MacMillan, G. A. | bioRxiv Science

bioRxiv2021

Trace elements in grey seals from the Gulf of St. Lawrence

We measured baseline levels of 19 trace element and mercury speciation for grey seals (Halichoerus grypus) from the Gulf of St. Lawrence (GSL), Quebec, Canada. With interest growing in commercializing grey seal products for human consumption in this region, the goal of this study was to measure essential and non-essential trace elements in grey seals to evaluate health concerns and nutritional benefits. From 2015 to 2019, 120 grey seals were sampled by hunters and researchers at 4 sites in the GSL. Muscle, liver, heart and kidney samples were analyzed for 10 non-essential elements (Sb, As, Be, B, Cd, Pb, Hg, Ni, Tl, Sn) and 9 essential elements (Co, Cr, Cu, Fe, Mg, Mn, Mo, Se, Zn). Both total mercury (THg) and methylmercury (MeHg) were analysed for a subset of samples. Many elements were undetected in liver (Sb, As, Be, B, Cr, Co, Pb, Ni, Tl, Sn) and muscle tissues (same, plus Cd, Mn, Mo). Results showed lower element concentrations in the muscle (Fe, Mg, Se) and livers (Cd, Cr, Hg, Mn, Mo, Se) of young-of-the-year harvested in the winter (< 6 weeks old) compared to older animals feeding at sea. For older seals ([~] 5 months to 29 years), we did not observe progressive age-dependent bioaccumulation. Sex-specific differences were not very pronounced, but a few elements were 30 - 70% higher in the muscle (THg, MeHg) and liver (Mn, Zn) of male seals. Comparison to Canadian dietary reference intakes shows that a weekly portion of liver from young-of-the-year (< 6 weeks old) is a good source of essential elements (Cu, Fe) and that muscle and liver from this age category does not exceed reference values for toxic elements (As, Cd, Pb, MeHg). Ongoing discussions with regional public health professionals will help to develop dietary recommendations for the consumption of older grey seals. HIGHLIGHTSO_LIWe measured baseline levels of 19 trace elements in grey seals harvested from the Gulf of St. Lawrence. C_LIO_LIWe evaluated nutritional benefits and health concerns of human consumption of grey seal products. C_LIO_LIOnce seals began feeding at sea ([~] 5 mo), many element concentrations increased, but did not bioaccumulate progressively with age afterwards. C_LIO_LISome elements were more concentrated in the muscle (mercury) and livers (manganese, zinc) of male seals. C_LIO_LIYoung seal (< 6 we) livers are a good dietary sources of copper and iron, while its muscle and liver were below reference values for toxic elements. C_LI GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=105 SRC="FIGDIR/small/458200v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@ad9ea6org.highwire.dtl.DTLVardef@8adf1borg.highwire.dtl.DTLVardef@13d992eorg.highwire.dtl.DTLVardef@113c8c7_HPS_FORMAT_FIGEXP M_FIG C_FIG

ecology↗

bioRxiv2017

Rare earth elements (REE) in freshwater, marine, and terrestrial ecosystems in the eastern Canadian Arctic

Few ecotoxicological studies exist for rare earth elements (REEs), particularly field-based studies on their bioaccumulation and food web dynamics. REE mining has led to significant environment impacts in several countries (China, Brazil, U.S.), yet little is known about the fate and transport of these contaminants of emerging concern. To understand how REEs behave in pristine northern food webs, we measured REE concentrations and carbon and nitrogen stable isotope ratios ({partial}15N, {partial}13C) in biota from marine, freshwater, and terrestrial ecosystems of the eastern Canadian Arctic (N=339). Northern ecosystems are potentially vulnerable to REE enrichment from prospective mining projects at high latitudes. Wildlife harvesting and tissue sampling was partly conducted by local hunters through a community-based monitoring project. Results show that REE generally follow a coherent bioaccumulation pattern for sample tissues, with some anomalies for redox-sensitive elements (Ce, Eu). Highest REE concentrations were found at low trophic levels, especially in vegetation and aquatic invertebrates. Terrestrial herbivores, ringed seal, and fish had low REE levels in muscle tissue (<0.1 nmolg-1), yet accumulation was an order of magnitude higher in all liver tissues. Age- and length-dependent REE accumulation also suggest that REE uptake is faster than elimination for some species. Overall, REE bioaccumulation patterns appear to be species- and tissue-species, with limited potential for biomagnification. This study provides novel ecotoxicological data on the behaviour of REE in ecosystems and will be useful for environmental impact assessment of REE enrichment in northern regions.

ecology↗