Autecology of Limnomysis benedeni Czerniavsky, 1882 (Crustacea: Mysida) in Lake Constance, Southwestern Germany

The Ponto-Caspian mysid Limnomysis benedeni was first recorded in Lake Constance in summer 2006, and a stable population developed at the site of discovery. Although this mysid is common in the Rhine and Danube rivers, little is known about its ecology and impact in systems of invasion. We investigated the autecology of L. benedeni in habitat-choice and food experiments. In the habitat-choice experiments, highly structured habitats, i.e., stones covered with zebra mussels (Dreissena polymorpha), macrophytes, and especially stonewort, were strongly preferred. In food experiments, L. benedeni fed mostly on food sources with a small particle size, e.g., biofilm on leaf litter, biodeposited material of zebra mussels, epilithon, and phytoplankton. We also compared the L. benedeni population data from Lake Constance with that from rivers. In Lake Constance, female L. benedeni were nearly 30% larger and carried more than three times more eggs in spring (9.4±0.6 mm and 28.4±5.7 eggs) than in summer (6.7±0.8 mm and 8.7±2.9 eggs). The mysids present in spring might be the generation that over-wintered; in summer, this generation was probably replaced by a new generation of smaller individuals. The large brood size and the detritivorous feeding strategy might allow L. benedeni to colonize Lake Constance rapidly.     

Residents’ urbanized landscape preferences in rural areas reveal the importance of naturalness-livability contrast

Journal of Geographical Sciences - Urbanization has caused significant landscape changes in rural areas, leading to the emergence of urbanized landscapes (ULs), which have been generally criticized...     

北京城市居民服务设施可达性偏好与现实错位

服务设施可达性对于居民生活质量的重要性越来越受到国内外研究和城市规划的广泛重视,然而中国城市发展过程中却暴露出服务设施可达性下降的问题。从居民的视角出发,构建影响中国城市居民服务设施可达性偏好与现实错位的分析框架。在此基础上,分析了基于北京市2005 年居住环境调查主观数据对居民的服务设施可达性偏好。利用北京城市服务设施空间数据借助GIS评估居民的客观服务设施可达性,通过多元回归模型讨论居民服务设施可达性偏好与现实的错位情况和相关因素并侧重验证城市空间结构和住房获取渠道的影响,这些因素与中国的城市发展和住房政策变化紧密相关并将基于此提出促进居民实现其服务设施可达性偏好的城市规划和政策建议。     

Distribution of n-alkanes and PAHs in atmospheric aerosols

The concentrations of n-alkanes and polycyclic aromatic hydrocarbons (PAHs) are determined in atmospheric aerosol samples collected at a rural sampling site in Hungary. For the n-alkanes the chromatographic profiles are established and the average carbon number and carbon preference index (CPI) are calculated. An attempt is made to obtain the origin of n-alkanes found in atmospheric aerosol samples. Based on the results of the measurements the probable importance of a round-the-year biogenic source for the n-alkanes with CPIs close to unity is emphasized.     

基于旅游需求的甘肃省国际旅游时空变动研究

从旅游需求的角度出发,通过地理集中指数、年际集中指数、亲景度和旅游流等指标对甘肃省国际旅游的时空变动进行分析,总结了甘肃省国际旅游的时空变化特征.按照对旅游目的地国际游客从来源到流向的分析思路,首先对甘肃省国际旅游的时空集中性和亲景度进行分析,提出根据亲景度和年际集中指数对主要客源市场进行有重点、分层次开发.其次通过国际游客在甘肃省内的流向分析,指出应在把握游客需求趋势的基础上,促进优势旅游资源的开发和空间布局的优化.     

