KOH TAO, THAILAND ⁹

In the end of September 2008, more than 100 volunteers of local dive schools and the community gathered to build 4 large metal domes which form the cathode of the Biorock.

PROJECT OBJECTIVE ¹⁰

The aim of this project is to compare growth rates of corals growing at the Biorock to that of corals at other (natural and artificial) reef areas around Koh Tao.

STUDY SITES ¹¹

SPECIFICATIONS ¹²

No. of domes: 4

Dimension /dome: H:4m Dia:6m

The domes are shaped into a square with about 12m space in-between, 250 meters from shore and with an average depth of 13m.

They have arch on the side and a gap at the top so divers can swim through the domes.

A power converter is placed in the middle of the domes converting alternating current delivered by a cable from shore to direct current supplied to the domes.

A smaller dome is placed close to the Biorock structure but is not connected to the power device and serves as a control dome

METHOD ¹³

  • When coral fragments are transplanted to a coral nursery, artificial reef or natural reef, some of these fragments will be marked. The marked coral fragments were monitored in time to get an indication of the state of all fragments growing in that area. It is important to mark specific fragments because when the fragment grows, the size, shape, colour and also environment of the fragment will change, which all make it hard to remember which fragment was being monitored.

  • Marking was carried out by numbering the nursery table the fragment is growing on or by attaching a PVC tag next to the coral colony.

  • From all the data collected by the ecological monitoring station, one growth form which had a sufficient amount of photos was selected. Coral colonies of Coryombose growth form (Acroporidae and Pocciliporidae coral families) were analysed.

GROWTH RATE ANALYSIS ¹⁴

In order to gain insight of the success of Biorock and other reef rehabilitation projects around Koh Tao, an ecological monitoring station has been taking transect photos for over 4 years. These photos can be used to assess growth and health of these corals.

Change in percentage coral cover on Koh Tao reefs based on data from only the 6 sites with most regular surveys between 2006-2014. Open circles denote no data for that site/year, broken lines have been extrapolated over missing years.

RESULTS ¹⁵

With the implementation of Biorock Technology, it was found that by 2014 the reefs reached their highest coverage level at 39.1% based on the 6 sites as in 2006.

As of 2014, 10 of the 11 reefs for which adequate data were available were in ‘fair’ condition, with one reef being in ‘good’ condition (Hin Wong, 69.1%).