Sources and Variations of Mercury in Tuna

Kraepiel, Anne M. L.; Keller, K.; Chin, Henry B; Malcolm, Elizabeth G.; Morel, François M. M.

doi:10.1021/es0340679

Cited by 123 publications

(96 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This is in contrast to the hypothesis that most of the MMHg in marine fish results from potential methylation sources in the deep ocean such as hydrothermal systems and sediments (Kraepiel et al, 2003). Although the source of MMHg in marine fish is largely unknown, Rolfhus and Fitzgerald (1995) greater than those estimated for the shelf sediments sampled in this study.…”

Section: Sediment−water Flux Of Mmhgcontrasting

confidence: 85%

“…This means that the biogeochemistry and bioaccumulation of MMHg in nearshore and continental shelf areas may be major factors affecting the exposure of humans to MMHg. However, and unfortunately, little is known about the production and cycling of MMHg in coastal marine systems and the open ocean, where most of the MMHg in biota has been hypothesized to result from production in deep sea sediments and/or hydrothermal systems (Kraepiel et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Methylmercury cycling in sediments on the continental shelf of southern New England

Hammerschmidt

Fitzgerald

2006

Geochimica et Cosmochimica Acta

169

127

View full text Add to dashboard Cite

Exposure of humans to monomethylmercury (MMHg) occurs primarily through consumption of marine fish, yet there is limited understanding concerning the bioaccumulation and biogeochemistry of MMHg in the biologically productive coastal ocean. We examined the cycling of MMHg in sediments at three locations on the continental shelf of southern New Moreover, the efflux of dissolved MMHg to overlying water (i.e., net production at steady state) is correlated with the gross potential rate of MMHg production in surface sediments. These results suggest that the production and efflux of MMHg from coastal marine sediments is limited by Hg(II), loadings of which presumably are principally from atmospheric deposition to this region of the continental shelf. The estimated diffusive flux of MMHg from the shelf sediments averages 9 pmol m −2 d −1 . This flux is comparable to that required to sustain the current rate of MMHg accumulation by marine fish, and may be enhanced by the efflux of MMHg from nearshore deposits contaminated more substantially with anthropogenic Hg. Hence, production and subsequent mobilization of MMHg from sediments in the coastal zone may be a major source of MMHg to the ocean and marine biota, including fishes consumed by humans.

show abstract

Section: Sediment−water Flux Of Mmhgcontrasting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Methylmercury cycling in sediments on the continental shelf of southern New England

Hammerschmidt

Fitzgerald

2006

Geochimica et Cosmochimica Acta

169

127

View full text Add to dashboard Cite

show abstract

“…The size of a fish is known as a determining factor of its Hg burden (Mackay et al, 1975;Jaffar and Ashraf, 1988;Bloom, 1992;Dietz et al, 1996;Gilmour and Riedel, 2000;Stafford and Haines, 2001;Kraepiel et al, 2003), and has been confirmed here.…”

Section: Mercury Size Sex Species and Locationsupporting

confidence: 76%

“…These interspecific differences in Hg levels were probably linked to differences in each species physiology, feeding rate, growth rate, lifespan, migratory patterns, foraging habits and/or diet. For instance, the low Hg levels in Wahoos could be explained by the surface foraging habits of this species (0-12 m) which contrasts with the others which feed from the surface to great depths (up to 800 m for Swordfish) where Hg methylation, in these poorly oxygenated waters, enhances its bioaccumulation (Monteiro et al, 1996;Kraepiel et al, 2003). A clear example of differential vertical distribution of Hg levels in fish is given by Monteiro et al (1996), who found a 4-fold increase in Hg levels from epipelagic (100-150 m) to mesopelagic (300-1 200 m) lanternfish species in the sub-tropical mid-North Atlantic.…”

Section: Mercury Size Sex Species and Locationmentioning

confidence: 99%

Mercury content in commercial pelagic fish and its risk assessment in the Western Indian Ocean

