Potential Effects of Phosphate Levels on Odonata Diversity in a NW Iowa Wetland Located in the Raccoon River Watershed

by Elizabeth McIntyre
Environmental Science
Faculty advisor: Dr. Melinda Coogan

As an important indicator of wetland system health, maintaining Odonata diversity in wetlands found within agricultural environments requires ongoing studies investigating various environmental parameters such as habitat modification, pesticide contamination, and nutrient concentrations. This spatial study investigated fall, 2010 phosphorus concentration levels and the potential effects on Odonata diversity of Blackhawk Lake Wetland, Iowa as well as two sites on the Raccoon River located equal distance above and below the wetland. Within each system, phosphorus levels, pH, conductivity, DO, and temperature assessments were conducted during the months of October and November, 2010. During the summer months, 2008, collections of Odonata were recorded and assessed through Shannon Diversity calculations. Results indicated the highest average phosphate level (15 ppm) and the lowest Odonata diversity level (1.33) were found within the Black Hawk Lake Wetland waters. The Raccoon River site results showed the same average phosphate levels (10 ppm), with the upstream site resulting in a diversity level of 1.75 and the downstream Whiterock site resulting in a diversity level of 2.40. Spring, 2011, water assessments of phosphate levels will be conducted, but our preliminary results show a trend of lower Odonata diversity within waters expressing higher phosphate levels.