Defense Date

11-6-2023

Graduation Date

Fall 12-15-2023

Availability

Immediate Access

Submission Type

thesis

Degree Name

MS

Department

Environmental Science and Management (ESM)

School

School of Science and Engineering

Committee Chair

Sarah Woodley

Committee Member

Elizabeth Dakin

Committee Member

Rickey Cothran

Keywords

amphipods, toxtrac, interactive effects, sublethal effects, dimethyloxazolidine, abandoned mine drainage, glutaraldehyde

Abstract

This thesis examined the sublethal effects of three pollutants, namely glutaraldehyde, 4,4-dimethyloxazolidine (DMO), and abandoned mine drainage (AMD), on amphipods. The primary objective was to investigate their combined effects on amphipods. The three pollutants, despite having the potential to combine in the environment, have not been studied to determine their potential for detrimental interactive effects which could result in unexpected environmental damage.

The research employed a series of experimental setups involving controlled exposure of amphipods to varying, putatively sublethal, concentrations of the chemicals of interest. Subsequently, effects were assessed via both behavioral and feeding assessments. To facilitate this analysis, novel methods were developed to effectively use an open-source tracking software (ToxTrac 2.92) to collect behavioral data on amphipods by integrating a dye bath and an image processing step.

There was no evidence for an interactive effect on chemical toxicity, as no statistically significant increase in mortality was observed when chemicals were combined. However, the findings revealed strong evidence of interactions among sublethal concentrations of glutaraldehyde, DMO, and AMD, affecting both average acceleration and feeding rates. DMO increased average acceleration, while increasing pH (relatively more neutral) decreased average acceleration and glutaraldehyde displayed a non-monotonic effect. All other mobility factors were not altered by the chemicals, indicating that the amphipods’ swimming abilities were not negatively impacted. Increases in acceleration were interpreted as indicating jerky, abnormal behavior, indicating a potential stress reaction to increasing levels of these pollutants. In general, accelerations increased as the environment became less optimal.

The results did not definitively establish a detrimental sublethal effect on the amphipods as the exact reasons for the acceleration differences are unknown. However, in the case of the interaction between glutaraldehyde and DMO, amphipods were observed to exhibit an unusual rapid circling behavior, suggesting that amphipods were neurologically stressed and attempted to avoid negative stimuli behaviorally.

The outcomes of the study provide valuable insights into the ecological risks associated with fracking biocides and AMD and highlight the importance of considering their combined impact on aquatic organisms. The methods developed for utilizing ToxTrac software with amphipods also offer potential new avenues for cost-effective future studies assessing chemical risks in aquatic ecosystems using amphipods.

Language

English

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