Araca Bay (Sao Sebastiao, State of Sao Paulo), within one of Brazil's most beautiful coastlines, has small relict mangrove stands and a very diverse marine ecosystem. As such, the bay is a natural laboratory as well as important for local small scale fishing. In this study we summarize the large literature base to comprehensibly list the flora and fauna as a preliminary biodiversity inventory of Araca Bay. We place this in the historical context of human impact on the environment of the bay and we emphasize new, introduced and threatened species as bioindicators and natural resources. With this information, we provide a basis to inform conservation decisions as well as data for conservation management plans and call attention to the urgent need to protect this fragile environment and biota. We also emphasize that this small and uniquely biologically rich bay should be preserved, revitalized and integrated into the growing urban environment.101219264