A negative association between recruitment of the eastern oyster Crassostrea virginica and the brown tide Aureoumbra lagunensis in Mosquito Lagoon, Florida

Within the Indian River Lagoon (IRL), blooms of the marine microalga Aureoumbra lagunensis in excess of 1310 cells ml 1 have occurred on three occasions after first being locally identified in 2012. All blooms coincided with times of peak reproduction and growth of the eastern oyster Crassostrea virginica in Mosquito Lagoon (northern IRL). Over six years of field data on monthly recruitment of C. virginica were compared to bi-monthly cell counts of A. lagunensis. In addition to expected temperature and salinity-driven variations in oyster recruitment, cell counts of A. lagunensis in excess of 10,000 ml 1 reduced oyster recruitment. A second method of analysis similarly found a negative association with oyster recruitment when cell counts exceeded 9658 ml . Understanding the impact of blooms of A. lagunensis is essential for managing harvesting, aquaculture, and restoration of this foundation shellfish species.