# 5367-70 - 2019 35c Coral Reefs (coil)

Coral reefs are home to over 4,000 species of marine life.  Due to their diversity, they are often called the "rainforests of the sea."  However, in recent decades, coral reefs have suffered a major decline, leading to a search for new ways to preserve them.

About half of 2,500 species of coral around the world are the hard coral that make up reefs.  A number of threats have led to their decline, including predators.  Crown-of-thorns sea stars can swarm reefs adn kill massive amounts of coral in less than a year.  Seaweed is also a threat because it grows quickly and has a chemical that is harmful to coral.  Other threats include overfishing, pollution, harvesting of coral, and soil erosion.  But the greatest threats to coral are rising water temperatures and oceean acidification.  Both of these are linked to rising carbon dioxide levels, created by the burning of fossil fuels.  High water temperatures can kill the tiny algae that provide coral with much of its nutrients, leading to bleaching.  Higher levels of acid make it difficult for coral to build the calcium carbonate skeletons that form the rocky parts of the reefs.

To prevent further destruction, scientists urge a reduction in the burning of fossil fuels.  In the meantime, marine protected areas, biosphere reserves, marine parks, and world heritage sites are doing their parts to preserve these beautiful underwater communities.