Simple shade plots aid better long-term choices of data pre-treatment in multivariate assemblage studies

Clarke, KR, Tweedley, JR and Valesini, FJ 2014 Simple shade plots aid better long-term choices of data pre-treatment in multivariate assemblage studies. Journal of the Marine Biological Association of the United Kingdom, 94 (01). 1-16.

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Shade plots, simple visual representations of abundance matrices from multivariate species assemblage studies, are shown to be an effective aid in choosing an overall transformation (or other pre-treatment) of quantitative data for long-term use, striking an appropriate balance between dominant and less abundant taxa in ensuing resemblance-based multivariate analyses. Though the exposition is entirely general and applicable to all community studies, detailed illustrations of the comparative power and interpretative possibilities of shade plots are given in the case of two estuarine assemblage studies in south-western Australia: (a) macrobenthos in the upper Swan Estuary over a two-year period covering a highly significant precipitation event for the Perth area; and (b) a wide-scale spatial study of the nearshore fish fauna from five divergent estuaries. The utility of transformations of intermediate severity is again demonstrated and, with greater novelty, the potential importance seen of further mild transformation of all data after differential down-weighting (dispersion weighting) of spatially clumped' or schooled' species. Among the new techniques utilized is a two-way form of the RELATE test, which demonstrates linking of assemblage structure (fish) to continuous environmental variables (water quality), having removed a categorical factor (estuary differences). Re-orderings of sample and species axes in the associated shade plots are seen to provide transparent explanations at the species level for such continuous multivariate patterns.

Item Type: Publication - Article
Additional Keywords: shade plots; multivariate statistics; community ecology; transformation choice; dispersion weighting; Western Australia; estuaries; fish assemblages; macrobenthos
Subjects: Ecology and Environment
Marine Sciences
Divisions: Plymouth Marine Laboratory > Science Areas > Marine Life Support Systems (expired)
Depositing User: Mrs Julia Crocker
Date made live: 02 Oct 2014 15:25
Last Modified: 06 Jun 2017 16:12

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