Coral reefs are dying in alarming numbers around the world. Reefs are a crucial part of marine ecosystems and provide food, shelter and breeding grounds for many species. According to the Independent, about half of our reefs have already died, and 90 percent may disappear by 2050. While researchers are scrambling to save the remaining reefs, coral gardening has become a popular preservation method.

Considered the rainforests of the sea, coral reefs have beautiful colors ranging from brown to blue. Reefs can vary in size, shape and color. Although they may look like rocks, corals are alive. Coral polyps are the animals that form reef colonies, and each polyp has a stomach with a mouth surrounded by tentacles that can capture food.

Hard corals form the reefs that attract tourists to destinations like the Great Barrier Reef in Australia. They make calcium carbonate skeletons for protection and have a mutualistic relationship with the photosynthetic algae zooxanthellae. The algae receive a safe space to live while the corals get food, oxygen and waste removal. In addition, zooxanthellae give corals their color. If you see a white or bleached coral, it lacks zooxanthellae.

Coral reefs provide homes for 25 percent – or 2 million – of all the ocean species in the world. Fish and other animals rely on the reefs for protection, shelter, food and breeding grounds. Reefs also protect shorelines and prevent erosion. For example, Florida's barrier reefs can reduce the impact of waves or storms while stopping the land from wearing away. In addition, corals help filter the water, so it remains clear.

According to the Smithsonian, coral reefs have a global value of at least $30 billion because of the resources they provide to people. In the United States, the NOAA Office for Coastal Management estimates that coral reefs have a value of $3.4 billion per year due to tourism, fisheries and shoreline protection while preventing $94 million in flood damage. Around the globe, 500 million people depend on reefs for income, protection or food.

Although there are natural dangers like disease and storms, people are the biggest threats to coral reef survival. Pollution, overfishing, too much tourism and other problems are destroying reefs around the world. Other important issues are warming ocean temperatures and ocean acidification linked to climate change.

Coral bleaching, which is when reefs turn white, can happen because of rising ocean temperatures. Pollution, runoff, low tides and too much sunlight can also contribute to bleaching. The coral polyps expel the zooxanthellae that give them their color because they're under stress and start to starve. If the problems persist, the corals can die.

Coral gardening is a method of growing coral polyps to help restore reefs around the globe. Sometimes called coral farming, this gardening method involves taking small coral fragments and growing them through asexual reproduction until they are mature. The two main types of gardening practices are ocean-based nurseries and land-based nurseries.

Ocean-based nurseries take coral fragments and grow them underwater. They attach the pieces to steel structures and monitor them. The fragments may need to grow for six to 12 months to reach maturity in the nurseries. Once they're ready, the researchers can transfer the colonies of new polyps to existing damaged reefs, so they can continue to grow.

On the other hand, land-based nurseries take coral fragments and grow them in laboratories or farms. Growing corals on land allows for faster processes such as microfragmenting. Since most corals grow about an inch per year, faster growing practices are important for the restoration of the reefs. In addition, land-based nurseries aren't exposed to the oceans' changing temperatures, predators, storms, accidents or other problems that can interfere with the gardening process. Once the corals are mature, they can still be transferred to the reefs underwater for replanting.

The Miami Herald reports that one of the biggest benefits of coral gardening is the ability of researchers to influence the reefs and make them more resilient. For example, the University of Miami’s Rosenstiel School of Marine and Atmospheric Science and the Frost Museum of Science are working together to make super corals. Engineered reefs can be more diverse and resistant to problems like climate change or rising ocean temperatures. Researchers can deliberately select coral fragments from reefs that appear to withstand stress better.

A study from the University of Miami’s Rosenstiel School of Marine and Atmospheric Science found that coral gardening is working. Scientists learned that taking small fragments doesn't cause serious damage. More importantly, replanting coral colonies grown in nurseries helps save reefs, and the transferred coral acts like wild colonies.

Want to get involved? If you're in Florida, you can join the Rescue a Reef project. You can be a part of the expeditions that help restore coral reefs in Miami by gathering fragments and planting them.

You can't start a coral garden in your swimming pool, but there are other things you can do to help preserve coral reefs globally. First, do not buy, sell or harvest any corals. From souvenirs to jewelry, you can find corals in many stores. By not purchasing coral pieces, you can limit the demand for them.

If you travel to a location that has coral reefs, be a responsible tourist. Don't go diving or swimming in restricted or protected areas. Avoid touching or doing any type of damage to existing coral reefs. Don't stand or sit on any part of the reefs. In addition, you can help by cleaning up your trash and not littering on beaches.

What you do on land can also affect coral reefs negatively or positively. Corals need clean water without sedimentation or runoff to survive. You can help by reducing your use of fertilizers or other chemicals that can end up in the water.