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  • Articles  (4)
  • canonical correspondence analysis  (4)
  • Springer  (4)
  • Wiley-Blackwell
  • 1
    Electronic Resource
    Electronic Resource
    The relative influences of exotic species and environmental factors (1998)
    Springer
    Environmental biology of fishes 51 (1998), S. 41-51 
    Details
    ISSN: 1573-5133
    Keywords: river environment ; endemism ; spatial organisation ; biotic interactions ; canonical correspondence analysis ; Portugal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Spatial variation in the native fish community of the lower Guadiana basin (southern Iberia) was related to both biotic (abundance of exotic species) and environmental factors using canonical correspondence analysis, CCA. After choosing the best predictors among the environmental and biotic variables, we partitioned the total variation in native species abundances (18 species-size combinations by 44 sampling locations matrix) into that accounted for (1) solely by selected environmental variables, (2) solely by selected biotic variables, (3) by both environmental and biotic variables together, and (4) that unexplained. Of the 22 variables initially considered in the environmental CCA, only RIVER (dummy variable codifying sampling locations belonging to the main river), SALT (dummy variable codifying sampling locations belonging to tributaries that discharge to the brackish Guadiana), substrate heterogeneity, and macrobenthos abundance were selected as best predictors. In the biotic CCA, three species-size combinations were selected from the eight considered: Micropterus salmoides 〉 150 mm in total length (TL), Lepomis gibbosus 〉 100 mm in TL and Gambusia holbrooki. The total variation in the native fish community was partitioned into the following components: pure environmental (24.4%), pure biotic (12.4%), shared (9.2%) and unexplained (54.0%). There was a significant influence of exotic fish on native community variation after accounting for the effect of environmental factors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007412714605
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  • 2
    Electronic Resource
    Electronic Resource
    River plants from an Iberian basin and environmental factors influencing their distribution (1999)
    Springer
    Hydrobiologia 415 (1999), S. 101-107 
    Details
    ISSN: 1573-5117
    Keywords: fluvial macrophytes ; anthropogenic factors ; Portugal ; Mediterranean rivers ; canonical correspondence analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract River plants were studied at 119 sites from a southern Iberian river basin. A site length of 50-100 m was found to be adequate for characterising local plant richness in these rivers. Average number of river plant species per site was 48 (range 21-76). Species richness showed a maximum at mid-course, with considerable variation in the upper course and a decreasing trend towards the floodplain. Sixteen environmental variables were initially considered to explain the biological variability. Nine, retained by the forward selection procedure, were significant predictors of the species distribution. Canonical correspondence analysis was used to directly relate plant species composition to these environmental variables. Altitude, conductivity, river width, pH, percentage of hard substrates and fine particulate organic matter on the river bed, average rainfall and temperature, and human-related disturbance were significantly related to the species distribution. Species positioned at the axes extremes could be arranged into species groups related to different geographical areas of the river system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003837802366
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The relative influences of exotic species and environmental factors (1998)
    Springer
    Environmental biology of fishes 51 (1998), S. 41-51 
    Details
    ISSN: 1573-5133
    Keywords: river environment ; endemism ; spatial organisation ; biotic interactions ; canonical correspondence analysis ; Portugal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Spatial variation in the native fish community of the lower Guadiana basin (southern Iberia) was related to both biotic (abundance of exotic species) and environmental factors using canonical correspondence analysis, CCA. After choosing the best predictors among the environmental and biotic variables, we partitioned the total variation in native species abundances (18 species-size combinations by 44 sampling locations matrix) into that accounted for (1) solely by selected environmental variables, (2) solely by selected biotic variables, (3) by both environmental and biotic variables together, and (4) that unexplained. Of the 22 variables initially considered in the environmental CCA, only RIVER (dummy variable codifying sampling locations belonging to the main river), SALT (dummy variable codifying sampling locations belonging to tributaries that discharge to the brackish Guadiana), substrate heterogeneity, and macrobenthos abundance were selected as best predictors. In the biotic CCA, three species-size combinations were selected from the eight considered: Micropterus salmoides 〉 150 mm in total length (TL), Lepomis gibbosus 〉 100 mm in TL and Gambusia holbrooki. The total variation in the native fish community was partitioned into the following components: pure environmental (24.4%), pure biotic (12.4%), shared (9.2%) and unexplained (54.0%). There was a significant influence of exotic fish on native community variation after accounting for the effect of environmental factors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007412714605
    Location Call Number Expected Availability
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    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    The environmental basis of diet variation in pumpkinseed sunfish, Lepomis gibbosus, and largemouth bass, Micropterus salmoides, along an Iberian river basin (1997)
    Springer
    Environmental biology of fishes 50 (1997), S. 105-115 
    Details
    ISSN: 1573-5133
    Keywords: exotic Centrarchidae ; stomach contents ; environment ; canonical correspondence analysis ; rivers ; Guadiana basin ; Portugal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The diet composition of largemouth bass, Micropterus salmoides, and pumpkinseed sunfish, Lepomis gibbosus, and its relation to environmental factors was studied in intermittent watercourses of the lower Guadiana basin (southern Iberia) during the particularly dry summer of 1994. Overall, both species took food items similar to those found in their North American and acclimatised ranges, with pumpkinseed consuming invertebrates (chiefly Chironomidae) and bass preying on invertebrates (chiefly Micronecta meridionalis) and fish (chiefly L. gibbosus and Gambusia holbrooki). Both bass and pumpkinseed were opportunistic feeders, feeding on the most frequent and abundant prey. However, Diptera larvae were apparently preferred by pumpkinseed and avoided by bass, while the contrary occurred with respect to Heteroptera. The two main fish prey of bass were eaten on the basis of random encounter. The relative abundance of macro-prey (i.e. fish and Atyephira desmarestii) were the principal environmental variables constraining bass dietary variation along the basin. On the contrary, pumpkinseed diet variation was mainly related to pumpkinseed size and the presence of piscivorous bass nearby, although habitat size and cyprinid abundance were also influential.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007302718072
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    Paper (German National Licenses)
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