Thursday, April 27, 2017

Scientific Publication in Marine Biology - Ecophysiology team

Nutritional strategies of shallow and mesophotic tropical corals

The cristal clear waters of the Gulf of Eilat (Israel) allow reef building corals to develop along an important depth and thus light gradient. Researchers from the ecophysiology team therefore performed a field trip in Israel in November 2015 to study the nutritional strategies of coral colonies thriving in the twilight zone or in « mesophotic » areas (below 30m), known as future refuges for colonies living in the shallower part of the water column, and already severly affected by anthropogenic stressors. 

© (CSM)
CSM and IUI teams members

In the tropics, reef-building corals usually thrive in the first highly lit 30 meters of the water column, mainly constrained by their symbiosis with photosynthetic algae, which are their main source of nutrition. However, some coral colonies can form large structures and host an important biodiversity in deeper (150 m) and darker environments, such as in some areas of the Red Sea. We name these reefs: mesophotic reefs. Although mesophotic coral reef ecosystems are widely distributed, they remain largely unexplored and little is known about the corals’ physiology and metabolism. They can however present morphological and physiological adaptations according to the depth gradient. The coral host can as well harbour diverse species of photosynthetic algae (or clades of Symbiodinium) to optimize its growth.

Researchers from the Ecophysiology team performed a field trip in the Gulf of Eilat (Israel) to understand and compare the nutritional strategies of colonies of S. pistillata hosting clade A1 in shallow waters and clade C1 in mesophotic environments.

Results showed that the specific association with clade C1 of Symbiodinium allows S. pistillata to optimize its photosynthetic capacities in the twilight zone, clade C1 being more efficient for light capture than clade A1. Moreover, the Symbiodinium clade specificity together with the light intensity characterizing the reef environment influence the absorption of inorganic nitrogen (ammonium and nitrate), feeding rates as well as the translocation of photosynthetic carbon within the symbiosis.

Thanks to its association with clade C1 of Symbiodinium, colonies of S. pistillata can colonize much deeper environments. Increasing our understanding on mesophotic coral reef ecosystems is therefore crucial since these reefs could serve, in the near future, as refuges for shallow water tropical corals, facing increasing threats from human activities.

© A. Dias Mota (CSM)
Coral Stylophora pistillata in the CSM aquariums

 

Ezzat, L., Fine, M., Maguer, J.-F., Grover, R. and Ferrier-Pagès, C. (2017) Carbon and Nitrogen Acquisition in Shallow and Deep Holobionts of the Scleractinian Coral S. pistillata. Frontiers in Marine Science 4, 102.

 
 

 


For more information, see www.centrescientifique.mc or contact :

- Dr Christine Ferrier-Pagès, Research Director, in charge of the Ecophysiology team of the Marine Biology Department, Scientific Centre of Monaco (ferrier@centrescientifique.mc)

- Dr Leïla Ezzat, Post-doctoral scientist in the Ecophysiology team of the Marine Biology Department, Scientific Centre of Monaco (leila@centrescientifique.mc)

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