Freshwater macroinvertebrate communities on exotic and native plants

Aquatic plants play an important role in the survival and proliferation of invertebrates in freshwater ecosystems. Exotic plants are now common in North American lakes and rivers, where they may displace native plants, thereby potentially altering epiphytic invertebrate communities. Differences in aquatic invertebrate communities on native and exotic plants are examined here through (1) a meta-analysis of published data, and (2) two field surveys in northeastern North America that compared invertebrates on the exotic Myriophyllum spicatum and Potamogeton crispus to those on their native congeners. The meta-analysis revealed that exotic plants generally support lower invertebrate abundance than do natives, while invertebrate taxa richness tends to be similar on exotic and native plants. The field surveys demonstrated that M. spicatum and P. crispus support significantly different invertebrate densities and lower taxa richness than their structurally similar native congeners. These results suggest that the replacement of native plants by exotics---even those with similar morphology---may cause concomitant changes to aquatic ecosystems.