Effects of chemically enhanced water-accommodated fraction of Iranian Heavy Crude oil on periphytic microbial communities in microcosm experiment

Abstract

On December 7th 2007, an estimated volume of 12,547kL of crude oil were released after a collision between the oil tanker M/V Hebei Spirit and a crane barge 6.5 nautical miles off the coast of Taean, South Korea. To determine the effects of oil spill on a periphytic microbial community, we conducted the exposure experiments with chemically enhanced water-accommodated fractions (CEWAF; control, 10, 20, 50 and100%) of Iranian Heavy Crude oil in culture systems of developed artificial benthic substrates. In the adhesive algal bio-assay, bacteria and heterotrophic nano-falgellate (HNF) grew well in all treatments excluding 100% CEWAF. However, periphyton did not adapt to the > 20% CEWAF. Among periphyton, datom Cylindrotheca spp. dominated in the treatment and the response of Cylindrotheca spp. on CEWAF (i.e., particularly 10%) was quite similar to the changes in Chl. a concentration. Therefore, the total petroleum hydrocarbons caused by the CEWAF had a negative effect on periphyton and growth-promoting effect on bacteria and HNF, respectively.