Perforated trapezoidal artificial reefs can augment the benefits of restoration of an island and its marine ecosystem

Abstract

The Gulf of Mannar (GoM) is located along the southeast coast of India. It has a chain of 21 low‐lying uninhabited islands extending from Rameswaram to Tuticorin. These islands are endowed with coral reefs, beds of seagrasses, and other associated marine life. Growing human population has led to accelerated coral mining and destructive fishing practices and this has brought about changes in the bio‐geomorphology of the islands, altered the hydrodynamic conditions, and resulted in severe erosion of the islands. The area of Vaan Island had decreased from 20.8 ha in 1969 to 2.33 ha in 2015. While hard measures have proven successful in preventing erosion, ecosystem‐based measures taking into account the resilience of the flora and fauna yield greater and more natural benefits. A total of 10,600 perforated trapezoidal artificial reef (AR) modules were deployed in clusters along two rows on the windward side of Vaan Island. ARs of 1 and 2 m height were placed respectively along contours of 2 and 3 m depth. The shape and arrangement of the ARs dissipated wave energy through the shoaling effect. As a result, a spit appeared and the area increased to 3.15 ha. The ARs also support epibenthic communities, benthic macrofauna, corals, and fishes. The deployment of an ecosystem‐based multipurpose perforated trapezoidal AR model has been successful not only in restoring the sinking island but also in enhancing the species richness, and it can be adopted as a tool in the restoration of islands and their marine ecosystems.

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.…”

Opportunistic spongivore fishes in a reef of Gulf of Mannar, India

“…Exploitation of spongivore fishes would allow space competing sponges to flourish which in turn would affect corals and would ultimately affect the dependant livelihood. Many initiatives have been taken in GoM to mitigate the impacts of climate change such as coral rehabilitation and artificial reef deployment (Edward et al 2006;Raj et al 2015bRaj et al , 2020Jayanthi et al 2019;Mathews et al 2021). Protection of spongivore fishes from 1 3 overexploitation becomes one of the important management actions in GoM.…”

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].…”