The coral reef, seen here in a photograph titled "Colonias de Acropora millepora en la Gran Barrera de Arrecifes de Australia" by Petra Lundgren, Juan C Vera, Lesa Peplow, Stephanie Manel and Madeleine JH van Oppen (CC BY 4.0, via Wikimedia), has been badly hurt by the increased acidity of the ocean (pp. 125-147)