Moderate thermal stress causes active and immediate expulsion of photosynthetically damaged zooxanthellae (Symbiodinium
) from corals.
Yamasaki, "Implication of nitric oxide in the heat-stress-induced cell death of the symbiotic alga Symbiodinium
microadriaticum," Marine Biology, vol.
Thome, "Glycerol outflow in Symbiodinium
under osmotic and nitrogen stress," Marine Biology, vol.
Instead, they recruit the Symbiodinium
and other microorganisms they need to survive early in their life cycle.
Senior author of the study, Professor JE[micro]rg Wiedenmann from Ocean and Earth Science at the University of Southampton, explains: "It was not clear whether this resilience is related to the presence of a new type of symbiotic alga (Symbiodinium
thermophilum) that was recently discovered by our team in this region.
Some of these coral types contain symbiotic microalgae, genus Symbiodinium
, and are generally called zooxanthellae .
Most corals can't survive without live-in help from various kinds of single-celled Symbiodinium
The quantity and quality of light or photosinthetically active radiation at five meters is lower than at three meters, which could lead to a greater loss of Symbiodinium
algae thereby increasing the bleaching event.
The researchers found, however, that clade A Symbiodinium
has complementary mechanisms for surviving in its coral hosts during periods of warmer-than-normal water temperatures and intense late-summer sun.
algae grow within coral tissue and use sunlight to convert carbon dioxide into carbohydrates for the coral to feed on--providing the primary energy source for entire reefs.
Genetic variation in Symbiodinium
isolates from giant clams based on random amplified polymorphic DNA (RAPD) patterns.
These surprisingly uniform symbionts are generally identified as Symbiodinium