Restoring corals

A middle school student cleans algae from a coral tree in the Florida Keys. Photo credit: Matt Strand Learn more and view a larger image.

Restoration is one way scientists are trying to save and enhance existing coral reefs. One way of doing this is to remove a healthy coral, or part of a coral, from the ocean to protect it, and grow smaller corals from it in nurseries on land or in the ocean. The new corals are then planted back onto coral reefs that have been degraded or impacted by a disturbance like a hurricane or damaged by a boat. Restoring corals in the wild is most successful when scientists use types of corals that are better able to withstand impacts to their environment like rising ocean temperatures and more intense storms.

What is coral rescue?

One way that scientists are working to rescue corals is through a process called gene banking. This is where scientists collect and store genetic material from various organisms, such as their tissues, cells, or DNA, to safeguard their genetic diversity for conservation, research, or potential applications in the future. By collecting coral species from the wild and maintaining them in land-based aquariums and nurseries, scientists can preserve the genetic diversity of reefs for future generations.

Coral propagation, also known as coral farming or coral husbandry, involves the collection of coral sperm, egg, and/or larvae to help the corals reproduce under controlled conditions in a laboratory.

Coral fragmentation is when a healthy coral colony is carefully cut or broken apart into smaller pieces, known as fragments, which can then grow into new independent colonies. This technique is commonly used in coral gardening, reef restoration efforts, and aquarium reproduction.

Large pieces of coral are cut into smaller quarter-sized pieces, and grown in aquarium tanks for future outplanting. View a larger image.

Various types of coral fragments are grown in aquarium tanks before being outplanted into the wild. Learn more and view a larger image.

Beyond corals: Restoring a reef ecosystem

Coral reef restoration goes beyond just corals to include key invertebrate species, like sea urchins and crabs. Learn more and view a larger image.

Restoring an entire coral ecosystem involves a lot more than just corals. While corals are crucial for reef ecosystems, there is a lot more that needs to be done in order to consider a reef ecosystem restored. These include stabilizing the substrate, or ocean bottom, where the reef is built, increasing the number and types of coral, fish, and other marine species on the reef, and controlling pests, like the crown-of-thorn starfish that feed on corals. Good water quality is critical for coral reefs to remain healthy. Good water quality is characterized by low turbidity (clear water), low levels of pollutants, balanced pH and temperature, sufficient oxygen levels, and the absence of contaminants or disease-causing organisms.