Assessing coral bleaching and recovery with a colour reference card in Watamu Marine Park, Kenya
With this study we estimated the changes in colour, bleaching and mortality of coral colonies from February to December 2007, using the colour reference card method. The study was developed in the Watamu Marine Park lagoon (Kenya), bridging the local summer when seawater temperatures were highest and coral bleaching risk was at its maximum. Seven coral genera were selected, and their colour recorded using a colour reference card (Coral Watch card). Seven different scenarios of bleaching and mortality were observed, varying among the coral genera and between two species in the genus Pocillopora. Twenty percent of the colonies bleached, of which 50% died. Only 15% of the coral that did not bleach died. Branching genera had a higher bleaching incidence than massive and sub-massive genera. Pocillopora showed the highest bleaching susceptibility, followed by Acropora, and the highest level of mortality. Of the two species of Pocillopora considered in this study, P. eydouxi showed higher bleaching and mortality levels, while P. verrucosa bleached less and experienced only partial mortality. Our results evidenced different patterns of coral bleaching and mortality which were easily and clearly detected with the colour card method during both bleaching and a post-bleaching events.
KeywordsCoral bleaching Reference card Pocillopora Watamu Marine Park
We are thankful to CORDIO (Coastal Oceans Research and Development in the Indian Ocean) and Kenya Wildlife Service (KWS) for the scientific support. We are grateful to Ms. Ellen Bermann for hospitality and for technical support. Finally we express our gratitude to Francesca Benzoni for her support and help throughout the study.
- Clarke, K. R. & R. N. Gorley, 2001. PRIMER v5 user manual/tutorial. PRIMER-E Ltd., Plymouth.Google Scholar
- Hoegh-Guldberg, O. & G. J. Smith, 1989. The effect of sudden changes in temperature, irradiance and salinity on the population density and export of zooxanthellae from the reef corals Stylophora pistillata (Esper 1797) and Seriatopora hystrix (Dana 1846). Experimental Marine Biology and Ecology 129: 279–303.CrossRefGoogle Scholar
- Hughes, T. P., A. H. Baird, D. R. Bellwood, M. Card, S. R. Connoly, C. Folke, R. Grosberg, O. Hoegh-Guldberg, J. B. C. Jackson, J. Kleypas, J. M. Lough, P. Marshall, M. Nystrom, S. R. Palumbi, J. M. Pandolfi, B. Rosen & J. Roughgarden, 2003. Climate Change, human impacts, and the resilience of coral reefs. Science 301: 929–933.CrossRefPubMedGoogle Scholar
- Obura, D., 1995. Environmental stress and life history strategies, a case study of corals and river sediment from Malindi, Kenya. PhD thesis, University of Miami, Miami, FL.Google Scholar
- Obura, D., 2001. Can differential bleaching and mortality among coral species offer useful indicators for assessment and management of reefs under stress? Bulletin of Marine Science 6: 421–442.Google Scholar
- Obura, D., 2005a. Resilience and climate change: lessons from coral reefs and bleaching in the Western Indian Ocean. Estuarine, Coastal and Shelf Science 63(3): 353–72Google Scholar
- Obura, D., 2005b. Kenya, coral reef resilience studies. In Souter, D., O. Linden, D. Wilhemsson, D. Obura & D (eds), Coral Reef Degradation in the Indian Ocean. Status Reports 2005. CORDIO/SAREC Marine Science Program, Stockholm: 25–31.Google Scholar
- Obura, D., 2009b. Bleaching as a life history trait in coral-zooxanthellae holobionts—relevance to acclimatization and adaptation. In Proceedings of the 11th International Coral Reef Symposium, Ft. Lauderdale, FL, 7–11 July 2008.Google Scholar