Mercury Most Fowl: A Meta-Analysis on the Effect of Mercury on Avian Reproduction

Author

Lydia Doughty, William & MaryFollow

Date Thesis Awarded

5-2024

Access Type

Honors Thesis -- Open Access

Degree Name

Bachelors of Science (BS)

Department

Computational & Applied Mathematics & Statistics

Advisor

M. Drew LaMar

Committee Members

Daniel Cristol

Leah Shaw

Richard Marcus

Abstract

Mercury is a ubiquitous pollutant that is commonly found in aquatic food chains, accumulating as it moves up trophic levels (Malcolm, 2012). It enters the food web in plants and bacteria and moves up as it is eaten, ending up in the blood and tissue of birds and other top predators. Such biomagnification is not in question, as there have been countless studies on the accumulation of mercury in avian species, but its impacts are still debated (Whitney & Cristol, 2017). While mercury is toxic to life at high concentrations, there is a gap in the scientific literature on the sublethal effects of mercury on birds. Songbirds have been largely ignored as subjects of mercury exposure as they are a part of terrestrial food webs, while mercury pollution is best known from aquatic systems (Cristol et al., 2008). Recent findings of high levels of mercury in songbirds, however, suggest that the invertebrates they consume and feed to their young contain mercury. Because most birds are songbirds (Rosenberg et al., 2019), it is important to know how this large, understudied taxon is affected by mercury exposure. There are a variety of studies examining the effects of mercury on aquatic birds, but the results are often inconclusive or contradictory (Ackerman et al., 2008; Evers et al., 2008). Papers examining the effects of mercury on songbirds are even more inconclusive, particularly in the realm of reproductive effects (Whitney & Cristol, 2017). In order to determine whether mercury affects reproduction in birds across both aquatic and terrestrial habitats, all of the available published literature was gathered on the effects of mercury on bird hatching and fledging. Since mercury has known effects on reproduction on animals (Wolfe et al., 1998) and reproductive success is critical to conservation (Cummings, 2016), the scope of this project was limited to studies on reproductive endpoints. A meta-analysis was performed on all published articles and theses containing data on mercury levels along with hatching and/or fledging success. Results of this meta-analysis showed a statistically significant negative impact of mercury on hatching success in terrestrial birds, but no effect on hatching in aquatic birds. The heterogeneity in fledging success was not explained by mercury levels or habitat (aquatic vs. terrestrial). Further research or a more thorough and inclusive meta-analysis is needed to determine the effect of mercury on reproductive behaviors and physiological factors.

Recommended Citation

Doughty, Lydia, "Mercury Most Fowl: A Meta-Analysis on the Effect of Mercury on Avian Reproduction" (2024). Undergraduate Honors Theses. William & Mary. Paper 2182.
https://scholarworks.wm.edu/honorstheses/2182