Dynamite or blast fishing, in which homemade bombs are illegally detonated over coral reefs, threatens many reef ecosystems in Southeast Asia. This research investigated several ecological factors that affect hard coral (Coelenterata: Scleractinia) recovery after disturbance by blast fishing in Komodo National Park (KNP) and Bunaken National Park (BNP), Indonesia. To assess long-term impacts of blast fishing and improve management decisions about protection of intact reefs and potential restoration of damaged areas, it is necessary to investigate coral recovery.

Recovery from acute and chronic blasting was examined in craters of known age caused by single bombs and in rubble fields generated by persistent blasting. No significant natural coral recovery occurred over three years as measured by coral recruitment or colony size. High current was correlated with increased rubble movement, which was shown to be detrimental to the survival of small corals.

Successful recruitment and survival of juvenile corals are prerequisites of either natural recovery or human-assisted rehabilitation. Early scleractinian coral recruitment to settlement tiles was assessed in paired blasted and unblasted sites in KNP from 1998 to 2000. While significant spatial and temporal variation existed across sites and seasons, no significant difference in recruitment was found between blasted and unblasted sites, suggesting that blasted sites are not recruitment limited. Therefore, failure of hard corals to recover in rubble fields is due to post-settlement mortality, either from shifting rubble damaging new recruits or from competition with soft corals. While soft corals clearly had negative impacts on hard corals, the possibility that they also enhance later survival through substrate stabilization cannot be discounted.

Because natural recovery was low or nonexistent, reef rehabilitation was investigated. Three low-cost, locally available methods to stabilize rubble and recreate a structural foundation were tested in KNP. Significantly greater scleractinian recruitment occurred on the rock and cement experimental treatments compared to netting or untreated rubble; nevertheless most plots broke apart or were buried after 2.5 years. To address these problems, larger-scale rock piles were installed. Two years post-installation, coverage by hard corals on the rocks continues to increase; this method is potentially a pragmatic large-scale rehabilitation technique.

Helen E. Fox, helenfox@alum.swarthmore.edu (permanent email address)