 The percentage of baby corals being born on the Great Barrier Reef dropped drastically in 2018 and scientists are describing it as the early stage of a "huge natural selection event unfolding".Many of the mature breeding adults died in the bleaching events of 2016–17 leading to low coral birth rates.The types of corals that reproduced also changed, leading to a "long-term reorganisation of the reef ecosystem if the trend continues."