Contribution of suspended particulate matter and zooplankton to MeHg contamination of the food chain in midnorthern Quebec (Canada) reservoirs

Plourde, Yanick; Lucotte, Marc; Pichet, Pierre

doi:10.1139/f96-340

Cited by 34 publications

(16 citation statements)

References 21 publications

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“…The main discrimination between MeHg and inorganic Hg in aquatic systems occurs during trophic transfer between biota at lower trophic levels, with the result that the proportion of MeHg in total Hg increases from 24% in phytoplankton to 96% in fish (Becker & Bigham 1995). Similar results have been reported by Watras & Bloom (1992), Plourde, Lucotte & Pichet (1997), Watras et al . (1998) and Bowles et al .…”

Section: Methodssupporting

confidence: 92%

“…1996; Tremblay et al . 1996; Plourde, Lucotte & Pichet 1997; Atwell, Hobson & Welch 1998) and provided detailed descriptions of temporal changes in accumulation rates (Thompson, Hamer & Furness 1991; Thompson, Furness & Walsh 1992). However, the mechanisms regulating MeHg formation, its initial incorporation in pelagic and benthic food chains, and subsequent trophic transfer, remain controversial (Watras et al .…”

Section: Introductionmentioning

confidence: 99%

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

Power

Klein

Guiguer

et al. 2002

Journal of Applied Ecology

235

161

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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.

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Section: Methodssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

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

Power

Klein

Guiguer

et al. 2002

Journal of Applied Ecology

235

161

View full text Add to dashboard Cite

show abstract

“…Even for the other elements the size fractions were often different for a given lake and date, but the differences were less consistent across lakes and dates (i.e., the date x size interaction within lakes accounted for the largest proportion of the variation). Similarly, other studies that tested for differences in MeHg concentrations across zooplankton size fractions found significant differences (Back et al, 2003; Cleckner et al, 2003; Kainz et al, 2002; Masson and Tremblay, 2003; Paterson et al, 1998; Plourde et al, 1997; Tremblay et al, 1998). However, our review of the literature revealed that most studies (74%) do not separate zooplankton size fractions.…”

Section: Discussionmentioning

confidence: 73%

Assessing element-specific patterns of bioaccumulation across New England lakes

Ward

Mayes

Stürup

et al. 2012

Science of The Total Environment

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Little is known about differences among trace elements in patterns of bioaccumulation in freshwater food webs. Our goal was to identify patterns in bioaccumulation of different elements that are large and consistent enough to discern despite variation across lakes. We measured methylmercury (MeHg) and trace element (As, Cd, Hg, Pb, and Zn) concentrations in food web components of seven New England lakes on 3–5 dates per lake, and contrasted patterns of bioaccumulation across lakes, metals and seasons. In each lake, trace element concentrations were compared across trophic levels, including three size fractions of zooplankton, planktivorous fish, and piscivorous fish. The trophic position of each food web component was estimated from N isotope analysis. Trace element concentrations varied widely among taxa, lakes and sampling dates. Yet, we identified four consistent patterns of bioaccumulation that were consistent across lakes: (1) MeHg concentration increased (i.e., was biomagnified) and Pb concentration decreased (i.e., was biodiminished) with increased trophic position. (2) Zinc concentration (as with MeHg) was higher in fish than in zooplankton, but overall variation in Zn concentration (unlike MeHg) was low. (3) Arsenic and Cd concentrations (as with Pb) were lower in fish than in zooplankton, but (unlike Pb) were not significantly correlated with trophic position within zooplankton or fish groups. (4) Average summer concentrations of As, Pb, Hg, and MeHg in zooplankton significantly predicted their concentrations in either planktivorous or piscivorous fish. Our secondary goal was to review sampling approaches in forty-five published studies to determine the extent to which current sampling programs facilitate cross-lake and cross-study comparisons of bioaccumulation. We found that studies include different components of the food web and sample too infrequently to enable strong cross-lake and cross-study comparisons. We discuss sampling strategies that would improve our capacity to identify consistent patterns of bioaccumulation and drivers of elevated trace element concentrations under naturally high levels of variability.

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“…Our study did not include data for mercury accumulation by nonalgal particulate matter, which is known to be a significant Hg source to nonselective grazers such as Daphnia in some natural systems (29). In these experiments, the tanks were low in nonalgal particulates.…”

Section: Resultsmentioning

confidence: 99%

Algal blooms reduce the uptake of toxic methylmercury in freshwater food webs

Pickhardt

Folt

Chen

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

373

273

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Mercury accumulation in fish is a global public health concern, because fish are the primary source of toxic methylmercury to humans. Fish from all lakes do not pose the same level of risk to consumers. One of the most intriguing patterns is that potentially dangerous mercury concentrations can be found in fish from clear, oligotrophic lakes whereas fish from greener, eutrophic lakes often carry less mercury. In this study, we experimentally tested the hypothesis that increasing algal biomass reduces mercury accumulation at higher trophic levels through the dilution of mercury in consumed algal cells. Under bloom dilution, as algal biomass increases, the concentration of mercury per cell decreases, resulting in a lower dietary input to grazers and reduced bioaccumulation in algal-rich eutrophic systems. To test this hypothesis, we added enriched stable isotopes of Hg to experimental mesocosms and measured the uptake of toxic methylmercury (CH 3 200 Hg ؉ ) and inorganic 201 Hg 2؉ by biota at several algal concentrations. We reduced absolute spike detection limits by 50 -100 times compared with previous techniques, which allowed us to conduct experiments at the extremely low aqueous Hg concentrations that are typical of natural systems. We found that increasing algae reduced CH 3Hg ؉ concentrations in zooplankton 2-3-fold. Bloom dilution may provide a mechanistic explanation for lower CH 3Hg ؉ accumulation by zooplankton and fish in algal-rich relative to algal-poor systems. N utrient enrichment with subsequent eutrophication is one of the most important problems impacting lakes worldwide (1, 2). Increased nutrient concentrations produce algal blooms, which in turn alter concentrations of nutrients, gases, pH, and metal ions in the water (3). It is our hypothesis that by increasing algal abundance, nutrient enrichment also alters Hg inputs to lake food webs. Mercury concentrations in fish have been related to metal burdens in their zooplankton prey (4-8), but the connection between Hg accumulation by zooplankton and increasing algal density under nutrient enrichment has not been established. It is critical to discern this association because algae can concentrate Hg from the aqueous phase (e.g., by 100-10,000ϩ times) and thus provide the greatest inputs of Hg to the food chain (9, 10). Here we report how an induced algal bloom affects the accumulation of methyl and inorganic Hg in the cladoceran Daphnia after 2 and 3 weeks of grazing on algae labeled with stable isotopes of Hg. Daphnia is a common zooplankton herbivore and known to be a major food for planktivorous fish (11), therefore factors affecting Hg burdens in this ''keystone'' (12, 13) prey taxon may have important ramifications for predicting CH 3 Hg ϩ burdens in fish across lakes of varying trophic status.We experimentally tested the hypothesis that at equal initial concentrations of aqueous Hg, an increase in algae will result in a decrease in Hg uptake-by zooplankton grazers. Our rationale for this hypothesis was that the concentration of metal per cel...

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Contribution of suspended particulate matter and zooplankton to MeHg contamination of the food chain in midnorthern Quebec (Canada) reservoirs

Cited by 34 publications

References 21 publications

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

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

Assessing element-specific patterns of bioaccumulation across New England lakes

Algal blooms reduce the uptake of toxic methylmercury in freshwater food webs

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