Wednesday, June 6, 2007 - 2:45 PM
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Relationships between macroinvertebrate community attributes and common carp occurrence in recently constructed wetlands

Timothy W. Stewart, Department of Natural Resource Ecology and Management, Iowa State University, Ames, IA 50010

I quantified macroinvertebrate community characteristics and environmental features in three wetland complexes (n = 9 ponds) that are intended to filter pollutants from surface water flowing toward a nearby lake.  In 2005, two years after wetland construction, total macroinvertebrate biomass and densities in ponds were positively related to coarse particulate organic matter (CPOM) abundance and negatively related to turbidity (p < 0.001; R2 = 0.92 and 0.94, respectively).  Macroinvertebrate taxa richness and total snail densities were also negatively related to turbidity (p < 0.018; r2 > 0.57), whereas mayfly (Caenidae) and chironomid (Chironomidae) densities were positively related to CPOM (p = 0.001; r2 > 0.69).  Turbidity was highly correlated with common carp (Cyprinus carpio) occurrence (r = 0.85), and the two ponds with carp had the highest turbidity and lowest CPOM in 2005.  Comparison of 2004 and 2005 results from the carp-infested complex revealed 50% and 90% declines in total macroinvertebrate biomass and chironomid densities between 1-2 years after wetland construction.  Results are similar to those from studies of other ecosystems, where carp reduced macroinvertebrate abundance and diversity by predation and habitat destruction.  By consuming macroinvertebrates and preventing macrophyte growth, carp reduce the capacity of a wetland to filter pollutants.