Artificial reefs as a reef restoration strategy in sediment‐affected environments: Insights from long‐term monitoring

Abstract

1. Artificial reefs provide substrates that facilitate the rapid recruitment of marine biota such as corals and fish, and are commonly employed as coral restoration tools to assist recovery in degraded areas. While this strategy is successful in the immediate years post-deployment, its contribution to restoration over longer time scales is less well understood.2. The biological communities on Reef Enhancement Units (REUs), which had been deployed for more than a decade on Singapore's sediment-affected coral reefs, were surveyed.3. The diversity of sessile lifeforms on the REUs was significantly higher in 2014 (H′ = 1.03) than 2004 (H′ = 0.60). Hard corals and coralline algae contributed most to the temporal dissimilarity and turf algae remained the dominant lifeform category in both years. 4. In 2014, hard corals and abiotic components contributed most to the spatial dissimilarity among the six REU plots that were surveyed. Shannon diversity values of these plots ranged from 0.74-1.3. Scleractinian cover ranged from 0.4-31.5% and differed significantly among the plots.5. The REUs also augmented ecosystem functioning at their respective plots. Colonies from 10 of the 30 scleractinian genera recorded were sexually mature, and a total of 119 sessile and mobile reef taxa utilized the REUs for food and habitat.6. The results demonstrate that artificial reefs can contribute to the development of biological communities and ecosystem functioning in degraded coral habitats over the long run, and underscore the need for long-term monitoring to validate the effectiveness of reef restoration efforts.

Coral Reef Restoration in Singapore — Past, Present and Future

“…In total, at least 119 taxa were recorded interacting with the REUs. The findings strongly demonstrated that the REUs complemented habitat rehabilitation efforts in Singapore by helping to improve reef life and restore ecosystem services (Ng et al, 2017).…”

“…The biological communities on these REUs were surveyed again a decade after they had been deployed (Ng et al, 2017). While the sessile communities that colonised the REUs varied across sites, the overall community was more diverse in 2014 (including hard corals, soft corals, seafans, sponges, sea squirts, anemones, hydroids, zoanthids, bryozoans and algae) than in 2004 (mainly coralline and algal turfs).…”

Interactions between coral restoration and fish assemblages: implications for reef management

“…By outplanting corals, managers aim to enhance ecological processes and re-create self-sustaining naturally growing habitats due to the ability of corals to colonise and build complex structures (Edwards, 2010;Edwards & Gomez, 2007). In some instances, other techniques may be used such as the culture and release of coral larvae or juveniles (Chamberland et al, 2017;dela Cruz & Harrison, 2017;Heyward et al, 2002), the transplantation of entire mature coral colonies (Mbije et al, 2013;McLeod et al, 2019b;Schopmeyer & Lirman, 2015) or other organisms such as giant clams (Cabaitan et al, 2008), coral gardening including an intermediate coral nursery phase (Bongiorni et al, 2011;Frias-Torres et al, 2015;Horoszowski-Fridman et al, 2015), algal removal (McClanahan et al, 1999(McClanahan et al, , 2000(McClanahan et al, , 2001 or even the deployment of artificial structures alone to provide a stable substrate for future colonisation (Jayanthi et al, 2020;Ng et al, 2017;Thanner et al, 2006). A description of these coral reef restoration methods can be found in Boström-Einarsson et al (2020), forming the basis for examining the relationship between these techniques and fish assemblages in this review.…”

Artificial Reefs in the North-East Atlantic Area: Present Situation, Knowledge Gaps and Future Perspectives

“…This evaluation must be undertaken and focus on research and monitoring programmes that clearly evaluate the cost-benefits of ARs in relation to the proposed goals [25]. Due to the growing interest in the use of ARs as means for ecosystem restoration and to mitigate increasing anthropogenic influences [38][39][40] it is essential that establishment is fully justified and guidance for management is of critical importance [38,41].…”