Date of Award

2021

Document Type

Thesis

Degree Name

Bachelors

Department

Natural Sciences

First Advisor

Diaz-Almedya, Erika

Area of Concentration

Marine Biology

Abstract

Symbiodiniaceae is a symbiotic, photosynthetic algae most commonly associated with providing nutrients to marine organisms such as anemones, jellyfish, and corals (Weber & Medina, 2012). Unfortunately, an increase in sea water temperature causes coral bleaching, the disruption of the symbiosis between Symbiodiniaceae and corals. Coral bleaching has been the largest cause of coral mortality since the early 1980’s (Hoegh-Guldberg et al., 2019) . It is suspected that if the corals coevolve with thermotolerant Symbiodiniaceae, the corals will also increase in thermotolerance (Chakravarti & Van Oppen, 2018). Previous work has shown intra-specific variation of physiological thermotolerance in Symbiodiniaceae (Díaz-Almeyda et al., 2017). This study aims to understand the intraspecific variability of the physiological response to combined thermal and light stress. The photochemical efficiency (Fᵥ/Fₘ) for three strains of Symbiodinium microadriaticum sensu stricto (CassKB8, RT362, RT61) was measured. The three strains were all placed under four conditions (26°C with low light, 26°C with high light, 32°C with low light, and 32°C with high light) and Fᵥ/Fₘ was measured every day over 9 days. This study showed the varying effects environmental stress has on strains within the species Symbiodinium microadriaticum sensu stricto. The effects showed a decrease in Fᵥ/Fₘ overtime, but this decrease varied by condition and strain. The most notable variation can be seen between the two thermotolerant strains, CassKB8 and RT61. This diverse physiological response encourages future study of Symbiodiniaceae to help expand the understanding of these interspecific variances. This increased understanding of Symbiodiniaceae and its unique properties builds way to developing successful methods for future coral climate change resilience efforts.

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