Review of ecological engineering techniques in marine environment : exceed practices or habits to improve effectiveness/efficiency.
Case of Indian Ocean coral reefs
Oral presentation, WIOMSA 12th symposium
Tuesday, October 11th 2022, room 6, 12:20 pm
Coral reef in Seychelles @IRD-Lola Massé
Authors
Aurore Léocadie: PhD Student (Geography, Human and social sciences) ; UMR Espace-Dev/University of Réunion Island/ Région Réunion (Presenting author) auroreleocadie@gmail.com
Gilbert David : Geographer of the sea and islands; Research Director at IRD (Institut de Recherche pour le Développement mean Research Institute for Development) gilbert.david@ird.fr
Sylvain Pioch : Geographer of Geography and Spatial Planning ; Research Director at LAGAM – University of Montpellier 3 sylvain.pioch@gmail.com
Mathieu Pinault : Marine Biologist ; PhD in Integrated Systems, Environment and Biodiversity ; Associate researcher at UMR ENTROPIE (Reunion Island) math.pinault@gmail.com
Background
Since the 1990s, ecological engineering has been practiced on many ecosystems with a wide range of approaches. The international journal "Ecological Engineering" saw its impact factor increase considerably between 2006 and 2010, from 1.33 to 2.201, in just five years (in 2022 the impact factor is 4.035), which shows a growing interest in ecological engineering. However, with regard to coral reefs, the effectiveness associated with the use of ecological restoration does not seem to meet the objectives set. It turns out that nowadays, the mechanisms leading to the ecological restoration of coral reefs are not well understood. However, the 7th Plenary of the IPBES or the 6th report of the IPCC reaffirms the need to find solutions in the face of the changes to come "Nature is declining globally at a rate unprecedented in human history - and the rate of "Species extinction is accelerating". Ecological engineering can be one of the assets to limit the damage caused to coral reefs, that’s why we seek to study the effectiveness/efficiency of ecological restoration techniques for coral reefs. How to judge the effectiveness/efficiency of coral reef ecological engineering projects? A comparison of ecological engineering projects carried out in a defined and restricted area (ie the Indian Ocean) would allow a better understanding of all the parameters that govern the ecological restoration of coral reefs.
Thus, in order to take a step back from the projects carried out in the Indian Ocean, we carried out a literature review with an analysis of all the data collected. From scientific literature or gray literature (snowball methodology), 82 documents relating to 62 ecological restoration projects carried out in the Indian Ocean were collected. We are interested here only in the scientific literature (n=41)
We observe that certain techniques are used more than others, coral transplantation and artificial reefs are a booming field, it represents 59% of the projects carried out (compared to 17% for mixed techniques including transplantation; 12%coral gardening ; 10% larval recruitment; for n= 41)
The follow-up of ecological restoration projects (for n= 41) very rarely exceeds 2 years, 71% of the projects carried out have a follow-up of less than or equal to 2 years (respectively 39% < 1 year and 32% between 1 and 2 years feedback).
We observe that 66% of ecological restoration projects for coral reefs are essentially intended and done for and through research, few projects are intended and done for local communities (compared to 12% of projects for restoration; 5% for compensation for the impact of coastal development; 17% for the improvement; for n= 41).However, the success of the techniques is very variable and depends on this monitoring time.
Blue trevally in the Seychelles coral reef @IRD Lola Massé
Conclusion
Although the practice of restoration has been around for decades, the field of ecological reef restoration is relatively new, unlike the terrestrial environment. The results show that we rely on essentially experimental knowledge whose objective is not yet or very little intended for local authorities. In addition, the scientific monitoring of the projects is carried out over periods that are too short (2 years maximum for most projects) which do not take into account the appearance of uncontrolled environmental phenomena beyond this project period of two years (diseases, predation, temperature increase, cyclones, etc.). However, to assess ecological restoration measures, 15 years would be the time period needed.
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