My Space! A Study Of Gause’s Law Of Competitive Exclusion With Upper Ohio River Valley Crayfish. Data Conclusion Purpose & Hypothesis Orconectes (P.) rusticus – taken by finalist Orconectesprocericambarusrusticus (Rusty crayfish) is a crayfish native to southeast Ontario, Michigan, Ohio, Kentucky, and Tennessee. However, due to a number of factors, O. (P.) rusticus has become an invasive species in a number of states including Iowa, Illinois, Minnesota, New Mexico, Wisconsin, West Virginia, and most of the New England states. There are many theories as to why O. (P.) rusticus is an accomplished invader and the purpose of this project is to determine if O. (P.) rusticus has any specific behavioral patterns that give it any specific advantages over native species by observing the behavioral patterns of O. (P.) rusticus and its ecological equivalent, Orconectescrockerinusobscurus (Allegheny crayfish), when competing for a single shelter. I hope to gain a better understanding of the species O. (P.) rusticusby studying the behavioral patterns displayed in this experiment. Better understanding of this species I hope will lead to the development of better ways to control or even stop the spread of this invasive species. Successful control of O. (P.) rusticuswill lead to a growth of native flora and fauna, not only of native crayfish population, but also algae, fish, and other wildlife affected by the invasion of O. (P.) rusticus. My hypothesis is that O. (P.) rusticus will posses specific behavioral patterns that give it an advantage over native species of crayfish and allow it to be an accomplished invader. I hypothesize that because of these specific behavioral patterns, O. (P.) rusticus will be able to outcompete its ecological equivalent, O. (C.) obscurus , most of the time in a controlled environment. The data confirmed my original hypothesis that there are specific behavioral pattern that give O. (P.) rusticuscertain advantages over native crayfish species. Though no statistically significant difference was noted in aggression rates between the two species, the data strongly suggest that O. (P.) rusticus is statistically more likely to guard its shelter more effectively than O. (C.) obscurus (p<0.005), a behavioral pattern that could aid in its ability to invade and maintain residency, thus disrupting native species. By studying the invasive behavioral patterns of O. (P.) rusticus, I hope to develop better mechanisms of control of the invasive population, thus protecting native populations and ecosystems. Maps Orconectes (P.) rusticus– taken by finalist Orconectes (P.) rusticus – taken by finalist Materials & Methods Materials - Two tanks holding tanks, five tanks smaller test tanks, seven bubble stones, nine meters of tubing, three air generators, five large, flat rocks, five clay pot saucers, twelve kg. of gravel, four bricks with holes, goldfish pellet food, bait cage, seine net, seine net poles, aquarium net, drill, calipers, stopwatch, video camera, tripod, and crayfish. Method- Before the actual experiment, set up the tanks in an indoor area so that the two holding tanks are near each other and the five test tanks are nearby as well. Drill a hole in the side of each tank for the tubing. Next, place the air generators so that the tank receiving air is lower than the generators to prevent backflow and clogging. Once the generators are in place, run a tube from the tank to the generator and so it goes through the hole drilled earlier. Place a bubble stone on the end of the tube. After that, fill each tank with gravel, burying the bubble stores. Then place the bricks in each holding tank and set up the test tank. Do this by placing a large rock in the tank and the flower pot saucer on top of the rock, so it is propped up and is now a shelter. Then fill all seven tanks with water so the water level is a just slightly higher than the tallest structure in the tank and turn the air generators on. Now is the time to collect the crayfish needed for experimentation. To do this, go to an area in a creek known to have the crayfish species needed. Find a large rock or two, preferable with a noticeable current in the water. Place the sieve net around the rock or rocks so that when the rock is lifted, the current will push anything into the sieve net. Quickly lift the rocks while holding the net. After lifting the rocks, quickly lift the net using the poles to examine what was caught. Do this by lifting both poles and lifting evenly so the net remains right and is parallel to the ground. With some luck, there will be some crayfish in the net. Carefully select which ones you need and put those in the bait cage, releasing the rest. Once you have sufficient crayfish, store in the holding tank until trials. The two holding tanks hold the two separate species being tested. The five test tanks are for experimentation and should have five resident crayfish, one in each tank. The resident should have at least 3 days to establish its shelter before trials. Every day feed the crayfish with a pinch of slow-sinking goldfish pellets. Clean the tanks out once a month. To clean, put the tank’s residents in a temporary tank with water and a bubbler. Remove any structures (bricks or rocks) except the gravel. Dump out the water and continue to rinse and dump with the gravel until the water is clear. Refill the tank with water and replace the structures, bubblers, and crayfish into clean tank. For the trials, select the residents and invaders so that out of 60 trials, 30 trials are with O. (C.) obscurus as a resident and 30 trials are with O. (P.) rusticus as the resident. It should also be that 20 trials are male and male, 20 trials are male and female, and 20 trials are female and female. Before the trials, use the calipers to measure the carapace and record the time, date and carapace length and the invader’s sex and species. Next, set up the camera on a tripod looking down on the test tank. Turn on the camera, identify the trial by announcing the invader and date, and place the invader in the tank. Leave for fifteen minutes while the trial is being recorded. Return in 15 minutes, turn off the camera, and remove the invader. Before watching the trials, make a chart on paper with two columns and fifteen rows. The columns are for the behaviors and the rows are for each minute of the trial. Then watch the trial, making a note of behaviors every twenty seconds. After finishing watching, review the data and mark the behavior for each minute that was most prevalent. After performing 60 trials, and recording their behaviors, record the behaviors on a color coded spreadsheet to better view trends. Alphabetize the data to easily see any major trends in the data. Using the data, graph the data in bar graphs of trials to see any other trends.
Orconectes (P.) rusticus – taken by finalist Anatomy/ common names of the Crayfish Collection of Orconectes (C.) obscurus - taken by finalist’s father Site of experimentation – taken by finalist All pictures here were taken by finalist. Orconectes (C.) obscurusin seine net – taken by finalist