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Investigation of Chemical Signals for Improving Trapping Efficiency and Preventing Further Expansion of Invasive Crayfish Species

Invasive crustacean species disturb existing food webs, macrophyte, benthic invertebrate and fish populations, and negatively affect overall ecosystem function (Hill and Lodge, 1999; Khulman and Hazelton, 2007). In Central Pennyslvania, the invasive Orconectes rusticus and Orconectes obscurus have invaded aquatic habitats, dominating the Susquehanna River and many of its tributaries while displacing native species (Lieb et al., 2011). Unfortunately, current practices to prevent further crustacean expansions have not been successful. Therefore, the main objectives our work have focused on 1) increasing public education about invasive species, 2) increasing our understanding of chemical communication in crayfish for potential development of pheromone baited traps that could enhance existing trapping methods, and 3) understanding distribution and possible hybridization of invasive crustaceans in local watersheds.

To address our first objective, we developed and held workshops for science teachers in the local schools. The workshops introduced teachers to the local invasive crustacean species O. rusticus and ways that these animals can be used as study organisms to address topics of biodiversity and biological invasions in specific lesson plans that meet the Pennsylvania Biology curriculum. Thirteen teachers attended the workshops and we have established an ongoing collaboration from teachers in two nearby schools.

To address our second objective, we have been conducting multiple studies that have help lay the groundwork for our ongoing research. We have designed and built a flow-through pheromone sampling tank that allows us to assess pheromone discrimination in crayfish. Using this behavioral paradigm, we have begun conducting experiments to assess how O. rusticus respond to same-sex and different-sex conspecific pheromones. We are expanding these pheromone discrimination assays to increase sample size and to include hetersospecific pheromones, as well as pheromones from individuals of different social status.

Furthermore, to understand the extent of the spread of invasive crayfish in Central Pennsylvania, we began sampling local watersheds and assessing the crustacean diversity in select Susquehanna River tributaries. We conducted molecular studies to better understand the specific geographical sources of the O. rusticus species that we found in our local watershed.

In conclusion, the funds from the Pennsylvania Sea Grant have allowed us to develop methods tailored to investigating crayfish chemical communication and to begin investigations, laying the groundwork for future development of pheromone-based traps to help manage invasive crayfish populations. Furthermore, with education workshops, we have been able to reach multiple schools with content that will increase awareness of biodiversity, expose students to environmental issues that are affecting their communities, and provide them with tools to help attenuate some of these impacts. Our sampling studies are an ongoing effort that we hope will give us insight about the abiotic factors that affect invasive and native species distribution. Finally, the funds from Pennsylvania Sea Grant have been used to provide research opportunities to several undergraduate science majors at Elizabethtown College. This research opportunity has given them experience designing, conducing, and presenting research; provided training in basic and applied behavioral ecology; and strengthened their preparation for graduate schools and future careers.

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