title: Comparative organochlorine accumulation in two ecologically similar shark species (Carcharodon carcharias and Carcharhinus obscurus) with divergent uptake based on different life history.
abstract: Trophic position and body mass are traits commonly used to predict organochlorine burdens. Sharks, however, have a variety of feeding and life history strategies and metabolize lipid uniquely. Because of this diversity, and the lipid-association of organochlorines, the dynamics of organochlorine accumulation in sharks may be predicted ineffectively by stable isotope-derived trophic position and body mass, as is typical for other taxa. The present study compared ontogenetic organochlorine profiles in the dusky shark (Carcharhinus obscurus) and white shark (Carcharodon carcharias), which differ in metabolic thermoregulation and trophic position throughout their ontogeny. Although greater organochlorine concentrations were observed in the larger bodied and higher trophic position white shark (e.g., p,p'-dichlorodiphenyldichloroethylene: 20.2 ± 2.7 ng/g vs 9.3 ± 2.2 ng/g in the dusky shark), slopes of growth-dilution corrected concentrations with age were equal to those of the dusky shark. Similar ontogenetic trophic position increases in both species, less frequent white shark seal predation than previously assumed, or inaccurate species-specific growth parameters are possible explanations. Inshore habitat use (indicated by δ(13)C values) and mass were important predictors in white and dusky sharks, respectively, of both overall compound profiles and select organochlorine concentrations. The present study clarified understanding of trophic position and body mass as reliable predictors of interspecific organochlorine accumulation in sharks, whereas regional endothermy and diet shifting were shown to have less impact on overall rates of accumulation.
authors.affiliation: Great Lakes Institute for Environmental Research, University of Windsor, Ontario, Canada.
authors.forename: Marina C
authors.initials: MC
authors.lastname: Beaudry
authors.affiliation: Great Lakes Institute for Environmental Research, University of Windsor, Ontario, Canada.
authors.forename: Nigel E
authors.initials: NE
authors.lastname: Hussey
authors.affiliation: Department of Integrative Biology, University of Guelph, Ontario, Canada.
authors.forename: Bailey C
authors.initials: BC
authors.lastname: McMeans
authors.affiliation: Great Lakes Institute for Environmental Research, University of Windsor, Ontario, Canada.
authors.forename: Anne M
authors.initials: AM
authors.lastname: McLeod
authors.affiliation: KwaZulu-Natal Sharks Board, Umhlanga, KwaZulu-Natal, South Africa.|Biomedical Resource Unit, University of KwaZulu-Natal, KwaZulu-Natal, South Africa.
authors.forename: Sabine P
authors.initials: SP
authors.lastname: Wintner
authors.affiliation: KwaZulu-Natal Sharks Board, Umhlanga, KwaZulu-Natal, South Africa.|Biomedical Resource Unit, University of KwaZulu-Natal, KwaZulu-Natal, South Africa.
authors.forename: Geremy
authors.initials: G
authors.lastname: Cliff
authors.affiliation: KwaZulu-Natal Sharks Board, Umhlanga, KwaZulu-Natal, South Africa.|Biomedical Resource Unit, University of KwaZulu-Natal, KwaZulu-Natal, South Africa.|Department of Agriculture, Forestry and Fisheries, Cape Town, South Africa.
authors.forename: Sheldon F J
authors.initials: SF
authors.lastname: Dudley
authors.affiliation: Great Lakes Institute for Environmental Research, University of Windsor, Ontario, Canada.
authors.forename: Aaron T
authors.initials: AT
authors.lastname: Fisk
mesh_terms: D000375:Aging; D000818:Animals; D001835:Body Weight; D002247:Carbon Isotopes / Q000032:analysis; D017753:Ecosystem; D005260:Female; D006843:Hydrocarbons, Chlorinated / Q000032:analysis / Q000378:metabolism*; D007553:Isotope Labeling; D008297:Male; D009587:Nitrogen Isotopes / Q000032:analysis; D012754:Sharks / Q000378:metabolism*; D013045:Species Specificity
chemical_list: D002247:Carbon Isotopes; D006843:Hydrocarbons, Chlorinated; D009587:Nitrogen Isotopes
keywords: Bioaccumulation; Dusky shark; Organochlorine; Stable isotopes; White shark