Trophic transfer of persistent toxic substances through a coastal food web in Ulsan Bay, South Korea: Application of compound-specific isotope analysis of nitrogen in amino acids

Abstract

Trophic magnification factor (TMF) of persistent toxic substances (PTSs: Hg, PCBs, PAHs, and styrene oligomers (SOs)) in a coastal food web (12 fish and four invertebrates) was determined in Ulsan Bay, South Korea. The nitrogen stable isotope ratios (delta N-15) of amino acids [delta N-15(Glu-Phe) based on glutamic acid (delta N-15(Glu)) and phenylalanine (delta N-15(Phe))] were used to estimate the trophic position (TPGlu-Phe) of organisms. The TPGlu-Phe of organisms ranged from 1.64 to 3.69, which was lower than TP estimated by delta N-15 of bulk particulate organic matter (TPBulk: 2.46-4.21). Mercury and CB 138, 153, 187, and 180 were biomagnified through the whole food web (TMF > 1), while other PTSs, such as PAHs and SOs were not (biodilution of SOs firstly reported). In particular, the trophic transfer of PTSs was pronounced in the resident fish (e.g., rock bream, sea perch, Korean rockfish). Of note, CB 99, 101, 118, and 183 were additionally found to be biomagnifying PTSs in these species. Thus, fish residency appears to represent an important factor in determining the TMF of PTSs in the coastal environment. Overall, delta N-15(Glu-Phe) provided accurate TPs of organisms and could be applied to determine the trophic transfer of PTSs in coastal food webs. (C) 2020 Elsevier Ltd. All rights reserved.