A comparison of constitutive and induced immune response in coral colonies of variable symbiont densities

Changsut, Isabella
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Scleractinian corals form the basis of diverse coral reef ecosystems. However, corals are in swift decline globally, in part due to rising disease prevalence. Most corals are dependent on symbiotic interactions with single-celled algae (family Symbiodiniaceae) to meet their nutritional needs. Preliminary evidence suggests that suppression of host immunity may be essential to this relationship. To explore potential immunological consequences of symbiotic relationships in corals, we investigated constitutive and induced immune activity in the facultatively symbiotic coral, Astrangia poculata. Brown (high symbiont density) and white (low symbiont density) colonies of A. poculata were collected from Rhode Island. First, we compared constitutive immune phenotypes between these two groups. Symbiont density was strongly correlated to several of these immune phenotypes; catalase activity and melanin were significantly positively correlated to symbiont density. Next, we investigated potential variation in induced immune response between the two groups. Colonies of A. poculata with variable symbiont densities were exposed to a pathogenic challenge. We then measured differences in constitutive and induced immunity using transcriptomic approaches. Preliminary results indicate significant differences in response to immune challenge as a result of variable symbiont density. Our results highlight the complex nature of symbiosis-immune interplay in cnidarians and emphasize the need for nuanced approaches when considering symbiosis.
Coral reefs, Ecoimmunology, Coral disease, Climate change
Changsut, I. V. (2022). <i>A comparison of constitutive and induced immune response in coral colonies of variable symbiont densities</i> (Unpublished thesis). Texas State University, San Marcos, Texas.