Date of Award
Master of Science
Endocrine disrupting chemicals in wild animals, including fish, can disrupt reproduction by causing intersexuality. Organic pollutants, specifically polychlorinated biphenyls (PCBs), have been shown to be estrogenic or anti-androgenic likely contributing to intersexuality in males. Organic pollutants persist in the environment despite being restricted for use in the United States. Bluegills, Lepomis macrochirus, play a crucial role in lake food webs as forage and sport fish and may be affected by PCBs. In the current study, male bluegills collected in 2010 from selected Illinois lakes were analyzed to quantify PCB body residues and the incidence of intersexuality (n=200). Experiments were then conducted in 2011 and 2012 to assess the reproductive output of mature males with varying PCB body residues paired with mature females containing no detectable PCB body residues held in uncontaminated 0.05-hectare research ponds (Southern Illinois University Touch of Nature Pond Facility). Lake-specific male bluegill whole-body tissue PCB body residues ranged from below reporting limit to 2 mg/kg dry weight (non-lipid normalized basis) and varied significantly among lakes (F7,32= 9.59, p<0.0001). No male intersex bluegills were found. In both reproductive experiments, abundance of young declined as male PCB body residues increased (F 4,18 = 13.28; P=0.002). Adult survival was unrelated to reproductive output. Taken together, these results suggest PCBs, which are ubiquitous in aquatic and terrestrial habitats, have the ability to alter male reproductive performance, and possibly population dynamics and community structure through reduced recruitment, in the absence of overt intersexuality.
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