Mercury in fish from the North East Atlantic: sources, bioaccumulation dynamics and co-occurrence with selenium

• Main Author: Azad, Atabak Mahjour
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: The University of Bergen 2019
• Subjects: atlantic cod; Gadus morhua; Molva dypterygia; North East Atlantic
• Online Access: http://hdl.handle.net/1956/20927

Mercury (Hg) is a global neurotoxin distributed at trace levels in the earth’s crust. Although Hg input from anthropogenic sources has been reduced in North America and Europe, in some other parts of the world the emission is still high. Considering the longrange transport and long atmospheric half-life, Hg and particularly its most toxic form monomethylmercury (MeHg), remains an environmental concern at the global level causing threat to both wildlife and human health. In general, seafood is the main source of MeHg exposure to humans and Hg is the main reason for seafood consumption advisories. Therefore, measuring the Hg levels in seafood species and understanding the processes governing the variation of Hg levels are very important for seafood safety and security. Synthesis, bioaccumulation and biomagnification of MeHg are very critical processes controlling the MeHg levels in the environment and the biota. The main goals of this study were to investigate how Hg levels vary between different fish species as well as between different communities in offshore, fjord and coastal areas of the North East Atlantic Ocean (NEAO). The contribution from different Hg sources and parameters influencing these variations were also investigated. Large variation in Hg levels between fish species form NEAO was found (Paper I). The pelagic species including Atlantic mackerel (Scomber scombrus) and blue whiting (Micromesistius poutassou) with mean value of 0.04 mg kg-1 ww had the lowest Hg concentrations. Blue ling (Molva dypterygia) had the highest Hg levels with a mean of 0.72 mg kg-1 ww. Selenium (Se) varied in a smaller range compared to Hg, with mean concentrations from 0.27 mg kg−1 ww in Atlantic cod (Gadus morhua) to 0.56 mg kg−1 ww in redfish (Sebastes spp.). The Hg level in fish increased from north towards south in most species and this process was independent of Hg pollution in the environment (sediment). It was hypothesized that a gradual increase in water temperature and primary production duration from the north ...