fishywiki t1_je9c799 wrote on March 30, 2023 at 11:05 AM

When fishing in Arctic Norway the authorities have banned the taking of halibut larger than 1m because of the risk of biological magnification of heavy metals. Is the Arctic really that polluted with mercury, etc.? If so, what's the source of these metals?

APECS_Polarscience OP t1_je9gf9j wrote on March 30, 2023 at 11:50 AM

Hi! This is Eva a Phd student in zooplankton ecosystem dynamics at UiT(Tromsø,Norway).

It has been shown that mercury accumulates in fish tissue, and humans who consume a lot of fish may consume elevated levels of mercury. The content f mercury is directly correlated with fish size. In 2006 it was reported Greenland halibut (GH) caught in the Barents Sea had shown mercury levels exceeding the European Union’s upper limit of 0.5 mg/kg wet weight. After this, a larger Study was initiated to gain more knowledge about mercury and other metal concentrations in GH. This larger Study showed that mercury concentrations in Greenland halibut fillets were higher than those found in other marine species living in the Barents Sea, Norwegian Sea, and North Sea and 14% of the analyzed fish contained elevated levels of mercury. In this study, it was found that mercury concentrations varied geographically, with much lower levels found in the shallower waters in the easternmost parts of the Barents Sea than in the deeper areas along the shelf slope. Because of this further investigation must be done to be able to know better know the sources of polluted metals such as studies relating to the diet of GH. But for the moment the source of these metals is associated with air emissions. So the reduction of Hg emissions will protect the environment and human health. You can look at this study model based which shows a temporal decrease in mercury in GH and they associate Hg in GH to Hg air emissions, decreasing trophic position, and lower demersal prey use.

Sources:

Bank, M. S., Frantzen, S., Duinker, A., Amouroux, D., Tessier, E., Nedreaas, K., ... & Nilsen, B. M. (2021). Rapid temporal decline of mercury in Greenland halibut (Reinhardtius hippoglossoides). Environmental Pollution, 289, 117843.

Julshamn, K., Frantzen, S., Valdersnes, S., Nilsen, B., Maage, A., & Nedreaas, K. (2011). Concentrations of mercury, arsenic, cadmium and lead in Greenland halibut (Reinhardtius hippoglossoides) caught off the coast of northern Norway. Marine Biology Research, 7(8), 733-745.