Proximate environmental drivers of coral communities at Palmyra Atoll: establishing baselines prior to removing a WWII military causeway     

Williams GJ  Knapp IS  Maragos JE  Davy SK 《Marine pollution bulletin》2011,62(8):1842-1851

A management proposal aims to partly remove a WWII military causeway at Palmyra Atoll to improve lagoon water circulation and alleviate sedimentation stress on the southeast backreef, an area of high coral cover and diversity. This action could result in a shift in sedimentation across reef sites. To provide management advice, we quantified the proximate environmental factors driving scleractinian coral cover and community patterns at Palmyra. The proportion of fine sedimentation was the optimal predictor of coral cover and changes in community structure, explaining 23.7% and 24.7% of the variation between sites, respectively. Scleractinian coral cover was negatively correlated with increases in fine sedimentation. Removing the causeway could negatively affect the Montipora corals that dominate the western reef terrace, as this genus was negatively correlated with levels of fine sedimentation. The tolerance limits of corals, and sediment re-distribution patterns, should be determined prior to complete removal of the causeway.  相似文献   

The effects of season and wrack subsidy on the community functioning of exposed sandy beaches     

Sílvia C. Gonçalves  João C. Marques 《Estuarine, Coastal and Shelf Science》2011

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西部乡村民族社区景区化的内涵及表征——以云南典型乡村民族社区为例   总被引：2，自引：0，他引：2  

王维艳  沈琼  李强 《云南地理环境研究》2011,23(2):9-14

从旅游活动要素及其空间效应着眼,对"景区化"与"乡村民族社区景区化"的内涵进行了界定,把社区事象的景观化、经济功能的旅游化、组织管理的业缘化等视为"乡村民族社区景区化"的具体表征;认为乡村民族社区景区化的结果,必将导致乡村民族社区向旅游社区的演变,并对乡村民族旅游社区的内涵及其类型特征作了初步探讨,进而细分出名义在场型、从业参与型、景观资产型、混合平衡型4种类型。对云南曼听五寨、雨崩村、泸沽湖落水村和里格村进行实证研究的结果表明,除了曼听五寨属于名义在场型外,其余为从业参与型旅游社区。  相似文献   

Terrestrial arthropod fauna of arid areas of SE Spain: Diversity, biogeography, and conservation     

F.S. Piñero  A. Tinaut  A. Aguirre-Segura  J. Miñano  J.L. Lencina  F.J. Ortiz-Sánchez  F.J. Pérez-López 《Journal of Arid Environments》2011,75(12):1321-1332

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鄂尔多斯盐沼湿地土壤盐分特征对植物群落的影响          下载免费PDF全文

崔乔  何彤慧  全晓塞  陈向全  何玉实 《盐湖研究》2022,30(1):25-32

为研究内陆盐沼植物群落的分布对土壤盐分的响应特征,选取鄂尔多斯盐湖盐沼区作为研究区,筛选了肉质耐盐植物群落、苔草植物群落和禾草植物群落3类典型植物群落,开展了土壤含水量、pH、电导率以及Na+、K+、Mg2+、Ca2+、Cl-、SO42-、CO32-和HCO3-测定,分析了区内典型植物群落对土壤水盐因子的响应规律.探讨...  相似文献   

Assessment of the ecological quality status of soft-bottoms in Reunion Island (tropical Southwest Indian Ocean) using AZTI marine biotic indices   总被引：2，自引：1，他引：1  

Bigot L  Grémare A  Amouroux JM  Frouin P  Maire O  Gaertner JC 《Marine pollution bulletin》2008,56(4):704-722

The ability of the two synthetic marine biotic indices, AMBI and M-AMBI, to account for changes in the ecological quality of coastal soft bottoms of Reunion Island according to disturbances was assessed from macrobenthic samples collected in five sectors between 1994 and 2004. Samples were collected under non-perturbed conditions and at two sites subjected to heavy organic enrichment. Both indices are based on a classification of macrofauna into ecological groups (EG), and their transfer to tropical waters required some adaptations. These indices proved efficient in detecting a degradation of habitat quality. Their use resulted in the classification of all sites sampled between 1996 and 1998 as "good" or "high". M-AMBI nevertheless tended to result in the attribution of a slightly worse ecological quality status than AMBI. Together with an update of the EG species list for the Indian Ocean area, our results support the extension of both indices for the assessment of tropical soft bottoms.  相似文献   

Seasonal and spatial distribution of the microbenthic communities of the Rio de la Plata estuary (Argentina) and possible environmental controls     

N. Gómez  M. Licursi  J. Cochero 《Marine pollution bulletin》2009,58(6):878-887

The relationship between microbenthic communities, the habitat characteristics, and physical and chemical gradients was studied in the Rio de la Plata estuary. Five replicates of the surface layer were collected seasonally, in 10 sampling sites influenced by different land uses. The distribution of microbenthic communities was governed by two gradients, the first one determined by anthropic factors, related to pollution, and the second one to conductivity and turbidity. The higher densities of producers were observed in sites characterized by fine sediments. During winter, spring, and summer cyanophytes were abundant, while in autumn the diatoms, particularly birraphideans, dominated. The ciliates were the most abundant group among consumers, particularly in winter, and their spatial distribution was influenced by the turbidity. The whole study area has an eutrophic condition. Turbidity and the enrichment with nutrients and organic matter explained 50% of the variability in the species’ distribution.  相似文献   

