coral bleaching

Doug Fenner d.fenner at
Thu Jul 2 18:27:01 EDT 1998

                                                               NOAA 98-
     CONTACT:   Patricia Viets, NOAA             FOR IMMEDIATE RELEASE
        (301) 457-5005                          xxxxxxx

     1998 Coral Reef Bleaching in Indian Ocean Unprecedented, 
     NOAA Announces

        An episode of extremely high ocean temperatures migrated from south 
     north throughout the Indian Ocean during the first six months of 1998 
     causing considerable coral reef bleaching in its wake, the National 
     and Atmospheric Administration reports.   

        Sea surface temperatures, exceeding the maximum values expected for 
     any time during the year, were observed by NOAA's satellites to have 
     exceeded levels critical to cause beaching where these waters overlay 
     Indian Ocean coral reefs. 

        A somewhat similar episode occurred following the 1987 El Nino in 
     Indian Ocean; however, in 1988 the extreme sea surface temperature 
     anomalies, toxic to corals, moderated sufficiently as the sun moved 
     the Northern Hemisphere.  In that year, reefs in the Indian Ocean 
     north of 
     the equator were spared heavy bleaching.  

        In 1998, this has not been the case.  Bleaching, earlier projected 
     NOAA, has been reported from the field on the following reefs: 
     Kenya; Reunion; Mauritius; Somalia; Madagascar; Maldives; Indonesia; 
     Lanka; Gulf of Thailand [Siam]; Andaman Islands; Malaysia; Oman; 
     India; and 

        This unprecedented round of bleaching in coral reefs throughout the 
     Indian Ocean follows El Nino-related bleaching events during late-1997 
     early-1998 both projected by NOAA's satellite HotSpot charts and 
     by reef scientists in Mexico (Pacific), Panama (Pacific); Galapagos; 
     Australia's Great Barrier Reef; Papua New Guinea; and American Samoa.

        In the Indian Ocean, sea surface temperature anomalies appear to be 
     coming less severe toward the end of June.  The total area covered by 
     "HotSpots" is now only in the northernmost fringes of the Indian 
     However, during June the Philippines and the Florida Keys regions have 
     seeing temperature anomalies sufficiently high that bleaching has been 
     reported and biologists are concerned for reefs there.  

        Coral reefs -- the "rainforests of the oceans" -- support a variety 
     sea life and provide resources of significant economic importance such 
     fishing and recreation.  Coral bleaching, induced by high water 
     temperatures, has raised concerns about these fragile ecosystems.  
     bleaching occurs as coral tissue expels zooxanthellae, a type of algae 
     resides in the structure of the coral, and is essential to the coral's 
     survival.  Corals normally recover, unless high ocean temperatures 
     for too long a period or become too warm.

        Coral Reef "HotSpots"  depicted as regions of yellow/orange in the 
     NOAA/NESDIS charts 
     those anomalies that are equal to or above the annual maximum sea 
     temperatures by +1 deg C or more.

        HotSpot animations are available at the Oceanic Research & 
     Applications Division's  WebSite:


(please send any replies to addresses found in these web sites, not the
forwarder of this message, as I have no further information on this.)
Douglas Fenner, Ph.D.
Coral Taxonomist
Australian Institute of Marine Science
PMB No 3
Townsville MC
Queensland 4810
phone 07 4753 4241
e-mail: d.fenner at

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