BENTHIC MACROINVERTEBRATE COMMUNITY STRUCTURE, FUNCTION AND PRODUCTION WITH RESPECT TO HABITAT TYPE, REACH AND DRAINAGE-BASIN IN THE SOUTHERN APPALACHIANS (USA)

1. Benthic macroinvertebrates were sampled for 1 year to assess functi onal and taxonomic differences in invertebrate biomass and production with respect to habitat types, reaches and catchments in Wine Spring B asin, western North Carolina. Quantitative samples were collected from depositional, cobble-riffle and bedrock outcrop habitats at four stre am 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 catchme nt were also compared with data from another catchment (Ball Creek) wi thin the same region. 2. The three habitat types had different current velocities and mean substratum particle sizes; both measures were gre atest in bedrock outcrop habitats and lowest in depositional habitats. Organic matter standing crops, invertebrate functional group producti vity and biomass also differed significantly with respect to habitat t ype. Cobble-riffle areas had the lowest standing crops of organic matt er, invertebrate productivity and biomass. 3. Both invertebrate commun ities 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 fun ctional group productivity and biomass. 4. Annual mean invertebrate bi omass and secondary production were greater in the Wine Spring Basin t han in Ball Creek. Sites in both the Wine Spring and Ball Creek catchm ents, however, exhibited similar functional group distributions per ha bitat type. 5. Local geomorphology and related physical parameters inf luenced the structure of invertebrate functional group composition, an d the distribution of organic matter standing crops. Furthermore, comp arison of community structure in Wine Spring with that in Ball Creek s uggested that taxonomic composition was more related to catchment-spec ific parameters (e.g. thermal regime, evolutionary history) than strea m size.