Eco-designed Mooring Project

 

Location

Deshaies bay, Guadeloupe (France)

 

The challenge

Our challenge was to design a new mooring system that would “kill two birds with one stone” by reducing the impacts, from boat anchors in coral reef and seagrass areas, and to enhance coral colonization and associated fauna. The new mooring system was to integrate an eco-design approach as a Nature Based Solution (NBS) which mimicked coral habitats and their ecological functions using methods of green engineering (Pioch et al. 2018).

 

Actions taken

First, protection actions were taken by prohibiting anchoring in the bay of Deshaies, and then eco-mooring devices were designed and implemented. A total of 40 mooring blocks were designed to attract coral larvae settlement. The blocks mimicked natural roughness, pits and the shape of small caves that could be found in surrounding coral reefs (see below). We also used four types of materials: metal, natural rocks (local basalt), low carbonate concrete (Hayek et al. 2020) and high-density polyethylene (HDPE) for marine aquaculture. As an NBS approach and eco-design construction (Pioch and Léocadie 2017), the size, orientation and aesthetic parameters were considered to enhance the ecosystem integration of this eco-mooring project.

concept ecomooring s pioch

The concept of eco-mooring to maintain safe boating or yachting tourism and effective coral substratum. Photo © S. Pioch

 

How successful has it been?

The six years of ecological monitoring showed a return of normal growth of coral and seagrasses in the bay of Deshaies, after boating anchoring prohibition and installations of the eco-moorings. After six years, 52% of local coral species had settled on the eco-moorings, even though the total surface of the 40 mooring blocks only covered 300 m² in the bay. Altogether, nine species of coral (Agaricia agaricites, Porites astreoides, Porites divaricata, Diploria labyrinthiformis, Pseudodiploria strigosa, Colpophyllia natans, Meandrina meandrites, Siderastrea radians, and Favia fragum) and 43 species of fish were recorded on and around the mooring blocks. In comparison, 17 species of corals and 25 species of fish were recorded in adjacent natural coral areas. Thus, ecological gains were calculated to assess the balance between losses and ecological restoration gains with MERCI-Cor methods (Pioch et al. 2017). This project has offsetted around 400 m² of coral reef ecosystem destroyed by unregulated boating anchoring.
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Mooring system with coral recruitment on a mangrove “skirt”. Photo © C. Bouchon

 

Lessons learned and recommendations

Design: Three different models were tested to assess the capacity of different concrete treatments and surface roughness to attract coral recruits. The “mangroves roots” design was by far the best for coral recruitment.

Storm resistance: The eco-mooring resisted (no destruction, scouring, nor displacement), and most of the settled corals survived the passage of the super hurricane Irma in 2017, and its 17 m high waves.

 

Funding summary

Regional environmental and development agency (SEMSAMAR; 50%), local community (city and county; 30%), European funding (20%). The cost of one eco-mooring was € 4,000 (US$4,320) with an expected durability of more than 50 years.

 

Lead organizations

 

Partners

National Natural Park of Guadeloupe, fishermen, local diver’s shops, diving clubs and French Water Agency.

 

This case study was developed in collaboration with the United Nations Environment Programme (UNEP) and the International Coral Reef Initiative (ICRI) as part of the report Coral Reef Restoration as a Strategy to Improve Ecosystem Services: A Guide to Coral Restoration Methodsopens PDF file .

 

Resources

opens in a new windowPioch, S., Léocadie, A. (2017). Overview on Eco-moorings facilities: Commented bibliography. International Coral. Reef Initiative (ICRI), Foundation for the Research on Biodiversity (FRB) report.opens PDF file

opens in a new windowPioch, S., Relini, G., Souche, J. C., Stive, M. J. F., De Monbrison, D., Nassif, S., Simard, F., Spieler, R., Kilfoyle, K. (2018). Enhancing eco-engineering of coastal infrastructure with eco-design: Moving from mitigation to integration. Ecological engineering, 120, 574-584.

opens in a new windowPioch S., Pinault M., Brathwaite A., Méchin A., Pascal N., (2017). Methodology for Scaling Mitigation and Compensatory Measures in Tropical Marine Ecosystems: MERCI-Cor. IFRECOR handbook, 78 p.

opens in a new windowHayek, M., Salgues, M., Habouzit, F., Bayle, S., Souche, J. C., De Weerdt, K., & Pioch, S. (2020). In vitro and in situ tests to evaluate the bacterial colonization of cementitious materials in the marine environment. Cement and Concrete Composites, 103748

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