Coral Reefs and Climate Change

What is coral, and how are reefs formed?

Coral reefs are known as the ‘rain forests of the oceans’ because of their immense diversity. They are home to 25% of all life in the oceans. 

There are around six thousand coral species found all around the world. Most of them reside in shallow tropical waters near coastlines, while others are located on the seafloor of the open ocean.

Corals are animals that attach themselves to solid hard surfaces to grow. They usually form colonies of many identical individual polyps, making them colonial organisms. The mouth of each polyp surrounds tentacles which help them catch small fish and zooplankton.

Why are coral reefs so important to the Maldives?

The island of the Maldives only came after the coral reefs were formed. Coral reefs produce sand and limestone foundations on which islands slowly develop. This is why our islands are often referred to as coral islands. The unique white sand we see on our beaches is created when corals break down. Our islands' longevity directly relies on the health of the surrounding coral reefs producing and replenishing lost sand due to storms and rough oceans.

The fringing reef systems surrounding our atolls, or "thoshigandu," are our primary coastal protection from the increasingly frequent and intense storms mainly caused due to climate change.

These reefs also directly drive the country's major economic industries, such as tourism and commercial fisheries.

How does climate change affect coral reefs?

Coral bleaching

This relationship between corals and the zooxanthellae relies on the water's temperature. As the water warms, zooxanthellae are expelled from a coral's tissue, causing it to lose its color and a primary source of food. This process is known as "coral bleaching." 

Any stress can also cause coral bleaching, including sedimentation from land reclamation, chemical wash-ups, pollutants and acidification of the water, and coral diseases.

Bleaching doesn't necessarily have to be the death of the coral reef. Corals can still recover their zooxanthellae if the surrounding temperature cools down.

Ocean acidification

Rising temperatures can cause corals to have a hard time building limestone skeletons. Rising carbon dioxide (CO2) levels contribute to ocean acidification. The Oceans absorb most of the carbon dioxide released into the atmosphere. Carbon dioxide lowers the pH of seawater, resulting in a decrease in the main compound for the formation of the calcium-carbonate skeletons of corals. Therefore, they have difficulty building up or maintaining their skeletons.

Over the next few decades and centuries, the coral reefs are predicted to undergo significant changes due to these climate-induced threats. 

New research suggests that corals may begin to dissolve at atmospheric CO2 concentrations as low as 560 parts per million, which could be reached by the middle of this century if emissions are not reduced. In 2010, atmospheric carbon dioxide levels were around 390 parts per million. - National Geographic Society. https://media.nationalgeographic.org/assets/reference/assets/coral-reefs-4.pdf

Coastal modifications and development

Most Maldivian Atolls have coastal development work ongoing. They carry chemicals, nutrients, and bacteria that can harm coral reefs and spur algae growth. Sand dredging and reclamation cause sedimentation and the water to become cloudy or murky. The corals get covered in sediments, the sunlight can’t get to zooxanthellae, and the corals lose that critical food source.

What are some of the things we can do right now to reduce the direct human impact on corals?

• Protect and manage the remaining healthy reef systems by creating effective MPAs
• Promote and encourage sustainable fisheries
• Support research and monitor coral reef health
• Reduce marine debris and pollution
• Reduce your climate impact by minimizing your carbon footprint
• Support and get involved in coral restoration efforts
• Raising more awareness about the importance of coral reefs
• When planning a trip, choose operators that follow the best practices and are actively involved in coral conservation/restoration
• Use reef-safe sunscreen when going in the water
• Support and donate to local coral conservation NGOs like, Save the beach, Maldives Coral institute, Reef scapers, etc.