Hope for Corals:

Growing Species Resilience in Coral Nurseries

The next level of coral conservation goes beyond protection to reef regeneration

Historically, coral conservationists have focused their efforts on protecting these invaluable marine resources from direct environmental threats, like land-based pollution and damaging fishing practices. While these efforts continue, researchers are now also looking at ways to tackle coral reef restoration more proactively.

Coral 'farmers' tend to small, found corals anchored to an underwater structure.

Coral “farmers” tend to small, found corals anchored to an underwater structure. Corals grown in nurseries like this one can be replanted on damaged reefs or studied by researchers trying to understand what makes corals more resilient to environmental stressors.

Individual corals build reefs over thousands of years, but environmental stressors, and damage from events like ship groundings or storms, can destroy a reef in mere decades—or even less. Since the 1980s, episodes of coral bleaching have been happening more often, meaning that corals don’t have time to recover between these events. That’s why, to help save the corals, and the benefits they provide, conservationists now want to give more active assistance.

What is a coral nursery?

Over decades, conservationists learned how to grow corals in nurseries to repopulate damaged reefs. Coral “farmers” nurture small, found pieces of coral on underwater structures until they can be replanted on existing reefs, stimulating recovery of these ecosystems.

On average, the fastest growing hard corals (or stony corals) grow naturally at about the same rate as human hair—about 10 centimeters a year. Many only grow at fraction of that rate. This slow growth rate makes recovery from mass death events, such as bleaching or disease, challenging. But, in the low stress environment of a nursery, conservationists can grow corals much faster, giving the reefs a fighting chance.

And, perhaps even more crucially, conservationists can manage the diversity of the coral population in nurseries. Not all corals are created equal. Some corals are able to withstand or recover from stresses better than others. Fostering diversity among corals means the overall population will be more resilient to changes in its environment, such as warming ocean waters.

In 2006, an oil tanker grounding damaged a coral reef in Tallaboa, Puerto Rico.

In 2006, an oil tanker grounding damaged a coral reef in Tallaboa, Puerto Rico.

Coral nurseries started out as a way to rebuild reefs that had been damaged by ship groundings or major storms, but the investment in coral nurseries has grown beyond that. These days, researchers are looking at ways to actively build the resilience of corals through coral nurseries in the ocean and in the lab.

Scientists want to know what factors allow corals to adapt to a changing climate—and how they might intervene to help the corals. For example, how do stress and location affect corals? Can corals that overcome stresses during their lifetimes pass these adaptations down to offspring? Or, might gene editing be more effective?

More research will help scientists answer these questions and take efforts to save coral reefs to the next level. In the meantime, conservationists continue to improve their ability to grow corals in nurseries and repopulate reefs.

What’s next?

At NOAA, the Coral Reef Conservation Program (CRCP), along with NOAA Fisheries and others, is engaged in research to try and better understand the challenges corals face and how coral conservationists can address them going forward.

The CRCP provides funding and technical expertise to groups to establish coral nurseries. In 2017, the CRCP gave the Guam Bureau of Statistics and Plans funds to work with the University of Guam Marine Lab and community partners to establish a coral nursery at Cocos Lagoon. At this nursery, they’ll grow corals to be replanted on reefs damaged by bleaching events.

This is a photo of the Tallaboa reef in 2015. Restorers stabilized rubble, reattached broken corals and rebuilt the reef with coral transplants from nurseries.

Here’s the Tallaboa reef in 2015. Restorers stabilized rubble, reattached broken corals and rebuilt the reef with coral transplants from nurseries. Nursery-grown corals can be used not only to help reefs damaged by groundings, storms or pollution but those harmed by changing ocean conditions as well.

And, the CRCP invested in multiple projects in Puerto Rico and the US Virgin Islands to grow and plant on established reefs well over 10,000 corals, which they expect to result in acres of restoration in a few short years.

Researchers still have a lot to learn about why certain corals thrive under different ocean conditions, or not. But, researchers recognize the urgency of the situation, and the pace of study has picked up.

The next step for nurseries is scaling their activities up, growing more corals that are more resilient to be transplanted on struggling reefs. The technology that can help corals overcome the challenges of a changing ocean is out there. Now, it’s just a matter of bringing it to the corals.

International Year of the Reef logo

2018 International Year of the Reef

What can you do to protect coral reefs?

Here’s some things you can do to help protect corals:

  • Corals are already a gift; don't give them as presents.
  • Conserve water. This reduces runoff and wastewater to the ocean.
  • Volunteer at local beach or reef clean-ups, or get involved in protecting your watershed.
  • When you visit coral reefs or coastal areas, consult local guides, clean up your trash, never touch or harass wildlife, and avoid dropping anchor near a coral reef. Remember your ocean etiquette.
  • Be an informed consumer! Your choices about recycling, food, energy consumption, and travel impact reefs.
  • Spread the word! Learn about the value of healthy coral reefs to the people, fish, plants, and animals that depend on them. Your excitement will help others get involved.
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