TRANSFERABILITY OF HYDRAULIC PREFERENCE MODELS FOR AQUATIC MACROINVERTEBRATES

Quantifying the transferability across stream reaches and sampling occasions of models relating the density of aquatic taxa to microhabitat hydraulics are important for increasing our understanding of the mechanisms explaining microhabitat selection. We revisited data collected at multiple occasions in two regions, that is, in nine reaches of seven German streams and in four reaches of a large French river, to provide detailed information by taxon on the transferability of hydraulic preferences of aquatic macroinvertebrates. In each region and for each taxon, we tested the statistical significance of a regional preference model relating density to microhabitat hydraulics simultaneously in all surveys (i.e. reach–occasion combinations). The transferability of hydraulic preferences was assessed using cross‐validation procedures within each region. The regional models showed significant associations with microhabitat hydraulics for 56% of the 151 taxa collected in Germany and for 67% of 66 taxa in France. Cross validations indicated that regional models significantly explained density variations within independent surveys for 60% of the cases in Germany and 54% in France. We conclude that both regional and survey‐specific models are useful in specific studies, depending on the taxa considered and the spatial extent and objectives of the application. Graphs of all raw data and models are supplied as supporting information. Copyright © 2012 John Wiley & Sons, Ltd.