The effects of diesel oil on the growth of three species of Marine Phytoplankton

Abstract

The effects of diesel oil on Phaeodactylum tricornutm, Isochrysis galbana and Chlorella salina and their potential application to bioremediation has been investigated. Phytoplankton growth inhibition tests were carried out using both batch and continuous culture conditions. Batch cultures were carried out to determine the 96 h 50% growth inhibition concentration (96 h IC50), the no observed effect concentration (NOEC) and the lowest observed effect concentration (LOEC). The degree to which diesel influenced the growth of phytoplankton varied with species, diesel concentration, pH of culture medium and the initial cell density. C. salina was the most tolerant species with the highest IC50 (241.9 mg/1) while I. galbana was the most sensitive to diesel. For P. tricornutum and I. galbana, the IC50 was lower at lower initial cell densities. Continuous culture conditions designed to achieve a dynamic equilibrium between phytoplankton growth and nutrient input were established for all three species. Under these conditions, which are more environmentally relevant, the population is relatively fragile and responds to perturbations.