Biology Ph.D. Dissertations

Reconsidering Exposure: The Effects of Dynamic Contaminant Plumes on Aquatic Organisms

Date of Award

2020

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Biological Sciences

First Advisor

Paul Moore (Advisor)

Second Advisor

Mohammadali Zolfagharian (Other)

Third Advisor

Rachelle Belanger (Committee Member)

Fourth Advisor

Robert Michael McKay (Committee Member)

Fifth Advisor

Louise Stevenson (Committee Member)

Abstract

This dissertation addresses the limited understanding of the effects of spatially and temporally dynamic toxicant plumes entering flowing systems on aquatic organisms. The research summarized in this dissertation builds upon the understanding of dynamic exposure effects by investigating: (1) differences due to the distribution of toxicants from varying sources, (2) the relative contribution of dynamic plume characteristics in changing the personality of organisms (3) the use of organisms subjected to exposure regimes as bioindicators, and (4) modeling the effects of dynamic exposure on population dynamics.

To analyze the effects of variable exposure regimes, the first aim of this dissertation worked to examine differences in agonistic interactions and enzymatic response of crayfish proceeding exposure to structurally different plumes of an herbicide pollutant. These toxicants entered as groundwater or runoff sources and the resulting differences in exposure paradigm characteristics altered the toxicity of the pollutant. The overall intensity of the agonistic interactions and enzymatic response was altered depending on the mode of entry (Steele et al. 2018). The second aim worked to improve the definition of toxicity by examining inter-individual variation in response to a toxicant. The pre-exposure and post-exposure expression of personality were assessed by examining responses to predatory threat. Personality-dependent sensitivity to all exposure regimes resulted, where bold individuals showed an increased change in response relative to shy animals (Steele and Moore 2019). The third aim worked to investigate the sensitivity of organisms exposed to pollutants in natural aquatic environments by establishing the utility of crayfish as a bioindicator for PFAS contamination. Changes in foraging and antipredator behavior displayed by crayfish collected from various field sites correlated with PFAS concentrations found at these locations. This study demonstrated the sensitivity of crayfish behavior to low levels of PFAS and their potential as bioindicators for PFAS contamination within aquatic environments. The final aim extrapolates from these individual-based studies to model the effects of dynamic exposure regimes on population dynamics of crayfish. This extrapolation involved the development of an Individual Based Model which allows for the study of how exposure induced changes in crayfish individuals’ behavior, growth, and reproduction affect population level processes.

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