Sponge halogenated natural products found at parts‐per‐million levels in marine mammals

Abstract

Several unknown, abundant brominated compounds (BCs) were recently detected in the blubber of dolphins and other marine mammals from Queensland (northeast Australia). The BCs were interpreted as potential natural products due to the lack of anthropogenic sources for these compounds. This study investigated whether some of the BCs accumulated by diverse marine mammal species are identical with natural BCs previously isolated from sponges (Dysidea sp.) living in the same habitat. Isolates from sponges and mollusks (Asteronotus cespitosus) were compared with the signals detected in the mammals' tissue. Mass spectra and gas chromatography retention times on four different capillary columns of the isolates from sponges and mammals were identical in all respects. This proves that the chemical name of the compound previously labeled BC-2 is 4,6-dibromo-2-(2',4'-dibromo)phenoxyanisole and that the chemical name of BC-11 is 3,5-dibromo-2-(3',5'-dibromo,2'-methoxy)phenoxyanisole. Using a quantitative reference solution of BC-2, we established that the concentrations of the brominated metabolites found in the marine mammals are frequently >1 mg/kg. The highest concentration (3.8 mg/kg), found in a sample of pygmy sperm whale (Kogia breviceps), indicates that BC-2 is a bioaccumulative, natural organohalogen compound. This is supported by the concentrations of the BCs in our samples being equal to the highest concentrations of anthropogenic BCs in any environmental sample. The quantitative determination of BC-2 in blubber of marine mammals from Africa and the Antarctic suggests that BC-2 is widespread. These results are direct proof that marine biota can produce persistent organic chemicals that accumulate to substantial concentrations in higher trophic organisms.

Complexity of Naturally Produced Polybrominated Diphenyl Ethers Revealed via Mass Spectrometry

“…1–5 PBDEs have been isolated from marine Eukarya, 6–12 where they can constitute up to 10% of the total mass of marine invertebrates such as sponges. 13 Together with structurally related polybrominated biphenyls, dibenzofurans and dibenzo- p -dioxins, production of PBDEs at lower trophic levels in the marine biota likely introduces these persistent molecules into the marine food chain, 14–16 from where they enter our food supply, 17,18 potentially leading to deleterious health effects in humans.…”

Occurrence of halogenated flame retardants in commercial seafood species available in European markets

“…Due to their origin, MeO-PBDEs are considered as a problem only in sea waters. In fact, they can present greater levels on the high seas than on the shore (Vetter et al, 2002). This directive observes eleven qualitative descriptors for determining good environmental status.…”

“…On the other hand, other brominated compounds naturally produced by sponges or red algae are present in the marine environment at levels similar to those of PBDEs, sometimes at even higher levels (Vetter et al, 2002). Methoxylated PBDEs (MeO-PBDEs) represent an example of these halogenated natural products.…”

Contemporary 14C radiocarbon levels of oxygenated polybrominated diphenyl ethers (O-PBDEs) isolated in sponge–cyanobacteria associations

“…6-MeO-BDE47; 2′-MeO-BDE68; 2′,6-diMeO-BDE68). The occurrence of the same compounds in sponges, dolphins and marine mammals in Queensland/ Australia (Vetter et al, 2001, 2002; Agrawal and Bowden, 2005), indicate that the bioaccumulation process in the marine food web might start in the same geographical area, perhaps limiting the extent of the bioaccumulation potential through the oceanic dispersion of these natural HOCs. Yet, the sponges containing cyanobacteria associations represent about 100 species in 29 families which is a large pool of O-PBDEs producing organisms mainly located in the tropical ocean.…”