A two-part study was devised to understand what changes will occur in North American inland lakes once they are colonized by the zebra mussel. Using Douglas Lake in Northern Michigan as a model, two questions were asked: First, can the mussels survive in the lake on the basis of available food and attachment sites; and secondly, what ecological effects will they have on the lake? To examine what algal resources could potentially be utilized by the zebra mussels, two size cohorts’ feeding response when exposed to whole Douglas Lake water was tested. Five trials were conducted throughout the summer at approximately two week intervals. Two size cohorts were tested, each with three replicates, as well as three controls. Larger mussels consumed more total biovolume of plankton than smaller animals throughout the summer (pdate<0.001, psize class=0.013, Two-way ANOVA). Sampling date proved to be highly significant in all cases, as a result of shifts in algal community structure over time. A second experiment was conducted to determine substrata suitability and preference. Substrata tested were live unionid clams, rocks, and algal mat (marl). Sand served as a base substratum. Thirty mussels were randomly distributed in each aquarium and their starting positions were recorded. After 48 hours, the mussels’ positions were again recorded. Mussels preferred live unionid clams in all comparisons and surprisingly had little trouble attaching to the algal mat. This study showed that zebra mussels can find adequate food and substrata for attachment in Douglas Lake. Implications of a colonization are a potential change in the plankton community based on selective herbivory by zebra mussels and a reduction in the unionid clam fauna as a result of zebra mussel attachment and competition for resources.