Meeting Abstract

P1-143  Saturday, Jan. 4  Recruitment and Survival of the Eastern Oyster Crassostrea virginica when Challenged by the Brown Tide Aureoumbra lagunensis: Field Results WALTERS, LJ*; PHLIPS, EJ; BADYLAK, S; MCCLENAHAN, G; SACKS, PE; DONNELLY, MJ; University of Central Florida, Orlando; University of Florida, Gainesville; University of Florida, Gainesville; University of Central Florida, Orlando; University of Central Florida, Orlando; University of Central Florida, Orlando linda.walters@ucf.edu

Within the Indian River Lagoon (IRL) estuarine system along Florida’s east coast, blooms of the marine microalga Aureoumbra lagunensis in excess of 1×10⁶ cells mL^-1 have occurred on three occasions since 2012. All blooms coincided with times of peak reproduction and growth of the eastern oyster Crassostrea virginica. Over five years of field data on monthly recruitment and four years of data on natural densities of C. virginica were compared to bi-monthly cell counts of A. lagunensis. In addition to expected temperature and salinity-driven variations in recruitment, A. lagunensis cell density negatively impacted oyster recruitment to the system. Cell counts in excess of 200,000 per ml had the greatest impact on recruitment, although significant negative effects began with cell counts greater than 9658 per ml. Our highest mean shell length (47 mm) and mean oyster densities (1060-1176 per m²) were, however, recorded in June 2015 and 2016 during a 15-month bloom event. Therefore, adult oysters did not die in large numbers either rapidly or slowly during this prolonged bloom of A. lagunensis. Reduced recruitment during blooms did lead to decreased adult oyster populations in subsequent years. While many biotic and abiotic variables simultaneously influence C. virginica, these field results demonstrate significant negative impacts of A. lagunensis on oyster recruitment but not on adult survival of C. virginica.