辽南丹东地区中生代金成矿的FIP的证据

辽南丹东地区产出有五龙、四道沟两个大型金矿床,两矿床与中生代燕山期三股流花岗岩体存在密切的空间华生关系。长期以来,对这一地区金的成矿作用时代存在有不同的认识,一种观点认为金的成矿作用只有一期,即中徨代（燕山期）;另一种观战认为金的成矿作用有两期,即元古代和中生代（燕山期）分别以四道沟金矿和五龙金矿为代表,作者利用流体包裹体面（ＦＩＰ）研究的新方法对金矿床及伴生花岗岩进行了研究。结果表明,三股流花岗     

Experimental investigation of the compositional variation of acyclic paraffins during expulsion from source rocks

Anhydrous non-isothermal heating experiments were conducted under controlled compressive stress on cylindrical plugs of six oil shales from Permian through Eocene age. The objective of this study was to compare the distribution of acyclic paraffins in initial, residual and expelled organic matter and to highlight causes of compositional differences resulting from expulsion. Pristane generation from kerogen is highest in the Eocene Messel shale and affects the pristane / phytane (pr / ph) ratio commonly used as a redox proxy. The isoprenoid to n-alkane ratios (pr / n-C₁₇, ph / n-C₁₈) decrease during generation and are lowest in the residual bitumen due to preferential generation and retention of n-alkanes. The n-alkane distribution shows that only lacustrine shales produce high wax oils. Evaporative fractionation leads to loss of n-alkanes up to n-C₂₀ with boiling points below 350 °C. This demonstrates that lacustrine and marine shales may lead to accumulation of low wax oils due to evaporative fractionation after expulsion.     

拟穴青蟹大眼幼体和第Ⅰ期仔蟹底质选择的研究

拟穴青蟹大眼幼体和仔蟹对海泥和泥沙底质的选择性显著高于各种粒径的沙底（粒度0.06～2.00mm）.其原因可能与海泥和泥沙底质在流动海水中物理稳定性高于沙砾有关.通过以埋栖选择性和相对埋栖率为指标考察了大眼幼体和仔蟹的栖息方式,发现白昼大眼幼体埋栖在底质中的比例显著高于夜间,也高于仔蟹;夜间大眼幼体栖息方式与仔蟹差别不明显;并发现大眼幼体栖息方式存在着昼夜差异和昼夜节律性.这揭示了拟穴青蟹大眼幼体对底质的选择性和在底质上栖息的方式表现出对FTT机制的适应.     

Foraging ecology of an endemic shorebird, the African Black Oystercatcher (Haematopus moquini) on the south–east coast of South Africa

We investigated small–medium (1–300 km) scale variation in the foraging ecology of the African Black Oystercatcher during its breeding season, using traditional diet analysis coupled with carbon and nitrogen stable isotope analysis. Fieldwork was conducted between January and March 2006 and 2007, on rocky shores on the south–east coast of South Africa at East London, Kenton and Port Elizabeth. Middens of shelled prey left by adults feeding their chicks were collected from five territories and the abundances of the collected prey on the foraging areas were estimated using quadrats. Blood samples from 45 birds (16 females, 10 males and 19 chicks) and tissues from the predominant prey species on the territory of each breeding pair were collected for isotope analysis. The Manly–Chesson selectivity index revealed that adults feed their chicks preferentially with the limpet Scutellastra cochlear and the Mediterranean mussel Mytilus galloprovincialis, if available. A slight enrichment in the ¹⁵N stable-carbon isotope signature was observed towards the west in both prey and oystercatchers. Differences in isotope signatures between males and females from the same breeding pair indicate sex-related differences in the diet. Both had signatures indicating a mixed diet, but with males exhibiting a signature closer to that of limpets and females closer to that of mussels. In the single case where mussels were rare on the feeding territory, the two members of a pair showed carbon signatures which were identical and very similar to that of limpets. These results indicate dietary partitioning between genders in breeding pairs.     

Prey versus substrate as determinants of habitat choice in a feeding shorebird

Many shorebirds on their non-breeding grounds feed on macrobenthic fauna which become available at low tide in coastal intertidal flats. The Eastern Curlew Numenius madagascariensis in Moreton Bay Australia, varies greatly in density among different tidal flats. This study asks: how important is the abundance of intertidal prey as a predictor of this variation? We quantified feeding curlews’ diet across 12 sites (different tidal flats, each re-visited at least eight times), through 970 focal observations. We also estimated the abundance of total macrobenthic fauna, potential prey taxa and crustacean prey on each tidal flat; measured as the number of individuals and a relative biomass index per unit substrate surface area obtained from substrate core samples. We estimated curlew density at each site using low-tide surveys from every site visit.