The race to save coral reefs from climate change

Ocean acidification, pollution, and overfishing all affect coral health, but above all, the temperature rise accompanied by climate change poses the largest threat to coral reefs.

When temperatures are too high, corals evict the symbiotic algae that live within their structures, and with that, lose their main source of food.

For instance, some scientists have grown corals in an ocean nursery and replanted them in damaged reefs to help encourage new wild corals to grow.

Teams in Israel and Australia have even 3D-printed structures that mimic the shape of corals. These structures are then installed in a reef and planted with live corals, encouraging growth.

In the lab, scientists are growing corals in all sorts of settings — warmer water or different carbon dioxide concentrations, for example — to see what happens to their genes. This research could help scientists genetically engineer heat-resistant coral.

Another strategy involves the symbiotic algae, which provides food for the coral as it photosynthesizes. In May 2020, scientists reported that they reared these algae for several generations in water slightly warmer than what it lives in normally.

Coral inoculated with the warm-water algae were able to survive in warmer temperatures in a lab setting.

Scientists have even genetically engineered these symbiotic algae, isolating genes from algae that live in rare heat-tolerant corals and transplanting those genes into the less heat-resistant coral.