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Living in a haze: Direct and indirect impacts of turbidity and diet on an African cichlid fish

Atkinson, Tiffany L
http://rave.ohiolink.edu/etdc/view?acc_num=osu1555434028656478

Abstract Details

2019, Master of Science, Ohio State University, Environment and Natural Resources.
Worldwide, a major threat to aquatic systems is increased sediment runoff, which can lead to elevated levels of turbidity. In an increasingly variable world, the ability for animals to respond rapidly to environmental disturbance can be critical for survival. Chronic and acute turbidity exposure can have both indirect and direct effects on fish across large and small spatial scales. Indirect impacts include alteration of the sensory environment of fishes (disrupting communications) and shifts in prey availability; while direct impacts include damage to respiratory organs or eliciting physiological compensatory mechanisms that influence fitness-related traits associated with reproduction and survival. I used a combination of field and laboratory studies to examine the effects of elevated turbidity on an African cichlid fish (Pseudocrenilabrus multicolor victoriae). This sexually dimorphic species is widespread across the Nile River basin and is found across extreme environmental gradients (e.g. dissolved oxygen, turbidity). I investigated if within-population variation in diet and male nuptial coloration are associated with turbidity on a microgeographic spatial-scale. Diet was investigated because many cichlid fish depend on dietary carotenoids (red and yellow pigments) for their reproductive displays and other physiological mechanisms associated with health. I found that fish from mostly clear waters ate a higher proportion of plant material and males were more colorful than fish found at more turbid locations. This could indicate that male reproductive traits are plastic across environmental extremes. In the laboratory study, I used a split-brood rearing experiment to investigate the effects of turbidity level (high/low) and dietary carotenoid concentration (trace/low) on reproductive traits in P. multicolor. I found that chronic turbidity and carotenoid diets had differential effects on males and females: nuptial coloration and gonadosomatic index were higher in males reared under high turbidity and the trace-carotenoid diet, while exposure to chronic turbidity (but not carotenoid diet) had a negative effect on the overall size of female P. multicolor. This could indicate that some level of stress from chronic turbidity and diet creates an environment where males invest more in immediate reproduction vs. future reproduction and long-term somatic health. It also indicates that the stress from turbidity negatively influenced female size, which is often correlated with fecundity, possibly due to reduced reaction distance and ability to acquire food. I also investigated the effect of acute and chronic turbidity exposure on the swimming performance of P. multicolor. I found that swimming performance was improved by acute turbidity exposure, and chronic turbidity exposure had no effect. This could mean that the aerobic capacity of P. multicolor, under low-to-moderate levels of chronic turbidity, is unaffected possibly due to compensatory adaptations. Additionally, the ability to perform better under acute turbidity exposure may point towards behavioral mechanisms as an attempt to remove themselves from an environmental stressor. This study has helped to emphasize that the impact of turbidity varies due to a number of circumstances such as concentration, duration of exposure, species, and sex. By further investigating the effects of turbidity as a stressor on traits associated with reproduction and survival of a fish found naturally across both extremes, we can further our understanding of the mechanisms that contribute to the persistence of fish facing human-induced environmental changes.
Suzanne Gray, Dr. (Advisor)
Lauren Pintor, Dr. (Committee Member)
Roman Lanno, Dr. (Committee Member)
Lauren Chapman, Dr. (Committee Member)
127 p.
Freshwater Ecology; Physiology
human-induced environmental change; turbidity; cichlid fish; sexual selection; carotenoids; reproductive traits; swimming performance

Recommended Citations

Citations

  • Atkinson, T. L. (2019). Living in a haze: Direct and indirect impacts of turbidity and diet on an African cichlid fish [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555434028656478

    APA Style (7th edition)

  • Atkinson, Tiffany. Living in a haze: Direct and indirect impacts of turbidity and diet on an African cichlid fish . 2019. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1555434028656478.

    MLA Style (8th edition)

  • Atkinson, Tiffany. "Living in a haze: Direct and indirect impacts of turbidity and diet on an African cichlid fish ." Master's thesis, Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555434028656478

    Chicago Manual of Style (17th edition)

osu1555434028656478
281
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