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Access Type

Open Access

Document Type


Degree Program

Animal Science

Degree Type

Master of Science (M.S.)

Year Degree Awarded


Month Degree Awarded



endocrine disruptors, vitellogenin, assabet river


The Assabet River located in eastern Massachusetts receives treated wastewater

discharges from four major municipal wastewater treatment plants (WWTPs): Westborough, Marlborough, Hudson and Maynard. In periods of low flow, up to 95% of the Assabet River is wastewater effluent. Chemical analyses have shown that municipal wastewaters can contain estrogenic and dioxin-like compounds. Estrogenic compounds such as the natural estrogen 17β-estradiol (E2), the synthetic estrogen 17α-ethinyl estradiol (EE2), and the industrial compound nonylphenol (NP) can induce vitellogenin (VTG) and lead to feminization in male fish. CYP1A1-inducing compounds such as the polycyclic aromatic hydrocarbons (PAHs) and polybrominated diphenyl ethers (PBDEs) can produce both overt toxicity and alter reproductive function through the metabolism of natural estrogens. The purpose of the present research is to analyze the estrogenic and CYP1A1-inducing compounds in the Assabet River and their physiological effects on Japanese Medaka (Oryzias latipes). I used a bioassay that measures the induction of VTG and CYP1A1 in the livers of male Medaka and report results obtained by the USGS and EPA on analytical measurements of selected compounds.

In the summers of 2010 and 2011 water samples were collected from the Assabet River, its tributaries and the four WWTPs. Male Medaka were exposed to the treatment samples as well as negative and positive controls. VTG and CYP1A1 induction were measured using real time RT-PCR. Concurrently collected samples from 2010 were analyzed by the USGS for more than 80 organic wastewater contaminants including several estrogenic EDCs and CYP1A1-inducing compounds. The USEPA also analyzed treated wastewater effluent samples collected from the four WWTPs for pharmaceuticals, hormones, nonylphenols and perfluorinated compounds. The bioassay from 2010 and 2011 reveal no statistically significant induction of VTG expression and only one significant induction of CYP1A1 expression. Few compounds were detected by the 2010 USGS and USEPA chemical analyses and the concentrations were low. Taken together the results indicate that VTG and CYP1A1 inducing compounds in the effluent-dominated Assabet River are present at low levels, which may be below the level of detection of the bioassays.

In addition to the biological assay and chemical analysis Geographic Information Systems (GIS) was used to analyze land use/land cover (LU/LC) data in the Assabet River Watershed. Much of the land surrounding the Assabet River is forested but there are several LU/LC types that could negatively impact the water quality. High impact and low impact LU/LC types were differentiated in buffers around the Assabet River and six GIS sites. The composition of each site varies widely in its proportions of high and low impact land cover. The GIS analysis established locations on the Assabet River where water quality is more susceptible to degradation due to the distribution of high impact land use types.


First Advisor

Kathleen F Arcaro