Symbiotic associations are common in our environment and, may be extremely important to the success of both plant and animal species. Some of the most interesting are found in the coral reef environment and involve an algal symbiont known as zooxanthellae and various invertebrate hosts. Coral reefs constitute a major ecosystem that is dependent on algal symbiosis. Global warming is thought to cause bleaching in coral symbionts and this inhibits reproduction of coral. An understanding of the relationship between symbiosis and reproduction in host organisms is essential to the understanding of symbiotic ecosystems. Algal symbionts form the basis for much of the reef's primary productivity since they convert carbon dioxide and other inorganic compounds into organic substances that can be utilized by host species. A high diversity of species may be supported in large numbers in the reef environment. Perhaps the most important, unasked, question about zooxanthellae symbiosis is: "What effects do symbiotic zooxanthellae have on the reproductive success of their invertebrate hosts?" The species to be used is Berghia verrucicornis, a marine slug. This species has a number of characteristics that make it particularly useful for studying the reproductive ramifications of zooxanthealle symbiosis. These include (1) its own zooxanthellae symbiosis, (2) its ease of culture in the lab, and (3) the fact that it lays discrete, easily collected egg masses. This project will utilize biochemical analyses, radioisotopes, and energetic analysis to determine what portion of the organic materials produced by zooxanthellae are incorporated into the eggs of Berghia verrucicornis. The results and conclusions derived from this research will provide for a better understanding of the role of zooxanthellae in the reproduction and success of reef-dwelling species that harbor these symbionts in their tissues.//