b'4 Carnegie Science|Fall 2019Coral and Algal MatchmakingWe also want to know if its possible that more heat-tolerant, non-preferred algae could revive bleached coral communities.The dinoflagellate Breviolium minutum, left, is one of the algae used for this research. The sea anemoneCarnegies Arthur GrossmanAiptasia pallida (right) that is hosting the algae is responsible for the red fluorescent in the body of the animal. Image courtesy Robin Kempster, Carnegie Institution for ScienceImages courtesy Tingting XiangA lgae are tenants of coral hosts. A Victorianon-preferred algae could revive bleached coral communities even University of Wellington-led team of experts,if the relationship is less efficient.including Carnegies Arthur Grossman,Other organisms such as sea anemones are part of the same investigated the factors that govern algaesCnidaria phylum as coral; they also host algae but are easier to success under optimal conditions and whenstudy. In this paper, published by The ISME Journal, the researchers ocean temperatures rise.analyzed the differences in cellular function that occurred when a Corals, marine invertebrates, build large exoskeletons thattype of anemone called Exaiptasia pallida was populated by two form colorful reefs. This reef building is only possible because ofdifferent genera of dinoflagellate algaeone native and highly a mutually beneficial relationship between the coral and thesusceptible to thermal bleaching and the other non-native but more single-celled algae called dinoflagellates that live inside the cellsheat-resistant. of coral polyps.In this study we hoped to elucidate proteins that function to Dinoflagellates are photosynthetic: they convert the Sunsimprove nutrient exchange between the anemone and its native energy into the chemical energy of food. Many of these nutrientsalgae and why the anemones success is compromised when it synthesized by an alga serve as food for its coral host, while thehosts the non-native heat resistant algae, Grossman said. host provides the alga with essential inorganic nutrients,The team found that anemones colonized by native algae including carbon dioxide, nitrogen as ammonium, andexpressed elevated levels of proteins associated with the phosphate. However, ocean warming with climate change ismetabolism of organic nitrogen and lipids, nutrients that can be causing many corals to lose their algal tenants, along with theefficiently synthesized by photosynthesis. These anemones also nutrients, a phenomenon called bleaching. If the bleached coralsynthesized a protein called NPC2-d, which is thought to be key to is not recolonized with new algae, it can die.cnidarians ability to take up the algae and recognize it as a Some species of the dinoflagellate algae form symbioticsymbiotic partner. relationships with multiple types of coral; others are moreIn contrast, anemones with the non-native tenant expressed specific.proteins associated with stress, which likely reflects less optimal Were interested in understanding the cellular processesintegration of the metabolisms of the two organisms. that maintain those preferential relationships, Grossman said.Our findings open doors to future studies to identify key We also want to know if its possible that more heat-tolerant,proteins and cellular mechanisms involved in maintaining a robust relationship between the alga and its cnidarian host and the ways in which the metabolism of the organisms are integrated, SUPPORT: Grossman concluded.The Marsden Fund of the Royal Society Te Aprangi supported this research.'