title: Developing a food web-based transfer factor of radiocesium for fish, whitespotted char (Salvelinus leucomaenis) in headwater streams.
abstract: We developed a food web-based transfer factor (TFweb) to study contaminant movements from multiple prey items to a predator based on the dietary contributions of prey items with their respective contamination levels. TFwebwas used to evaluate the transfer of137Cs into whitespotted char (Salvelinus leucomaenis) from the trophic structure of a stream-riparian ecosystem in headwater streams draining a Japanese cedar forest. We also examined the applicability of this method by comparing sites with different contamination levels but similar surrounding environments in Fukushima and Gunma. All samples were collected from August 2012 to May 2013. The dietary contributions from both aquatic and terrestrial prey items to whitespotted char were analyzed using stable carbon and nitrogen isotope ratios.137Cs activity concentrations in char ranged from 704 to 6082 Bq kg-1-dry in Fukushima and from 193 to 618 Bq kg-1-dry in Gunma. Dominant prey taxa such as mayflies (Ephemera japonica), spider crickets (Rhaphidosphoridae gen. spp.), and freshwater crabs (Geothelphusa dehaani), each of them accounted for 3-12% of the fish diet, based on lower and upper estimates, respectively. TFwebranged from 1.12 to 3.79 in Fukushima and from 1.30 to 4.30 in Gunma, which suggested bioaccumulation from prey items to predator. Widely used ecological parameters TFs by media-char and TTF by single prey-char showed high variability with both dilution and accumulation. TFwebis applicable for137Cs transfer in predator-prey systems with complex food web structures of stream-riparian ecosystems.
authors.affiliation: Department of Symbiotic Science of Environment and Natural Resources, United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan; Department of Zoology, Faculty of Biological Sciences, Jahangirnagar University, Savar, Dhaka 1342, Bangladesh. Electronic address: enamul31@yahoo.com.
authors.forename: Md Enamul
authors.initials: ME
authors.lastname: Haque
authors.affiliation: Department of International Environmental and Agricultural Science, Faculty of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Gomi
authors.affiliation: Department of Integrated Science and Engineering for Sustainable Society, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan.
authors.forename: Masaru
authors.initials: M
authors.lastname: Sakai
authors.affiliation: Faculty of Environmental Earth Science, Hokkaido University, N10, W5, Kita-ku, Sapporo, Hokkaido 060-0860, Japan.
authors.forename: Junjiro N
authors.initials: JN
authors.lastname: Negishi
mesh_terms: D000818:Animals; D002588:Cesium Radioisotopes / Q000032:analysis*; D020387:Food Chain; D062406:Fukushima Nuclear Accident; D007313:Insecta; D011834:Radiation Monitoring / Q000379:methods*; D045483:Rivers / Q000737:chemistry; D014337:Trout / Q000502:physiology*; D014875:Water Pollutants, Radioactive / Q000032:analysis*
chemical_list: D002588:Cesium Radioisotopes; D014875:Water Pollutants, Radioactive
keywords: Detrital food web; Freshwater salmonid; Radiocesium; Stable isotope; Transfer factor