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U.S. GEOLOGICAL SURVEY
Data Series 286

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Organic Chemical Concentrations and Reproductive Biomarkers

Concentrations of organic chemical compounds in whole body tissue, reproductive biomarker measures, and physical characteristics for individual common carp collected at Las Vegas Bay and Overton Arm in Lake Mead during May 1999 through May 2000 are presented in eight attached Microsoft® Excel spreadsheets. Reproductive biomarkers for common carp are presented as follows: Las Vegas Bay females (appendix A), Overton Arm females (appendix B), Las Vegas Bay males (appendix C), and Overton Arm males (appendix D). Organic chemical concentrations are presented as follows: Las Vegas Bay females (appendix E), Overton Arm females (appendix F), Las Vegas Bay males (appendix G), and Overton Arm males (appendix H). Each spreadsheet contains all data for each month of sampling as well as monthly medians. Relevant quality assurance and quality control information also is included. Monthly median summaries for selected biomarkers and analytical chemistry for common carp in Lake Mead are presented in the following tables: table 3, analytical chemistry for both males and females; table 4, biomarkers for females; and table 5, biomarkers for males.

Chemistry

Thirty-three organic chemical compounds plus total concentrations for four groups of compounds (chlordanes, PCBs, BDEs, and triclosans) were analyzed in extracts of whole body tissue by GC/MS with electron ionization and electron capture negative ion detection in male common carp from Las Vegas Bay and Overton Arm during May 1999 through May 2000. All 33 compounds analyzed were detected in at least one sample of whole body tissue from male common carp collected in Las Vegas Bay. In Overton Arm, 37 organic compounds plus total concentrations of 3 groups of compounds (PCBs, BDEs, and triclosans) were analyzed in male common carp where 20 (54 percent) of the compounds were detected. Sixteen of the compounds detected in male common carp from Las Vegas Bay and 10 compounds detected in male common carp from Overton Arm are suspected of being able to disrupt the endocrine system in fish (Keith, 1997). During May and June 1999, the mean concentration of all organic compounds detected in male common carp was 670 µg/kg at Las Vegas Bay and 109 µg/kg at Overton Arm (fig. 2).

Twenty-seven organic compounds plus total PCBs were analyzed from extracts of whole body tissue in female common carp collected in both Las Vegas Bay and Overton Arm during May 1999. Twenty-four (86 percent) of these compounds were detected in at least one sample of whole body tissue from female common carp collected from Las Vegas Bay while 10 (36 percent) chemical compounds were detected in female common carp from Overton Arm during that same period. Median concentrations of all chemical compounds were higher in female common carp from Las Vegas Bay compared to those collected from Overton Arm except Dacthal (DCPA) which was similar between sites (table 3).

Biomarkers

Biomarker measures obtained for male and female common carp include gonadosomatic index (percentage of gonad weight to total body weight), plasma vitellogenin (a phospholipid protein normally produced by female common carp and other oviparous fish), and condition factor [body weight/(fork length)³]. Biomarker measures for male common carp include five indicators of sperm quality: viability, motility, mitochondrial function, distribution of germ-cell stages, and concentration of sperm. Biomarker measures for female common carp include fecundity (estimate of total number of follicles available for spawning), normalized fecundity (number of follicles per kilogram of body weight) during January and March 2000 only, and follicle-frequency size distribution.

Monthly medians for reproductive biomarkers were variable between sites and among months. Median concentrations of Vtg in blood plasma from male common carp collected from Las Vegas Bay ranged from not detected (detection limit 0.005 mg/mL) to 0.631 mg/mL, whereas median concentrations in male common carp from Overton Arm ranged from not detected to a high of 0.100 mg/mL. Vitellogenin concentrations in individual male common carp collected from Las Vegas Bay were as high as 68.1 mg/mL.

Monthly median sperm counts also varied between sites and among months; values in male common carp ranged from 1.20 × 10¹⁰ per milligram of testis to a high of 6.42 × 10¹⁰ per milligram of testis at Las Vegas Bay, and from 1.52 × 10¹⁰ per milligram to 7.41 × 10¹⁰ per milligram of testis at Overton Arm. Another sperm quality biomarker, viability had monthly medians from 79.6 percent to a high of 98.2 percent in male common carp from Las Vegas Bay and from 90.0 percent to 97.3 percent in male common carp from Overton Arm. Monthly median Vtg concentrations in blood plasma ranged from 0.863 to 9.368 mg/mL in female common carp from Las Vegas Bay and from 0.785 to 11.126 mg/mL in female common carp from Overton Arm (fig. 3). Vitellogenin generally increased in late autumn through winter reaching a maximum just before spawning in March. Total fecundity (number of follicles per kilogram of body weight) was more variable during the pre-spawning months of January and March 2000 in female common carp from Las Vegas Bay (ranges from 190,883 to 231,232, follicles per kilogram of fish, respectively) but was fairly consistent in female common carp from Overton Arm (medians of 164,054 and 162,409, follicles per kilogram of fish, respectively).

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