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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 23 (1990), S. 0 
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY. 1. The paper describes diatom communities from a series of linked urban lakes in relation to water chemistry and uses multivariate statistical techniques to show how indicator groups can he defined.2. Diatoms are classified into ecological groups using two-way species indicator analysis (TWINSPAN). Each ecological group is associated with a specific range of water-quality conditions. The headwater stream environments are differentiated from the lake habitats at level 1. At level 2 of TWINSPAN. the sampling sites are grouped into five ecological groups, according to their water chemistry and irrespective of the time of year.3. Detrended correspondence analysis (DCA) and principal components analysis (PCA) provide two statistically independent methods of assessing the environmental gradients along which the ecological groups are distributed. The most important physico-chemical parameters are total hardness, specific conductance and pH, followed by phosphates and nitrates.4. Ecological groups I-V correspond to an environmental gradient ranging from the forested headwaters, which are acidic, of low specific conductance, total hardness and nutrient content, through the urban lakes, which are alkaline and of relatively high total hardness, specific conductance and nutrient content.5. Twelve site groups are identified at level 3 of TWINSPAN, each of which corresponds to a narrower range of water-quality conditions within the ecological groupings. A specific diatom assemblage is associated with each site group.6. Benthic diatoms form an integral part of the diatom assemblages found in the water column and this is identified as a topic for further study.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 23 (1990), S. 0 
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY. 1. Five diatom assemblages and their corresponding site groups were associated with the urban lakes. When treated as a single dataset, DC A and PCA grouped these diatom assemblages along an environmental gradient from circum natural. dilute waters to strongly alkaline, concentrated, nutrient-rich waters.2. When treated as individual datasets, 75% of the known variance was explained by the first axis of DCA in all five diatom assemblages; this indicated the existence of a strong primary environmental gradient. The PCA results showed that the identity of this primary environmental gradient can be different for each assemblage.3. The statistical analyses showed that the physicochemical gradients were continuous and not discrete. Nevertheless, fine-scale analysis can identify smaller, more precise species and site groups.4. Two types of species response could be identified within most sub-assemblages in the urban lakes: the first was a quasi-seasonal response and was characterized by a gradual rise to a peak relative abundance of one dominant or several co-dominant species which could be sustained for a period of weeks before a gradual decline. A quasi-seasonal response was sometimes interrupted by a storm response. The storm response was characterized by a sudden increase in the relative abundance of one or more diatom species following a storm, after which the species declined to pre-storm abundances within 7 days.5. The effects of urban runoff on the water quality of urban lakes can override the effects of true seasonal factors such as water temperature and day length on the relative abundance of species.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 288 (1980), S. 50-55 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] During the intertropical cold dry phase from ∼20,000 to 12,500 yr BP, the aggrading Nile was a braided, highly seasonal river. With a headwaters change to warmer, wetter conditions, it became an incised, sinuous, suspended load river. Overflow from Lake Victoria and severe floods in Egypt ...
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 265 (1977), S. 42-45 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The results come from a multidisciplinary 5-yr project, and supporting detail is available elsewhere1. Analyses of diatom associations, which are sensitive indicators of ecological conditions, were carried out on 492 samples, and supplemented toy convergent evidence from sedimentary facies and ...
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 282 (1979), S. 29-33 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Widespread artefact-bearing gravels overlie Pliocene diatomites in the plain of Gadeb (7°02′–7°13′N, 39° 15′–39°28′E) at 2,300 m in east-central Ethiopia. The diatomites are from 2.7 to 2.35 Myr old, and the bulk of the Developed Oldowan and ...
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Earth and Planetary Science Letters 126 (1994), S. 435-456 
    ISSN: 0012-821X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of paleolimnology 12 (1994), S. 191-196 
    ISSN: 1573-0417
    Keywords: diatoms ; saline lakes ; palaeolimnology ; palaeoclimate ; transfer functions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The Climate and Salinity (CASPIA) Project is concerned with diatoms as environmental indicators in inland waters and their use in reconstructing salinity and major ion composition from fossil diatom assemblages in lake sediments. By comparing saline lake diatom floras from around the world the project aims to establish a common, harmonised approach to sample collection, diatom identification and nomenclature, and to develop techniques for numerical analysis and data storage.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The 1989 Sino-French expedition (Kunlun-Karakorum Programme, CNRS-Academia Sinica) investigated lakes in western Tibet (mean elevation 〉 5,000m above sea level), the coldest and driest part of the Tibetan-Qinghai plateau11. Located in the rain shadow of two high mountain ranges, the Kunlun and ...
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Stratified carbonaceous, sediments lie in closed depressions of the hamada plateau. Some of them formed when dry valleys were blocked by the displacement of sand dunes in th Great Western Erg. At the present time,, the water table of the aquifer is at about -50 m. The topography of the basins and ...
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Tigalmamine (32° 54' N, 5° 21' W, area 6 ha, maximum depth 16m) is the largest of a group of solution lakes in Lower Lias dolomite bedrock, at 1,628 m above sea level in the Middle Atlas of Morocco. The lake (Table 1) is fed by ground water, surface springs, and winter runoff ...
    Type of Medium: Electronic Resource
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