As the globe warms, so does its seas, and coral reefs are paying the price. Corals are bleaching: they eject the colorful algae that inhabit them, and eventually they die. Corals are a foundational part of ocean biodiversity, and much of their stress is related to human activity: dive-related breakage, coastal development, blast fishing, and pollution.

http://sciencebulletins.amnh.org/?sid=b.v.coral_reefs.20110511&src=l