This document summarizes research on the impact of invasive quagga mussels on freshwater microbial communities. Specifically, it discusses 1) feeding experiments that showed quagga mussels significantly reduced bacteria populations compared to control samples, and 2) field observations noting lower bacterial abundances and changes in bacterial composition in lakes invaded by quagga mussels compared to non-invaded lakes. The research suggests invasive species can significantly impact native microbial communities through trophic interactions and biogeochemical cycling.