Feeding rates and prey selection of the invasive Asian clam, Corbicula fluminea, on microplankton in the Columbia River, USA

Abstract   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) lg 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.