Coral reefs are some of the most biodiverse ecosystems on Earth. Image courtesy of Andrés Felipe Suárez-Castro.

Coral reefs around the world are facing many conservation challenges. Approximately half of the world’s coral reefs have experienced decline of coral since the 1990s.

One of the problems facing coral reefs is when sediment (dirt, sand, and mud) from surrounding land areas gets into the ocean and blocks sunlight from reaching the corals. 

Corals are animals and cannot create their own food. Coral has microscopic algae living with it that provides it with nutrients (food). The algae needs sunlight to photosynthesize. When sediment from land blocks out the sun, the algae dies back. The coral that the algae feeds also dies back.

Scientists studying how sediment from land hurts corals have found a possible solution to the problem. They say it is important to protect and restore coastal forests near coral reefs. The forests keep the sediment in place on land so that it does not run off into the sea. As a result, the algae can photosynthesize without being choked by sediment, and the coral and the algae are happy.

Researchers and conservationists consider sediment runoff from disturbed coastal catchments to be a major threat to marine ecosystems. Image courtesy of Andrés Felipe Suárez-Castro.

Mangroves are coastal forests that are particularly adept at binding soil with their roots and reducing sediment erosion into the ocean. Image by Anton Bielousov via Wikimedia Commons (CC BY-SA 3.0).

Based on an article from Mongabay.com:

https://news.mongabay.com/2021/12/restoring-coastal-forests-can-protect-coral-reefs-against-sediment-runoff-study/