RESPONSE OF REEF CORAL COMMUNITIES TO SEA-LEVEL RISE - A HOLOCENE MODEL FROM MAURITIUS (WESTERN INDIAN-OCEAN)

The hinging reef at Pointe-au-Sable (Mauritius, Indian Ocean) was used to examine the effects of Holocene sea-level rise on coral growth. Th is reef is about 1000 m wide and comprises a forereef slope (30 m maxi mum depth), a narrow reef crest and a very shallow backreef (1.5 m max imum depth). Four major coral communities were recognized, which devel oped within relatively narrow depth ranges: a Pachyseris/Oulophyllia c ommunity (deeper than 20 m), an Acropora 'tabulate'/Faviid community ( 20-6 m); a robust branching Acropora community (less than 6 m) and a P avona community (less than 10 m). Three high-recovery cores show the H olocene reef sequence is a maximum of 19.3 m thick and comprises four coral biofacies which are similar to counterparts identified in modern communities: robust branching, tabular-branching, robust branching-do mal and foliaceous coral facies. A minimum sea-level curve for the pas t 7500 years was constructed. Using distribution patterns of coral bio facies and radiocarbon dates from corals, reconstruction of reef growt h history indicates that both offshore and onshore reef zones were dev eloping coevally, aggrading at rates of 4.3 mm year(-1) from 6900 year s B.P. The reef caught up with sea-level only after sea-level stabiliz ed. Changes in coral community and reef growth rates were driven princ ipally by increasing water agitation due to the decrease in accommodat ion space. Based on the composition of the successive coral assemblage s, the reef appears to have grown through successive equilibrium stage s.