The reef morphology and the changes in coral community at Dreamcenter
Reef morphology
The reef of Dreamcenter site protrudes to outer ocean and is exposed to strong wave action from northerly wind in winter. The reef crest is well developed together with the spur-and-groove structure on the upper reef slope. The reef slope inclines moderately at the upper part, but the slope is steep at the depth between 5m and 15m.
Changes in coral community
Information on the status of coral communities at Dreamcenter site before 1988 is unavailable. It is quite likely that this site also suffered predation of the Crown-of-Thorns Starfish in early 1970s in the same manner as the neighboring reefs.
In 1988, coral cover on the upper reef slope was about 1%, but it increased with depth to about 20% at 10m. Poritid and Faviid corals were the dominant group at the lower reef slope. The recovery of Acropora community on the upper reef slope became remarkable in 1994. Coral cover with tabular and corymbose Acropora colonies at several survey points near Dreamcenter exceeded 50%. Colonies of Poritids and Faviids at 10m depth also increased to have the coverage of 32%. However, in 1998, coral cover decreased down to 10% due to the mass bleaching event causing extensive mortality of corals and it further reduced to 6% in 2003.
On the upper reef slope, coral recovery was very slow in the period between 2006 and 2009 (1.0% to 1.5%), but it rapidly increased to 3.2% in 2010 and reached 4.7% in 2012. A large proportion of the increase in total coral cover between 2006 (4.6%) and 2012 (16.3%) at 10m depth was mainly due to the growth of Poritid colonies.