Photosynthetic and Biochemical Response of Ulva lactuca to Marine Pollution by Polyaromatic Hydrocarbons (PAHs) Collected from Different Regions in Alexandria City, Egypt

Abstract

Activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (GR), Lipid peroxidation (expressed as MDA), the accumulation of H2O2 and photosynthetic activities in Ulva lactuca (Ulvales, Chlorophyta) were determined in the present investigate their response to polyaromatic hydrocarbons (PAHs) at residential and industrial sites in Alexandria, Egypt. Increasing in PAHs concentrations caused significant (p ˂ 0.01) inhibition in the activities of SOD and CAT by 32% each, while, the activity of GR was significantly increased by 1-fold (p ≤ 0.001). MDA levels were increased with increasing of concentrations of PAHs, however, their levels were inversely proportional to activities of antioxidant enzyme (especially CAT). Moreover, photosynthetic rates (Pn), chlorophyll fluorescence (Fv/Fm) and total chlorophyll were significantly reduced (p ˂ 0.01) with increasing PAHs by 24, 25 and 19%, respectively. The apparent increase in GR activity could indicate that alga acclimatized to the oxidative stress of PAHs, although oxidation of membrane lipids was not totally prevented as indicated by stimulated MDA levels. The results indicated that PAHs could exert oxidative damages and the harmfulness occurred mainly in samples collected from the industrial site with higher concentrations of PAHs. To the best of our knowledge, this is the first study to investigate the novel and conventional effects of PAHs on physiological and biochemical traits of alga.