Importance of flood regime to invertebrate habitat in an unregulated river–floodplain ecosystem

Abstract

AbstractUnlike most large rivers of the northern hemisphere, several medium-sized rivers in the southeastern USA Coastal Plain remain unregulated. These smaller rivers possess 2 habitat types (snags and floodplain) that were historically important for invertebrate assemblages in many rivers and are strongly dependent on flood regime. I reviewed and compared 2 models of habitat inundation (snags and floodplain) that were developed for the Ogeechee River (Georgia, USA) to understand the ecological significance of these habitats. These models showed that snag habitat surfaces varied from only ∼20 to 50% of channel bottom surfaces, but floodplain inundation varied from 0 to 37 times the width of the channel at 100% inundation. Long-term analysis of inundation patterns from a 58-y record of discharge demonstrated that substantial flooding occurred almost annually for 1 to 2 mo/y. Habitat-specific invertebrate biomass was highest on snags (mostly aquatic insects), followed by the main channel (dominated by Corb...