Meeting Abstract
Previously we documented that recreational boat wakes negatively impact intertidal reefs of the eastern oyster Crassostrea virginica in shallow estuaries by eroding sediment away from the buried bases of clusters, thus promoting dislodgement with the next large wake pushing loose clusters above the high tide line. Here, we provide data on the role that the brown tide microalga Aureoumbra lagunensis plays when present in these same shallow estuaries. A. lagunensis reached bloom concentrations in the Indian River Lagoon in summer 2012, spring 2013 and, currently with a start in February 2016. C. virginica recruitment was negatively impacted by brown tide (but some recruitment did occur), while their primary competitors (barnacles) were not negatively impacted, giving the latter a potential advantage. In replicated, laboratory flume trials, settlement of oyster larvae was negatively impacted by algal concentration and salinity. After a short exposure (1 week) of oyster spat (juveniles) to a range of concentrations of A. lagunensis (0 – 1 million cells/ml) and subsequent monitoring for 1 month in lagoon water with no brown tide, we found a significant reduction in survival by individuals exposed to bloom concentrations of brown tide. This decline in survival was from 95% to 85%, thereby suggesting the importance of A. lagunensis in altering shallow estuary ecosystems, but also the resiliency of the eastern oyster C. virginica to this stressor.
