The Sound of a Coral Reef

Coral

Corals are living colonies of tiny tube-like animals called polyps. Each polyp has a mouth surrounded by tentacles and produces a hard outer skeleton made of calcium carbonate.

Although coral covers less than 0.1% of the ocean surface, it provides shelter and food for 25% of all marine life. Reefs diffuse wave energy by up to 97%, protecting millions of people living in coastal communities as well as fragile habitats such as mangrove and sea grass.

Corals get 70% to 90% of their energy from photosynthetic algae that live inside their tissue, giving the coral its colour. When the sea temperature rises, the symbiotic relationship between coral and algae breaks down and the algae are ejected from the polyp. The coral starts to starve and turn white which is why the process is known as bleaching.

Warming seas, ocean acidification and human disturbance are killing the world’s coral reefs, almost two-thirds of the corals on the northern part of the Australian Great Barrier Reef have died in the last few years.

Healthy coral reefs generate a surprising amount of sound and are one of the noisiest places in the ocean. Many marine animals use this sound to locate reefs, which are an important source of food and shelter. It is difficult to determine if coral can recover but recent studies suggest that these sound recordings can help assess the health of vulnerable reefs. You can listen to the sound of both a healthy and degraded coral reef below: