One of the major impacts of climate change on coral reef environment are marine heatwaves. Marine heatwaves, which are periods of higher-than-average temperatures cause thermal stress for the plants and animals that call the reef home. This includes corals.

Corals are made up of small animals called polyps. But coral polyps can’t survive alone. They actually have small algal cells living inside them called zooxanthellae. These algal cells help produce food for the corals.

However, when corals are exposed to high temperatures for prolonged periods they ‘bleach’. When the corals get too hot, the corals expel their alga, which are what gives the coral colour. When the algae are expelled, the coral turns white and is ‘bleached’.

If the water stays too hot for too long, the corals polyps starve and die. This has downstream impacts on all the communities that call the reef home, including many fish species that are important for fisheries.

Coral bleaching events have been increasing in both frequency and severity due to climate change. Because of this, research into coral bleaching and coral recovery has been a big focus globally.

New research into recovery of bleached corals has made an interesting discovery – corals can recover more rapidly from bleaching if they are touching another coral!

Two independent studies, one in Environmental Microbiology Reports by a team from the Australian Institute of Marine Science,and one in Science Advancesby a team from Stanford University, found that touching by touching a piece of bleached coral to a healthy piece, algae transfusion can occur. Algae from the healthy piece of coral can be passed into the bleached piece of coral, aiding in recovery.

Understanding how corals recover from bleaching could help researchers develop new ways to support reef recovery after marine heatwaves. While these approaches can’t prevent bleaching or remove the pressures caused by warming oceans, they may help reefs recover more quickly after a stressful event.

For the fisheries and communities that depend on healthy reefs, this research is a reminder that climate adaptation can involve finding practical ways to help ecosystems recover from change. The next step is working out whether these findings can be applied at a larger scale to support coral reefs into the future.