Probing the thermo tolerant endosymbiont genus Durusdinium (Clade D) in the scleractinian corals of Palk Bay, Southeast coast of India

The world's coral reef ecosystems are built by a symbiotic relationship between reef corals and the dinoflagellates of the family Symbiodiniaceae. Climate change has already impacted the world's coral reef ecosystems. Some corals can survive in extreme environmental conditions through the acquisition of stress-tolerant endosymbionts. In the present study, the genetic diversity of endosymbionts of fourteen coral genera such as Porites (Five), Favia (Two), and Acropora (Seven) sampled from the reefs of Mandapam and Rameswaram, Palk Bay, Tamil Nadu, India was assessed by sequencing both large (LSU) and small subunit (SSU) gene fragments. The phylogenetic construction of LSU revealed the diversity of thermo tolerant Clade D that was monophyletic throughout various coral taxa. Comparison of thermo tolerant Glade D with SST (> 32 degrees C) has provided valid evidence for the presence of the endosymbiont Durusdinium sp. (Clade D) across different coral species in the Palk Bay.