Metal bioaccumulation and transfer in benthic species based on isotopic signatures of individual amino acids in South China Sea cold seep environments

Cold seeps are deep-sea 'oases' with dense and dominant coexisting populations of large mussels and tubeworms under extreme environments. Under such natural source of high metal concentrations, the present study investigated the metal bioaccumulation and transfer with trophic positions in six benthic species by the isotopic δ15N and δ13C signatures in the active Haima cold seep, South China Sea. Comparing the isotopic signatures of bulk-tissue and amino acids by compound-specific isotopic analysis (CSIA-AA), we found that the bulk trophic (TPB) values in the benthos except mussels were significantly higher than those of CSIA-based TPGlu-Phe values. The estimated CSIA-based TPGlu-Phe values showed a relatively compressed food chain with much changeable and unique amino acid isotopic heterogeneity, followed slim tubeworms (1.20)