en Concentration of Mercury in Selected Tissues of the Caspian Lamprey (Caspiomyzon wagneri) Migrants in Spawning Season عمومى General پژوهشي Research <span style="font-weight: bold">Background:</span> Mercury (Hg) is considered a global pollutant because Hg0 which is the predominant form of atmospheric Hg resides in the atmosphere for as long as 0.5 to 2 years. Mercury has many negative effects on the reproductive, respiratory, and immune systems. <span style="font-weight: bold"><br>Methods:</span> In this study, 24 Caspian lampreys (Caspiomyzon wagneri) were transported to the university laboratory and then stored in -20 oC until they were dissected. The liver, muscle, skin, ovaries, and testes were all dissected out. All samples were freeze-dried and ground by a mortar and pestle into powder. The specimens were analyzed by a Leco AMA254 mercury analyzer. <br><span style="font-weight: bold">Results:</span> The order of mercury concentration in the lamprey tissues was as follows: Muscle > ovaries > liver > skin > testes. The mean values of mercury in muscle and testes were 192.25 ± 7.10 and 21.42 ± 1.48 Hg ng/g dry weight, respectively. There were no significant differences (N = 24) between the sexes in the Hg level of most tissues except for gonads. Discussion: A comparison with some ammocoetes of jawless fishes shows a 10 times less concentration than other records. This difference probably is due to non-parasitic behavior and use of various sources of nutrition in other species. <br><span style="font-weight: bold">Conclusion:</span> In comparison of other kind of sea lamprey, due to detritivore habits of Caspian lamprey on a very specific part of food web (non-live food only in the sea floor), the supposed species can introduce as a special indicator of mercury and heavy metal levels in the aquatic ecosystem. Biomonitor, Caspian Lamprey, Mercury level, Shirud River, Iran Biomonitor, Caspian Lamprey, Mercury level, Shirud River, Iran 460 467 http://ijt.arakmu.ac.ir/browse.php?a_code=A-10-2-17&slc_lang=en&sid=1 Sharif Joorabian Shooshtari شریف جورابیان شوشتری sharif_shooshtari@yahoo.com 10031947532846003230 10031947532846003230 Yes Department of Environment, Faculty of Natural Resources and Marine Sciences, Tarbiat Modares University, Noor, Iran Department of Environment, Faculty of Natural Resources and Marine Sciences, Tarbiat Modares University, Noor, Iran Mojtaba Shirood Najafi مجتبی شیرود نجفی 10031947532846003231 10031947532846003231 No Department of Fisheries, Faculty of Natural Resources and Marine Sciences, Noor, Iran Department of Fisheries, Faculty of Natural Resources and Marine Sciences, Noor, Iran Neda Khosravi ندا خسروی 10031947532846003232 10031947532846003232 No Department of Fisheries, Faculty of Natural Resources and Marine Sciences, Noor, Iran Department of Fisheries, Faculty of Natural Resources and Marine Sciences, Noor, Iran Seyed Mahmoud Ghasempouri سید محمود قاسم پوری 10031947532846003233 10031947532846003233 No Department of Environment, Faculty of Natural Resources and Marine Sciences, Tarbiat Modares University, Noor, Iran Department of Environment, Faculty of Natural Resources and Marine Sciences, Tarbiat Modares University, Noor, Iran Abbas Esmaili Sari عباس اسماعیلی ساری 10031947532846003234 10031947532846003234 No Department of Environment, Faculty of Natural Resources and Marine Sciences, Tarbiat Modares University, Noor, Iran Department of Environment, Faculty of Natural Resources and Marine Sciences, Tarbiat Modares University, Noor, Iran