Visiting Researchers Study Coral Symbionts

19 August, 2013

Visiting researchers study coral symbionts in Palau

Palau International Coral Reef Center (PICRC) welcomed a research team from the United States to its facilities last week. The research team is a collaboration between PICRC and three US universities, and it includes Dr. Todd LaJeunesse from Penn State University, Dr. Mark Warner from University of Deleware (UD), Dr. Dustin Kemp from University of Georgia (GU), postdoc fellow Dr. Tye Pattey (UD), graduate student Kenneth Hoadley (PhD student at UD), graduate student Drew Wham (PhD student at Penn State), and graduate student Allison Lewis (PhD student at Penn State). They are in Palau to establish local partnerships and begin setup for a three-year research study, entitled, “The Physiology and Ecology of Widespread “Stress-Tolerant” Coral Endosymbionts: Coral “Saviors: or Opportunistic Invaders?” This study is funded by the National Science Foundation.

The primary focus for the study is to understand the effects of global warming on the symbiosis between reef building corals and the dinoflagellate algae (also called zooxanthellae) that live inside them. To do this, the research team will study the physiology of different species of coral symbionts (the symbiotic dinoflagellate algae that nourish corals) in response to stressful elevated temperatures that are expected to become normal in the coming decades. The team chose to work in Palau because they had a previous working relationship with Dr. Yimnang Golbuu, PICRC CEO, and because Palau’s corals are currently thriving in conditions more extreme than is found in the Caribbean—where coral populations are threatened– and in other Indo-Pacific regions.

This project will investigate the symbiosis ecology and physiology of S. trenchi in corals from the Atlantic and Pacific Oceans. The team will determine whether symbiont response varies between different symbiont species, and whether there are trade-offs that allow certain symbionts to function well under extreme conditions. Pacific ocean corals seem to be more tolerant to increased temperatures and more resistant to bleaching than Caribbean corals. These Pacific corals co-evolved with the symbiont S. trenchi, which is now migrating or expanding into the Caribbean. However, Caribbean corals have not co-evolved with S. trenchi and, thus, the symbiosis between S. trenchi and Caribbean corals might be poorly optimized and inefficient.

The team will set up two sites; one in Nikko Bay and one in an outer reef on the western side of Palau.Lab work will include the experimental manipulation of key species, including simulated bleaching. The team will also record photosynthetic health, or how well the algae feed the corals, by measuring the carbon and nitrogen transfer from the symbionts to corals. The study will provide information about whether the continued spread of S. trenchi into the Caribbean will affect coral growth. It will also investigate the potential for S. trenchi to spread to the outer reef coral communities in Palau, if waters in the Pacific become warmer.

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