1. Background The monitoring of our natural environment is becoming an increasingly important matter. With the human population reaching 7 billion, more and more wastes are being dumped into the environment. It is important to continue to monitor the environment so that the effects humans are having on it can be evaluated. One way of doing this is through the use of biological indicators, or bioindicators. Different organisms can be used as bioindicators, for the purpose of this study aquatic invertebrates were used. Aquatic invertebrates are a good bioindicator due to the fact that they are sensitive to many different materials (Walsh et al., 1982, 879). Thus the presence or absence of these organisms allows the overall health of a particular ecosystem to be evaluated. Dragonflies and their larvae are particularly useful in this endeavor (Simaika, Samways, 2011, 371). In this study aquatic invertebrates were used to assess the overall health of the Kokosing River in central Ohio. The Kokosing River is a 57 mile long river that drains an area of 482 square miles. The Ohio EPA rates the Kokosing River as one of the more healthy waterways in Ohio (Ohio EPA). The Kokosing travels through a small city, as well as many other areas where anthropogenic factors could have a potential impact. Objective To survey the Kokosing River with a focus on Odonata, as well as to determine if anthropogenic factors have an effect on the diversity and abundance of aquatic invertebrates. Hypothesis Sites experiencing fewer anthropogenic factors will have a higher invertebrate abundance and greater diversity. Five sites were chosen based on their proximity to anthropogenic factors. All sites were easily accessible, and previously sampled by the Ohio EPA in past surveys (Ohio EPA). The sites were sampled during late summer 2012. Qualitative and quantitative sampling methods were used. The qualitative testing was conducted by the use of a d-ring net, and strictly odonata larvae were collected with this method. Quantitative testing was performed through the use of a surber sampler, all aquatic invertebrates were collected during the quantitative testing phase. After collection the invertebrates were indentified. All odonata were identified to species through the use of Dragonflies of North America by James Needham, Minter Westfall Jr, and Michael L. May. The rest of the invertebrates were identified to order (family when possible) via Aquatic Insects of Wisconsin by William Hilsenhoff. After identification of the insects, the sites were then analyzed by the diversity, and abundance of the collected specimens. Anthropogenic Factors Effect On Invertebrate Population Chase Oberfield Advisor: Dr. McShaffrey Introduction Ninety-one odonata were collected from the 5 sites via the qualitative sampling. There were 10 different species identified. Quantitative testing yielded the relative abundance of invertebrates found at each site which can be seen in Figure 2. Figure 1: Sample Sites Figure 1 shows the Kokosing River, as well as the sites surveyed. The map is oriented with north being towards the top, and the flow of water being from west to east. Figure 2: Quantitative Results: Relative Abundance at each Site. The hypothesis that sites experiencing fewer anthropogenic factors will have a higher invertebrate abundance and greater diversity is partially supported. The abundance portion of the hypothesis agrees whereas the diversity portion is inconclusive. Figure 2 shows that the Farm, Killduff and Jelloway area all have much higher invertebrate abundance then Mt. Vernon and Waste Water. Literature states that areas that have anthropogenic impacts such as habitat modification, and altered water chemistry will have negative effects on invertebrate populations (Malmqvist, 2002, 135). Both of the sites with low abundance are subject to both of these criteria, which could attribute to the low abundance found at these sites. This same trend was not seen when species diversity was analyzed at each site. Figure 3 shows the amount of species found at each site. The Farm, Mount Vernon, and Jelloway sites all have similar amounts of species diversity. However Killduff road has a significantly higher amount of species, and Waste Water had no species found at all. Based on the variation in the data no solid conclusion could be made. The variation seen in the data could be product of several factors. The time of year the samples were collected were not optimal for many of the odonata, as many of them have grown into adults and have flown from the water(Dr. Dave McShaffrey, Personal Communication, 2012). Also there were relatively few samples taken at each site. I would like to thank Dr. McShaffrey for advising me on this project. I would also like to thank Marietta College for providing the materials needed to complete this study. I would also like to thank my parents for letting me keep dead bugs in the house over the summer. Figure 3: Number of Odonata Species at Each Site. Results Materials and Methods Discussion Literature Cited Acknowledgments Figure 2 shows that the Farm, Killduff, and Jelloway areas, had the highest abundance, while Mt. Vernon, and the Wastewater area had much lower relative abundance. Figure 3 Shows that the Farm, Mt. Vernon, and Jelloway all had similar species diversity. Killduff was the most diverse site. No odonata were caught at the Waste Water site Malmqvist B, Rundle S. 2002. Threats to the running water ecosystems of the world. Environmental Conservation 29: 134-153 Ohio EPA (Environmental Protection Agency). 2007. Biological and water quality study of the Kokosing River watershed. EAS/2010-05-09. State of Ohio Environmental Protection Agency. Division of Surface Water. Columbus, Ohio. Simaika JP, Samways MJ. 2011. Comparative assessment of indices of freshwater habitat conditions using different invertebrate taxon sets. Ecological Indicators 11(2011): 370-378 Walsh GE, Duke KM, Foster RB. 1982. Algae and crustaceans as indicators of bioactivity of industrial wastes. Water Research 16(6):879-884.