Cooperative Fish and Wildlife Research Units Program: Maine
Education, Research and Technical Assistance for Managing Our Natural Resources

While fishless ponds provide a potentially unique habitat for many aquatic invertebrates intolerant of vertebrate predation, widespread fish introductions have led to a decline in naturally fishless habitats throughout North America. We compared odonate assemblages associated with fishless ponds (n=5) in eastern Maine with those found at similarly located and sized (2.7 to 7.7 ha) ponds dominated by either salmonid (n=5) or centrarchid (n=5) fish predators. Three belt transects were established in littoral macrophyte zones at each study pond, and adult Zygoptera (23 spp) and larval Anisoptera (37 spp) were sampled in each transect during two survey periods in June and July 2004. We also quantified a number of site variables at each pond. Fishless ponds were slightly more acidic than centrarchid and salmonid ponds, but there were no differences in other site variables among pond types. Odonate richness and abundance were similar among the three pond types, but species assemblage composition differed significantly with pond type. Non-metric multidimensional scaling and multiple response permutation procedure revealed discrete differences in Zygoptera assemblages at fishless ponds, but not at salmonid and centrarchid ponds. Anisoptera assemblage composition differed among each of the three pond types. We conclude that fishless ponds provide habitat for native odonate assemblages that is unique from that of ponds hosting either warmwater or coldwater fish taxa.