Are Male Bluegills (Lepomis macrochirus) Experiencing Altered Reproductive Output Due to Exposure to Chlorinated Hydrocarbons?EPA Grant Number: FP917335
Title: Are Male Bluegills (Lepomis macrochirus) Experiencing Altered Reproductive Output Due to Exposure to Chlorinated Hydrocarbons?
Investigators: Hillis, Jeffrey J
Institution: Southern Illinois University - Carbondale
EPA Project Officer: Lee, Sonja
Project Period: August 1, 2011 through July 31, 2013
Project Amount: $84,000
RFA: STAR Graduate Fellowships (2011) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Fellowship - Pesticides and Toxic Substances
The overall objective of this study is to quantify the concentration of chlorinated hydrocarbons (CHs) in male bluegill (BLG) in Illinois and relate these concentrations to the incidence of gonad abnormalities and the gonadosomatic index observed in field collected fish. This research will evaluate whether environmentally relevant levels of CHs affect the reproductive success of male BLG.
The objective of this study will be answered by collecting 50 bluegill (both male and female) from lakes with fish consumption advisories for polychlorinated biphenyls (PCBs). All fish will be dissected, and male gonads will be weighed and preserved for histology. Histology slides will be stained with hematoxylin and eosin. The slides will be evaluated at 400X magnification, and pictures of testicular oocytes or other abnormalities will be obtained. The carcass, minus gonads, will be homogenized with a high-speed blender and frozen for contaminant analysis. The whole body fish tissue sample will be analyzed for 28 PCB congeners and nine organochlorine pesticides. Two surrogates will be used to verify extraction efficiency. Male gonad abnormalities will be compared to chlorinated hydrocarbon concentrations to examine if there is a positive relationship. In addition, a reproductive trial in outdoor ponds will be conducted using male bluegill from the highest contaminant concentration group observed from the field collection. These male bluegill will be paired with females from a reference lake (less than background concentrations) to examine male reproductive success. These fish will be compared to a control group with both male and female bluegill collected from the same reference lake.
The results of the field collection will show that the gonadosomatic index from male BLG taken from the CH lakes will be statistically significantly lower than males in the reference lake (Fisher’s exact test [α = 0.05]). Concentrations of CHs in body residues of adults will be elevated in lakes with sediment concentrations >1.7 mg/kg (extreme effect concentration). The reproductive trial hypothesis is that male BLG from CH contaminated lakes will have significantly lower (α = 0.05) reproductive output (amount of young produced) than that of males from the reference lake. Whether this condition is due to altered mating behavior or impaired reproduction will not be evaluated. Research into how CHs reduce reproductive output should be pursued further if this is observed. Application of this research may reveal that it is important for fisheries managers to assess the incidence of intersex and sex ratio of BLG in lakes that have a history of CH contamination. Maternal transfer of CHs depends on the contaminant concentrations of the female parent. Therefore, it is hypothesized that this will minimize the concentration of CHs observed in the juvenile BLG during the reproduction trial.
Potential to Further Environmental/ Human Health Protection
Male behavior and fertility is an important reproductive component in animal populations. Legacy contaminants such as polychlorinated biphenyls and organochlorine pesticides are long lived and their effects still are being understood. Using the BLG species as a surrogate, this research will evaluate how CH concentrations may affect the reproductive ability of male animals including humans. Insight into reduced fertility found in bluegill may provide information about how legacy contaminants are reducing male fertility by either affecting behavior or via physical impairment.