Coastal Communities Ocean Acidification Act of 2019 This bill requires the National Oceanic and Atmospheric Administration (NOAA) to conduct and update at least once every seven years an ocean acidification coastal community vulnerability assessment with a corresponding public report. The assessment must identify (1) U.S. coastal communities that are most dependent on coastal and ocean resources that may be impacted by ocean acidification; (2) the nature of those communities' vulnerabilities; and (3) key knowledge gaps where research could be devoted to better understand the possible ocean acidification impacts and possible adaptation strategies for the communities. In carrying out the assessment, NOAA must collaborate with state, local, and tribal government entities that are conducting or have completed vulnerability assessments, strategic research planning, or other similar activities related to ocean acidification to determine whether those activities may serve as a model for others and to identify opportunities for federal agencies to support those activities.