Quantifying mercury isotope dynamics in captive Pacific bluefin tuna (Thunnus orientalis)
Abstract Analyses of mercury (Hg) isotope ratios in fish tissues are used increasingly to infer sources and biogeochemical processes of Hg in natural aquatic ecosystems. Controlled experiments that can couple internal Hg isotope behavior with traditional isotope tracers (δ13C, δ15N) can improve the...
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| Format: | Article |
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BioOne
2016-02-01
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| Series: | Elementa: Science of the Anthropocene |
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| Online Access: | http://elementascience.org/article/info:doi/10.12952/journal.elementa.000088 |
| _version_ | 1829513898317840384 |
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| author | Sae Yun Kwon Joel D. Blum Daniel J. Madigan Barbara A. Block Brian N. Popp |
| author_facet | Sae Yun Kwon Joel D. Blum Daniel J. Madigan Barbara A. Block Brian N. Popp |
| author_sort | Sae Yun Kwon |
| collection | DOAJ |
| description | Abstract Analyses of mercury (Hg) isotope ratios in fish tissues are used increasingly to infer sources and biogeochemical processes of Hg in natural aquatic ecosystems. Controlled experiments that can couple internal Hg isotope behavior with traditional isotope tracers (δ13C, δ15N) can improve the applicability of Hg isotopes as natural ecological tracers. In this study, we investigated changes in Hg isotope ratios (δ202Hg, Δ199Hg) during bioaccumulation of natural diets in the pelagic Pacific bluefin tuna (Thunnus orientalis; PBFT). Juvenile PBFT were fed a mixture of natural prey and a dietary supplement (60% Loligo opalescens, 31% Sardinops sagax, 9% gel supplement) in captivity for 2914 days, and white muscle tissues were analyzed for Hg isotope ratios and compared to time in captivity and internal turnover of δ13C and δ15N. PBFT muscle tissues equilibrated to Hg isotope ratios of the dietary mixture within ∼700 days, after which we observed a cessation in further shifts in Δ199Hg, and small but significant negative δ202Hg shifts from the dietary mixture. The internal behavior of Δ199Hg is consistent with previous fish studies, which showed an absence of Δ199Hg fractionation during Hg bioaccumulation. The negative δ202Hg shifts can be attributed to either preferential excretion of Hg with higher δ202Hg values or individual variability in captive PBFT feeding preferences and/or consumption rates. The overall internal behavior of Hg isotopes is similar to that described for δ13C and δ15N, though observed Hg turnover was slower compared to carbon and nitrogen. This improved understanding of internal dynamics of Hg isotopes in relation to δ13C and δ15N enhances the applicability of Hg isotope ratios in fish tissues for tracing Hg sources in natural ecosystems. |
| first_indexed | 2024-12-16T13:08:40Z |
| format | Article |
| id | doaj.art-049098055cee4cb6ac6d308073838526 |
| institution | Directory Open Access Journal |
| issn | 2325-1026 |
| language | English |
| last_indexed | 2024-12-16T13:08:40Z |
| publishDate | 2016-02-01 |
| publisher | BioOne |
| record_format | Article |
| series | Elementa: Science of the Anthropocene |
| spelling | doaj.art-049098055cee4cb6ac6d3080738385262022-12-21T22:30:40ZengBioOneElementa: Science of the Anthropocene2325-10262016-02-0110.12952/journal.elementa.000088ELEMENTA-D-14-00003Quantifying mercury isotope dynamics in captive Pacific bluefin tuna (Thunnus orientalis)Sae Yun KwonJoel D. BlumDaniel J. MadiganBarbara A. BlockBrian N. PoppAbstract Analyses of mercury (Hg) isotope ratios in fish tissues are used increasingly to infer sources and biogeochemical processes of Hg in natural aquatic ecosystems. Controlled experiments that can couple internal Hg isotope behavior with traditional isotope tracers (δ13C, δ15N) can improve the applicability of Hg isotopes as natural ecological tracers. In this study, we investigated changes in Hg isotope ratios (δ202Hg, Δ199Hg) during bioaccumulation of natural diets in the pelagic Pacific bluefin tuna (Thunnus orientalis; PBFT). Juvenile PBFT were fed a mixture of natural prey and a dietary supplement (60% Loligo opalescens, 31% Sardinops sagax, 9% gel supplement) in captivity for 2914 days, and white muscle tissues were analyzed for Hg isotope ratios and compared to time in captivity and internal turnover of δ13C and δ15N. PBFT muscle tissues equilibrated to Hg isotope ratios of the dietary mixture within ∼700 days, after which we observed a cessation in further shifts in Δ199Hg, and small but significant negative δ202Hg shifts from the dietary mixture. The internal behavior of Δ199Hg is consistent with previous fish studies, which showed an absence of Δ199Hg fractionation during Hg bioaccumulation. The negative δ202Hg shifts can be attributed to either preferential excretion of Hg with higher δ202Hg values or individual variability in captive PBFT feeding preferences and/or consumption rates. The overall internal behavior of Hg isotopes is similar to that described for δ13C and δ15N, though observed Hg turnover was slower compared to carbon and nitrogen. This improved understanding of internal dynamics of Hg isotopes in relation to δ13C and δ15N enhances the applicability of Hg isotope ratios in fish tissues for tracing Hg sources in natural ecosystems.http://elementascience.org/article/info:doi/10.12952/journal.elementa.000088methylmercuryturnoverisotopes |
| spellingShingle | Sae Yun Kwon Joel D. Blum Daniel J. Madigan Barbara A. Block Brian N. Popp Quantifying mercury isotope dynamics in captive Pacific bluefin tuna (Thunnus orientalis) Elementa: Science of the Anthropocene methylmercury turnover isotopes |
| title | Quantifying mercury isotope dynamics in captive Pacific bluefin tuna (Thunnus orientalis) |
| title_full | Quantifying mercury isotope dynamics in captive Pacific bluefin tuna (Thunnus orientalis) |
| title_fullStr | Quantifying mercury isotope dynamics in captive Pacific bluefin tuna (Thunnus orientalis) |
| title_full_unstemmed | Quantifying mercury isotope dynamics in captive Pacific bluefin tuna (Thunnus orientalis) |
| title_short | Quantifying mercury isotope dynamics in captive Pacific bluefin tuna (Thunnus orientalis) |
| title_sort | quantifying mercury isotope dynamics in captive pacific bluefin tuna thunnus orientalis |
| topic | methylmercury turnover isotopes |
| url | http://elementascience.org/article/info:doi/10.12952/journal.elementa.000088 |
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