DRAUGHON, Lisa D.*; SCARPA, John; HARTMANN, James X.; KEATING, Patricia; Florida Atlantic University, Boca Raton; Harbor Branch Oceanographic Institution, Ft. Pierce, FL; Florida Atlantic University, Boca Raton; Florida Atlantic University, Boca Raton: Potential bioremediation of bacterial contamination in marine waters by the tunicate Styela plicata: filtration rate.
The tunicate Styela plicata, as with other ascidians, is capable of indiscriminate filtration of particles of inorganic and organic content, including bacteria, and may be useful for bioremediation of bacterially contaminated marine waterways. In this study, filtration rate in relation to wet weight was determined. Individual tunicates (n=14, mean wt = 26.8 ± 21.2 g) in six liters of sea water (28 ppt., 26° C) were exposed to heat-killed microalgae (Nanochloropsis sp. 1) at concentrations of either 105 or 106 cells ml-1 for six hours. Water samples were taken hourly and analyzed by phase contrast microscopy for remaining algal concentration. Tunicates exposed to 105 cells ml-1 of Nanochloropsis sp. exhibited a mean filtration rate, based on 100% particle retention, of 111 ± 46 ml h-1 g-1 wet weight, while tunicates exposed to 106 cells ml-1 exhibited a mean filtration rate of 125 ± 39 ml h-1 g-1 wet weight. The experiment was repeated using E. coli, however water samples were analyzed by flow-cytometry, yielding comparable results with the microalgae. Both experiments demonstrated a steady depletion of the remaining experimental particle concentration of ∼40 % hour-1, verifying indiscriminate filtration. These results suggest possible remediation of turbidity, as well. Given the widespread population dispersal of S. plicata and the potential positive impact on the marine environment, further investigation of its use as a bacterial bioremediator is warranted.
