The use of invertebrate functional groups to assess ecosystem attributes.

P.C. Andrade and M.B. Berg. Department of Biology, Loyola University Chicago, Chicago, IL, USA

The structure and function of streams can be evaluated by directly measuring ecosystem attributes, however these can be costly and time intensive. In contrast, functional analyses of invertebrate communities are more economical and can be used as surrogates of direct attribute measurements. The objective of this study was to assess whether functional group analyses reflect true ecosystem attributes. Three ecosystem attributes (primary production as a proportion of community respiration (P/R), coarse particulate organic matter as a proportion of fine particulate organic matter (CPOM/FPOM), and suspended particulate organic matter as a proportion of benthic particulate organic matter (SPOM/BPOM)) were evaluated based on direct measurements and functional groups. Ecosystem attributes and functional groups were assessed in seven sites, four runs and three riffle areas, in a midwestern stream that was restored from agricultural activities. Direct measurements of ecosystem attributes were conducted using P/R chambers, and by collecting water and benthic sediment samples. Functional group surrogates were assessed using 30–s kick samples to collect benthic invertebrates. Preliminary results show that invertebrate functional analysis can be a good predictor of ecosystem attributes and that functional group ratios based on biomass better reflect direct measurements than those based on densities.