The Selective Dietary Accumulation of Planar Polychlorinated Biphenyls in the Otter (Lutra Lutra)

Abstract

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-orthosubstituted 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 (⌺CB) 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 ⌺CB; however, on the basis of toxic equivalent concentrations (⌺TEQ), 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 ⌺TEQ, 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.

Polycyclic Aromatic Hydrocarbons in Freshwater Isopods and Field-Partitioning Between Abiotic Phases

“…The variation of PAH patterns was investigated with the principal component analysis (PCA) routine included in the software package Sirius 2.3 TM (Karstang and Kvalheim 1990). The data transformation procedure applied in the PCA analysis was similar to methods applied in Leonards et al (1997) and included normalization (with respect to total PAH concentrations) and standardization (with respect to total variance of individual PAH) in order to rule out confounding effects of concentration differences and to give all PAHs equal weight.…”

A model compound study: The ecotoxicological evaluation of five organic contaminants employing a battery of marine bioassays

“…While no natural sources of PCBs exist they can enter the aquatic environment through leakage, recycling, transboundary influx via major rivers and long-range atmospheric transport (Ockenden et al, 1998). PCBs are persistent in the environment and are biomagnified up the food chain and have been found in top predators in the marine environment (Leonards et al, 1997). The congener PCB 153 was selected for this study, primarily on the basis of its relative environmental persistence and as it is routinely monitored in Ireland in sediments and biota.…”

Temporal and Spatial Trends in Chlorinated Hydrocarbon Concentrations of Mink in Canadian Lakes Erie and St. Clair

“…In our Great Lakes samples, non-ortho PCBs accounted for 67 to 83% of sum TEQs, with congener 126 providing a major contribution to this. In the current study, mink from western Lake Erie in particular, have extremely high concentrations of congener 126 as well as congener 169, which is another toxic congener found to biomagnify in aquatic mustelids (Leonards et al, 1997(Leonards et al, , 1998.…”

“…However, this congener profile is seen in all mink samples and may suggest that mink have difficulty metabolizing these highly chlorinated congeners. Leonards et al (1997) determined that congeners 170, 180 and 194 were selectively accumulated in otters relative to their food source. Concentrations of the non-ortho PCB congener 126 is an order of magnitude higher than those of the less toxic non-ortho congeners PCB 77 and 37 in mink livers.…”

“…Leonards et al (1998) determined that mustelids generally were highly efficient at metabolizing PCB 77, but selectively bioconcentrated congener 126 from their prey. Leonards et al (1997) found that, whereas this congener contributed 30 to 50% of the sum TEQs in fish, it contributed 60 to 80% of sum TEQs in the otters (Lutra canadensis) that consumed them. In our Great Lakes samples, non-ortho PCBs accounted for 67 to 83% of sum TEQs, with congener 126 providing a major contribution to this.…”