Seasonal closures as a measure of trawling effort control in two Mediterranean trawling grounds: effects on epibenthic communities     

Demestre M  de Juan S  Sartor P  Ligas A 《Marine pollution bulletin》2008,56(10):1765-1773

Within the framework of ecosystem-based management, we focused on the use of seasonal closures as effective measures to minimise the degradation of benthic communities by trawling. These closures imply the complete cessation of trawling fleet activity and are commonly used in the Mediterranean to reduce the annual fishing effort, with the ultimate goal of effective resource management. In this study, we aimed to investigate how epibenthic communities respond to seasonal closures. The potential benefits of short-term annual closures in two Mediterranean fishing grounds were evaluated by analysing changes in community structure and composition that were linked to the closure. A decrease of faunal abundance was observed with the resumption of fishing activity after the closure at both fishing grounds. Remarkably, results indicated that some large and mobile fauna were able to respond to these closures. We concluded that the currently planned closures are too short to benefit benthic communities.  相似文献   

中国北方森林群落现代花粉与植被和气候的关系     

李月丛  许清海  张丽艳  王学丽  曹现勇  阳小兰 《地理学报(英文版)》2009,19(6):643-659

53 pollen traps and surface samples were collected in order to detect the characteristics of pollen assemblages and their relationships with vegetation and climate in 16 forest communities located in 10 mountains in northern China. The results show that 72% of the pollen taxa (80 taxa) are the same between the traps and the surface samples. The dominant taxa in the plant communities are consistent with the main pollen taxa in the pollen assemblages at the same sites. In Pinus plant communities, both Pinus pollen influx and concentration are higher, indicating the high pollen productivity and good pollen preservation ability of Pinus. In Picea and Abies plant communities, Picea and Abies have lower pollen influxes but higher concentrations, suggesting their low pollen productivities but better pollen preservation abilities. In Betula and Quercus plant communities, Betula and Quercus have higher pollen influxes but lower concentrations, revealing their high pollen productivities but poor pollen preservation abilities. The study of relationships between pollen and vegetation with discriminant analysis shows that pollen assemblages from both trap and surface samples can reflect the characteristics of different communities and distinguish different ecological areas, but surface samples can reflect the dominant components of communities much better than the traps. The study on correlations between pollen assemblages and climate with DCCA reveals that significant correlations exist between pollen assemblages and mean temperature of the coldest month (r = 0.84 for trap samples, r = 0.72 for surface samples), and then annual mean precipitation (r = 0.73 for trap samples, r = 0.71 for surface samples).  相似文献   

西伯利亚水库和叶尼塞河中物质及生态系统条件的预测：生物物理方法     

Andrei Degermendzhy  Vladimir Gubanov 《湖泊科学》1998,10(S1):203-228

An avenue to integrate theoretical, experimental and field research methods to forecast water quality in water bodies for different scenarios of water management is proposed. Exploration of the laws of organization, stability and controllability of laboratory "ideal" water microbial communities (model ecosystems) is the basis to build the following biophysical research chain:to formalize with primary field information a conceptual block-diagram of a water ecosystem →to real chemical and other density-dependent and population-growth-controlling factors → to find our limiting factors for natural ecosystems → to conduct experiments with isolated chemical factors and hydrobionts to derive kinetic dependencies and quantitative parameters→ to transfer regularities of operation and kinetic dependencies to the natural ecosystem→ retrospective verification of the model on the base of available field and derived theoretical-experimental data →prognostic calculations for the scenario. Efficiency of the approach is demonstrated in microalgal "blooming" models for Krasnoyarsk and Kantat reservoirs and in prognostication of radioecological state of great Yenisei river:1) radionuclide distribution in the Yenisei''s bottom sediment is nonuniform-"spotty"; 2) it is theoretically shown, that due to biological interactions and tro-phical radioniclide migration there is "spotive" type of space radionuclide distribution. The research is to make use of the novel methods of ecological biophysics:Monitoring:spectral analysis of surface waters (algal pigments), fluorescent techniques to evaluate productivity and condition of algae; rapid bioassays for water toxicity (bioluminescence, chemotaxis techniques). Kinetic experiments:microcosms on evaluating self-purification rates; special cultivators to evaluate the rates of growth of hydrobionts and radioactive engulfing, nutrition spectra; methods of finding growth limiting factors. Models:application of Bellman Principle to optimizing the river water use; theory and peculiarities of microbiological decomposition of pollutants in the river ecosystem. The composition of Prognostication Simulation Model is the next:1) hydrodynamical unit to calculate 2-dimensional space-time rate of stream on any depth; 2) hydrophysical unit to calculate:water temperature and level of solar radiation inside the water body; 3) ecosystem unit to calculate dynamic of concentration of phytoplankton, zooplankton, bacteria, major chemical matters and pollutants in water, content pollutants inside of hydrobionfs cells and dynamic of bentos; 4) radioe-cological unit to forecast the dynamic of radionuclides in the water body and bottom, their hydro-bont''s concentration; 5) database. Reservoirs and river models are provided by monitoring and kinetic experiments data.  相似文献