ƒThe reef morphology and the changes in coral community at Beach-Aquarium„

Reef morphology

The reef of Beach-Aquarium site is semi-sheltered from seasonal northerly wind. As seen on the aerial photograph, strong tidal current occasionally goes out through the reef flat. Therefore the reef structure resembles that of the back reef, which lacks distinctive reef crest and spur-groove system. The reef slope on shelf-like rocks is gentle down to the depth of 5m, but it becomes steep in the deeper part. The bottom substrate of the lower reef slope is comprised of boulders and coral rubble.


Changes in coral community

Information on the status of coral communities at Beach-Aquarium 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 West Bise.
According to the results of the first line survey conducted in 1988, coral cover throughout the reef profile between 0-15m ranged between 1% and 16%. Coral community were mostly dominated by Poritid and Faviid corals. In 1994, coral cover at the upper reef slope increased to 15-30% due to the recovery of Acropora communities. Coral cover at the lower reef slope also increased to about 25% with branching Porites communities. These results concur with the data obtained by Environment Agency's coral reef survey. However, the 1998 bleaching event caused extensive coral mortality on the neighboring reefs as well as Beach-Aquarium site. Coral cover decreased down to the range between 0.3% and 8.6% soon after the bleaching event. It was even more lowered to the average of 2% in 2003 and remained at the same level until 2006 (1.0% at 3m and 1.7% at 10m). Coral community mainly comprised of Poritids and Faviids has recovered since 2008. In 2012, coral cover at 3m and 10m was 3.8% and 8.3%, respectively.