Lower Columbia River Reed Canarygrass Macroinvertebrate and Macrodetritus Production Study

Reed Canarygrass (Phalaris arundinacea) is a dominant invasive plant species found in emergent wetland habitats throughout the lower Columbia River. Previous observations in the lower river indicate that the presence of P. arundinacea may decrease plant species diversity and affect aquatic food web function; however, the extent of these ecological effects is unknown. Juvenile salmon utilize emergent wetland habitats for foraging and refuge during outmigration. Macroinvertebrates, such as Diptera (Chironomidae, in particular) are a preferred prey item for juvenile Chinook salmon, thus production and availability of these prey in wetland habitats are crucial for rearing success. Since invasive plant species often cause declines in the diversity, quantity, and quality of wetland plant communities, as well as reduced macrodetrital contribution and quality, P. arundinacea may also affect insect assemblages in the lower Columbia River.