Coral symbioses are comprised of animal, algal, and microbial members. The primary association, between the coral animal and its photosynthetic algal symbiont, is crucial for the coral host; most tropical corals are highly dependent on their algal symbionts and will bleach and subsequently die if this symbiosis is disrupted by poor environmental conditions, e.g. warming ocean waters. The Northern Star Coral, Astrangia poculata, a common species found in temperate coastal waters of eastern North America, exhibits a flexible symbiosis with its algal symbiont. Adjacent colonies, subjected to the same environmental conditions, can be found with few to many algal symbionts; some colonies appear stark white, seemingly bleached, whereas others are brown in color, containing photosynthesizing algal symbionts, and yet both types of colonies can be healthy. This unique aspect of the biology of A. poculata with its algal symbiont, Breviolum psygmophilum, will be used to examine how symbiosis affects the energy corals devote towards the basic tasks required of all organisms: development, growth, body maintenance, and reproduction. Given rapidly deteriorating ocean conditions for most corals worldwide, understanding how corals acquire and use energy with and without their symbionts, in different environmental conditions, is imperative. The project will support the education and research training of numerous undergraduate students from diverse backgrounds, and will support outreach efforts