Date of Award

2022

Degree Name

Environmental Science

College

College of Science

Type of Degree

M.S.

Document Type

Thesis

First Advisor

Dr. Scott Simonton, Committee Chairperson

Second Advisor

Dr. Mindy Yeager-Armstead

Third Advisor

Mandee Wilson MS

Abstract

Ephemeroptera taxa are not frequently used in toxicity testing; however, some mayfly taxa may be more sensitive to aquatic pollutants than standard test organisms used to determine anthropogenic effects on aquatic ecosystems. Additionally, some standard test organisms are not native to the Appalachian region and may not be truly reflective of the effects on native organisms. With mayflies not being the typical test organism, there is not a great deal of literature on culturing methods for this organism. For a standard acute toxicity test, there must be 80% survival within the control organisms for the test to be considered viable. On that account, culture methods for rearing larval mayflies to emergence, collecting viable eggs, and rearing them to hatch have been developed in the Marshall University Lab. Further development of the methods in order to conduct native mayfly toxicity testing is dependent on a suitable food source being established for cultured mayfly nymphs. The objectives of this study were to investigate adequate feed treatments that will lead to a minimum of 80% survival in the first 48 hours for future acute toxicity testing, the optimal food source for chronic toxicity testing, and for long[1]term survival in laboratory culturing. Evaluations utilizing a variety of laboratory cultured diets given to individual nymphs in separate chambers were conducted. Mortality rate was used to narrow food types to the ones yielding the best results for further testing. Success is evidenced by 80% survival in the first 48 hours, growth and development of the nymphs, and long-term survival. Two of the four feeding treatments provided over 80% survival of newly hatched mayfly nymphs in 48 hours. One feeding treatment provided over 50% survival over 7 days. For long term survival, only 1 of the treatments, laboratory cultured Navicula sp. and leaf disks supported survival over the length of the 36-day study. Once an adequate food source was confirmed, toxicity testing was conducted using the optimal food source for ideal organism fitness. Furthermore, traditional toxicity testing uses reconstituted laboratory water as a base for the dilution series, which is not representative of natural conditions. Therefore, field collected water from Mash Fork, the same stream where mayflies were collected, was used as a base for the dilution series. A preliminary acute toxicity test was run on High Sulfate Simulated Mine Effluent, using the field collected water and the optimal food source. The results did not generate a statistically significant LC50; however, the 100% concentration (~2,400 µS/cm) resulted in ~50% mortality. Therefore, further rounds of testing should include a higher concentration or use organisms of ideal fitness and generate a statistically valid LC50.

Subject(s)

Toxicity testing – Appalachian Region.

Mayflies – Research – Appalachian Region.

Marshall University.

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