Importance of Corbicula fluminea in the trophic dynamics of the Upper Savannah Basin

A coral reef is a rich resource patch in an otherwise nutrient poor ocean. In an analogous manner patches of clams may serve a similar function in oligotrophic fresh waters. By filtering the water column, clams are able to remove and concentrate nutrients from the water. The mucoid nature of feces and pseudofeces keeps substantial quantities of this nutritional material from washing away.; Corbicula fluminea increase nutrient quality of water by the production of feces and pseudofeces. The shells of living and dead bivalves furnish substrate for attachment of sessile organisms and increase calcium concentration. A potential synergistic relationship exists between phytoplankton and clams in nutrient-poor waters. Corbicula supply areas of concentrated nutrients, rich in phosphate, which allows algal cells to grow. The increased concentrations of algal cells provide food to Corbicula.; In a divided tank, containers with Corbicula were placed on one side and containers without clams were placed on the other side. Lake water was pumped through the tank for one month, then clams were removed and AGPT (Algal Growth Potential Test) phosphorus and calcium assays were performed on water samples from the containers. There was no difference in phosphorus and calcium results of water from containers with and without clams. AGPT results from containers with and without clams were notably higher than lake water. Containers with clams had statistically higher AGPT than containers without clams. Increased potential nutrients were attributed to feces and pseudofeces production.; Leaching of calcium from clamshells incubated at 15°, 25° and 35°C in various ionic concentrations was also determined. These shells can serve as an additional source of calcium in oligotrophic waters.