Coral at risk as Red Sea epidemic decimates sea urchins.

A deadly epidemic caused by a ciliate parasite is spreading through the Red Sea, killing off an entire species of sea urchin in the Gulf of Aqaba, which is known for helping keep coral reefs healthy. The epidemic has also caused mass mortality in other countries in the region, including Jordan, Egypt, and Saudi Arabia. The sea urchins play an important role in maintaining balance by feeding on algae that would otherwise block sunshine and smother the reefs. The epidemic imperils the region's uniquely resilient coral reefs, and there is nothing that can be done to stop it at the moment.