ENSO Climate Forcing of the Marine Mercury Cycle in the Peruvian Upwelling Zone Does Not Affect Methylmercury Levels of Marine Avian Top Predators.

Autor:	Renedo M; Géosciences Environnement Toulouse (GET)-Institut de Recherche pour le Développement (IRD), CNRS, Université de Toulouse, 14 Avenue Edouard Belin, Toulouse 31400, France., Point D; Géosciences Environnement Toulouse (GET)-Institut de Recherche pour le Développement (IRD), CNRS, Université de Toulouse, 14 Avenue Edouard Belin, Toulouse 31400, France., Sonke JE; Géosciences Environnement Toulouse (GET)-Institut de Recherche pour le Développement (IRD), CNRS, Université de Toulouse, 14 Avenue Edouard Belin, Toulouse 31400, France., Lorrain A; Univ Brest, CNRS, IRD, Ifremer, LEMAR, Plouzané F-29280 France., Demarcq H; IRD, MARBEC (Univ. Montpellier, CNRS, Ifremer, IRD), Sète 34203, France., Graco M; Instituto del Mar del Perú (IMARPE), Esquina Gamarra y General Valle, Callao 07021, Peru., Grados D; Instituto del Mar del Perú (IMARPE), Esquina Gamarra y General Valle, Callao 07021, Peru., Gutiérrez D; Instituto del Mar del Perú (IMARPE), Esquina Gamarra y General Valle, Callao 07021, Peru., Médieu A; Univ Brest, CNRS, IRD, Ifremer, LEMAR, Plouzané F-29280 France., Munaron JM; Univ Brest, CNRS, IRD, Ifremer, LEMAR, Plouzané F-29280 France., Pietri A; Instituto del Mar del Perú (IMARPE), Esquina Gamarra y General Valle, Callao 07021, Peru., Colas F; LOCEAN IPSL (IRD/CNRS/SU/MNHN), 4 Place Jussieu, Paris 75252, France., Tremblay Y; IRD, MARBEC (Univ. Montpellier, CNRS, Ifremer, IRD), Sète 34203, France., Roy A; IRD, MARBEC (Univ. Montpellier, CNRS, Ifremer, IRD), Sète 34203, France., Bertrand A; IRD, MARBEC (Univ. Montpellier, CNRS, Ifremer, IRD), Sète 34203, France., Bertrand SL; IRD, MARBEC (Univ. Montpellier, CNRS, Ifremer, IRD), Sète 34203, France.
Jazyk:	angličtina
Zdroj:	Environmental science & technology [Environ Sci Technol] 2021 Dec 07; Vol. 55 (23), pp. 15754-15765. Date of Electronic Publication: 2021 Nov 19.
DOI:	10.1021/acs.est.1c03861
Abstrakt:	Climate change is expected to affect marine mercury (Hg) biogeochemistry and biomagnification. Recent modeling work suggested that ocean warming increases methylmercury (MeHg) levels in fish. Here, we studied the influence of El Niño Southern Oscillations (ENSO) on Hg concentrations and stable isotopes in time series of seabird blood from the Peruvian upwelling and oxygen minimum zone. Between 2009 and 2016, La Niña (2011) and El Niño conditions (2015-2016) were accompanied by sea surface temperature anomalies up to 3 °C, oxycline depth change (20-100 m), and strong primary production gradients. Seabird Hg levels were stable and did not co-vary significantly with oceanographic parameters, nor with anchovy biomass, the primary dietary source to seabirds (90%). In contrast, seabird Δ 199 Hg, proxy for marine photochemical MeHg breakdown, and δ 15 N showed strong interannual variability (up to 0.8 and 3‰, respectively) and sharply decreased during El Niño. We suggest that lower Δ 199 Hg during El Niño represents reduced MeHg photodegradation due to the deepening of the oxycline. This process was balanced by equally reduced Hg methylation due to reduced productivity, carbon export, and remineralization. The non-dependence of seabird MeHg levels on strong ENSO variability suggests that marine predator MeHg levels may not be as sensitive to climate change as is currently thought.
Databáze:	MEDLINE
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