Leaf Decay Rates and Litter-Dwelling Invertebrates in Georgia Coastal Plain Rivers

Leaf litter processing rates and the concomitant macroinvertebrate assemblages were studied in main-channel habitats of three Coastal Plain rivers in Southeast Georgia: Altamaha, Ogeechee, and Savannah. Study sites were chosen to assess the effects of flow regime, particularly the magnitude of discharge, on leaf litter breakdown and community structure. Ninety-six single-species packs of water oak leaves were deployed in mid-September 2014 and retrieved at two-week intervals over an eight-week period. During the study period, a distinct gradient in discharge was observed (average Q = 150.8, 75.3, and 8.2 m3/s on the Savannah, Altamaha, and Ogeechee, respectively). Among basins, mean leaf litter processing coefficients (k) ranged from medium to fast (range: -0.0077 to -0.0129). Overall, species composition was similar between basins. Chironomidae was the most abundant taxon in all assemblages, with nearly half (48.2%) of the Ogeechee’s total abundance attributed to midges. In the Altamaha, hydrobiid snails were the second most common taxon (15.4%). Over one quarter (25.6%) of the Savannah’s assemblage was composed of caddisflies, with Hydropsychidae being the dominant family (14.1%)