Publication Abstract

Application of multivariate statistics to ecotoxicological field studies

S. Maund, P. Chapman, T. Kedwards, L. Tattersfield, P. Matthiessen, R. Warwick and E. Smith

Ecotoxicological field studies are now an established component of ecological risk assessments. The purpose of such studies is usually to evaluate, under field conditions, the potential for unacceptable effects on populations or communities within the ecosystem. Recent symposia in Environmental Toxicology and Chemistry have discussed the performance and use of community and ecosystem studies in risk assessment for a variety of ecosystem types . Analyzing and interpreting the results of these studies remains one of the major challenges. It requires not only in-depth ecological knowledge but also tools for presenting and analyzing large, complex data sets in a meaningful way. Furthermore, since these studies should be focused on effects at the community and ecosystem levels, analysis and interpretation should be performed at the same level.

Analysis of field studies has relied mainly on traditional univariate statistics, which can bring a number of problems relating to power and experimental variability. It is often limited to a single or a handful of variables at one time, making overall assessment of effects on the community or ecosystem difficult. Furthermore, with the vast number of potentially confounding variables that can affect population dynamics, such approaches can lead to problems in determining cause and effect.

Using techniques that deal with a large number of variables at one time allows inferences to be drawn about responses to the toxicant and makes presentation of data in a tractable form possible. Multivariate statistical approaches offer such a solution, and now a range of tools are readily available to most ecotoxicologists. Previously, these may have been beyond the grasp of most ecotoxicologists either because of computational demands or impenetrable statistics and software. However, many of these techniques have their origins in community ecology and are therefore readily applicable to ecotoxicological field studies. Issues and techniques were discussed at a workshop held prior to the 1996 SETAC Annual Meeting in Washington, DC, USA; the papers in this special section represent a portion of the results of this meeting.

Reference:

S. Maund, P. Chapman, T. Kedwards, L. Tattersfield, P. Matthiessen, R. Warwick and E. Smith, 1999. Application of multivariate statistics to ecotoxicological field studies. Environmental Toxicology and Chemistry, 18: 111-112.