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Examining Production Possibility Frontiers and the Effect of Chemical Photosynthetic Inhibition in a Cliona varians forma varians:Symbiodinium Symbiotic Relationship

Date of Award


Document Type

Restricted Thesis: Campus only access

Degree Name

Bachelor of Science



First Advisor

Dr. Malcolm S. Hill


Symbiotic relationships between sponges and algae are based on the translocation of photosynthetic products from the symbiont to the host. It is hypothesized that when photosynthetic products cease translocation to the host, the host will digest and evict the algae (the Arrested Phagosome Hypothesis of Hill and Hill (2012)). Furthermore, if energy from photosynthesis is used to purchase residency within the host, any disruptions in energy production may lead to reductions in the population size of the symbiont community. The result of loss of algae from a host is known as bleaching, and this phenomenon is increasing in frequency around the globe with deleterious consequences for the host. Photosynthetic products may stop flowing from the algae to the host for a number of reasons, including photoinhibition caused by, for example, thermal damage induced by warmer-than-usual seawater. I was interested in determining whether reductions in photosynthesis caused by chemical means might also lead to changes in the number of algae harbored by a host sponge. Clade G Symbiodinium from Cliona varians forma varians was chemically photoinhibited using DCMU (diuron), a chemical that blocks flow of electrons in photosystem II, in an effort to decrease the total amount of photosynthetic products available. While previous studies have shown that treating coral species with DCMU resulted in host:symbiont destabilization, my results indicate that DCMU- induced damage of photosystem II did not induce a loss of symbionts nor did it change the chlorophyll concentration per symbiont cell. I discuss the importance of these findings in the context global bleaching patterns observed in corals.

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