Experimental assessment of coral reef rehabilitation following blast fishing

Illegal fishing with explosives has damaged coral reefs throughout Southeast Asia. In addition to killing fish and other organisms, the blasts shatter coral skeletons, leaving fields of broken rubble that shift in the current, abrading or burying new coral recruits, and thereby slowing or preventing reef recovery. Successful restoration and rehabilitation efforts can contribute to coral reef conservation. We used field experiments to assess the effectiveness of different low-cost methods for coral reef rehabilitation in Komodo National Park (KNP), Indonesia. Our experiments were conducted at three different spatial scales. At a scale of 1 x 1 m plots, we tested three different rehabilitation methods: rock piles, cement slabs, and netting pinned to the rubble. Significantly more corals per square meter grew on rocks, followed by cement, netting, and untreated rubble, although many plots were scattered by strong water current or buried by rubble after 2.5 years. To test the benefits of the most successful treatment, rocks, at more realistic scales, we established 10 x 10 m plots of rock piles at each of our nine sites in 2000. Three years after installation, coverage by hard corals on the rocks continued to increase, although rehabilitation in high current areas remained the most difficult. In 2002 rehabilitation efforts in KNP were increased over 6000 m(2) to test four rock pile designs at each of four rubble field sites. Assuming that there is an adequate larval supply, using rocks for simple, low-budget, large-scale rehabilitation appears to be a viable option for restoring the structural foundation of damaged reefs.