Many reef areas around the world have been subjected to damage from dragging boat anchors and fishing nets. Physical damage to the reef breaks the coral skeletons and forms broken rubble fields. These rubble areas host very little life and erode neighbouring areas of reef with their mobile substrate. The rubble “killing fields” expand with little chance of recovery.

A coral restoration site needs to first have the rubble stabilized before coral can be transplanted to the area. Without a stable substrate to grow upon, young corals will smother and die. So the basic steps of active reef restoration are:

Structural stabilization of the rubble substrate
Transplant a selection of suitable coral species
Encourage other species of a reef ecosystem to inhabit the area

Blue Corner Marine Research has conducted experiments to determine different methods for stabilizing rubble. At the coral restoration project in Nusa Penida we have used the following methods:

Metal wire mesh: Mesh is rolled across the seafloor to stop rubble from moving and eroding. The mesh allows rubble to become trapped long enough for sponge, soft corals, and coralline algae to bind the rubble together. This method of biostabilization can be effective in areas of reef slope.

Rebar frames: Modular frames are placed across the rubble field to reduce the amount of rubble movement. Rubble is slowly trapped against the frames and then becomes colonized with reef organisms.

Coral Ropes: between frames young corals are grown on ropes a short distance off the seafloor. As these corals grow bigger they increase the coverage of living coral and create terraces to increase reef topography.

To learn more about coral restoration methods read our project summary of the Nusa Penida coral restoration project. Or join one of our training programs: