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  • Grazing  (1)
  • Multivariate analyses  (1)
  • heavy metal  (1)
  • 1
    Electronic Resource
    Electronic Resource
    A method for analysing spatial scales of variation in composition of assemblages (1998)
    Springer
    Oecologia 117 (1998), S. 570-578 
    Details
    ISSN: 1432-1939
    Keywords: Key words Assemblages ; Hierarchy ; Multivariate analyses ; Spatial scale
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In several areas of research on ecological assemblages, it is useful to be able to analyse patterns of spatial variation at various scales. Multivariate analyses of dissimilarity or similarity in assemblages of species are limited by problems of non-independence caused by repeated use of the sample-units. Where rank-order procedures are used, no comparative quantitative measurements of dissimilarity at different scales are produced. An alternative method is described that uses the sample's average assemblage (or centroid). These estimates are themselves averaged to give centroids for larger spatial scales. Dissimilarities from the centroids at each scale are then calculated using independent replicates for each scale from those in each sample. The dissimilarity measures can then be examined by analysis of variance to detect spatial scales of differences for each sample at every level of a hierarchy of scales. The method is illustrated using data from mangrove forests and rocky shores, involving up to 97 taxonomic groups (species, other taxa). Differences among assemblages at the scales of sites (tens of meters apart) or locations at shores (hundreds of meters apart) were identified. Consequences of different numbers of replicates are discussed, with some potential problems (and their solutions) in application.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050694
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of gastropod grazers on recruitment and succession of an estuarine assemblage: a multivariate and univariate approach (1997)
    Springer
    Oecologia 109 (1997), S. 442-453 
    Details
    ISSN: 1432-1939
    Keywords: Key words Assemblage structure ; Gastropods ; Grazing ; Oysters ; Multivariate effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Grazers have been shown to affect assemblages of species in many habitats. Here we studied the effects of the gastropod grazers, Austrocochlea porcata and Bembicium auratum, on intertidal estuarine assemblages in a sheltered bay in New South Wales, Australia. We examined the effects of gastropods on individual species and on the assemblage as a whole. The multivariate response was compared with data on succession in these assemblages to estimate potential effects of grazers on succession. The experiment was repeated several times to determine the generality of grazer effects in the light of possible variation in the timing or intensity of recruitment. There were different responses of individual species to the presence of grazers. Grazers reduced the abundance of ephemeral algal species, bryozoans, copepods, insect larvae and Balanus spp. barnacles. They had a positive effect on oysters and spirorbids and no effect on the barnacles Elminius covertus and Hexaminius spp. These effects were consistent through time. Multivariate analyses confirmed that grazers caused significant changes to whole assemblages and that these effects were far-reaching and not only caused by changes to algal species. The removal of grazers appeared to neither speed up nor slow down succession, but rather caused a completely different assemblage to develop. Apparent important mechanisms affecting the composition of animal species when grazers were removed included accumulation of sediments and detritus and pre-emption of space by algae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050104
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Technical Note: Using an Experimental Manipulation of Contaminants in Intertidal Sediments (1999)
    Springer
    Ecotoxicology 8 (1999), S. 495-501 
    Details
    ISSN: 1573-3017
    Keywords: manipulative experiment ; heavy metal ; pollution ; soft-sediment ; benthic animals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Manipulative experiments in the field are important tools, for improving understanding of disturbances, such as contaminants, causing environmental impacts. We tested a method to create patches of increased concentrations of metals in intertidal sediments. The method produced persistent concentrations of metals, which were as large as those observed in contaminated areas and it appears to be applicable in different habitats. The utility of this technique as a tool to improve predictions about environmental effects needs to be evaluated by repeated experimentation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008976324070
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    Paper (German National Licenses)
    Fulltext
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