The Ascidian Styela plicata As a Potential Bioremediator of the Brown Tide Pelagophytes Aureoumbra lagunensis and Aureococcus anophagefferens

A brown tide bloom of the pelagophyte Aureoumbra lagunensis caused significant impacts to north Indian River Lagoon (IRL) in 2012-2013, including seagrass die-offs, fish kills, and reduced growth and grazing of ecologically important bivalves. There is potential for another pelagophyte, Aureococcus anophagefferens, to expand into this system. Filtration rates (FR) of the pleated tunicate Styela plicata exposed to Aureoumbra lagunensis and Aureococcus anophagefferens were measured against exposure to a control alga (Tisochrysis lutea) in order to determine its potential use as a bioremediator against these harmful algal blooms (HABs). In addition, whether S. plicata might serve as a vector of HABs was studied by culturing fecal deposits. Short-term exposure to HABs significantly reduced FR, whereas long-term exposure indicates comparable cell removal compared to the control. Vector potential of S. plicata was inconclusive. Results warrant further research to determine whether S. plicata can acclimate or respond to HAB conditions over time.