title: Novel associations between contaminant body burdens and biomarkers of reproductive condition in male Common Carp along multiple gradients of contaminant exposure in Lake Mead National Recreation Area, USA.
abstract: Adult male Common Carp were sampled in 2007/08 over a full reproductive cycle at Lake Mead National Recreation Area. Sites sampled included a stream dominated by treated wastewater effluent, a lake basin receiving the streamflow, an upstream lake basin (reference), and a site below Hoover Dam. Individual body burdens for 252 contaminants were measured, and biological variables assessed included physiological [plasma vitellogenin (VTG), estradiol-17β (E2), 11-ketotestosterone (11KT)] and organ [gonadosomatic index (GSI)] endpoints. Patterns in contaminant composition and biological condition were determined by Principal Component Analysis, and their associations modeled by Principal Component Regression. Three spatially distinct but temporally stable gradients of contaminant distribution were recognized: a contaminant mixture typical of wastewaters (PBDEs, methyl triclosan, galaxolide), PCBs, and DDTs. Two spatiotemporally variable patterns of biological condition were recognized: a primary pattern consisting of reproductive condition variables (11KT, E2, GSI), and a secondary pattern including general condition traits (condition factor, hematocrit, fork length). VTG was low in all fish, indicating low estrogenic activity of water at all sites. Wastewater contaminants associated negatively with GSI, 11KT and E2; PCBs associated negatively with GSI and 11KT; and DDTs associated positively with GSI and 11KT. Regression of GSI on sex steroids revealed a novel, nonlinear association between these variables. Inclusion of sex steroids in the GSI regression on contaminants rendered wastewater contaminants nonsignificant in the model and reduced the influence of PCBs and DDTs. Thus, the influence of contaminants on GSI may have been partially driven by organismal modes-of-action that include changes in sex steroid production. The positive association of DDTs with 11KT and GSI suggests that lifetime, sub-lethal exposures to DDTs have effects on male carp opposite of those reported by studies where exposure concentrations were relatively high. Lastly, this study highlighted advantages of multivariate/multiple regression approaches for exploring associations between complex contaminant mixtures and gradients and reproductive condition in wild fishes.
authors.affiliation: U.S. Geological Survey, Texas Cooperative Fish & Wildlife Research Unit and Departments of Natural Resources Management and of Biological Sciences, Texas Tech University, Lubbock, TX 79409-2120, USA. Electronic address: reynaldo.patino@ttu.edu.
authors.forename: Reynaldo
authors.initials: R
authors.lastname: Patiño
authors.affiliation: Texas Cooperative Fish & Wildlife Research Unit, Texas Tech University, Lubbock, TX 79409-2120, USA.
authors.forename: Matthew M
authors.initials: MM
authors.lastname: VanLandeghem
authors.affiliation: U.S. Geological Survey (Emeritus), High Point, NC 27262, USA.
authors.forename: Steven L
authors.initials: SL
authors.lastname: Goodbred
authors.affiliation: U.S. Fish and Wildlife Service, Las Vegas, NV 89144, USA.
authors.forename: Erik
authors.initials: E
authors.lastname: Orsak
authors.affiliation: U.S. Geological Survey, National Wetlands Research Center, Lafayette, LA 70506, USA.
authors.forename: Jill A
authors.initials: JA
authors.lastname: Jenkins
authors.affiliation: U.S. Geological Survey, Columbia Environmental Research Center, Columbia, MO 65201, USA.
authors.forename: Kathy
authors.initials: K
authors.lastname: Echols
authors.affiliation: U.S. Geological Survey, Water Science Field Team, Carson City, NV 89701, USA.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Rosen
authors.affiliation: Texas Cooperative Fish & Wildlife Research Unit, Texas Tech University, Lubbock, TX 79409-2120, USA.
authors.forename: Leticia
authors.initials: L
authors.lastname: Torres
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis*; D001822:Body Burden; D002347:Carps / Q000382:microbiology*; D060106:Lakes; D008297:Male; D015999:Multivariate Analysis; D012098:Reproduction; D014481:United States; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D014874:Water Pollutants, Chemical
keywords: DDTs; Gonadosomatic index; Multivariate analysis; PCBs; Sex steroids; Wastewater