Benthic food web structures as an explanation for prolonged ecological half-life of 137Cs in flatfish species in the Fukushima coastal area. (May 2022)

• Record Type: Journal Article
• Authors: Holmerin, Isak; Svensson, Filip; Hirawake, Toru; Ishimaru, Takashi; Ito, Yukari; Kanda, Jota; Nascimento, Francisco; Bradshaw, Clare
• Is Part Of: Journal of environmental radioactivity. Volume 246(2022)
• Publication Date: 2022-05
• Subjects: Radioactivity -- Periodicals; Radiation, Background -- Periodicals; Radioecology -- Periodicals; Radioactive pollution -- Periodicals; Environmental Pollutants -- Periodicals; Radioactive Pollutants -- Periodicals; Radioactivity -- Periodicals; Radioécologie -- Périodiques; Pollution radioactive -- Périodiques; Fond de rayonnement -- Périodiques; 539.752
• DOI: 10.1016/j.jenvrad.2022.106844
• Languages: English
• ISSNs: 0265-931X

Abstract

Abstract: After the accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP), Japan, in March 2011, 137 Cs in demersal fish had, between 2011 and 2015, a prolonged ecological half-life when compared to pelagic fish. Using stable isotope mixing models combined with gut content analysis and 137 Cs activity concentrations, this study investigated the hypothesis that an unexplored food web structure could be a contributing factor explaining the ecological half-life of 137 Cs in benthic flatfish. Benthic invertebrates and demersal fish species sampled in 2015 still showed 137 Cs activity concentrations higher than pre-accident. The mixing models of stable N and C isotopes and gut content analysis identified deposit, suspension and filter feeders to be the main flatfish food items in the benthos. There was a significant correlation between 137 Cs activity concentrations in specific flatfish species and benthos, and between 137 Cs activity concentrations in benthos and surface sediment. The results of this study partially explained the 137 Cs activity concentrations found in the analysed demersal fish, suggesting that the benthos can be a continuous source of 137 Cs for the demersal fish during this period of time. Extending monitoring programmes to include invertebrates that are not food species for humans would greatly improve our ability to understand the role of trophic transfer pathways and take appropriate management actions. Highlights: Benthos in fish diet identified using stable isotope mixing models and gut content Significant correlation between specific flatfish species and 137 Cs in benthos Food web transfer may explain the long ecological half-life of 137 Cs in flatfish Common dietary species like polychaetes should be included in monitoring programmes