What is the Guam Coral Bleaching Alert Network (CBAN)?

The Guam Coral Bleaching Alert Network (CBAN) is an alert system that will notify the public, marine tour operators, and any others visiting Guam’s waters either recreationally or commercially when Guam’s coral reefs are at risk of coral bleaching. Broad reaching communications will aim to reduce physical stressors during bleaching events and encourage activities at alternate sites, while providing general education about coral bleaching. This includes information about what coral bleaching is, how to recognize it, and how to report it. 

CBAN uses the NOAA Coral Reef Watch portal to monitor coral bleaching alerts for Guam’s waters based off satellite-derived sea surface temperatures and degree heating weeks.

Why Guam CBAN?

Elevated sea surface temperatures contributed to coral bleaching on Guam’s coral reefs in 2013, 2014, 2016, and 2017. In addition, extreme low tides associated with the naturally-occurring El Nino ENSO cycle began in 2014 and continued into 2015 contributing to additional coral loss. Due to these events, Guam lost ⅓ of all shallow corals from 2013-2017.

Coral bleaching was first reported on Guam in 1994, and then in 1997 and 1998 in association with an El Nino event. Another bleaching event occured in 2006 and 2007. Guam’s bleaching frequency is increasing, and this trend is projected to continue into the future. 

As bleaching events occur more frequently, reefs do not have the opportunity to recover. However, there are local actions we can all take to reduce stress on Guam’s coral reefs to help their recovery. The Guam CBAN is intended to raise awareness of coral bleaching and encourage the community to actively participate in protecting our coral reefs for the future. By being aware of coral bleaching and involved with the Guam CBAN, we hope you will learn how to RECOGNIZE, AVOID, AND REPORT.

Learn to Identify and Report Coral Bleaching with EOR Marianas
You can learn to identify coral bleaching on Guam's coral reefs with the Eyes of the Reef Marianas Coral Bleaching Training Module. Click here. Other training materials are available here.
Please send us a message if you'd like to register for a virtual EOR Coral Bleaching Identification Webinar.


Information you will need:

  • Site name or GPS coordinates (preferred)
  • Date of observation
  • Depth
  • Level of severity based on percentage of colonies affected (mild, moderate, severe, very severe)
  • PHOTO (as many photos as you can get, the better). Please try to get focused, macro photos as well from different angles.

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 NOAA Coral Reef Watch - Bleach Watch - Guam - Guam CBAN - GCBAN