Influence of habitat heterogeneity and bed surface complexity on benthic invertebrate diversity in a gravel-bed river

Maintaining or restoring physical habitat diversity is a central tenet of sustainable river management, yet a link between habitat and ecological diversity in fluvial systems has long remained equivocal. The lack of consistent evidence partly reflects the problems of characterizing habitat in ways that are ecologically meaningful. This paper assesses the influence of habitat heterogeneity and complexity on macroinvertebrate assemblages in a mountain gravel-bed river. With the use of 0.1-m resolution data obtained from an acoustic Doppler current profiler, heterogeneity and complexity in hydraulic conditions and bed topography were characterized using 13 metrics applied to 30 areas, each 1 m(2), with an invertebrate sample collected from each area. Turnover of invertebrate taxa (i.e., beta-diversity) between sampled areas was rather limited, but observed differences in diversity were related significantly to several metrics of habitat heterogeneity. Invertebrate abundance was related to habitat diversity, patch size coefficient of variation, and patch size, whereas the Shannon diversity was related to the number of patches and patch size. None of the habitat complexity metrics accounted for a significant amount of observed variation in invertebrate communities between sampled areas. The paper demonstrates that high-resolution data can help reveal relationships between habitat and benthic invertebrate diversity.