Biomagnification of mercury and selenium in two lakes in southern Norway

Abstract

We have investigated bioaccumulation and trophic transfer of both mercury (Hg) and selenium (Se) in two lakes in southern Norway to reveal a suggested mitigating effect of Se on Hg biota accumulation. The study included analysis of total Se (Se), total Hg (Hg), and methyl-mercury (MeHg) in water, littoral and pelagic invertebrates and perch (Perca fluviatilis), together with stable isotope analysis (δ(15)N and δ(13)C) in biota. Mean dissolved Se ranged from 22 to 59ngL(-1), while Hg and MeHg in lake water ranged from 1 to 3ngL(-1) and 0.01 to 0.06ngL(-1). Biota Se and Hg concentrations (dry weight) ranged from 0.41mgSekg(-1) and 0.06mgHgkg(-1) in primary littoral invertebrates and up to 2.9mg Sekg(-1) and 3.6mgHgkg(-1) in perch. Both Hg and Se biomagnified in the food web, with a trophic magnification factor (TMF) of 4.64 for Hg and 1.29 for Se. The reported positive transfer of Se in the food web, despite the low measured dissolved Se, suggest that a major proportion of the Se in these lakes are both highly bioavailable and bioaccumulative. However, we did not find support for a Se-facilitated inhibition in the accumulation of Hg in perch, as Se and Hg concentrations in perch muscle correlated positively and Se did not explain any variations in Hg after we controlled for the effects of other important covariates. We postulate that this may be a result of insufficient concentrations of dissolved Se and subsequently in biota in our studied lakes for an efficient Hg sequestration up the food web.

Species and correlations between selenium and mercury in fishpond ecosystems

“…This result is also in accordance with that obtained by Okelsrud et al. () when selenium and mercury in perch of two lakes in Norway were investigated.…”

“…A high selenium concentration in water would decrease the accumulation of mercury in aquatic organisms, by which obvious negative correlations are presented between TSe-W and THg-C in Table 3. This result is also in accordance with that obtained by Okelsrud et al (2016) when selenium and mercury in perch of two lakes in Norway were investigated.…”

“…However, high aquaculture density, excessive fertilization of fish feed, and weak environmental protection consciousness can easily lead to the deterioration of water quality in ponds, lakes, and neritic mudflats. Although selenium and mercury usually exist at trace or ultratrace levels in most environments, they can still lead to undesirable effects on organisms and human health resulting from their bioaccumulation and biomagnification properties (Arcagni et al., ; Matulik et al., ; Okelsrud, Lydersen, & Fjeld, ). Therefore, the studies on the existing forms, contents, distributions, and correlations between selenium and mercury in aquaculture ecosystems are of great significance.…”

Percentage of methylmercury in the muscle tissue of freshwater fish varies with body size and age and among species

“…Given that diet is the main source of Hg for fish (Hall et al ), it is possible that variation in the %MeHg of food sources may contribute to similar variation in fish. Invertebrate prey have particularly variable but usually lower %MeHg (e.g., 10–85%) compared with fish (Becker and Bigham ; Tremblay et al ; Økelsrud et al ), and invertebrate consumers may therefore be exposed to lower dietary %MeHg than piscivores. To the best of our knowledge, however, no study has yet considered the effect of diet or trophic ecology on the %MeHg in fish muscle tissue.…”

Hg Concentrations in Muscles and Gills of Fish from Shallow Lakes of Different Trophic Status (Eastern Poland)

“…Previous studies of Hg content in fish have mainly dealt with Scandinavian ecosystems [12][13][14], marine environments [15][16] or the large ecosystems of American and African lakes [17][18][19][20][21]. Considerably fewer studies have dealt with Hg contamination of fish in shallow lakes in the temperate zone [22].…”