title: Biomagnification of DDT and its metabolites in four fish species of a tropical lake.
abstract: The concentrations and biomagnifications of dichlorodiphenyltrichloroethane (DDT) and its metabolites were examined in four fish species (Clarias gariepinus, Oreochromis niloticus, Tilapia zillii, and Carassius auratus) from Lake Ziway, Rift Valley, Ethiopia. Paired stomach content analysis, and stable isotope ratio of nitrogen (δ(15)N, ‰) and carbon (δ(13)C, ‰) were used to study the trophic position of the fish species in the lake. 4,4'-DDE, 4,4'-DDT and 4,4'-DDD were the main DDTs identified in the fish samples, with 4,4'-DDE as the most predominant metabolite, with mean concentration ranging from 1.4 to 17.8 ng g(-1) wet weight (ww). The concentrations of DDTs found in fish from Lake Ziway were, in general lower than those found in most studies carried out in other African Lakes. However, the presence of DDT in all tissue samples collected from all fish species in the lake indicates the magnitude of the incidence. Moreover, the observed mean 4,4'-DDE to 4,4'-DDT ratio below 1 in C. auratus from Lake Ziway may suggest a recent exposure of these species to DDT, indicating that a contamination source is still present. 4,4'-DDE was found to biomagnify in the fish species of the lake, and increases with trophic level, however, the biomagnification rate was generally lower than what has been reported from other areas. Significantly higher concentrations of 4,4'-DDE were found in the top consumer fish in Lake Ziway, C. gariepinus than in O. niloticus (t=2.6, P<0.01), T. zillii (t=2.5, P<0.02) and C. auratus (t=2.2, P<0.03).
authors.affiliation: Norwegian University of Life Sciences, Department of Plant and Environmental Sciences, Ås, Norway. ermiasderibe2003@yahoo.com
authors.forename: Ermias
authors.initials: E
authors.lastname: Deribe
authors.forename: Bjørn Olav
authors.initials: BO
authors.lastname: Rosseland
authors.forename: Reidar
authors.initials: R
authors.lastname: Borgstrøm
authors.forename: Brit
authors.initials: B
authors.lastname: Salbu
authors.forename: Zinabu
authors.initials: Z
authors.lastname: Gebremariam
authors.forename: Elias
authors.initials: E
authors.lastname: Dadebo
authors.forename: Lindis
authors.initials: L
authors.lastname: Skipperud
authors.forename: Ole Martin
authors.initials: OM
authors.lastname: Eklo
mesh_terms: D000818:Animals; D002397:Catfishes / Q000378:metabolism*; D023681:Cichlids / Q000378:metabolism*; D003634:DDT / Q000032:analysis* / Q000378:metabolism; D004784:Environmental Monitoring; D005002:Ethiopia; D005766:Gastrointestinal Contents / Q000737:chemistry; D006054:Goldfish / Q000378:metabolism*; D060106:Lakes; D010575:Pesticides / Q000032:analysis* / Q000378:metabolism; D013045:Species Specificity; D017210:Tilapia / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000378:metabolism
chemical_list: D010575:Pesticides; D014874:Water Pollutants, Chemical; D003634:DDT
keywords: Biomagnification; DDTs; Fish species; Lake Ziway; Trophic position