Status of Coral Reefs of the World 2000

Status of Coral Reefs of the Southern Indian Ocean
importance of abiotic forms (57.4%) compared with living corals (28.5%), which were
mostly branching and digitate Acropora (22.3%).
Comparison of 1998 and 1999 monitoring data:
• Nosy Tanikely - coral cover increased on the reef flat from 46.9% in 1998 to
65.8% in 1999; and 56% to 68% on the outer slope. The increase is attributed to
the increased level of protection initiated by tourist organisations;
• Dzamandjar - there was an increase of 5% in coral cover on the outer slope in 1999;
• Foulpointe - similar coral cover between the two years - 33.3% in 1998 and
35.0% in 1999, but an increase in rock and sand from 43.3% in 1998 to 54.3%, in
1999, reflects the increased sedimentation;
• Ifaty – on the reef flat, coral cover was 29% in 1998 and 25.3% in 1999, and rock
and sand covered 63% against 69.6%. The reduction in cover reflects the
continuing deterioration of the reef.
Mauritius
Two permanent monitoring sites were established in 1998: Trou Aux Biches (sheltered
coast) near the major tourism developments and including a public beach; and Bambous
Virieux (exposed coast). The reef flat at Trou Aux Biches is partially degraded by
recreational activities, with coral cover at 2m depth being predominantly branching
Acropora, showed little variation (45% in 1998, 41% in February 1999, 45% in July 1999).
Algal coverage decreased to 10% and 5%, and dead coral cover rose from 15% to 29%.
Fish populations were diverse with 6 major families. On the outer slope at 7-9m depth,
coral cover (Porites dominating) was unchanged at 43% and 42% in February and July 1999
respectively, however, algal cover decreased considerably from 17% to 8% in February
1999, but increased to 10% in July 1999, which are seasonal changes.
The lagoon at Bambous Virieux is 5km wide, with an average depth of 2-3m. There is coral
and sand mining and it is adjacent to an estuary draining a major agricultural area. Coral
cover, predominantly Pavona and Porites, on the reef flat decreased from 56% in 1998 to
54% in March, 1999, and further to 30% in August 1999. Algae cover went from 32% in
1998 to 30% in March 1999, and 56% in August 1999, while dead coral increased from
15% to 29%. The second reef flat site also showed coral cover variations from 54% in 1998
to 48% in March 1999 and to 55% in August 1999, but algal cover showed a consistent
decrease; 24% in 1998, to 17% in March 1999 and 11% in August 1999.
Comparison of 1998 and 1999 monitoring data:
• Trou aux Biches – there was no significant change in living coral cover between
1998 and 1999, however, algal cover was significantly reduced;
• Bambous Virieux - coral cover between July 1998 and July 1999 remained the
same. However, a reduction was observed in March 1999. Algal cover rose in
summer, but dropped back to the 1998 level in winter, indicating seasonal
variations and the impacts of agricultural waste discharges.
81