Community analysis of planktonic protozoa following exposure to dispersant only and physically and chemically dispersed crude oil with environmental data

This study involved a 7 day land-based mesocosm experiment within 120 gallon tanks placed in a temperature controlled water bath. The mesocosm set up is located at UTMSI, Port Aransas, Texas. Natural seawater was pumped from the shipping channel into each tank during an incoming tide to obtain natural plankton communities. Each tank had a gentle aeration system installed to provide mixing and ensure oxygenation levels remain consistent. The experiment was carried out between December 7th and 14th, 2016 during which three treatments were tested alongside a control. All treatments plus the control were tested in triplicate tanks. These treatments consisted of crude oil only at 10ppm, chemically dispersed crude oil at 10ppm (dispersant to oil ratio of 1:20) and dispersant only at the same concentration used in the 10ppm dispersed oil treatment (5µg/L). Samples were collected every 24hrs to analyze protozoan community alterations. Both live and preserved samples were analyzed via microscopy methods and Flow imaging cytometry. This allowed the examination of daily survival, mortality and potential recovery rates of protozoan species within conditions which best reflect ambient environmental conditions.