1 Role of hydrology and spring diatom bloom on Dreissena polymorpha (zebra mussel) recruitment

Diatoms are known to be an important food source for Dreissena polymorpha, an invasive zebra mussel species introduced into the Great Lakes region. An outbreak in diatom and D. polymorpha populations was noticed in the summer of 2004 in Ford Lake, after a season of reduced flushing rates. However, diatoms seemed to have little affect on zebra mussel recruitment after a whole-lake experiment was performed in the summer of 2008 to enhance the vertical mixing of water. Diatoms prospered, while there was little zebra mussel production. Hydrology seems to indirectly affect zebra mussel recruitment. In 2004, average flushing rates exceeded 20 days in the month of April and in the first-half of May. That summer, zebra mussel recruitment was large. In subsequent years from 2005-2008, flushing rates were faster and zebra mussel production was minimal. Hydrology seems to serve as a master-control on D. polymorpha recruitment by altering trophic level interactions