The assemblage of dragonfly species emerging from small wetlands along an urbanization gradient

M.A. Aliberti¹ and H.S. Ginsberg².¹Dept. of Plant Science and Entomology, University of Rhode Island, Kingston, RI 02881, ²USGS Patuxent Wildlife Research Center, Coastal Field Station, University of Rhode Island, Kingston, RI 02881

Land–use in surrounding wetland buffers, fish presence, water quality measurements and wetland size and distance from the coast were evaluated to assess their effects on dragonfly species distributions and species richness at 21 small wetlands in Rhode Island. These palustrine wetlands range from highly anthropogenic sites in greater Providence, to small, natural ponds in rural RI. Dragonfly exuviae were collected at each site in standardized samples and identified to species in the laboratory. Results from 2004 indicate that dragonfly species composition was related to chloride concentration in the water (a measurement pertaining to ‘urbanization’) and surrounding vertical structure at the wetlands in this study. Different dragonfly species responded differently to the presence of fish. However, dragonfly communities in 2005 appear to be very different from the previous year at each wetland. Weather factors, visibility of the wetlands to ovipositing adults and the structure of wetland vegetation should be evaluated for their effect on the community composition.