Broadscale distribution, ecological associations, and potential impacts of the invasive Asian clam Corbicula fluminea in the Columbia River Basin

Background/Question/Methods

The invasive Asian clam Corbicula fluminea was introduced to North America in the 1930’s and now inhabits most regions of the contiguous United States. However, the current distribution of C. fluminea in the Columbia River Basin is poorly understood. We conducted a two-year field study to characterize the distribution and abundance of larval C. fluminea and associated environmental drivers (both biotic and abiotic) in the Columbia River Basin.  During both 2013 and 2014, five main stem reservoirs were sampled monthly from May through September, along with 22 additional lakes and reservoirs in late summer. A rapid microscopic particle imaging system, the FlowCam, was used to characterize plankton communities (60-300 μm size range).  Associations between larval C. fluminea, other components of the plankton, and environmental parameters are being analyzed using non-metric multi-dimensional scaling.

Results/Conclusions

Our results show larval C. fluminea are found in high abundances in all five main stem Columbia River reservoirs, with mean abundances reaching 1142.6 individuals m^-3.  Peak abundances occurred in July of each year, and planktonic larvae were predominantly found at stations  >3 meters deep.  Only three of the 22 lakes and (non-main stem) reservoirs sampled contained C. fluminea, with abundances considerably lower (peak = 21.2 individuals m^-3) than in the main stem Columbia River reservoirs, suggesting that management to reduce the spread of this non-indigenous invasive species is still possible. These findings will be of interest to ecologists concerned with fundamental ecological processes such as population establishment and range expansion, as well as managers and policy makers interested in reducing the impacts of invasive species.