Great Barrier Reef Hit by Coral Bleaching

But, new video shows a high level of bleaching in the northern stretch of the reef. That's when sea temperatures get too high or too low and coral gets stressed, losing its original color...and begins struggling to survive.

Experts mainly blame the current widespread bleaching on warmer than average ocean temperatures. An aerial survey of the northern Great Barrier Reef revealed 95% of the reefs are now severely bleached. Authorities raised the response level to the highest level, allowing more surveying and monitoring of the fragile reef ecosystem.

But researchers working on a massive project which spans 56 islands and includes 450 coral reef locations say there is reason for optimism. The group found that reefs around uninhabited, or unpopulated, islands were able to bounce back from environmental stressors.