Large‐scale coral reef rehabilitation after blast fishing in Indonesia

Abstract

The severely degraded condition of many coral reefs worldwide calls for active interventions to rehabilitate their physical and biological structure and function, in addition to effective management of fisheries and no-take reserves. Rehabilitation efforts to stabilize reef substratum sufficiently to support coral growth have been limited in size. We documented a large coral reef rehabilitation in Indonesia aiming to restore ecosystem functions by increasing live coral cover on a reef severely damaged by blast fishing and coral mining. The project deployed small, modular, open structures to stabilize rubble and to support transplanted coral fragments. Between 2013 to 2015, approximately 11,000 structures covering 7,000 m 2 were deployed over 2 ha of a reef at a cost of US$174,000. Live coral cover on the structures increased from less than 10% initially to greater than 60% depending on depth, deployment date and location, and disturbances. The mean live coral cover in the rehabilitation area in October 2017 was higher than reported for reefs in many other areas in the Coral Triangle, including marine protected areas, but lower than in the no-take reference reef. At least 42 coral species were observed growing on the structures. Surprisingly, during the massive coral bleaching in other regions during the 2014-2016 El Niño-Southern Oscillation event, bleaching in the rehabilitation area was less than 5% cover despite warm water (≥30 ∘ C). This project demonstrates that coral rehabilitation is achievable over large scales where coral reefs have been severely damaged and are under continuous anthropogenic disturbances in warming waters.

Coralclip®: a low‐cost solution for rapid and targeted out‐planting of coral at scale

“…S1). As such, use of Coralclip® in combination with other out‐planting techniques, such as tetrapods (Chamberland et al ), microfragmentation (Page et al ) and on structures that consolidate substrates (Williams et al ), would also provide a means to further improve their respective viability, cost‐effectiveness, and hence scalability. However, clearly how Coralclip® performs relative to (or in combination with) other attachment methods, notably commonly used chemical adhesives, warrants further detailed assessment.…”

“…Levy et al ; Kotb ; Suggett et al ) and larval rearing‐based (e.g. Guest et al ; Chamberland et al ) propagation, coupled with substrate stabilization structures (Williams et al ). Whilst these various practices continue to show improvements in “building biomass” (Boström‐Einarsson et al ; Williams et al ), the rate and effectiveness of out‐planting (re‐attaching) corals and larval settlement devices onto the reef often serves as the main bottleneck limiting scalability and hence economic viability (Ferse ; Chamberland et al ; Boström‐Einarsson et al ).…”

Rebuilding coral reefs: success (and failure) 16 years after low‐cost, low‐tech restoration

“…This rate of recovery is similar to other measured coral recovery rates under both active restoration and natural recovery. In a similar restoration project in Indonesia that combined coral transplantation with substrate stabilization, coral recovered from about 30–70% over 3 years following blast fishing (Williams et al ). Elsewhere in Indonesia, natural recovery in single blast craters was about 5% annually over 5 years (Fox & Caldwell ).…”

“…At minimum, providing stable substrate allows for recruitment where there is sufficient larval supply. Where this is not the case, an even more active (and often more expensive) approach includes coral transplantation that may hasten coral growth (Williams et al ). Like these authors, we predicted, and our findings support, their conclusion that a simple structure providing stable substrate can successfully restore a coral reef.…”

Testing Industrial-Scale Coral Restoration Techniques: Harvesting and Culturing Wild Coral-Spawn Slicks

“…It remains unclear whether the current application of traditional coral restoration approaches can be operationalized to achieve effective ecosystem-scale restoration. Recent successes on coral reefs destroyed from dynamite fishing have shown the effective transplantation of fragments onto stable substrata made from steel rods to restore approximately 7,000 m 2 (Williams et al, 2019), and increases from 0 to 44% coral cover over 16 years when stable substrata from quarried rocks was provided in rubble fields in an area of reef with abundant larval supply from nearby reefs (Fox et al, 2019). Yet such 'gardening' or substrate stabilization approaches aren't viable options when donor colonies or natural larval supply are limited.…”