The impact of 4-nonylphenol on reproduction of arrow gobies (Clevelandia ios) in Morro Bay, CA
Authors:Kristy Forsgren, Eric Kessler, Sean Lema
Mentor:Kristy Forsgren, Assistant Professor of Biology, California State University, Fullerton
Endocrine disrupting compounds (EDCs) are chemicals that alter the synthesis, secretion, transport, binding, and/or action of endogenous hormones. Of particular interest are anthropogenically produced nonylphenol ethoxylates, which are used as stabilizers and surfactants in a variety of industrial and consumer plastics, pesticides, detergents, and personal care products. Nonylphenol ethoxylates are degraded during the wastewater treatment process and form numerous byproducts. One byproduct is the estrogenic EDC 4-nonylphenol (4-NP). 4-NP has the potential to bioaccumulate in animal tissues due to its hydrophobic nature and has been shown to impair reproduction by mimicking natural estrogens. The sediment and coastal water at Morro Bay, CA contain relatively low concentrations of 4-NP compared to other estuaries worldwide. Interestingly, arrow gobies (Clevelandia ios) collected from Morro Bay have some of the highest 4-NP liver tissue concentrations recorded. We hypothesized that arrow gobies collected from Morro Bay would show evidence of reproductive dysfunction as a result of exposure to and the bioaccumulation of 4-NP. We collected arrow gobies (n=18) during the non-breeding season and histologically examined gonadal tissue. Ovarian follicle stage (primary or secondary oocyte stage) was determined and documented, as well as any observed reproductive abnormalities. Arrow gobies had a skewed female sex ratio (5:1), advanced secondary ovarian follicles during the non-breeding season, and a few ovaries had ovarian cysts and/or tumors. We suspect that the estrogenic effects of 4-NP may be resulting in the abnormal reproductive health of arrow gobies. Currently, we are exposing laboratory-bred zebrafish (Danio rerio) embryos to environmentally relevant concentrations of 4-NP to advance our knowledge of the impact 4-NP has on the reproductive physiology of fish and how it may induce reproductive dysfunction. Understanding EDCs, such as 4-NP, and how they effect reproduction will aid fisheries managers and researchers in protecting important commercial and sport species.