Do invertebrate communities in floodplains change predictably along a river's length?

摘要: Summary 1. Invertebrate assemblages were described for nine floodplain sites located on a longitudinal gradient of river discharge in the Altamaha River catchment. The and its tributaries constitute one few remaining ‘unregulated’ catchments southeastern U.S. We predicted that, as character lateral flood pulses into backwater swamps changed along gradient, so would structure invertebrate communities. also examined relationship between physicochemical factors (degree inundation, pH, conductivity nutrient concentrations). 2. Cluster analyses both abundance biomass separated three groups corresponding to their positions catchment (upper, mid- lower reach clusters). Non-metric multidimensional scaling ordinations further corroborated groupings (with combined axis scores 92% 73% biomass, respectively) showed significant correlations with degree inundation (abundance), conductivity, nitrate phosphate concentrations (biomass). 3. Floodplains upper reaches dominated by terrestrial taxa, such earthworms, oribatid mites, collembolans assorted fly larvae, some rapidly developing aquatics (harpacticoid crustaceans mosquitoes). In mid-reach, dominant taxa longer lived aquatic organisms mayflies oligochaetes, although (elaterid beetles mites) still common. families dependent water flow, riffle mayflies, common only mid-reach sites. Lower lentic dytiscid asellid isopods, which commonly persist wetlands after they dry. 4. Our study indicates that community varies predictably among floodplains catchment, headwater habitats being rapidly-developing invertebrates, mid-reaches characterised an influx invertebrates from wetland desiccation-resistant stages. This spatial variability should be considered when applying Flood Pulse Concept.