Toscano, M. A., Strong, A. E., Guch, I. C.

New analyses for ocean hotspots and coral reef bleaching

1999

Reef Encounter

26

31

"In Reef Encounter 24, Strong, Goreau and Hayes described the "HotSpot" technique employed to identify and map areas of the global tropics where satellite-derived surface temperatures (SSTs) have exceeded a threshold of 1.0 C above the warm season monthly mean temperature. The technique is highly successful in providing early warnings of coral reef bleaching linked to thermal stress. In 1997 and 1998, HotSpot mapping illuminated all areas of the tropics that were subjected to intense and prolonged warming, coral bleaching, and subsequent mortality. We have recently incorporated a new treatment of the HotSpot data to help study thermal stress as a primary cause of coral bleaching. Ninety day overlapping HotSpot accumulation maps (accessible from our main web page) create a Degree Heating Weeks (DHWs) Index relating the duration and magnitude of HotSpots to the timing of coral bleaching in the tropical oceans (Toscano et al. 1999). One DHW is equivalent to one week of SSTs one degree warmer than the expected summer-time maximum. DHWs determine the time and degree of accumulated thermal stress that leads to bleaching (although concurrent environmental factors e.g. low winds and direct sunlight may be essential to force bleaching)...."

FY2007 CRCP Project ID 1195; Project Title: Coral Reef Watch - Satellites; Principal Investigator: Mark Eakin