The Chagos Reef was vibrant before the heat wave.
Ken Marks/Khaled bin Sultan Living Oceans Foundation
Scientists watched in real time as rising ocean heat transformed the sprawling reef. It was a harbinger for ecosystems everywhere as the planet warms.
The Pacific Ocean produces oxygen, helps regulates the weather, provides food and livelihoods. It's a place of fun, solace and spiritual connection. But its delicate ecology is under threat.
Sexual reproduction helps keep coral colonies diverse and resilient. Now, scientists are doing it in a lab to restock flagging reefs.
Corals release millions of sperm and eggs in synchrony to reproduce.
The largest reproductive event on the planet is under threat.
Bleached staghorn coral on the Great Barrier Reef. Many species are dependent on corals for food and shelter.
Corals, mangroves and seagrass habitats have been affected by extreme weather events, and some may never recover.
A school of juvenile bocaccio in the midwaters of Platform Gilda, Santa Barbara Channel, Calif.
Californians love their coast and strongly oppose offshore drilling. Will they support converting old oil rigs to artificial reefs – a policy that benefits both marine life and oil companies?
Recent marine heatwaves have devastated crucial coastal habitats, including kelp forests, seagrass meadows and coral reefs.
Marine heatwaves, like their land counterparts, are growing hotter and longer. Sea species in southeastern Australia, southeast Asia, northwestern Africa, Europe and eastern Canada are most at risk.
Solenosmilia coral reef with unidentified solitary yellow corals.
In the cold southern oceans, underwater mountains support deep-sea reefs.
Deep sea corals off Florida.
A massive new discovery this summer of miles of corals in deep waters off South Carolina shows how much we have yet to learn about life on the ocean floor.
A healthy coral reef on Millennium Atoll, Southern Line Islands.
Field samples, satellite measurements and isotopic data have shed new light on corals' eating habits.
Staghorn and tabular corals suffered mass die-offs, robbing many individual reefs of their characteristic shapes.
ARC Centre of Excellence for Coral Reef Studies/ Mia Hoogenboom
The 2016 bleaching event resulted in 30% mortality on the Great Barrier Reef, with many corals dying of the heat before they bleached and the loss of branching corals creating less complex reef structure.
The increasingly bleached coral at Black Point on the Cobourg Peninsula is a worrying sign of what’s to come for other coral reefs in Australia.
Coral bleaching has struck the Northern Territory, adding urgency to the need for better national management strategies for our warming oceans.
A plastic bottle trapped on a coral reef.
Coral reefs in the Asia-Pacific have been deluged with an estimated 11.1 billion pieces of plastic waste, increasing the risk of coral disease more than 20-fold.
Giant triton molluscs are a useful ally in battling the coral-grazing crown-of-thorns starfish.
AAP Image/AIMS, K Goodbun
The federal government's new funding aims to spread the net wide in investigating possible ways to protect the Great Barrier Reef's corals. Winning this battle will require a wide range of weapons.
Some reefs are strong sources of coral larvae.
A new study identifies dozens of individual reefs on the Great Barrier Reef that are especially important for coral larvae dispersal and which could help the entire ecosystem bounce back.
How the Great Barrier Reef can be helped to help repair the damaged reef.
Corals on the Great Barrier Reef that are tolerant to warmer waters can be used to help repair other parts of the reef damaged by recent coral bleaching events.
The southern Great Barrier Reef escaped both of the recent mass bleaching events. But time is running out.
AAP Image/ARC Centre of Excellence for Coral Reef Studies, Tory Chase
Tropical coral reefs can be saved from climate change and other pressures, but the window of opportunity is closing. And reefs are guaranteed to be markedly different in the future.
A typical reef scene within the Chagos Archipelago.
The British overseas territory faces an environmental crisis.
Coral reefs in Australia’s northwest have experienced severe bleaching and coral mortality in 2016.
Western Australia's super-corals are adapted to high temperatures, but even they didn't escape the recent bleaching event unscathed.
We think of coral reefs as a diverse ecosystem, but each coral is an entire and complex microworld of organisms imperceptible to our eyes.
Just like humans, corals live with myriad microscopic organisms. We are just starting to understand this unseen world.