Effects of benthic barriers on aquatic habitat conditions and macroinvertebrate communities

Physical and chemical conditions of sediments and benthic community composition were evaluated under synthetic fabric barriers, used to control aquatic macrophytes in confined areas. Macroinvertebrate density declined by 69% within 4 weeks at Eau Galle Reservoir, WI. Within a few weeks of placement at ponds near Dallas, TX, invertebrate densities declined by more than 90%. At Eau Galle Reservoir, benthic barriers apparently blocked sedimentation and caused an increase in NH4 and a decline in dissolved oxygen to near zero beneath the fabric. Barriers reduced macroinvertebrate taxa richness at both locations. Community effects were most severe in warm water; Chironomidae was eliminated by barriers at the Texas ponds. Barriers substantially reduced macroinvertebrate density and altered community composition; however, biotic conditions in affected areas recovered rapidly after barrier removal.