ATOLL RESEARCH BULLETIN NO. 335 THE WORLDWDE CORAL REEF BLEACHING CYCLE AND RELATED SOURCES OF CORAL MORTALITY BY ERNEST H. WILLIAMS, JR AND LUCY BUNKLEY-WILLIAMS ISSUED BY NATIONAL MUSEUM OF NATURAL HISTORY SMITHSONIAN INSTITUTION WASHINGTON, D.C, USA. January 1990 TABLE OF CONTENTS ABSTRACT ........................................................................................................................................................1 INTRODUCTION ...........................................................................................................................................1 MATERIALS AND METHODS ..................................................................................................................2 DEFINITION OF TERMS ............................................................................................................................2 DESCRIPTION OF THE 1987-88 EVENTS BEGINNING OF THE EVENT ..........................................................................................................4 HOSTS AND NON-PHOTOSYMBIOTIC ANIMALS BLEACHED .......................................... 9 SMALL SCALE FEATURES ...............................................................................................................12 ' LARGE SCALE FEATURES ...............................................................................................................14 MORTALITIES ........................................................................................................................................21 RECOVERY .............................................................................................................................................25 VARIATION AND COMPARISONS .................................................................................................26 PREVIOUSLY UNREPORTED BLEACHING EVENTS AND COMPARISON TO KNOWN REPORTS 1969 ..............................................................................................................................................................27 1979-80 ........................................................................................................................................................27 1981 ..............................................................................................................................................................28 1983 .............................................................................................................................................................. 28 1986 .............................................................................................................................................................. 28 UNKNOWN RECENT DATES ........................................................................................................... 29 POTENTIAL CAUSES OF THE 1987-88 EVENTS DISEASE .................................................................................................................................................... 29 LIGHT EFFECTS .................................................................................................................................... 30 LOW TIDES .............................................................................................................................................. 31 DOLDRUMS ............................................................................................................................................ 31 HYPERSALINE WATER ...................................................................................................................... 32 TURBID WATER ................................................................................................................................... 32 EL NI~~OSOUTHERN OSCILLATION ........................................................................................... 32 DETERIORATION ................................................................................................................................. 33 TEMPERATURE ....................................................................................................................................33 MISCELLANEOUS ................................................................................................................................. 36 COMPOUNDING DISTURBANCES (1) BLACK LONGSPINED SEA URCHIN MASS MORTALITY .............................. 37 (2) WHITE BAND DISEASE EPIZOOTOICS ................................................................. 37 (3) BLACK BAND DISEASE OUTBREAKS ................................................................... 38 (4) OTHER DISEASES OF HOSTS ................................................................................... 38 (5) CROWN OF THORNS OUTBREAKS ........................................................................ 38 (6) OTHER CORALLIVORE/BIOERODER OUTBREAKS ...................................... 39 (7) RED TIDES ........................................................................................................................ 39 CONCLUSIONS WORLD-WIDE BLEACHING EVENTS .......................................................................................... 40 CAUSE OF THE 1986-88 EVENTS .................................................................................................. 40 CAUSE OF THE 1982-83 EVENTS .............................................................................................. 41 THE 1991 OR 1992 CORAL REEF BLEACHING EVENTS ..................................................... 41 PRECEDING AND FOLLOWING EVENTS .................................................................................... 42 CARIBBEAN BLEACHING PA'lTERNS IN 1987 ......................................................................... 42 WHY WORSE IN 1987 THAN 1983? ................................................................................................ 42 EASTERN PACIFIC 1983 AND 1987 COMPARISON .................................................................. 42 INDO-PACIFIC BLEACHING ............................................................................................................. 43 FUTURE CORAL REEF BLEACHING .......................................................................................... 43 CONSEQUENCES .................................................................................................................................. 43 RELATED MAJOR MARINE ECOLOGICAL DISTURBANCES ........................................ 44 ALERT AND COMMUNICATION CENTER AND NETWORKS ........................................ 50 ACKNOWLEDGMENTS ............................................................................................................................... 52 LITERATURE CITED .................................................................................................................................. 52 PERSONAL COMMUNICATIONS LIST ................................................................................................. 62 APPENDICES: QUESTIONNAIRE ........................................................................................................ 64 CLASSIFICATION OF ORGAINSMS ...................................................................... 67 THE WORLD-WIDE CORAL REEF BLEACHING CYCLE AND RELATED SOURCES OF CORAL MORTALITY BY ERNEST H. WILLIAMS, JR AND LUCY BUNKLEY-WILLIAMS* ABSTRACT World-wide "coral reef bleaching complexes" occurred in 1979-80, 1982-83 and 1986-88. Each included a "preceding event" 1 year (1979, 1982, 1986) before the most extensive ("main event") bleaching began. The 1986-88 complex also possessed a "following event" (1988). A number of minor bouts also occurred during each complex. Preceding events may be used to predict main bleaching events. We believe the world-wide coral reef bleaching complex "cycle" is caused by increased global temperatures of the 1980's. The progressive deterioration of inshore regions, including coral reefs, may have contributed to the intensity of the events. El Niiio southern oscillation (ENSO) events of 1982-83 and 1986-88, on top of these problems, increased overall seawater temperatures, or provided conditions favoring increased inshore temperatures, to the levels necessary to bleach and kill coral reef photosymbiotic hosts. Decreased temperatures also caused minor bouts in 1988, 1989 and possibly other times. Deterioration of coral reefs has also lowered photosymbiotic hosts' resilience, or resistence to the bleaching process. Our model explaining coral reef bleaching employs increased global temperatures, increasing deterioration of reefs, and ENS0 events. These conditions are not only well established, but seem almost certain to continue. The cycle may repeat in 1991 or 1992, possibly with more intensity, and will probably continue and increase until coral dominated reefs no longer exist. INTRODUCTION Coral reef bleaching has recently attracted considerable interest when spectacular and sudden bleaching occurred in 1987. This event led to a U. S. Senate Hearing (Hollings, 1988); Special Bleaching Sessions during scientific meetings in Mayaguez, Puerto Rico (November 1987), Curacao (November 1987), Sarasota, Florida (May 1988), Florida Keys (June 1988), San Salvador, Bahamas (June 1988), Townsville, Australia (August 1988), La Parguera, Puerto Rico (May 1989), and Havana, Cuba (June 1990); and a recent special volume by Brown (1989). In this paper, we describe the bleaching events of 1987-1988,