Resident Symbiodinium spp. remained stable within corals following a cold-water stress event off Baja, California, Mexico. Photo: T.C. LaJeunesse, M. D. Aschaffenburg, D.T. Pettay 2008

Resident Symbiodinium spp. remained stable within corals following a cold-water stress event off Baja, California, Mexico. Photo: T.C. LaJeunesse, M. D. Aschaffenburg, D.T. Pettay 2008

In a collaborative project between New York University Abu Dhabi and the University of Southampton, in the UK, researchers have identified a unique species of symbiotic algae that occurs in corals in the southern Arabian Gulf. The new species has been named Symbiodinium thermophilum, after its heat-loving properties. The discovery was published this month in Nature’s journal Scientific Reports.

“The Arabian Gulf is the world’s hottest sea,” said John Burt, Associate Professor of Biology and head of the NYU Abu Dhabi marine biology lab. “Abu Dhabi reefs can provide incredible insight into how corals may adapt to increasing temperatures expected under future climate change.”

“We used novel molecular biological approaches to identify this species,” explains Professor Jörg Wiedenmann, Professor of Biological Oceanography and Head of the Coral Reef Laboratory at the University of Southampton. “These approaches allowed us to get much higher resolution to distinguish these symbionts (co-dependents) from those in other parts of the world’s oceans.”

Coral-Symbiodinium sampling locations with the Persian/Arabian Gulf. (A-E) represents previous sampling locations from Baker et al. 2004. 1-3 represent sampling locations from this study; Dalma (1), Saadiyat (2), and Umm Al Quwain (3).

Coral-Symbiodinium sampling locations with the Persian/Arabian Gulf. (A-E) represents previous sampling locations from Baker et al. 2004. 1-3 represent sampling locations from this study; Dalma (1), Saadiyat (2), and Umm Al Quwain (3).

Reefs are made up of many coral species, most of which live in a mutually beneficial relationship with microscopically small algae hosted in their tissue. These symbiont algae produce sugars that contribute to the diet of the coral in return for shelter and nutrients that are vital for algal growth.

However, the symbiotic association is vulnerable to changes in environmental conditions, in particular to increases in seawater temperature. Heat-stress induced loss of the algal partners from the coral host can result in the often fatal process known as “coral bleaching.”

“Understanding how corals survive under the extreme temperatures in the Arabian Gulf will give us important insights into the ability of reef corals to handle the heat stress, which is threatening their survival in the oceans that are warming up in response to climate change,” said Professor Wiedenmann. “It gives hope to find that corals have more ways to adjust to stressful environmental conditions than we had previously thought.”

“We monitored the stability of the symbiotic partnership seasonally for two years to ensure that this partnership was stable through a range of temperatures,” said Professor Burt. “We can confirm that this new type of alga is indeed a consistently dominant symbiont across several common coral species in Abu Dhabi. This finding shows us the unique nature of corals in Abu Dhabi, but it also highlights the importance of coral reef ecosystems in the Emirates and the need to ensure their conservation into the future.”

Recent conservation and research efforts supported by the Environment Agency-Abu Dhabi (EAD) have helped in this regard, Professor Burt said. “The EAD has been extremely progressive in their support for research on coral reefs, and they are making excellent strides in preserving these important ecosystems by proposing a series of new marine protected areas that would conserve important reefs around Saadiyat Island and Ras Ghanada,” a larger reef near the Abu Dhabi-Dubai border.

The Paper: Hume BCC, D’Angelo C, Smith EG, Stevens JR, Burt J, and Wiedenmann J. “Symbiodinium thermophilum sp. nov., a thermotolerant sumbiotic alga prevalent in corals of the world’s hottest sea, the Persian/Arabian Gulf” (2015) Scientific Reports. 5: 8562. DOI: 10.1038/srep08562