Mercury accumulation in the fish community of a sub‐Arctic lake in relation to trophic position and carbon sources

Abstract

Summary1. Stable isotope analysis has improved understanding of trophic relationships among biota. Coupled with contaminant analysis, stable isotope analysis has also been used for tracing the pattern and extent of biomagnification of contaminants in aquatic food webs. 2. Combined analysis of nitrogen ( δ 15 N) and carbon ( δ 13 C) isotopes from fish species in a sub-Arctic lake were related to tissue mercury (Hg) concentrations to assess whether carbon sources influenced Hg accumulation in fish, in addition to trophic position. 3. Statistical models were used to estimate Hg biomagnification and uptake, to elucidate Hg accumulation dynamics and to appraise the relative importance of Hg exposure routes for the fish species. 4. Species Hg contamination increased as a function of trophic position ( δ 15 N) and was inversely related to the δ 13 C signature. Species connected to the benthic food chain had lower Hg concentrations than species connected to the pelagic food chain. Species undergoing ontogenetic dietary shifts with increasing size, e.g. lake trout Salvelinus namaycush , also showed increased Hg concentrations with increasing reliance on pelagic fish as prey. 5.The results indicate that both vertical (trophic) and horizontal (habitat) food web structure influence Hg concentrations in fish tissue. 6. The biomagnification and uptake models indicated that contamination at the base of the food chain in the lake exceeded estimates for more southerly environments, thereby demonstrating the importance of dietary and water column Hg exposure routes in the sub-Arctic for determining Hg concentrations in fish. 7. Overall, the data reported here demonstrate how a combination of ecological concepts (food webs), developing ecological methods (stable isotopes) and environmental geochemistry can combine profitably to indicate the risks of exposure to environmental contaminants. Additional studies of the dynamics of Hg accumulation in the food webs of sub-Arctic lakes are needed, particularly in the light of the estimated high biomagnification rates and the heavy reliance of Inuit communities on subsistence fish harvests.

Mercury in alpine fish from four rivers in the Tibetan Plateau

“…2), suggesting trophic transfer and biomagnification of Hg in fish from Lhasa River. Similar results were also observed for Hg in Arctic marine food chain (Atwell et al, 1998;Campbell et al, 2005), sub-Arctic lake (Power et al, 2002) and in Lake Murray, Papua New Guinea (Bowles et al, 2001). Contents of THg and MeHg in fish from Lhasa River decreased on the descending order: Schizothorax waltoni > Schizothorax macropogon and O. stewartii > Schizopygopsis younghusbandi and Schizothorax o'connori (one-way ANOVA analysis, p < 0.05) (Fig.…”

Concentration and Biomagnification of Heavy Metals in Biota of the Coastal Marine Areas of Tanzania

“…The trophic transfer (trophodynamics) of elements along a food chain can result in an increase (biomagnification), a decrease (biodilution) or even may cause no change in elemental concentration along that particular food chain [16]. The trophodynamics of mercury (Hg) has been well studied and shows consistent biomagnification trends [12][13][14][15]. Other elements such as iron have been reported as not biomagnifying in food webs [9].…”

“…However, the great majority of these studies have been conducted in temperate systems, and information on the sources of energy and food web structure in tropical aquatic systems in general and in estuaries of Tanzania in particular is still lacking. TP (Trophic Position) can be related with contaminant concentrations in order to trace the pathways of contaminant biomagnification by top predators in aquatic and terrestrial food webs [14,29,30]. Net bioaccumulation of an element occurs when its trophic transfer is greater than that of carbon and the concentration thus increases with increasing TL [31,32].…”

“…The role of food chains in carrying contaminants to top predator fish which is a possible source for human dietary exposure, has received attention for several decades [9][10][11][12][13][14][15]. The trophic transfer (trophodynamics) of elements along a food chain can result in an increase (biomagnification), a decrease (biodilution) or even may cause no change in elemental concentration along that particular food chain [16].…”

Avaliação da dinâmica do mercúrio (Hg) na Bacia do Rio Madeira nos ambientes lêntico e lótico

“…Os invertebrados possuem maior concentração de HgT e MeHg (tabela 20) em relação aos níveis tróficos anteriores, essa tendência é apontada em estudos anteriores (BLOOM, 1992;MASON et al, 2000;MONTEIRO et al, 1999). O ciclo biogeoquímico do Hg, o qual resulta na bioacumulação do MeHg, é muito complexo e dinâmico (ENGSTROM, 2007;POWER et al, 2002). O potencial de bioacumulação da libélula depende da sua exposição ao Hg e ao nível trófico dos seus alimentos (KENNEDY, 1950;CORBET, 1999).…”