Yes I know all about the symbiotic relationship between coral and zooxenthellae. Except bleached corals are weaker and might break off, which forms the substrate that coral reefs are built on. But most of the time new zooxenthellae that are more suited to the local climate will recolonise the coral.
They are different to a tree losing their leaves, because a tree can't just move location when the weather changes. A coral can however change their zoonxethellae. Otherwise known as bleaching.
