Quantifying mercury isotope dynamics in captive Pacific bluefin tuna (<i>Thunnus orientalis</i>)

Kwon, Sae Yun; Blum, Joel D.; Madigan, Daniel J.; Block, Barbara A.; Popp, Brian N.

doi:10.12952/journal.elementa.000088

Cited by 30 publications

(49 citation statements)

References 81 publications

(146 reference statements)

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“…In cores of sediment and peat, δ 202 Hg is used as a source indicator to investigate historical deposition or changes in Hg source profiles (13, 15). In fish, however, using δ 202 Hg for MeHg in a diagnostic manner is more challenging than simply identifying inorganic Hg sources, because MDF also occurs during photochemical demethylation (5), during microbial methylation and demethylation (59), and potentially during metabolic processing (22, 60). We expect, however, that these variables will not impart considerable changes to the δ 202 Hg of these lake trout due to the consistency in sampling protocol.…”

Section: Resultsmentioning

confidence: 99%

“…This biennial sampling therefore captured time-discrete δ 13 C and δ 15 N in lake trout, and results can trace the sensitive dynamic equilibrium sufficiently. Other studies have demonstrated that MeHg in fish has a modestly longer half-life than C and N (60, 62) and that fish can respond rapidly to MeHg source perturbations (6). Based on those observations, along with the rapid, coherent δ 202 Hg shift in lake trout, we believe that the lake trout rapidly respond to cessation in Hg emissions from regional sources.…”

Section: Resultsmentioning

confidence: 99%

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Mercury source changes and food web shifts alter contamination signatures of predatory fish from Lake Michigan

Lepak

Hoffman

Janssen

et al. 2019

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

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To understand the impact reduced mercury (Hg) loading and invasive species have had on methylmercury bioaccumulation in predator fish of Lake Michigan, we reconstructed bioaccumulation trends from a fish archive (1978 to 2012). By measuring fish Hg stable isotope ratios, we related temporal changes in Hg concentrations to varying Hg sources. Additionally, dietary tracers were necessary to identify food web influences. Through combined Hg, C, and N stable isotopic analyses, we were able to differentiate between a shift in Hg sources to fish and periods when energetic transitions (from dreissenid mussels) led to the assimilation of contrasting Hg pools (2000 to present). In the late 1980s, lake trout δ202Hg increased (0.4‰) from regulatory reductions in regional Hg emissions. After 2000, C and N isotopes ratios revealed altered food web pathways, resulting in a benthic energetic shift and changes to Hg bioaccumulation. Continued increases in δ202Hg indicate fish are responding to several United States mercury emission mitigation strategies that were initiated circa 1990 and continued through the 2011 promulgation of the Mercury and Air Toxics Standards rule. Unlike archives of sediments, this fish archive tracks Hg sources susceptible to bioaccumulation in Great Lakes fisheries. Analysis reveals that trends in fish Hg concentrations can be substantially affected by shifts in trophic structure and dietary preferences initiated by invasive species in the Great Lakes. This does not diminish the benefits of declining emissions over this period, as fish Hg concentrations would have been higher without these actions.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Mercury source changes and food web shifts alter contamination signatures of predatory fish from Lake Michigan

Lepak

Hoffman

Janssen

et al. 2019

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

View full text Add to dashboard Cite

show abstract

“…The difference in the timing of the inflection points for yellowfin tuna (1998) and bigeye tuna (2002) may be an artifact of sampling error (no bigeye tuna sampled in 1998; sample sizes low in 2002) or because of the contrasting biology and ecology of the 2 species. Kwon et al determined the time that so‐called new mercury is at steady state in Pacific bluefin tuna ( Thunnus orientalis ) to be >1070 d. Time to steady state depends on metabolic rate (inverse relationship), which in turn is (directly) related to temperature . At a given temperature, bigeye tuna have lower metabolic rates and likely a longer time to steady state (for mercury), compared with yellowfin tuna.…”

