title: Population Characteristics and Habitat Use by the Recently Introduced Asiatic Clam (Corbicula fluminea) in Lake Whatcom, Washington
Creators: name: Buehler, Jason A.
Publisher: name: Western Washington University
Year: 2017

description: <p>The Asiatic Clam (Corbicula fluminea) was found in Lake Whatcom in 2011. This exotic clam is common throughout North America and is spread between watersheds by infested boats, fishing activities, as well as passively by waterfowl. Corbicula fluminea is a well documented invasive species that survives in many environments and exhibits an rselected life history which can lead to potentially rapid population growth via a clonal reproductive ability typical among invasive bivalves and members of the family Corbiculidae. There are more reproductive strategies in Corbiculidae than any other freshwater bivalve. This rapid growth of a single organism and its associated consumption and excretions can lead to undesired changes in an aquatic ecosystem. Studies have shown a drop in species richness, alterations to algal communities and their availability to other organisms, and water quality changes associated with burrowing, shell accumulation, and clam decomposition. My research included an assessment of the growth of representative Lake Whatcom clam populations during 2012 and 2013 using shellfish surveying methods that have been applied to the marine intertidal environment. Surveying was based on multiple transects with randomly sampled 0.25-square meter quadrats. Three sites were identified that had populations of the clam and were accessible for surveys. These sites were Bloedel Donovan Park in the City of Bellingham, Lakewood, a facility run by Western Washington University, and a small park beach within the community of Sudden Valley. Surveys showed sample areas with 200 or more individual clams per square meter at all three sites. Studies state this density to be indicative of a self-sustaining population for C. fluminea. Some sites exhibited an increase in biomass and size from 2012 to 2013. All sites showed significant changes among some size classes that suggest growth. The sand and fine sediment substrate of the Sudden Valley site hosted significant density increases and biomass increases from 2012 to 2013. The harder rocky substrate of Lakewood hosted multiple size classes but did not show evidence of growth. Bloedel Donovan Park differed from the other sites in that it had a small size class in 2013 that was not present in 2012 suggesting a new generation of clams had reseeded the habitat. The overall environment within Lake Whatcom does not appear to be conducive to extended periods of reproduction based on the presence of distinct size classes. Distinct size classes are representative of specific reproductive windows during the year made available during the warmer months of summer. Density and biomass changed with depth within the nearshore shallows suggesting that the cooler deeper waters of the lake are not as suitable to the clam as the warmer, shallower areas within the littoral zone. Another explanation is less phytoplankton availability due to light limitations imposed by depth. Corbicula fluminea appears to be reproducing to varying degrees at all three sites in this study, and it will likely continue to spread to suitable habitat within Lake Whatcom. Typical impacts associated with the clam should be expected. These include changes in species richness, especially changes in native filter feeder concentration as well as changes to phytoplankton density, and alterations to the seston nutrient load because of burrowing and biological functions associated with C. fluminea</p>