Biological and physiological responses during 14 day incubations of 15 phytoplankton species in culture exposed to oil and combinations of oil and dispersant

Culture experiments were conducted on fifteen phytoplankton species to examine their biological and physiological responses during exposure to oil and a combination of oil and dispersant at Texas A&M University at Galveston. The species tested included Species 1: Thalassiosira pseudonana CCMP 1335, Species 2: Synechococcus elongatus CCMP 1334, Species 3: Skeletonema grethae CCMP 776, Species 4: Dunaliella tertiolecta UTEX LB999, Species 5: Skeletonema grethae CCMP 775, Species 6: Chaetoceros diversum CCMP 179, Species 7: Odontella mobiliensis CCMP 597, Species 8: Phaeodactylum tricornutum UTEX 646, Species 9: Lithodesmium undulatum CCMP 472, Species 10: Emiliania huxleyi CCMP 371, Species 11: Odontella aurita CCMP 816, Species 12: Emiliania huxleyi CCMP 1280, Species 13: Chaetoceros affinis CCMP 159, Species 14: Navicula sp. UTEX BSP11, and Species 15: Skeletonema costatum UTEX LB2308. Cultures (300 mL initial volume) grown in standard f/2 media were maintained at 19°C under 12-hour diurnal light cycle conditions for a 14-day period in triplicate for controls and each experimental treatment. Treatments including WAF (water accommodated fraction of oil), a combination of WAF and Corexit (CEWAF), and a combination of WAF and Corexit diluted (DCEWAF), such that the concentration of oil (mg L-1) was the same as the WAF-only addition, were applied to each species. Further, non-phytoplankton controls (i.e. f/2 media) were also exposed to each treatment type in order to account for the photodegradation of the oil when exposed to light. At two-day intervals the cultures were sampled to determine the concentration of oil (EOE, estimated oil equivalence), chlorophyll a relative fluorescence intensity and chlorophyll a fluorescence induction and relaxation (FIRe) curve parameters (Fv/FM, σPSII, P, and t1).