鸭绿江口湿地鸻鹬类停歇地的生物生态研究

鸭绿江口湿地是鸻鹬类在东亚一澳大利亚北迁路线上的最重要停歇地,潮间带上的双壳类、腹足类、多毛类等底栖动物为鸻鹬类提供了能量保障.2010年3月-2011年6月对鸭绿江口潮间带的生物生态进行了调查研究.研究结果表明,生物群落结构相对简单,主要以双壳类、腹足类和多毛类为主,优势种演替明显,系统具有低多样性低密度的特点.鸻鹬类能量补充来源相对匮乏,饵料生物量的更新速度较慢,所提供的能值也相对较低,江户明樱蛤、青蛤(幼体)和长吻沙蚕是鸻鹬类的主要食物来源.鸻鹬类主要集中在低潮带下区觅食,在北迁高峰期对低潮带下区饵料生物影响较显著,尤其对江户明樱蛤丰度影响最明显.泥螺作为优势种,生态位最宽,分布于整个调查断面和潮带,但因体表分泌一种毒性粘液而不被鸻鹬类取食.饵料生物的种群补充能力较强,在鸻鹬类迁徙高峰期之后,饵料丰度和生物量又会恢复到正常水平.虽然目前人类对鸻鹬类的威胁显现较小,但使人类一生态系统一滨鸟之间持续和谐统一,必须综合考量鸭绿江口湿地包括人类在内的生态系统各关键组分之间的生态关联,兼顾生态系统的完整性和人类社会经济发展的可持续性.     

Influences of chronic contamination of oil field exploitation on soil nematode communities at the Yellow River Delta of China

Oil production related activities have led to many environmental problems. Around 80% of the total output of crude oil is generated from terrestrial oilfields in the world. However, the impact of oil exploitation procedures on soil animal communities has not been fully understood. This study investigated the responses of soil nematode communities to the oil exploitation activities in the Yellow River Delta of China. By setting 10 oilfield sites and 5 relatively uncontaminated sites (controls), we found that the content of soil total petroleum hydrocarbons (TPH) was significantly higher at oilfield sites than at controls. With a longer oil exploitation history, the content of soil TPH increased. Soil nematode community structure at oilfield sites was largely different from that at controls. Soil nematodes were significantly less abundant but more diverse at oilfield sites than at controls. The proportions of fungal feeders were significantly lower at oilfield sites than at controls, attaining only half of those at controls. The nematode trophic diversity and genus number negatively correlated with the duration of petroleum exploitation history. This study elucidated the difference in soil nematode communities caused by oilfield exploitation and indicated that the nematode diversity was most obviously influenced by the soil TPH content and the oil exploitation history.     

Where do Sardinian orchids come from: a putative African origin for the insular population of Platanthera bifolia var. kuenkelei?

Because of the complex geoclimatic dynamics of the Mediterranean basin, resulting from a combination of Tertiary geological processes and Quaternary climatic oscillations, the current species composition of the main continental islands is a mosaic resulting from relative contribution of vicariance, geodispersal and long‐distance dispersal by seed. To help distinguish among the contributions of these different dispersal modes to the orchid species richness on the island of Sardinia, we investigated the genetic structure and phylogeographic relationship of the only Platanthera bifolia var. kuenkelei population on the island. By using plastid DNA sequence variation, we show that this recently discovered population is more closely related to the Tunisian P. bifolia var. kuenkelei than to the geographically closer P. bifolia populations from peninsular Italy. Results from haplotype network construction support the hypothesis that the current distribution of P. bifolia var. kuenkelei (Sardinia and Tunisia) is most likely explained by over‐sea dispersal. However, haplotype diversity and mismatch analysis of this unique Sardinian population suggest that, if a long‐distance dispersal event did occur, it was not recent. More likely, temporarily favourable climatic conditions generated a suitable habitat on the island (also in terms of suitable mycorrhizas and pollinators) and thus a transient opportunity for seedling growth and population establishment of P. bifolia var. kuenkelei from North Africa. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 167 , 466–475.     

Impacts of past glaciation events on contemporary fish assemblages of the Ohio River basin

