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Abstract

Ecosystem risk assessments after oil spills need at least one biological component"s response to have some degree of understanding of the risks associated with the spill. In this study, crude oil spill impacts were studied under a spill scenario in Iskenderun Bay, which is a highly prone area to oil tanker accidents due to the high levels of transpassing. The study evaluated phytoplankton communities" response in 4 different seasons. Photosynthetic pigments data, obtained by HPLC, was used to assess community shifts of phytoplankton under different doses of the crude oil. It was found that the time of year of incidence is critical to understanding the consequences because a highly significant response difference was detected, which is more than an order of magnitude between winter and fall seasons. Due to physical conditions of seawater and initial phytoplankton compositions, the ecosystem showed more tolerance to the crude oil in winter than other seasons. EC 50 values varied between 11.5 and 122.3 µg/L total petroleum hydrocarbon (TPH) concentrations for all seasons.It is shown that the time of the year and known TPH concentrations of the seawater can possibly tell us about the potential impact of an oil spill in this region.