High levels of halogenated natural products in large pelagic fish from the Western Indian Ocean

Abstract

Concentrations, profiles and muscle-liver distribution of halogenated natural products (HNPs) and anthropogenic persistent organic pollutants (POPs) were investigated in five large pelagic fish species and one smaller planktivore fish species from the Western Indian Ocean. Analysis of swordfish muscle from the Seychelles revealed the predominance of HNPs, with the highest concentrations found for 2′-methoxy-2,3′,4,5′- tetraBDE (2′-MeO-BDE 68 or BC-2), 6-methoxy-2,2′,4,4′- tetraBDE (6-MeO-BDE 47 or BC-3) and 2,3,3′,4,4′,5,5′-heptachloro-1′-methyl-1,2′-bipyrrole (Q1), along with varied contributions of further HNPs. The mean concentration of ∑HNPs (330 ng/g lw) was one or two orders of magnitude higher than ∑DDTs (60 ng/g lw) and ∑PCBs (6.8 ng/g lw). HNPs (BC-2, BC-3 and Q1) were also predominant in individual samples of three tropical tuna species from the Seychelles and from other regions of the Western Indian Ocean (Mozambique Channel, off Somalia and Chagos Archipelago). Non-targeted gas chromatography coupled with electron capture negative ion mass spectrometry operated in the selected ion monitoring mode (GC/ECNI-MS-SIM) analysis of one swordfish sample indicated low abundance of rarely reported HNPs (three hexachloro-1′-methyl-1,2′-bipyrrole (Cl6-MBP) isomers and pentabromo-1,1′-dimethyl-2,2′-bipyrroles (Br5-DBP)) but no further abundant unscreened polyhalogenated compounds.

Marine natural products

“…heptachloromethylbipyrrole, tetrabrominated methoxylated diphenyl ethers, PCBs and DDT metabolites, has been extended to large fish in the Seychelles pelagic ecosystem. 733 Two shark bile components, 5β-scymnol and 5β-scymnol sulfate are agonists of the TGR5 “Takeda G-protein receptor 5” bile acid receptor, the former being almost four-times more potent, highlighting potential roles in preventing the progression of atherosclerosis. 734…”

Persistent and Bioaccumulative Halogenated Natural Products in Various Tropical Reef Fish Species from the Seychelles, Western Indian Ocean

“…In this context, the Seychelles waters in the Western Indian Ocean (FAO Major Fishing Area 51, subarea 51.5 (Somalia, Kenya, Tanzania), Figure S1) host very diverse marine ecosystems, 18 but to our knowledge, HNPs were only reported in two large pelagic fish species, swordfish and tuna, in which the levels were comparably high. 5 The goal of our study was to determine and compare the levels of HNPs and POPs in tropical fish of the Seychelles marine ecosystem and to get more insights into the relevance of HNPs in them. Studies documenting environmental levels of POPs usually focus on analyzing many samples from one or a few fish species.…”

Cracked and Shucked: Gc-Apci-Ims-Hrms Facilitates Identification of Unknown Halogenated Organic Chemicals in French Marine Bivalves

“…The presence of HNPs in marine samples have been reported, sometimes at even higher concentrations than halogenated organic contaminants (HOCs). (Wu et al, 2021;Fernando et al, 2018) How do we then unravel this chemical space, wherein many chemical features remain unknown?…”