title: Effect of eutrophication on mercury, selenium, and essential fatty acids in bighead carp (Hypophthalmichthys nobilis) from reservoirs of eastern China.
abstract: Analyses of the risks and benefits of consuming fish assess the content of beneficial fatty acids found in fish relative to harmful pollutants such as methylmercury (MeHg). Quantifying the effect of eutrophication on mercury (Hg), selenium (Se) and essential fatty acids (EFAs) in fish is necessary to determine how measures of risk vary with productivity. Total Hg and MeHg, Se and fatty acids, including the EFA eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3), were analyzed in Bighead Carp (Hypophthalmichthys nobilis) dorsal muscle tissue from seven subtropical reservoirs of eastern China. Individual elements and fatty acids, as well as derived measures of risk (Se:Hg and hazard quotient, HQ(EFA)) were regressed against indicators of eutrophication, including total phosphorous (TP), chlorophyll-a (chl-a) and phytoplankton species composition. We found low MeHg concentrations (range=0.018-0.13 μg/g ww) and Se concentrations (range=0.12-0.28 μg/g ww), and Se:Hg molar ratios that were well above 1.0, indicating a low risk of Hg toxicity. Bighead Carp had a high content of total polyunsaturated fatty acids (∑PUFAs=44.2-53.6%), which included both EPA (6.9-12.5%) and DHA (16.1-23.2%). However, fish had significantly lower Se:Hg molar ratios in reservoirs with high TP, and lower EPA content with increasing plankton density (i.e. higher chl-a). Phytoplankton species composition predicted Se concentrations, but not Hg concentrations or EFA content. Overall, Hg concentrations in Bighead Carp were very low relative to consumption guidelines, and Se concentrations were adequate to confer protective benefits against MeHg toxicity. Our findings suggest that changes to plankton species composition and density with eutrophication may result in fish of lower nutritional value and thus increase risks to fish consumers by changing the availability of Se and EPA relative to MeHg.
authors.affiliation: Department of Biology, Queen's University, Kingston, Ontario K7L 3N6, Canada. Electronic address: roxanne.razavi@queensu.ca.
authors.forename: N Roxanna
authors.initials: NR
authors.lastname: Razavi
authors.affiliation: Department of Chemistry and Biology, Ryerson University, Toronto, Ontario M5B 2K3, Canada.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Arts
authors.affiliation: Department of Biology, Queen's University, Kingston, Ontario K7L 3N6, Canada.
authors.forename: Mingzhi
authors.initials: M
authors.lastname: Qu
authors.affiliation: Center for Watershed Ecology, Institute of Life Science and Key Laboratory of Poyang Lake Environment and Resource Utilization, Ministry of Education, Nanchang University, Nanchang, Jiangxi, 330031, China.
authors.forename: Binsong
authors.initials: B
authors.lastname: Jin
authors.affiliation: Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
authors.forename: Wenwei
authors.initials: W
authors.lastname: Ren
authors.affiliation: Department of Biology, Queen's University, Kingston, Ontario K7L 3N6, Canada.
authors.forename: Yuxiang
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Environmental Science, Saint Mary's University, Halifax, Nova Scotia B3H 3C3, Canada.
authors.forename: Linda M
authors.initials: LM
authors.lastname: Campbell
mesh_terms: D000818:Animals; D002347:Carps / Q000378:metabolism*; D004784:Environmental Monitoring; D005068:Eutrophication; D005228:Fatty Acids, Essential / Q000378:metabolism*; D008628:Mercury / Q000378:metabolism*; D012643:Selenium / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D005228:Fatty Acids, Essential; D014874:Water Pollutants, Chemical; D008628:Mercury; D012643:Selenium
keywords: Asian carp; Fatty acids; Hazard quotient; Methylmercury; Risk–benefit; Selenium:mercury molar ratios