CORRESPONDENCE BETWEEN COLD TOLERANCE AND TEMPERATE BIOGEOGRAPHY IN A WESTERN ATLANTIC SYMBIODINIUM (DINOPHYTA) LINEAGE(1).

Many corals form obligate symbioses with photosynthetic dinoflagellates of the genus Symbiodinium Freudenthal (1962). These symbionts vary genotypically, with their geographical distribution and abundance dependent upon host specificity and tolerance to temperature and light variation. Despite the importance of these mutualistic relationships, the physiology and ecology of Symbiodinium spp.

Enhanced photoprotection pathways in symbiotic dinoflagellates of shallow-water corals and other cnidarians.

Photoinhibition, exacerbated by elevated temperatures, underlies coral bleaching, but sensitivity to photosynthetic loss differs among various phylotypes of Symbiodinium, their dinoflagellate symbionts. Symbiodinium is a common symbiont in many cnidarian species including corals, jellyfish, anemones, and giant clams. Here, we provide evidence that most members of clade A Symbiodinium, but not clades B-D or F, exhibit enhanced capabilities for alternative photosynthetic electron-transport pathways including cyclic electron transport (CET).