Date of Graduation
Davis College of Agriculture, Natural Resources and Design
Wildlife and Fisheries Resources
An intersex condition, defined as the presence of oocytes in the testes of male gonochoristic fish, has been observed in smallmouth bass in the South Branch of the Potomac River, West Virginia, which indicates exposure to exogenous estrogens. Endocrine disrupting chemicals (EDC's) are generally hydrophobic and would tend to be found within the sediment of aquatic environments. Few studies have attempted to show the effects of exposure to EDC's on fish using sediment chemical extracts. We have developed a mass sediment extraction technique using 2 solvents (hexane, ethyl acetate:acetone 50:50) to determine the effects of extracted chemicals from three sites (Springfield, Petersburg, and Franklin, WV) on reproductive performance and physiological parameters of adult mating pairs of Japanese medaka (Oryzias latipes) for 14 days. Sediment aliquots (200g dry weight) were mixed with solvent 3 times, sonicated, and filtered. Pairs were subjected to extracts at the ratio of 10g of extracted sediment in 1L of water. Hatching success significantly decreased due to exposure to Franklin extract (both solvents) and Petersburg extract (ethyl acetate:acetone). Springfield exposed females had a significantly increased hepatosomatic index (HSI) and showed a trend towards increased vitellogenin (Vtg) production. Results indicate that non-polar and moderately polar compounds may be disrupting development of fertilized eggs and this is most likely due to mixture effects because results were similar with both extracts. Smallmouth bass in the South Branch are likely experiencing chronic exposure or periodic exposure at critical life periods, which may explain why estrogenic effects were not observed in a 14-d exposure. We suggest this method be used in combination with in vitro assays and analytical chemistry in order to investigate mixtures within sediment.
Davis, Seth R., "Reproductive consequences of exposure to sediment extracts from the South Branch of the Potomac River on Japanese medaka (Oryzias latipes)" (2007). Graduate Theses, Dissertations, and Problem Reports. 2554.