Benthic Macroinvertebrates Colonizing Leaf Packs in the Ogeechee River Near Rocky Ford: Contrasting Assemblages Between Drought vs. Wet Years

<p> During the Fall of 2012 approximately 56% of the state of Georgia experienced moderate-to-exceptional drought conditions. During this time, the lower Ogeechee River exhibited abnormally low river stages and reduced &fllig;ow conditions. During the same time period the following year (2013), river stages and dis-charge returned to average conditions in part due to a wet summer season. We used packs &filig;lled with oak (Quercus sp.) or maple (Acer sp.) leaves to collect colonizing invertebrates from September to November of 2012 and 2013 as a means for assessing the health and condition of a reach of the Ogeechee River near Rocky Ford (Screven County). We found significant differences in macroinvertebrate assemblages between study years (p=0.001). However, there were no differences in colonizing communities between leaf types (p=0.05). Pleurocerid snails and non-predatory chironomids (85% combined) contributed most to macroinvertebrate assemblages in 2012, while non-predatory chironomids, longhorned caddisflies, and &fllig;atheaded may&fllig;ies (83%) contributed most to assemblages in 2013. Macroinvertebrate functional feeding group composition also differed between study years with scraper-grazers (61%) and collector-gatherers (28%) being dominant in 2012 and collector-gatherers (79%) as the major contributors in 2013, suggesting differences in organic matter resources from year to year. Biotic index estimates (i.e., NCBI) yielded a slight increase from 2012 (4.81&plusmn;0.75) to 2013 (5.43&plusmn;0.61) indicating fairly substantial organic pollution likely at the site. However, %EPT taxa increased from 10% to 33% from 2012-2013. Our study supports a need for multi-year, continuous monitoring to accurately assess the health and biotic integrity of these systems.</p>