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Publication Date

2021

First Advisor

Rachel M. Wright

Second Advisor

Marguerite Itamar Harrison

Document Type

Honors Project

Degree Name

Bachelor of Arts

Department

Biological Sciences

Keywords

Corals, Reefs, Exaiptasia pallida, Clonal lines, Light stress, Nutrient stress, Symbiosis, Climate change

Abstract

Understanding in which conditions corals survive, die, and adapt enhances our understanding of the biology and the mechanisms driving stress tolerance and adaptation. But, effective restoration is limited by gaps in our understanding of the various ways climate change affects reef-building corals and coral-Symbiodiniaceae symbiosis. In this thesis, the responses of five (VWA, VWB, CC7, H2, and “bulk”) genets of Exaiptasia pallida sea anemones were examined after exposure to light and nutrient stress. Mortality and algal density were recorded. Adverse conditions, such as increased nutrient availability or high light (~100 μmol photons m−2 s −1 ), can lead to the production of reactive oxygen species (ROS) that damage host DNA and other cellular components. Anemones in the Combined treatment (elevated light + nutrients) experienced highest mortality (40–100%) with the Nutrient treatment experiencing intermediate levels of mortality (33–40%). ANOVA revealed a significant difference in mortality rates among treatments (p < 4.64e-15 ) and the post-hoc analysis demonstrated significant differences between every other pair of treatments except between Control and Light treatments (p = 1). The Combined treatment had an interactive effect as compared to only Light or Nutrient stress. The ANOVA and post-hoc analyses run on algal density did not detect significant differences across genets (p = 0.147) or treatments (p = 0.511), or any pairwise differences in algal density between treatments, respectively. Light on its own does not seem to present a substantial threat; however, interactive effects of having both light and nutrients were observed in the Combined treatment. Adverse conditions may lead to chemical or nutritional imbalances within the host, where a normally-mutualistic symbiosis becomes parasitic. Future directions of this thesis include transcriptomic and microbiome analyses to investigate the mechanisms behind the differences in stress responses across anemone clonal lines.

Rights

©2021 Giovanna Sylvia Sabini-Leite. Access limited to the Smith College community and other researchers while on campus. Smith College community members also may access from off-campus using a Smith College log-in. Other off-campus researchers may request a copy through Interlibrary Loan for personal use.

Language

English

Comments

42 pages : color illustrations. Includes bibliographical references (pages 38-42)

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