Abstract—Current annual amounts of oil entering the Persian Gulf region are over 150000 tones and due to polycyclic aromatic hydrocarbons (PAHs) toxicity, there is a need to evaluate the induction capacity of PAH biomarkers on its marine organism. So two biochemical biomarker responses were measured in mudskipper Periophthalmus waltoni from Soltani inlet with high and Ameri port with low pollution. The selected biomarkers were ethoxyresorufin O- deethylase (EROD) and glutathione S-transferase (GST). EROD and GST activities were significantly elevated in Soltani inlet and the highest elevation was up to 4 and 2 times for EROD and GST activity (respectively), comparing with Ameri Port (P<0.05). In male mudskippers enzymatic activity was greatest at both stations but it wasn’t significant between different sexes in the same site. These biomarker assessments can be used in this region to detect the toxic effects of chronic oil pollution even in low concentrations as early warning responses. Keywords— EROD, GST, mudskipper, oil pollution, PAHs, Persian Gulf. I. INTRODUCTION IL spills is one of the most important hazards in the estuarine and coastal water, which often exhibit long- term impacts [1]. The Persian Gulf has many characteristics and it’s under pressure from industrialization, and particularly, oil and petroleum pollution. Two different types of hydrocarbons exist in crude oil which are aliphatic and aromatic, among them the second type have attracted more concerns because of its adverse effects on aquatic organisms. Polycyclic aromatic hydrocarbons (PAHs) constitute about 0.2 to 7% of the total hydrocarbons in the oil. Among this The Persian Gulf have high amounts of PAHs compounds and every 16 of them that are reported by US Environmental Protection Agency (EPA) and World Health Organization (WHO) as priority pollutants that are present in this water body [2&3]. The biomarker approach is widely used for in vivo and in Mehrnoosh Shirani is MSc. Graduate, Department of Fishery, University of Tehran (e-mail: Shiranimehrnoosh66@gmail.com) Alireza Mirvaghefi is Associate Professor, Department of Fishery, Faculty of Natural Resources, University of Tehran Hamid Farahmand is Associate Professor, Department of Fishery, Faculty of Natural Resources, University of Tehran Mohammad Abdollahi is Professor, Department of Toxicology & Pharmacology, Faculty of Pharmacy, Tehran University of Medical Science. vitro studies to evaluate the effects of xenobiotics on the selected biological models [4]. In this study 2 biomarkers from detoxification process in biochemical level responses of biological organization were selected for analyzing; the enzymes that are involved in this process, can biotransform the xenobiotics with activation and conjugation reactions (Phase I & II), between them, ethoxy resorufin O-deethylase (EROD), has been used to determine phase I responses, because EROD activity especially in fish liver has been used as a biomarker for the effects of PAHs and some other organic contaminants and a number of field studies have established [5,6&7]. Phase II involves in the deactivation synthesis of xenobiotic or a phase I activated metabolite by covalent linkage to an endogenous hydrophilic molecule, like glutathione resulting in a non toxic or less toxic compound [5], in this phase GST activity is an important marker that is commonly assessed [8], and in this case was assayed too. Mudskippers Periophthalmus waltoni (Gobiidae) are completely amphibious fish, they are uniquely adapted to intertidal habitats. These fish are air-breathing species [9&10] and have a suitable distribution in northern and southern coastal area of the Persian Gulf [11]. They have a high density on tidal mudflats that are formed in creeks and estuaries and mangrove forest floors which are important in supporting the fish population by providing food sources (like organic matter and detritus) [12]. In this study we were assessed EROD and GST in mudskipper’s liver to evaluate the differences between selected sites with different amounts of petroleum compounds. II. MATERIALS & METHODS Mudskippers were collected from 2 stations along the Persian Gulf in Bushehr coastal area. Sampling was performed with survival fishing technique. PAHs have low vapor pressure and solubility in seawater, they tend to be absorbed by suspended organic matter and finally deposit in sediment [3]. Ameri Port and Soltani Inlet were selected with low and high amounts of organic matter (OM) in their mud which were analyzed for total organic matter and total organic carbon. Sampling took place between April and June 2011 (it’s their reproduction time so sex was determined in all individuals). The fish were collected from both stations and killed and EROD & GST Responses in Liver of Mudskipper Periophthalmus waltoni at Oil Polluted Areas Mehrnoosh Shirani, Alireza Mirvaghefi, Hamid Farahmand and Mohammad Abdollahi O International Conference on Ecological, Environmental and Biological Sciences (ICEEBS'2012) Jan. 7-8, 2012 Dubai 392