title: Influence of seasonality and exposure on the accumulation and reproductive effects of p,p'-dichlorodiphenyldichloroethane and dieldrin in largemouth bass.
abstract: Two studies investigated the accumulation and reproductive effects of p,p'-dichlorodiphenyldichloroethane (DDE) and dieldrin over 30 or 120 d of oral exposure in captive Florida, USA, largemouth bass (Micropterus salmoides floridanus). The 30-d exposures were conducted during the peak reproductive season, and the 120-d study was conducted to simulate exposure throughout the ovarian cycle. Whole body chemical residue concentrations were similar, regardless of exposure duration, for the medium and high feed concentrations of either chemical; however, the low-dose residue concentrations were much lower, yet similar to natural exposures. No clear dose-response relationships were identified between chemical dose and morphological (length, weight, hepatosomatic index) or reproductive endpoints (sex steroid concentration, gonadosomatic index, percentage of fry hatching). Reproductive parameters were variable within treatment groups, indicating that circulating sex steroids and percent hatch endpoints have high natural variability among fish of the same age and reproductive stage. However, in general there was a decrease in plasma estradiol and 11-ketotestosterone for female and male fish, respectively, that were exposed to dieldrin. Overall, results suggest that exposure throughout ovarian (follicular) development to either DDE or dieldrin alone does not result in the depressed endocrine status and poor reproductive success reported in highly organochlorine pesticide-contaminated environments in Central Florida, USA.
authors.affiliation: Department of Fisheries and Aquatic Sciences, University of Florida College of Agricultural and Life Sciences, Gainesville, Florida 32653, USA.
authors.forename: Kevin G
authors.initials: KG
authors.lastname: Johnson
authors.forename: Jennifer K
authors.initials: JK
authors.lastname: Muller
authors.forename: Bertram
authors.initials: B
authors.lastname: Price
authors.forename: Adam
authors.initials: A
authors.lastname: Ware
authors.forename: María S
authors.initials: MS
authors.lastname: Sepúlveda
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Borgert
authors.forename: Timothy S
authors.initials: TS
authors.lastname: Gross
mesh_terms: D000818:Animals; D001492:Bass / Q000502:physiology*; D015415:Biomarkers / Q000032:analysis; D049628:Body Size; D001835:Body Weight; D003632:Dichlorodiphenyldichloroethane / Q000633:toxicity*; D004026:Dieldrin / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005431:Florida; D006066:Gonads / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D010575:Pesticides / Q000633:toxicity*; D012098:Reproduction / Q000187:drug effects* / Q000502:physiology; D012621:Seasons; D013256:Steroids / Q000097:blood; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D015415:Biomarkers; D010575:Pesticides; D013256:Steroids; D014874:Water Pollutants, Chemical; D004026:Dieldrin; D003632:Dichlorodiphenyldichloroethane