Using Mosquitofish, Gambusia affinis, as Bioindicators for the presence of Endocrine Disrupting Compounds in Greenville's Wastewater Effluent

ECU Author/Contributor (non-ECU co-authors, if there are any, appear on document)
Allyson B Middleton (Creator)
East Carolina University (ECU )
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Abstract: Endocrine disrupting compounds (EDCs) are compounds that arise from an assortment of manufactured sources (plastics, pharmaceuticals, pulp mill waste), which have the potential to interrupt hormone pathways by mimicking hormones naturally produced in the body. The secondary sex characteristics of mosquitofish Gambusia affinis respond to the presence of EDC's by becoming more masculinized or feminized, based on the type of compound and what it has the ability to mimic. Mosquitofish have proven to be model organisms to serve as bioindicators of whether EDCs are present in their environment due to their sexual dimorphism. Previous studies have shown the degree to which females develop masculinized features is directly proportional to the concentrations of androgen-mimicking compounds to which they are exposed. The most pronounced male secondary characteristic that was observed to be induced on female mosquitofish in previous studies was the development of a male gonopodium, which is an elongation of anal rays 3,4, and 5. The gonopodium is used by males to transfers sperm to females. This study seeks to answer the question of whether mosquitofish populations exhibit changes in the sex ratio and gonopodium of females in sewage effluent when compared with nearby reference locations and previous collections of mosquitofish made by Hildebrand (1932) in North Carolina prior to the widespread use of EDC's. My results show that the sex ratio of mosquitofish was significantly different in Greenville utilities effluent water when compared with other locations and Hildebrand's collections. There was a 1.421 female to male ratio in Greenville wastewater effluent populations, whereas the ratio was 20.521 at broad run, 22.521 the coastal studies Institute Pond in Manteno, and 4.4 to 1 in Hildebrand's populations from 1927. It is normal to have a female bias in the sex ratio of this species because males die earlier in females get larger than males. This result is consistent with my hypothesis that exposure to EDC's can result in masculine features in females because I classified males bio looking for a gonopodium in females exhibited male characters due to EDC's, then the sex ratio would be expected to decrease. Further supporting evidence consisted of females that had a ratio of anal fin with an link similar to that of males in the sewage treatment plant effluent water.

Additional Information

Language: English
Date: 2014
Mosquitofish, Gambusia, Wastewater, Endocrine disrupting compounds, Bioindicator

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