Abstract

Coral reefs are a critical habitat in tropical ecosystems. They create a barrier that reduces storm surge, provide medicines, and are estimated to affect 25% of the fish in the ocean. Unfortunately, coral reefs around the world are dying at an alarming rate. Corals survive by having a symbiotic relationship with Symbiodiniaceae, a photosynthetic dinoflagellate that lives within the tissue of corals. Symbiodiniaceae uses photosynthesis to turn sunlight into glucose, glycerol and amino acids for its holobiont (coral host). Understanding the role that temperature plays in this relationship is crucial to understanding how to help corals survive mass bleaching events. This experiment tests the ability of the coral Montipora capricornis to expel its Symbiodiniaceae and gain a different species of Symbiodiniaceae. M. capricornis naturally has one of the most abundant species of Symbiodiniaceae from the genus Cladocopium (C15h). The Cladocopium sp. was purposefully expelled from the M. capricornis by increasing the water temperature of the tank, simulating rising temperatures in the ocean, to allow for the reintroduction of Symbiodinium trenchii, a Durusdinium sp. with a greater resistance to temperature change. The S. trenchii were cultured, and once the M. capricornis was successfully bleached, the S. trenchii was introduced. We sampled coral tissue to determine if the S. trenchii successfully replaced the original zooxanthellae, DNA and Chlorophyll A. In addition, oxygen concentrations in the coral boundary layer were measured in light and dark before, during, and after the bleaching to test the differences in oxygen production.

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