The Diversity of the Giant Clams and Their Associated Symbiodiniaceae Algae in the Red Sea

The Red Sea is host to one of the world's largest reef systems where invertebrates make up the majority of the diversity. Of those marine invertebrates, those that host microscopic algae or zooxanthellae are of the utmost importance in climate change research. Giant clams are photosymbiotic organisms and are protected under Appendix II of CITES. However, overfishing, habitat destruction, and climate change threaten their populations. The Red Sea is home to 3 of the 12 species of giant clams, Tridacna maxima, Tridacna squamosa, and Tridacna squamosina. Tridacna squamosina has the smallest geographical range, limited to the northern Red Sea, and is only present in low abundance. Overfishing in the past and present has been the main contributor to the loss of species in the Red Sea and globally. Climate change also threatens this symbiotic relationship between the giant clam and zooxanthellae in the family Symbiodiniaceae. Giant clams in the Red Sea have only been found to harbor Symbiodinium type A1 as their dominant type. However, as genetic techniques improve, the classification system of Symbiodiniaceae will improve and allow for better detection of diverse species within a host, which will allow for better understanding of the future of these organisms.