Kojadinovic

Potier

Corre³

et al. 2006

Science of The Total Environment

123

View full text Add to dashboard Cite

As top predators of pelagic food webs, large fish naturally bioaccumulate mercury (Hg). Determining Hg burdens in commercialized fish is essential considering the concern about effects of contaminants on human health and the legal thresholds that are therefore set for local consumption and/or exportation. Total Hg levels were measured in the muscular tissue of 183 fish of five commercially important species from the tropical zone of the Western Indian Ocean. All individuals were measured and sexed in order to study the impregnation of Hg with size and sex within each species. Values of Hg found in this part of the Indian Ocean were comparable to Hg in muscular tissue of the same species studied in other areas. The highest Hg levels were noted in Swordfish (Xiphias gladius) caught in waters surrounding Reunion Island (3.97 ± 2.67 µg.g −1 dry weight). Following the Swordfish, in decreasing order of Hg content, were the Yellowfin Tuna (Thunnus albacares) and the Skipjack (Katsuwonus pelamis), then the Common Dolphinfish (Coryphaena hippurus) and the Wahoo (Acanthocybium solandri). In the North of the Mozambique Channel, Swordfish had higher Hg levels than Yellowfin Tunas, and Dolphinfish exhibited intermediate Hg levels. The size of a fish was a determinating factor of its Hg burden, as was the species. Differences in size-normalized Hg levels were observed between the two study zones for Swordfish and Common Dolphinfish. Sex, in contrast, did not influence Hg levels suggesting that females and males have similar feeding habits. The muscular Hg levels presented here suggest that consumers of fish originating from the Western Indian Ocean should limit themselves to one Swordfish based meal per week, or one fish meal a day if they choose to eat tuna or Common Dolphinfish.

show abstract

“…MMHg production in the oxygen minimum zone (OMZ) of the oceanic water column has been hypothesized 7,13 and recent field studies have offered new evidence supporting in situ methylation not only in OMZs (refs 3,6) but also in oxic surface waters 4,5,[15][16][17] . Vertical differences in ocean biogeochemistry and the relative contributions of different Hg sources to the overall MMHg burdens in fish have wide-ranging implications for understanding how MMHg levels in marine biota will respond to future changes in anthropogenic Hg emissions 3,18 .…”

mentioning

confidence: 99%

Methylmercury production below the mixed layer in the North Pacific Ocean

et al. 2013

View full text Add to dashboard Cite

Mercury enters marine food webs in the form of microbially generated monomethylmercury. Microbial methylation of inorganic mercury, generating monomethylmercury, is widespread in low-oxygen coastal sediments. The degree to which microbes also methylate mercury in the open ocean has remained uncertain, however. Here, we present measurements of the stable isotopic composition of mercury in nine species of marine fish that feed at different depths in the central North Pacific Subtropical Gyre. We document a systematic decline in δ 202 Hg, 199 Hg and 201 Hg values with the depth at which fish feed. We show that these mercury isotope trends can be explained only if monomethylmercury is produced below the surface mixed layer, including in the underlying oxygen minimum zone, that is, between 50 and more than 400 m depth. Specifically, we estimate that about 20-40% of the monomethylmercury detected below the surface mixed layer originates from the surface and enters deeper waters either attached to sinking particles, or in zooplankton and micronekton that migrate to depth. We suggest that the remaining monomethylmercury found at depth is produced below the surface mixed layer by methylating microbes that live on sinking particles. We suggest that microbial production of monomethylmercury below the surface mixed later contributes significantly to anthropogenic mercury uptake into marine food webs.M ercury (Hg) is a globally distributed atmospheric pollutant that can form monomethyl-Hg (MMHg), which is neurotoxic and bioaccumulative in aquatic food webs. The main pathway for human exposure to MMHg is through consumption of piscivorous marine fish 1 . In the ocean Hg primarily exists as inorganic Hg(ii) or Hg (0) [5][6][7] . In agreement with these vertical profiles, total Hg (THg) levels in commercially important predatory pelagic fish and their prey increase with median depth of occurrence 8,9 , which is indicative of both foraging depth and habitat utilization. However, the biogeochemical factors controlling the distribution and speciation of Hg in the ocean and the bioaccumulation of MMHg in marine food webs are still not well understood 10 .Microbial activity and both dark and photochemical inorganic reactions ultimately control the chemical speciation and subsequent bioavailability of Hg (ref. 2), thus an understanding of the competing processes that produce and degrade MMHg at different depths in the ocean is critical to tracing its bioaccumulation in fish and biomagnification in marine food webs. MMHg typically comprises only a small fraction of THg in North Pacific sea water (<15%; ref. 4) but nearly all of the Hg (>95%) in large marine fish 2,11 and most of the Hg (>80%) in small fish with trophic position (TP) as low as 2.5 (ref. 12). DMHg concentrations are generally small relative to MMHg (refs 3,4,13), although at some (refs 13,14). As DMHg is not bioaccumulated and because its Hg isotopic composition has not been measured, it is not treated in detail here. MMHg production in the oxygen minimum zone (OMZ) of...

show abstract

Sources and Variations of Mercury in Tuna

Cited by 123 publications

References 51 publications

Methylmercury cycling in sediments on the continental shelf of southern New England

Methylmercury cycling in sediments on the continental shelf of southern New England

Mercury content in commercial pelagic fish and its risk assessment in the Western Indian Ocean

Methylmercury production below the mixed layer in the North Pacific Ocean

Contact Info

Product

Resources

About