Aquatic Macroinvertebrates and Water Quality Characteristics in Five Wetland Types: Preliminary Results on Biomonitoring
Golladay, Stephen W.
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In southwest Georgia, wetlands can be classified based on source of inundation and vegetation. Depressional wetlands are inundated predominantly through rainfall and are identified as grass-sedge marshes, cypress savannas, and cypress-gum swamps. Riparian sloughs, composed of cypress and gum, occur along river corridors and are flooded when rivers are at high flow. During 1998-2000, we sampled water and aquatic invertebrates in replicates of these 4 wetland types, as well as, agriculturally disturbed marshes. Multivariate analysis indicated that sloughs had the highest levels of inorganic carbon and pH, which we attributed to river water inputs. Compared to the other depressional wetlands, disturbed marshes had approximately five-fold higher PO₄₋P concentrations. Disturbed wetlands most likely derive nutrient inputs from soil and fertilizer runoff from nearby agricultural fields. Macroinvertebrate communities were similar between sloughs and swamp sites given that both wetland types had rather low diversity and numbers. Marsh and disturbed wetlands were also comparable and characterized by Belostomatidae and Tropisternus. Vegetation appears to be the primary factor that determines macroinvertebrate assemblages. Preliminary results indicated that of the proposed 31 metrics four were potentially capable of distinguishing disturbed and reference marshes with the best metrics being % isopods and % scavengers. Ongoing research will confirm whether these metrics can be used to monitor impacted/restored wetlands.