A multispecies-monitoring study about bioaccumulation of mercury in Iranian birds (Khuzestan to Persian Gulf): Effect of taxonomic affiliation and trophic level $ Ghasem Zolfaghari a,Ã , Abbas Esmaili-Sari b,ÃÃ , Seyed Mahmoud Ghasempouri b , Raziyeh Rajabi Baydokhti a , Bahram Hassanzade Kiabi c a Department of Environment, Faculty of Natural Resources, Zabol University, Zabol, P. O. Box 98615-538, Sistan and Baluchestan, Iran b Department of Environment, Faculty of Natural Resources and Marine Sciences, Tarbiat Modares University, Noor, Iran c Department of Wild Life Ecology, Faculty of Sciences, Shahid Beheshti University, Tehran, Iran article info Article history: Received 14 September 2008 Received in revised form 20 June 2009 Accepted 6 July 2009 Available online 8 August 2009 Keywords: Bioindicators Mercury Feather Iran Persian Gulf abstract In the present study, the first baseline concentration of mercury (Hg) in different species of Iranian birds was investigated. From April to October 2005, the tail feathers of 100 birds belonging to 27 species (14 families) from different places in southwest Iran (Khuzestan to Persian Gulf) were collected. The Hg levels were evaluated in relation to taxonomic affiliation and trophic level (type of food). The results showed that the Hg levels in the feathers were between 0.07 and 4.71 mg/kg dry weight (dw), and there was a significant effect of taxonomic groups in relation to Hg concentration (po0.001). The highest mercury concentrations were in Laridae and Ciconidae. Alcedinidae had intermediate values, whereas Upupidae, Glareolidae, Scolopacidae, Turdidae, Ardeidae, Anatidae were in subsequent orders; and the lowest concentrations of Hg were in Rallidae, Cuculidae, Pycnonotidae, Corvidae and Columbidae. The results indicated a significant difference between the trophic levels (po0.001). Fish predators had the highest level of Hg (3.07 mg/kg). Invertebrate predators and herbivorous birds had the lowest concentration of Hg (0.84 and 0.64 mg/kg, respectively), whereas crab and fish predators and omnivorous birds had moderate values (1.73 and 1.70mg/kg, respectively). In the present study, the concentration of Hg was significantly higher in tail feathers than in primary and secondary (po0.001). A significant positive correlation among Hg concentration of feather types was observed (r40.96). The results obtained in this study indicated that among 100 birds tested, 6% of them had Hg concentrations greater than 5 mg/kg in feather (adverse level). & 2009 Elsevier Inc. All rights reserved. 1. Introduction In the environment mercury comes from both natural cycling in the biosphere and anthropogenic activities. The natural cycling of Hg involves its breakdown from rocks and minerals and its evaporation from water, atmospheric transport, and deposition back to land and water, with oceans playing an important role in this global cycling (Fitzgerald, 1989). When mercury enters the environment, it circulates in the atmosphere and finally precipitates in lakes, seas and oceans (Furness and Kees, 1997). This element is a special concern in marine ecosystems, where methylation occurs during the process of biotransformation and accumulates in biota (Bryan, 1979; Lindqvist, 1991). Bioconcentration, bioaccumulation and biomagnifications of chemical material in oceanic biota are active processes that depend on chemical characteristics, environmental factors (salinity and temperature), trophic level, concentration of fat, metabolism and bioavailability (entry and transfer of contaminants) (Rocque and Winker, 2004). Because of the high affinity of methyl mercury (Me-Hg) to sulphydryl groups of proteins, this heavy metal is rapidly incorporated into the food chain and bioaccumulated in aquatic organisms (Ochoa-Acuna et al., 2002). High toxicity of Hg and its increase in the environment bring about the need for local and temporal monitoring of Hg (Scheuhammer, 1987). Seabirds are particularly vulnerable to contaminants, because they are long-lived and are often at the top of their food chains and this makes them suitable for monitoring (Hunter and Jhonson, 1982; Lock and Thompson, 1992; Burger et al., 1992; Hernandez et al., 1999). ARTICLE IN PRESS Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/envres Environmental Research 0013-9351/$ - see front matter & 2009 Elsevier Inc. All rights reserved. doi:10.1016/j.envres.2009.07.001 $ This paper was supported by Tarbiat Modares University of Iran. Furthermore, there was no study on humans or experimental animals. The birds had been collected for Museum of Natural History, Faculty of Natural Resources of Tarbiat Modares University. Ã Corresponding author. Fax: +98 542 2226765. ÃÃ Also corresponding author. Fax: +98 122 6253499. E-mail addresses: ghr_zolfaghari@yahoo.com (G. Zolfaghari), abbasesmailisari@yahoo.com (A. Esmaili-Sari). Environmental Research 109 (2009) 830–836