Community-based, low-tech method of restoring a lost thicket of Acropora corals

Abstract

Abstract Due to unregulated blast fishing and episodic bleaching events, the back-reef zone near Barangay Lucero in Bolinao, Pangasinan, Philippines, was reduced to a barren area of unconsolidated sand and coral rubble. Anecdotal accounts from local inhabitants, scientific reports, and examination of rubble on the substratum revealed that the area had been dominated by staghorn Acropora corals prior to degradation. With no significant signs of natural recovery, a low-tech restoration method that is both transferable to the community and cost-effective was devised and implemented. Through the help of local inhabitants, 450 fragments of two staghorn coral species (Acropora intermedia and A. pulchra) were transplanted, without using SCUBA equipment, in a total of six 4 × 4 m plots. There were two transplant density treatments: low and high, receiving 25 and 50 fragments of each coral species, respectively. Survivorship and growth of transplants, as well as the assemblage of fishes and macroinvertebrates inside the transplantation and control plots, were monitored periodically for up to 19 months. Transplant survivorship was generally high (68–89%) at the end of the study. There was also an average of a 15-fold increase in ecological volume of the transplants (from 1784.25 ± 162.75 to 26 540.765 ± 4547.25 cm3). Consequently, a significantly higher number of fish and of macroinvertebrates was recorded inside the transplantation plots than in the control plots, indicating signs of restoration success with the reintroduction of the two coral species. Exhibiting significant differences in coral cover, fish biomass and abundance, high-density is more cost-effective than low-density treatment, attaining optimal effects on key reef recovery parameters. The total cost of restoring a thicket of Acropora in a sandy-rubble field using this low-tech rehabilitation method with community participation was estimated to be US$9198.40 ha−1 (US$0.90 m−2), and thus ∼60% cheaper than without community involvement. Community involvement not only reduced the cost of the restoration activity but also provided the community with a sense of ownership and responsibility for their resources, thus ensuring the long-term success of the intervention.