Reef degradation following mass coral bleaching in Kenya

Summary form only. Elevated seawater temperature in March and April 1998 caused by the El Nino Southern Oscillation (ENSO) caused mass coral bleaching along the Kenya coast. ENSO event had an effect on the climate of Kenya coast and the Western Indian Ocean region in general, with heavy rains starting in October 1997, and continuing to July 1998. Seawater temperatures in March and April rose to an average 1.5°C above values measured in the same period in 1997, with daytime low-tide highs of over 32°C. Coral bleaching is the whitening of corals resulting from the loss of symbiotic zooxanthellae and/or reduction of photosynthetic pigment concentrations in the zooxanthellae. Bleaching was first observed in Kanamai in October 1997 during and after the El Nino rains, most likely due to sedimentation and seawater dilution in the shallow lagoon. In November bleaching was observed in Malindi Marine Park caused by sediment discharge from the Sabaki River. Later, extensive temperature induced bleaching and subsequent coral mortality was observed in mid March 1998 covering the entire coast of Kenya. Over 90% bleaching and mortality was recorded in Mombasa Marine Park, Malind Marine Park and Kanamai