BIOLOGIYA MORYA, 2014, Vol. 40, No. 4, pp. 293-301 |
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The influence of repetetive thermal stresses on the dominance of reef-building Acropora spp. (Scleractinia) on coral reefs of the Maldive Islands Samara State Academy of Social Sciences and Humanities, Samara 443080 E-mail: The distribution and size-age structure of Acropora corals were studied in two Maldivian atolls that differ in their geographic position and sea surface temperature regimes. The frequency and strength of thermal anomalies for the last two decades had a significant influence on the abundance, mortality rates, and age structure of acroporid communities. The long-term temperature amplitude was higher and the maxima were more pronounced in the northernmost Ihavandippolu Atoll than those in the equatorial South Huvadhoo Atoll. These differences resulted in a 10.4% mean cover of Acropora in Ihavandippolu Atoll, whereas the Acropora cover in the South Huvadhoo Atoll reached 59.5%. In the northern atoll, the coral mortality rate after a 2010 thermal anomaly was 3 times that in the southern atoll. Younger acroporid colonies (up to 2 years old) dominated the northern atoll reefs, while the southern atoll showed a high proportion of older mature colonies. In both atolls, healthy table colonies of Acropora cytherea with a disk diameter > 2 m were observed that apparently survived three thermal anomalies since 1998. The mechanisms of acclimatization of Acropora and the prospects for their dominance in the Maldives under changing environmental conditions are discussed. Key words: thermal stress, coral bleaching, Acropora, Maldives. |
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