Section: Resultsmentioning

confidence: 99%

Mercury in tunas and blue marlin in the North Pacific Ocean

Drevnick

Brooks

2017

Enviro Toxic and Chemistry

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Models and data from the North Pacific Ocean indicate that mercury concentrations in water and biota are increasing in response to (global or hemispheric) anthropogenic mercury releases. In the present study, we provide an updated record of mercury in yellowfin tuna (Thunnus albacares) caught near Hawaii that confirms an earlier conclusion that mercury concentrations in these fish are increasing at a rate similar to that observed in waters shallower than 1000 m. We also compiled and reanalyzed data from bigeye tuna (Thunnus obesus) and blue marlin (Makaira nigricans) caught near Hawaii in the 1970s and 2000s. Increases in mercury concentrations in bigeye tuna are consistent with the trend found in yellowfin tuna, in both timing and magnitude. The data available for blue marlin do not allow for a fair comparison among years, because mercury concentrations differ between sexes for this species, and sex was identified (or reported) in only 3 of 7 studies. Also, mercury concentrations in blue marlin may be insensitive to modest changes in mercury exposure, because this species appears to have the ability to detoxify mercury. The North Pacific Ocean is a region of both relatively high rates of atmospheric mercury deposition and capture fisheries production. Other data sets that allow temporal comparisons in mercury concentrations, such as pacific cod (Gadus macrocephalus) in Alaskan waters and albacore tuna (Thunnus alalunga) off the US Pacific coast, should be explored further, to aid in understanding human health and ecological risks and to develop additional baseline knowledge for assessing changes in a region expected to respond strongly to reductions in anthropogenic mercury emissions. Environ Toxicol Chem 2017;36:1365-1374. © 2017 SETAC.

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“…Slow changes in tuna Hg may be driven by long (>1 year) histories reflected by muscle Hg of large marine predators. Kwon et al 36 reported a biological half-life of Hg in captive Pacific Bluefin tuna (PBFT) of ~500 days. Assuming comparable metabolic rates of ABFT and PBFT and given the larger size of ABFT in this study, Hg levels in ABFT likely represent exposure periods of ≥500 days.…”

Section: Resultsmentioning

confidence: 99%

Declining Mercury Concentrations in Bluefin Tuna Reflect Reduced Emissions to the North Atlantic Ocean

Lee

Lutcavage

Chandler

et al. 2016

Environ. Sci. Technol.

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Tunas are apex predators in marine food webs that can accumulate mercury (Hg) to high concentrations and provide more Hg (~40%) to the U.S population than any other source. We measured Hg concentrations in 1292 Atlantic bluefin tuna (ABFT, Thunnus thynnus) captured in the Northwest Atlantic from 2004 to 2012. ABFT Hg concentrations and variability increased nonlinearly with length, weight, and age, ranging from 0.25 to 3.15 mg kg−1, and declined significantly at a rate of 0.018 ± 0.003 mg kg−1 per year or 19% over an 8-year period from the 1990s to the early 2000s. Notably, this decrease parallels comparably reduced anthropogenic Hg emission rates in North America and North Atlantic atmospheric Hg0 concentrations during this period, suggesting that recent efforts to decrease atmospheric Hg loading have rapidly propagated up marine food webs to a commercially important species. This is the first evidence to suggest that emission reduction efforts have resulted in lower Hg concentrations in large, long-lived fish.

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Quantifying mercury isotope dynamics in captive Pacific bluefin tuna (Thunnus orientalis)

Cited by 30 publications

References 81 publications

Mercury source changes and food web shifts alter contamination signatures of predatory fish from Lake Michigan

Mercury source changes and food web shifts alter contamination signatures of predatory fish from Lake Michigan

Mercury in tunas and blue marlin in the North Pacific Ocean

Declining Mercury Concentrations in Bluefin Tuna Reflect Reduced Emissions to the North Atlantic Ocean

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