The selective dietary accumulation of planar polychlorinated biphenyls in the otter (Lutra lutra)

Abstract

The decline of the populations of otters in Western Europe is assumed to be related to the accumulation of polychlorinated biphenyls (PCBs) in this species. A study was conducted to investigate the trophic transfer of non‐ortho, mono‐ortho‐, and di‐ortho‐substituted PCBs in the food web of the otter (Lutra lutra) in the Oude Venen lake system in the Netherlands, with relatively low PCB contamination. This area was one of the last strongholds of otters in the Netherlands and the species is considered to be virtually extinct since 1988. A marked increase in concentration of chlorinated biphenyls (CBs) was observed with successive trophic levels of the aquatic food web. Mean concentrations of the sum of 28 CB congeners (ΣCB) increased from 142 ng CB/g (organic carbon basis) in sediment and particulate matter to 588 ng CB/g (lipid weight basis) in invertebrates, to 2,450 ng CB/g (lipid weight) in fish, and 70,940 ng CB/g (lipid weight) in otter. A diet‐specific biomagnification factor (BMF) of 14 was calculated from fish to otter based on ΣCB; however, on the basis of toxic equivalent concentrations (ΣTEQ), a BMF of 41 was found. This higher BMF on TEQ basis was mainly due to the enrichment of non‐ortho‐substituted CB 126 in otter, compared to fish. In fish CB 126 contributed 30 to 50% to ΣTEQ, while this congener contributed 60 to 80% in otters. A shift in the CB patterns was found from relatively high concentrations of lowly chlorinated CBs in the abiotic compartments to the higher chlorinated CBs (five to seven chlorine atoms) at the highest trophic level. The relatively low concentrations of CB 77 and CBs with vicinal H‐atoms at the meta‐para position in otter compared to fish indicates that otters can metabolize these CBs and have P4501A‐like and P4502B‐like enzyme systems. It appears that even in an ecosystem with relatively low CB contamination, concentrations of CBs can be relatively high in aquatic top predators. The non‐ortho‐substituted CBs seem to be the most important toxic threat for otters, firstly because of the relatively high BMFs of CB 126 and CB 169 and secondly because of the formation of metabolites of CB 77.

Preferential Biomagnification of Aryl Hydrocarbon Hydroxylase–inducing Polychlorinated Biphenyl Congeners in the Lake Michigan, Usa, Lower Food Web

“…Significant differences among all levels are also observed (p Ͻ 0.005) in this case. A similar increase of concentration with increased trophic level has been reported by many studies in a variety of locations [14,17,[27][28][29].…”

“…In contrast to the biological phases, congeners 123 and 158 contributed more than 105 in the dissolved phase. Other food web studies involving AHH PCBs have also found 138, 118, or both to dominate in biological samples [8,14,15,25].…”

“…In Green Bay (WI, USA), it was suggested that these compounds account for more than 95% of the dioxinlike toxic activity affecting Forster's terns [13]. Even with this toxicity potential, only a handful of reports have concerned the distribution of AHH PCBs or their trophic transfer in aquatic ecosystems [8,11,[14][15][16].…”

Bioaccumulation Profiles of Polychlorinated Biphenyl Congeners and Organochlorine Pesticides in Ganges River Dolphins

“…Therefore, TEFs specific to marine mammals are needed for an accurate risk assessment. The EC50 for mink reproduction was 160 pg TEQ/g [16,17]. The TEQs estimated in river dolphin blubber were greater than those that cause adverse effects in mink.…”

“…Exposure to great concentrations of persistent, bioaccumulative, and toxic contaminants such as DDT (1,1,1-trichloro-2,2-bis[p-chlorophenyl]ethane) and polychlorinated biphenyls (PCBs) has been shown to elicit adverse effects on reproductive and immunological functions in captive or wild aquatic mammals [10][11][12][13][14][15]. Aquatic mammals inhabiting freshwater systems, such as otters and mink, have been reported to be sensitive to chemical contamination [16,17]. Despite this information on the effects of contaminants in aquatic mammals, only few studies have examined the accumulation of toxic contaminants in river dolphins.…”