Shane Gross / Elkhorn corals (Acropora palmata) at night silhouetted by a scientist's light during the annual coral spawn. Abaco, Bahamas.

Juergen Freund / Bleached Staghorn corals (Acropora cervicornis), Great Barrier Reef, Australia, 2017.

Jordi Chias / Wave breaking over the reef, Table coral (Acropora) Safaga, Egypt, Red Sea.

Alex Mustard / Scissortail sergeants (Abudefduf sexfasciatus) swimming over hard corals (Acropora sp.) on shallow reef at sunset, split level view. Gubal Island, Egypt. Red Sea.

Georgette Douwma / Coral line nursery with Acropora corals grown to reintroduce to the Bonaire, Netherlands Antilles, Caribbean, Atlantic Ocean.

Michael Pitts / Tracking shot over bleached Table coral (Acropora), Maldives, Indian Ocean.

Alex Mustard / Shallow coral reef flat with corals (Pocillopora damicornis, Acropora humilis and Pocillopora verrucosa) in evening light. Gordon Reef, Strait of Tiran, Sinai, Egypt. Gulf of Aqaba, Red Sea.

Franco Banfi / Reef under the surface of shallow waters, at sunset, covered with hard corals, Brush Coral (Acropora hyacinthus) Robust Acropora (Acropora robusta) and other Acropora, Maldives, Indian Ocean

Franco Banfi / Reef under the surface of shallow waters, at sunset, covered with hard corals, Brush Coral (Acropora hyacinthus) Robust Acropora (Acropora robusta) and other Acropora, Maldives, Indian Ocean

Floris van Breugel / Staghorn corals (Acropora) on the coast of tropical island Ofu, one of the Manu'a islands, American Samoa. 2012.

Georgette Douwma / Masked butterflyfish (Chaetodon semilarvatus) with acropora coral. Egypt, Red Sea. Red Sea endemic.

Georgette Douwma / Bleached coral {Acropora sp} caused by loss of algae with living purple polyps. Maldives.