Aim We evaluated variation in fish assemblages on the basis of taxonomic composition and functional groups based on Pleistocene glacial boundaries in the Ohio River basin. We tested for the influence of habitat and hydrology on fish assemblage variation. Location Ohio River basin of North America, including the states of Ohio, Indiana and Illinois. Methods Fish collection sites were identified as Wisconsinan, pre‐Wisconsinan or unglaciated regions. Multivariate analyses, multi‐response permutation procedures, discriminant analysis and indicator species analyses were used to test whether taxonomic and functional assemblages were distinct among regions with varying glacial histories. Principal components analysis was used to identify habitat and water quality, as well as hydrological gradients that could be discerned by glacial region. Results We identified significant differences in both taxonomic and functional fish assemblage structure and habitat variation among regions that had different glaciation histories. The largest differences in taxonomic and functionally based fish communities were for unglaciated and pre‐Wisconsinan regions, while unglaciated and Wisconsinan regions were most similar. We correctly classified study regions in 71% and 60% of sites using taxonomy and functional analyses, respectively. Wisconsinan sites were characterized by Cyprinidae and Catostomidae assemblages with high abundances of tolerant fishes that tended to occur in habitats with reduced current velocity. Pre‐Wisconsinan sites were characterized by Cyprinidae, Catostomidae, Centrarchidae and Percidae families with increased abundances of intolerant fishes that tended to occur in habitats with coarser substrates and increased water velocity in streams of varying size. Unglaciated sites were characterized by Cyprinidae and Percidae families and were not closely associated with any habitat‐based functional group. Habitat in the unglaciated and pre‐Wisconsinan sites was significantly different from that in the Wisconsinan sites, which were characterized by increased channel structure and reduced stream size. Main conclusions Pleistocene glaciation events formed a lasting template of predictable regional differences in stream habitat and in the corresponding taxonomic and functional fish assemblage structures. While many factors impact the distribution of fishes, these results suggest that historical influences such as glaciation may be used to further explain the underlying mechanisms of spatial variation in fish assemblages.     

A comparison of breeding population estimators using nest and brood monitoring data

For many species, breeding population size is an important metric for assessing population status. A variety of simple methods are often used to estimate this metric for ground‐nesting birds that nest in open habitats (e.g., beaches, riverine sandbars). The error and bias associated with estimates derived using these methods vary in relation to differing monitoring intensities and detection rates. However, these errors and biases are often difficult to obtain, poorly understood, and largely unreported. A method was developed to estimate the number of breeding pairs using counts of nests and broods from monitoring data where multiple surveys were made throughout a single breeding season (breeding pair estimator; BPE). The BPE method was compared to two commonly used estimation methods using simulated data from an individual‐based model that allowed for the comparison of biases and accuracy. The BPE method underestimated the number of breeding pairs, but generally performed better than the other two commonly used methods when detection rates were low and monitoring frequency was high. As detection rates and time between surveys increased, the maximum nest and brood count method performs similar to the BPE. The BPE was compared to four commonly used methods to estimate breeding pairs for empirically derived data sets on the Platte River. Based on our simulated data, we expect our BPE to be closest to the true number of breeding pairs as compared to other methods. The methods tested resulted in substantially different estimates of the numbers of breeding pairs; however, coefficients from trend analyses were not statistically different. When data from multiple nest and brood surveys are available, the BPE appears to result in reasonably precise estimates of numbers of breeding pairs. Regardless of the estimation method, investigators are encouraged to acknowledge whether the method employed is likely to over‐ or underestimate breeding pairs. This study provides a means to recognize the potential biases in breeding pair estimates.     

Seasonal and Spatial Variation in Hydrochemical Characteristics of a Semi-Arid River Basin,China

The analysis of river pollution and assessment of spatial and temporal variation in hydrochemistry is essential for control of river water pollution in China. Here, we investigated water quality issues based on an analysis of monitoring data from 32 sites in the Luanhe River Basin in northern China. During 2000–2010, flow and 12 hydrochemical parameters were monitored monthly in the main channel and breach streams. Hydrochemical characteristics of river water were assessed using the water quality identification index. Our results showed that concentrations were not necessarily related to flow. Flow was greatest in summer, but concentrations of nutrients and some heavy metal indicators were smallest in autumn; flow was smallest and concentrations of nutrients were greatest in winter, and concentrations of metals were greatest in spring. Hydrochemical parameters showed significant spatial variation as well; the most seriously polluted sites are located in urban areas, mainly due to discharge of wastewater from domestic and industrial sources. Sites with large and intermediate levels of pollution were located primarily in the main river channel and the larger tributaries, whereas sites of low-level pollution were in the smaller tributaries. Our findings provide valuable information for water pollution control in the Luanhe River Basin.     

