To provide insight into coastal microbial dynamics, we sequenced the V6-V8 region of the 16S rRNA gene for the bacterial assemblage present in surface seawater samples from the Martha's Vineyard Coastal Observatory on the New England Shelf. Bimonthly to monthly samples were taken between 2010 and 2018. The resulting amplicon time series provides key information about the identity and relative abundance of different bacteria at this location and how environmental and biological factors can affect their relative abundance and seasonal dynamics.