Graduate Program

Biological Sciences

Degree Name

Master of Science (MS)

Semester of Degree Completion

Spring 2021

Thesis Director

Thomas Canam

Thesis Committee Member

Karen F. Gaines

Thesis Committee Member

Anabela Maia

Abstract

Natural habitats of fish are gradually declining due to land use and pollution caused by industrial wastes, intensive agriculture and contamination from sewage systems. The United States has 14,780 wastewater treatment facilities that discharge effluent into navigable waters, and in some cases these discharge waters represent a considerable proportion of the water system flow. These activities make it critical to discern the effects of pollutants that are entering our waterways at a consistent rate, such as 17β-estradiol (E2) and nickel, on aquatic organisms. To determine the effects of 17β-estradiol on endocrine disruption in fish, Bluegill Sunfish (Lepomis macrochirus) were exposed to 40 and 80 ng L-1 of E2 for 21 days, and the change of vitellogenin levels was determined from caudal vein blood via semi- quantitative ELISA. The Kruskal-Wallis test indicated no statistical difference between treatment groups. The other portion of this study examined the consequences of the Sanitary District of Decatur (SDD) exceeding their monthly effluent permit limits of nickel (0.015 mg L-1), with an average concentration of 0.0214 mg L-1. To assess the impact this had on fish assemblages downstream, three Catostomidae populations (Shorthead Redhorses, Smallmouth Buffalo and River Carpsuckers) were captured from the Sangamon River using electrofishing and compared to the same species collected from the Embarras River, which has a lower concentration of nickel. Tissue nickel concentrations were analyzed via ICP-MS at the Savannah River Ecological Laboratory. The Mann-Whitney U Test indicated that River Carpsuckers had statistically higher nickel concentrations in the Sangamon River compared to the Embarras populations. When examining the potential for bioaccumulation using the bioaccumulation factor (BAF = (x)organism/(x)water), all populations indicated no potential for accumulation with values well below the critical threshold of 1000. To assess the potential for human risk the target hazard quotient (THQ = EDI/RfD) was calculated for all populations. Each population’s THQ was well below 1; indicating no potential risk for human consumption.

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