Uptake and trophic changes of PBDEs in the benthic marine food chain

We examine the influence of sediment factors on uptake of PBDEs into marine deposit and filter feeders, and transfer to higher trophic levels. Sediment PBDEs increase with %toc, AVS, organic flux, and fines. As a result, coarser, less organic sediments in JdF have lower [PBDEs] than the southern SoG. Sediment feeder [PBDE] variance was best explained by AVS\u3e[PBDEs]\u3e%TOC\u3eOC flux. Therefore, increasing organic input and burn-down, and sediment PBDEs enhance tissue PBDEs. Dry weight PBDE accumulation (tissue/sediment) in sediment feeders decreased with increasing sediment PBDEs, resulting in tissue dilution at sediment concentrations \u3e10,000pg/g in urban harbours. PBDE accumulation decreased with increasing fines. As a result, accumulation was higher in JdF than SoG. These patterns imply low bioavailability at high sediment PBDEs. Dry weight PBDEs increased ~107x from background benthos to predators, crabs and seal blubber, whereas lipid weight differences were 1. Thus bio-accumulation trends require understanding of food resources in higher trophic fauna. The greatest change in congenor composition occurs at sediment uptake. Dominant nona/deca- BDEs in sediments decline concurrent with increasing tetra-hexa BDEs. Sediment feeders near outfalls and in background locations had similar proportions of congenors. Harbour feeders had a composition similar to sediments. Along with the noted bio-dilution, this suggests that uptake of PBDEs is so rapid at high sediment levels that most passes un-modifed through guts. BDE-209 varies throughout the food chain, reflecting shifting dependence on sediment versus pelagic food resources. In higher trophic level fauna, debromination of penta/hexa to tetra BDEs is much slower than initial debromination of deca/nona-BDEs. Tetra-BDEs appear to be a metabolic dead-end