonas sp. in this area. Bivariate correlation analysis showed that the diversity of AOB was significantly correlated with soil organic matter, conductivity, total phosphorus and nitrate in the Ebinur Lake Wetland in Xinjiang.

Comparison of meiofaunal abundance in two mangrove wetlands in Tong’an Bay, Xiamen, China

To compare meiofaunal community in the two mangrove wetlands in Tong’an Bay, Xiamen, China, and probe the response of meiofauna to high organic matter, sampling was carried out in Fenglin and Xiang’an mangrove wetlands in the bay. The results showed that the Ne/Co ratio (nematode to benthic copepod) and organic matter in Fenglin mangrove wetland were higher than those in Xiang’an mangrove wetland. The meiofaunal abundance in Fenglin mangrove was all lower than that in Xiang’an mangrove wetland in summer, autumn and spring, while the meiofaunal abundance in Fenglin mangrove was higher than that in Xiang’an mangrove wetland in winter. Two-way ANOVA results showed that the meiofaunal abundance and nematode abundance were significantly different between regions, seasons and region×season. With all the results in the present study, we confirmed that the positive response of meiofaunal and nematode abundance were only detected for medium organic matter contents according to the Xiang’an wetland’s level, and that the distribution of meiofaunal abundance would be influenced by sand content. Higher copepod abundance and lower N/C value usually suggest better environmental quality.

Effects of a saturated layer and recirculation on nitrogen treatment performances of a single stage Vertical Flow Constructed Wetland (VFCW)

Upgrades to enhance nitrogen removal were tested in a 2 year old pilot vertical flow constructed wetland in spring and summer periods. The effects of a saturated layer and of recirculation were tested in particular. Two pilots (L = 2 m, W = 1.25 m, H = 1.2 m), filled with expanded schist (Mayennite(®)), were designed with hydraulic saturated layers of 20 and 40 cm at the bottom. Each pilot was fed with raw domestic wastewater under field conditions according to a hydraulic load of 15-38 cm d(-1) (i.e. 158-401 g COD (chemical oxygen demand) m(-2) d(-1)) and to recirculation rates ranging from 0% up to 150%. The initial load during the first 2 years of operation resulted in an incomplete mineralized accumulated sludge leading to total suspended solids (TSS), COD and biochemical oxygen demand (BOD5) release. A 40 cm hydraulic saturated layer enabled an increase of 5-10% total nitrogen (TN) removal compared to a 20 cm saturated layer. Recirculation allowed the dilution of raw wastewater and enhanced nitrification in a single stage. A design of 1.8 m² pe(-1) (48 cm d(-1), 191 g COD m(-2) d(-1)) with a 40 cm saturated layer and 100% recirculation enabled the French standard D4 (35 mg TSS L(-1), 125 mg COD L(-1), 25 mg BOD5 L(-1)), nitrogen concentrations below 20 mg TKN (total Kjeldahl nitrogen) L(-1) and 50 mg TN L(-1), to be met.

Shorebird abundance and species diversity in natural intertidal and non-tidal anthropogenic wetlands of the Colorado River Delta, Mexico

Shorebirds constitute the highest abundance group of birds that use the Upper Gulf of California and Colorado River Delta (CRD) wetlands for nesting, spring stopover and overwintering sites. From August 2005 to December 2008 ground surveys were conducted on three natural intertidal wetlands (Golfo de Santa Clara, Isla Montague and Bahia Adair) and three brackish anthropogenic wetlands (Cienega de Santa Clara, Cerro Prieto and Mesa de Andrade) in the Upper Gulf and CRD. The goal was to determine the overall importance of the CRD in supporting shorebirds, and in particular the role of the anthropogenic wetlands, which face uncertain futures. Species richness varied from 15 to 26 species among sites and 29 species were detected across sites. The most abundant species was Calidris mauri, which was most abundant in Isla Montague and Golfo de Santa Clara in winter and spring, while it was most abundant in the Cienega de Santa Clara and Mesa de Andrade wetland in spring and fall. Cienega de Santa Clara and Golfo de Santa Clara had the highest bird density with 168 and 105 individuals/ha in the peak migration month. Birds tended to use the intertidal wetlands during the winter and spring migration period while the inland wetlands were most used during spring and fall. The Cerro Prieto geothermal power plant wetlands were most used by Phalaropes species during fall migration. Bahia Adair, an extensive intertidal wetland system south of the CRD, had a low density of shorebirds (10 individuals/ha) compared to CRD sites, but it had higher species diversity and the highest proportion of large size shorebirds. This study shows the importance of both intertidal and anthropogenic wetlands in supporting shorebirds along the Pacific Flyway. Management decisions that might impact these wetlands should consider their habitat value for migratory shorebirds as documented here.