title: Unexplained gonad alterations in whitefish (Coregonus spp.) from Lake Thun, Switzerland: levels of persistent organic pollutants in different morphs.
abstract: Since 2000, a surprisingly high number of macroscopical gonad alterations has been reported in whitefish (Coregonus spp.) from Lake Thun, Switzerland. This unique phenomenon is still unexplained and has received much public attention. As one possible trigger for these effects, the presence of persistent, bioaccumulative and toxic compounds acting as endocrine disruptors in the lake has been discussed. In this study, concentrations of selected persistent organic pollutants were examined in two morphs of whitefish from Lake Thun and their link to the observed abnormalities was investigated. Analyzed compound classes included polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and dibenzofurans, polychlorinated naphthalenes, polybrominated diphenyl ethers and hexabromocyclododecanes. The target substances were identified in all samples and concentrations of the analyzed compounds were highly correlated among each other. These correlations show that the analyzed substances have the same distribution pattern throughout the lake and that uptake, accumulation and elimination processes are similar. Significant differences in contaminant levels within the samples existed between the two analyzed morphs of whitefish, most likely due to different age, food patterns and growth rate. No difference in contaminant levels was observed between fish with abnormal gonads and fish with normal gonads, suggesting no causal link between the investigated lipophilic organohalogen compounds present in fish and the observed gonad abnormalities in whitefish from Lake Thun. A comparison to existing data shows that concentrations in Lake Thun whitefish are at the lower bound of contaminant levels in whitefish from Swiss lakes or from European waters.
authors.affiliation: Empa, Swiss Federal Laboratories for Materials Testing and Research, Laboratory for Analytical Chemistry, Uberlandstrasse 129, CH-8600 Dübendorf, Switzerland. christian.bogdal@empa.ch
authors.forename: Christian
authors.initials: C
authors.lastname: Bogdal
authors.forename: Michael
authors.initials: M
authors.lastname: Naef
authors.forename: Peter
authors.initials: P
authors.lastname: Schmid
authors.forename: Martin
authors.initials: M
authors.lastname: Kohler
authors.forename: Markus
authors.initials: M
authors.lastname: Zennegg
authors.forename: Daniel
authors.initials: D
authors.lastname: Bernet
authors.forename: Martin
authors.initials: M
authors.lastname: Scheringer
authors.forename: Konrad
authors.initials: K
authors.lastname: Hungerbühler
mesh_terms: D000367:Age Factors; D000818:Animals; D004435:Eating; D005618:Fresh Water; D006066:Gonads / Q000002:abnormalities* / Q000187:drug effects* / Q000378:metabolism; D006842:Hydrocarbons, Brominated / Q000032:analysis / Q000378:metabolism / Q000633:toxicity*; D006843:Hydrocarbons, Chlorinated / Q000032:analysis / Q000378:metabolism / Q000633:toxicity*; D007306:Insecticides / Q000032:analysis / Q000378:metabolism / Q000633:toxicity*; D018570:Risk Assessment; D012487:Salmonidae / Q000002:abnormalities / Q000254:growth & development / Q000378:metabolism*; D013557:Switzerland; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000378:metabolism / Q000633:toxicity
chemical_list: D006842:Hydrocarbons, Brominated; D006843:Hydrocarbons, Chlorinated; D007306:Insecticides; D014874:Water Pollutants, Chemical