Liver and Breast Feather Mercury in Piscivorous Birds of the Caspian Sea: Monitoring Changes F. Rajaei • A. Esmaili Sari • M. Savabieasfahani • N. Bahramifar • M. Ghasempouri Received: 27 November 2010 / Accepted: 16 March 2011 / Published online: 27 March 2011 Ó Springer Science+Business Media, LLC 2011 Abstract Mercury in the liver and breast feathers of the Common Cormorant, and in three species of Grebes from the southern coast of the Caspian Sea, were determined. The Common Cormorant had significantly more mercury in its tissues (liver: 8.5 ± 1.5; feather 8 ± 1 mg/kg dry weight) than Grebes (Great Crested Grebe: 3 ± 0.5, 8 ± 1.5; Black-necked Grebe: 3 ± 0.5, 5.5 ± 1; Little Grebe 2.5 ± 0.5, 4 ± 0.5). Unlike Common Cormorants, Grebes had less mercury in the liver than in breast feathers. Mercury in the Common Cormorant was not different between 2002 and 2008 collections. The mercury threshold for adverse effects is currently 5 ppm, which was exceeded by all but Little Grebes in this study. Keywords Mercury Á Liver Á Feather Á Caspian Sea Á Common Cormorant Á Grebe species Habitat destruction, caused by metal pollution, poses a critical global challenge. A dramatic two to ten folds increase in Hg levels during the past one and half centuries has made Hg contamination a growing international con- cern (Swain et al. 1992; Wiener et al. 2003). The Caspian Sea is an important wintering ground for up to 12 million aquatic birds that come to the Caspian from as far away as the Nile basin and western Siberia. The unique habitats of the Caspian are believed to be in danger of serious deg- radation and collapse due to Hg pollution. Caspian pollution is primarily due to inflow from the Volga, which contributes [ 80% of the total inflow, and the municipal and industrial waste that are released into this ancient lake (Karpinsky 1992). Each day, the Pulp Mill Plant of Mazandaran releases over 10,000 m 3 of untreated sewage into the Caspian Sea (Center for Data and Scientific Documents of Iran). Chlor-alkali industrial plants of Azerbaijan have released significant Hg into the Caspian and have caused serious contamination of the sediment. Mercury contamination of the sediment, fish, and birds of the Caspian have been reported (Agah et al. 2007) and a decline in the number of Caspian birds has been observed. Conditions of the Caspian Sea are common in many eco- systems worldwide where reckless human activity and negligence has culminated in serious ecosystem decline and destruction. But, despite the seriousness of global Hg pollution, no international legally-binding agreement exists to curb Hg release. In Iran, public awareness and demand has led to the installation of some basic pollution prevention and reme- diation measures to protect the vulnerable ecosystems of the southern Caspian region (Rahbar 2002). To determine the effectiveness of these efforts, we measured and com- pared Hg levels in liver and breast feather of common shorebirds that were collected as early as January 2002 with those that were collected 6 years later, in 2008. Materials and Methods In December 2008, twenty-five freshly injured or killed bird carcasses were confiscated from poachers by the Environmental Protection Agency guards responsible for F. Rajaei Á A. Esmaili Sari Á N. Bahramifar Á M. Ghasempouri Department of Environment, Faculty of Natural Resources and Marine Science, Tarbiat Modares University, P.O. Box 46414-356, Noor, Mazandaran, Iran M. Savabieasfahani (&) P.O. Box 7038, Ann Arbor, MI 48107, USA e-mail: mozhgan_savabieasfahani@hotmail.com 123 Bull Environ Contam Toxicol (2011) 86:521–524 DOI 10.1007/s00128-011-0259-2