Leaf Litter Decomposition and Macroinvertebrate Communities of a 6th Order Blackwater River in the Southeastern Coastal Plain

To examine the role of consumers on organic matter processing, we sampled benthic macroinvertebrates, litter decomposition, and litterbag invertebrates in a 6th order reach of the Ogeechee River. Macroinvertebrates were sampled in riffles, runs, and pools using Surbers, kicknets, and cores. Litter decomposition and colonizing invertebrates were examined by placing litterbags filled with oak (  Quercus  sp.) or maple ( Acer  sp.) leaves in the stream over a 56d period. Benthic macroinvertebrate community composition was dominated by scrapers (77%) with snails accounting for most scraper abundance. Collectors (gatherers 11%; filterers 7%) and predators (4%) accounted for the remaining ~1/4 of the benthic community, while shredders were poorly represented (<1%). Decomposition rates (k) ranged between -0.02 to -0.04 for Quercus  and  Acer , respectively, suggesting that both litter types break down quickly in this system. Total macroinvertebrate abundance in litterbags was highest after 56d, but differed little between leaf types. Macroinvertebrates colonizing litterbags were also dominated by grazing snails with  Pleurocera  accounting for most consumer biomass. Results suggest that leaf breakdown in this system may be more readily associated with factors other than invertebrates.