"U-Th dating reveals regional-scale
decline of branching Acropora corals on the Great Barrier Reef over the past century"
https://www.pnas.org/doi/pdf/10.1073/pnas.1705351114from 2017
Now -
"But in this instance, it’s more likely the reef is being dominated by only few species, as the report states
that branching and plating Acropora species have driven the recovery of coral cover.
Acropora coral are renowned for a “boom and bust” life cycle. After disturbances such as a cyclone, Acropora species function as pioneers. They quickly recruit and colonise bare space, and the laterally growing plate-like species can rapidly cover large areas.
Fast-growing Acropora corals tend to dominate during the early phase of recovery after disturbances such as the recent series of mass bleaching events. However, these same corals are often susceptible to wave damage, disease or coral bleaching and tend to go bust within a few years."
https://theconversation.com/record-coral-cover-doesnt-necessarily-mean-the-great...So they declined to much gnashing of teeth and now they are resurgent with much gnashing of teeth.