Presentation on theme: "Background The larval form of Odonata is extremely different from the adult form. The reason that the anatomy is different is because the larval stage."— Presentation transcript:
Background The larval form of Odonata is extremely different from the adult form. The reason that the anatomy is different is because the larval stage has to be able to cope with the different aquatic habitats (Glotzhober and McShaffrey, 2002, 8). The larval stage has very different legs, body shape, a hinged labium, and is also lacking wings (Glotzhober and McShaffrey, 2002, 8). The larval stage of the genus Macromia prefers to live within small to medium sized streams where they are able to withstand the currents (Glotzhober, McShaffrey, 2002, 246). This genus is also described as a sprawler and hider. A few species will spread their legs and lay flat, burying their body with sediment during the day and foraging at night (Corbet, 1999, 52). Only three species of this genus have been found in the Little Muskingum River (Ohio Odonata Survey Database). Another part of this project was to collect Hagenius larvae. This dragonfly larva looks like a leaf, and it is considered to be a hider because its habitat consists of bark and leaf-litter which it lies in (Corbet, 1999, 154). These larvae are commonly found in silt-sand sediment along banks as well as in leaf litter in rivers or streams (Burcher, 2002, 85). Objective To survey and collect Macromia and Hagenius larvae from the Little Muskingum River. This research will show what types of habitats that these genus of dragonflies prefer. Hypothesis Several species of Macromia and Hagenius in the Little Muskingum River will divide the river habitat up by inhabiting riffles vs. pools or by sections of the river. Null Hypothesis Macromia and Hagenius will be found in pools throughout the Little Muskingum River in random places. Collecting of the specimen occurred during fall of 2010. Collecting took place in accessible areas, as well as areas where the larva is described to live. Other types of habitats were samples as well, such as the middle of the river. To collect the larva, aquatic dip nets were used to get down into sediments. Another person holding an aquatic kick screen stood downstream of where sampling occurred, in case larva got picked up by the current. These techniques were modeled after an article titled The Structure of Larval Odonate Assemblages in the Enoree River Basin of South Carolina by Wade Worthen. Larvae were then placed into jars and the habitat was recorded. All Odonata larvae were the key objects of the collection. The reason that all Odonata were collected is so that they could be properly identified to eliminate potential error. Each specimen was taken back to the lab where it was identified to genus and species. Taxonomic keys were used to identify each species. The key that was used for this experiment was Dragonflies of North America by James Needham, Minter Westfall Jr, and Michael L. May. Once all of the collected specimens were identified, the habitat from which they were collected was analyzed. Habitat use by larval Macromia and Hagenius (Insecta: Odonata) within the Little Muskingum River Nicole Stone Advisor: Dr. McShaffrey Introduction A total of 9 sites were sampled throughout the collection period. There were 341 Odonata larvae collected. Of the total number of Odonata collected, 181 were Macromia larvae and 26 were Hagenius larvae. In all, there were 12 different taxa within the collection. Figure 1: Macromia and Hagenius species preference of pools vs. riffles. Figure 1 shows that Macromia illinoiensis had a preference for riffles and Hagenius brevistylus a preference for pools. Figure 2: Macromia and Hagenius preference for different types of habitat. The hypothesis that species would divide the river by riffles and pools was partially supported. Macromia illinoiensis preferred riffles and Hagenius brevistylus preferred pools. However, Macromia taeniolata and Macromia pacifica were found in both the riffle and pool habitats, which supports the null hypothesis that the species would randomly divide the river. Also the collection showed that Macromia species preferred habitats located down river in areas of the middle of the river and leaf litter. Hagenius preferred habitats up river in areas that consisted of snags and leaf litter. This distribution shows that the Little Muskingum River is able to support these aquatic organisms. The river has the types of habitats that support these species as well as generally clean water. Some interesting observations with this experiment were that smaller Macromia were located in the central region of the river while larger specimens were found along the banks of the river in silty sediment. In research articles, Macromia were mainly found around banks of the river as well as snags (Burcher, 2002, 78). However, in the Little Muskingum River, Gomphidae and Aeshnidae were commonly found along the banks, perhaps displacing Macromia. Also, the Macromia found in the center of the river were of a lighter color and those found in decomposing leaf litter were of a darker color, matching the color of the decaying leaves. Lastly, Hagenius larvae were located in leaf litter and snags, which correlated with the articles used for research on this species (Corbet, 1999, 154). Hagenius was generally found alone in snags or leaf litter. Burcher C, Smock L. 2002. Habitat distribution, dietary composition and life history characteristics of Odonate nymphs in a Blackwater Coastal plain stream. American Midland Naturalist: 148 (1): 75-89. Corbet P. 1999. Dragonflies; behavior and ecology of Odonata. Ithaca (NY): Cornell University Press: 30-160. Glotzhober R, McShaffrey D. 2002. The dragonflies and damselflies of Ohio. A project of the Ohio Odonata Society sponsored by the ODNR. Columbus (OH): Ohio Biological Survey; 364p. Needham J, Westfall M, May M. 2000. Dragonflies of North America. Gainesville (FL): Scientific Publishers, Inc; 95-868. Worthern W. 2002. The structure of larval Odonate assemblages in the Enoree River Basin of South Carolina. Southeastern Naturalist; 1 (3); 205-216. I would like to thank Dr. McShaffrey for being my capstone supervisor and helping with my overall project. Dr. Brown for being such a great capstone professor. Ken Tennessen and Bob Glotzhober for taking the time to help with the identification of my specimen. And lastly, I would like to thank Mike Pankowski for being a stellar field assistant. Figure 3: The distribution of Odonata throughout the sample sites. Results Materials and Methods Discussion Literature Cited Acknowledgments Figure 2 shows that Macromia illinoiensis preferred sandy substrates. Macromia pacifica preferred leaf litter and sand. Hagenius brevistylus preferred leaf litter and snags, while Macromia taeniolata had no clear preference. Figure 3 shows that Macromia spp. larvae preferred habitats located downstream while the Hagenius larvae preferred habitats located upstream.