Why Are Some Zooxanthellae Resistant to Bleaching?
This question begs an answer why do some corals perform better than others at higher light intensity and/or temperatures and seem immune from the effects of radiation? There are many reasons why a coral could be resistant to bleaching: • Protection from UV Radiation. As we have seen, some zooxanthellae are able to protect themselves from ultraviolet radiation by production of mycosporine-like amino acids. Others can not produce these protectants, and hobbyists have no way of predicting which corals (or other animals for that matter) may be harmed by UV. See Riddle 2004a for reasons why we should eliminate ultraviolet radiation from aquaria. • Protection from Intense Light. Some zooxanthellae are able to produce and incorporate xanthophylls to protect themselves from high light intensity. Not all do, and there are alternative protective pathways such as spillover or non-radiant heat dissipation once absorbed light energy enters the reaction center of Photosystem II (See Riddle, 2004b fo
