Many species of cnidarians, including vulnerable reef-building corals, are dependent on partnerships with symbiotic algae. In most cases these are obligate relationships, but a handful of species display facultative symbioses, including the temperate coral, Astrangia poculata. We are interested in using this species to understand how host immunity modulates and regulates symbiosis, how symbionts might circumvent these processes, and the consequences of symbiotic interactions on the ability of hosts to mount immune responses to pathogenic threats. Projects include following up on initial work from Dr. Fuess, which showed an inverse relationship between symbiont density and host coral immunity. We are particularly interested in exploring the mechanisms of this trade-off, as well as how changes in host energetic budget might play into these trade-offs. This work is supported in part through an NSF GRF to I. Changsut and an NSF PRFB to E. Borbee.