山西平陆黄河湿地植物分类学多样性

传统的物种多样性通常使用物种数量指标α和β等多样性指数进行测度,由于其对取样和样本大小有依赖关系且极其敏感,因此取样方法的不同会对多样性的结果产生显著影响。分类学多样性方法基于分类学系统关系测量物种多样性,弥补了传统方法的不足,同时面对各种变量和不受控制的取样具有稳健性,同时也考虑了集合的分类学均匀度。不仅能反映植物群落多样性,还能间接反映环境与扰动间的关系,用于识别生态系统或生境是否处于退化阶段。为了探究平陆黄河湿地的物种多样性,检验分类学多样性方法在植物生态学方面的应用,选取了16个样地进行植物调查,并结合历史资料整理了种子植物名录,结果表明平陆黄河湿地共有植物368种,隶属于36目67科213属。含种最多的科为菊科和禾本科,分别为54种和45种。应用平均分类学差异指数(Δ+)和分类学差异变异指数(Λ+)研究了各样地的植物物种多样性:Δ+和Λ+的理论平均值分别为74.24和480;位于三门峡大坝上游和下游的样地和不同群落类型的分类学多样性均没有显著差异(P0.05)。受人类干扰较大的车村和鳖干平均分类学差异指数值显著较低,Δ+分别为62.28和67.41,位于95%的置信漏斗外;而水分条件较好且人为干扰较少的南沟渡口和三湾湖平均分类学差异指数值最高为分别81.30和79.94。车村的分类差异变异指数值最高为814.44,其物种在不同分类阶元分布最不均一,涧北的分类差异变异指数值最低为423.31,其物种分布相对较均一。传统的多样性方法难以全面的反映某个区域的物种组成、分布和多样性,此外分类学多样性的高低与物种数量的多少没有一定的相关关系,Δ+与S、Λ+与S的相关关系分别为-0.257和-0.187(P0.05)。耕作、生态旅游、日常活动等人为干扰因素可能是造成平陆黄河湿地分类学多样性降低及物种在不同分类等级间分布不均匀的主要原因。     

Experimental study of 60Co behaviour in Tejo River sediments

The objective of this study was to obtain information on the transfer of radiocobalt in freshwater environments that can be used to predict its environmental distribution. The sediment-water behaviour of ⁶⁰Co in freshwater systems was studied through adsorption and desorption experiments undertaken using sediments and water from Fratel Reservoir in the Tejo River. The suspended sediment concentrations (C_s: 500–2000 mg 1^–1) and Co distribution coefficient (K_d) were inversely related: K_d = 2211–2001 ln [C_s]; K_d ranged from 4000 to 8000 ml g^–1. With a suspended sediment concentration of 1000 mg 1^–1, the ⁶⁰Co concentration remaining in solution (C_t) was given by: C_t = 49.4 e^–0.584t + 46.3 e^–0.014t; where t is the time in days and the half-life periods are 1.2 and 50 days. In a closed system, desorption of ⁶⁰Co could be described by a one-component relation with a half-life of 104 days, and a two component relation (half-life 5 hours and 45 days) in an open system. In river water the ⁶⁰Co was found to be almost 100% in cationic forms, however, in the presence of sediment there was a decrease in the proportion of cationic forms (to 50%), with some anionic forms appearing.     

Anaerobic degradation of tetrachlorobisphenol-A in river sediment

This study investigated the anaerobic degradation of tetrachlorobisphenol-A (TCBPA) in sediment samples collected at three sites along the Erren River in southern Taiwan. TCBPA anaerobic degradation half-lives (t_1/2) in the sediment were 12.6, 16.9 and 21.7 d at concentrations of 50, 100, and 250 ??g g⁻¹, respectively. TCBPA (50 ??g g⁻¹) anaerobic degradation half-lives (t_1/2) in the sediment were 10.1, 11.8, 11.0, 11.6, 10.8, 9.1, 8.5, 18.2, 19.3, and 16.1 d by the addition of yeast extract (5 mg l⁻¹), cellulose (0.96 mg l⁻¹), sodium chloride (1%), brij 30 (130 mg l⁻¹), brij 35 (43 mg l⁻¹), rhamnolipid (55 ??M), surfactin (91 ??M), phthalic esters (2 mg l⁻¹), nonylphenol (2 mg l⁻¹), and heavy metals (2 mg l⁻¹), respectively. The degradation rate of TCBPA was enhanced by the addition of yeast extract, cellulose, sodium chloride, brij 30, brij 35, rhamnolipid, or surfactin. However, it was inhibited by the addition of phthalic esters, nonylphenol, or heavy metals. Also noted was the presence of dichlorobisphenol-A and bisphenol-A, two intermediate products resulting from the anaerobic degradation of TCBPA accumulated in the sediments.     

Macrofilamentous microbial communities in the metal-rich and acidic River Tinto, Spain

A novel type of macroscopic microbial community consisting of large dendritic filaments (up to 1.5 m) in a pH 2.0 dam of the River Tinto (South-western Spain) is described. The combined use of 16S rRNA-gene surveys and fluorescent in situ hybridisation (FISH) suggested that gamma-proteobacteria and a relative large diversity of alpha-proteobacteria dominated these structures. beta-Proteobacteria, Actinobacteria and Firmicutes were also detected. Whereas acidophilic bacteria of the genera Acidithiobacillus, Leptospirillum and Acidiphilium, and archaea belonging to the Thermoplasmatales dominate mine acid drainage waters and streamers (riverbed filamentous biofilms), none of the lineages identified in this study affiliate to typical acid mine drainage acidophilic bacteria. Bacteria of the Tinto macrofilaments might be heterotrophic, and could be feeding on the organic matter entrapped in the filamentous structure.