Date of Award
Master of Science
Natural Resource Ecology and Management
Timothy W. Stewart
Macroinvertebrates of open-water habitat in 17 semipermanent and permanent prairie pothole wetlands of north-central Iowa were quantitatively sampled in June 2007. Several macroinvertebrate community characteristics (i.e., metrics) were quantified, including metrics based on biomass, numerical densities, and taxonomic diversity. Several environmental features of each wetland were also measured. Land cover within a 50-m radius of each wetland was recorded in terms of % agriculture, % grassland, % tree/woodland, % urban, and % water. Physicochemical features measured within wetlands included dissolved oxygen, total nitrogen, total phosphorus, pH, temperature, and turbidity. Additional biological features that were measured included coarse particulate organic matter (CPOM) abundance (i.e., living and nonliving plants) and presence or absence of predaceous fish and salamanders. Multiple regression analyses and nonmetric multidimensional scaling ordination were used to examine relationships between macroinvertebrate metrics and environmental features. A total of 44 macroinvertebrate taxa were recorded from wetlands and overall taxa composition was typical of most Midwestern USA and prairie pothole wetlands. Of 52 macroinvertebrate metrics that were measured, 32 were significantly related to one or more environmental features. CPOM abundance and turbidity (and nitrogen and phosphorus that were highly correlated with turbidity) were strongly associated with macroinvertebrate community characteristics and appeared to be the greatest causes of community variability across wetlands. CPOM and turbidity, respectively, were consistently positively and negatively related to several biomass, density, and diversity metrics. Based on nature and strength of relationships between metrics and environmental features that were quantified in this and previous studies, I complied a set of eight metrics (total macroinvertebrate biomass as ash-free dry weight, Chironomidae density, Amphipoda density, total Mollucsa density, total Ephemeroptera, Odonata, and Trichoptera (EOT) density, total Coleoptera density, EOT taxa richness, and total taxa richness) that should be considered for use in an ecosystem health index for prairie pothole wetlands in Iowa. Wetlands receiving high scores and ranks in a preliminary ecosystem health index that was based on these metrics also had higher CPOM abundance and lower turbidity than wetlands with low index scores. In conclusion, my results suggest that wetland ecosystem health and functionality would be improved by management strategies that enhance CPOM abundance and reduce turbidity. Additionally, measurement of CPOM, turbidity, and a standard set of macroinvertebrate metrics should be considered as a future standard practice in wetland ecosystem health monitoring programs. Although the candidate set of metrics described above appears to be a reliable bioassessment tool, research is still needed to identify the most reliable set of metrics, in addition to developing an effective, user-friendly ecosystem health index based on these metrics.
Valerie Ann Hentges
Hentges, Valerie Ann, "Macroinvertebrate community characteristics and related environmental features in prairie pothole wetlands of Iowa" (2008). Graduate Theses and Dissertations. 10639.