Feeding rates and prey selection of the invasive Asian clam, Corbicula fluminea, on microplankton in the Columbia River, USA
The Asian clam, Corbicula fluminea, was introduced into North America in the 1920s first observed in the Columbia River and has expanded its range across the continent and into South America and Europe, yet little is known about its ecology and potential to impact food webs. To evaluate prey selectivity and feeding rates of C. fluminea, we conducted laboratory feeding experiments using water from two distinct Columbia River environments (unimpounded river and reservoir) during July and October 2016. The mean clearance rate on microplankton was 270 53.6 SE) ml water clam 1 h 1 and mean ingestion rate was 2.45 0.83 SE) ug C clam 1 h 1, although rates varied with season and location. In the reservoir in July, clams preferred diatoms and showed an avoidance of dinoflagellates and flagellates; during October in the unimpounded river, clams preferred flagellates while showing a significant avoidance of cyanobacteria. Diatoms were dominant at both sites, and were ingested by clams; however, clams ingested cyanobacteria at very low rates. Substantial consumption of microplankton such as diatoms and rejection of cyanobacteria by C. fluminea may provide competitive advantages to cyanobacteria, leading to microplankton community composition shifts and other changes to food webs in the Columbia River.
Hydrobiologia