Benthic macroinvertebrate community structure, function and production with respect to habitat type, reach and drainage basin in the southern Appalachians (U.S.A.)

1. Benthic macroinvertebrates were sampled for 1 year to assess functional and taxonomic differences in invertebrate biomass and production with respect to habitat types, reaches and catchments in Wine Spring Basin, western North Carolina. Quantitative samples were collected from depositional, cobble-riffle and bedrock outcrop habitats at four stream reaches (two headwater sites, one second order, and one third order). Other measures included physical parameters, periphyton and organic matter standing crops. Invertebrate data from the Wine Spring catchment were also compared with data from another catchment (Ball Creek) within the same region. 2. The three habitat types had different current velocities and mean substratum particle sizes; both measures were greatest in bedrock outcrop habitats and lowest in depositional habitats. Organic matter standing crops, invertebrate functional group productivity and biomass also differed significantly with respect to habitat type. Cobble-riffle areas had the lowest standing crops of organic matter, invertebrate productivity and biomass. 3. Both invertebrate communities and organic matter standing crops differed significantly between the two headwater reaches. First- to third-order reaches differed in taxonomic composition at the genus level, yet had similar relative functional group productivity and biomass. 4. Annual mean invertebrate biomass and secondary production were greater in the Wine Spring Basin than in Ball Creek. Sites in both the Wine Spring and Ball Creek catchments, however, exhibited similar functional group distributions per habitat type. 5. Local geomorphology and related physical parameters influenced the structure of invertebrate functional group composition, and the distribution of organic matter standing crops. Furthermore, comparison of community structure in Wine Spring with that in Ball Creek suggested that taxonomic composition was more related to catchment-specific parameters (e.g. thermal regime, evolutionary history) than stream size.