BIOLOGICAL GUIDELINES FOR FRESH-WATER SEDIMENT BASED ON BENTHIC ASSESSMENT OF SEDIMENT (THE BEAST) USING A MULTIVARIATE APPROACH FOR PREDICTING BIOLOGICAL STATE

This paper describes the first results for an alternative approach to the development of sediment quality criteria in the nearshore areas of the Laurentian Great Lakes. The approach is derived from methods deve loped in the United Kingdom for establishing predictive relationships between macroinvertebrate fauna and the physico-chemistry, of riverine environments. The technique involves a multivariate statistical appro ach using (i) data on the structure of benthic invertebrate communitie s, (ii) functional responses (survival, growth and reproduction) in fo ur sediment toxicity tests (bioassays) with benthic invertebrates; and (iii) selected environmental variables at 96 reference ('clean') site s in the nearshore areas of ail five Great Lakes (Lakes Superior, Huro n, Erie, Ontario and Michigan). Two pattern recognition techniques (us ing the computer software package PATN) are employed in the analysis: cluster analysis and ordination. The ordination vector scores from the original axes of the pattern analysis are correlated (using CORR in S AS) with environmental variables which are anticipated to be least aff ected by anthropogenic activities (e.g. alkalinity, depth, silt, sodiu m etc.). Multiple discriminant analysis (MDA) is used to relate the si te groupings from the pattern analysis to the environmental variables and to generate a model that can be used to predict community assembla ges and functional responses at new sites with unknown but potential c ontamination. The predicted community assemblages and functional respo nses are then compared with the actual benthic communities and respons es at a site, and the need for remedial action is determined. The pred ictive capability of the discriminant model was confirmed by performin g several. validation runs on subsets of the data. An example of the u se of the model for sediment in Collingwood Bay (an area of concern de signated by the IJC in Georgian Bay, Lake Huron) is presented and the technique is shown to be more precise in determining the need for reme diation than the currently used provincial sediment quality criteria b ased on Screening Level Concentration (SLC) and laboratory toxicity te sts. The ultimate goal of the study is the development of a method to determine the need for, and the success of, remedial action and to pre dict what benthic communities should look like at a site if it were cl ean and what responses of organisms in sediment toxicity tests constit ute an acceptable end-point.