EFFECTS OF BENTHIC BARRIERS ON AQUATIC HABITAT CONDITIONS AND MACROINVERTEBRATE COMMUNITIES

Physical and chemical conditions of sediments and benthic community co mposition were evaluated under synthetic fabric barriers, used to cont rol aquatic macrophytes in confined areas. Macroinvertebrate density d eclined by 69% within 4 weeks at Eau Galle Reservoir, WI. Within a few weeks of placement at ponds near Dallas, TX, invertebrate densities d eclined by more than 90%. At Eau Galle Reservoir, benthic barriers app arently blocked sedimentation and caused an increase in NH4 and a decl ine in dissolved oxygen to near zero beneath the fabric. Barriers redu ced macroinvertebrate taxa richness at both locations. Community effec ts were most severe in warm water; Chironomidae was eliminated by barr iers at the Texas ponds. Barriers substantially reduced macroinvertebr ate density and altered community composition; however, biotic conditi ons in affected areas recovered rapidly after barrier removal.