Abstract
In the 1970s, the scientific community began to highlight the collapse of biodiversity, across all living groups, on a global scale. Research carried out since then has revealed an increasingly worrying situation. As a result, the need for biodiversity governance has emerged on the international stage. The objectives of the major international organisations and conventions (IPBES, IUCN, CBD, COP, etc.) have focused on the importance of preserving and conserving ecosystems in the face of the ecological emergency. Over the last ten years, coral reefs have suffered a progressive loss of their global coverage, with significant historical losses and a rapid decline. Their functional equilibrium has been reached, making it increasingly difficult for them to remain resilient. The development of sustainable, cost-effective and innovative solutions is at the centre of discussions aimed at achieving the sustainability of this ecosystem. Sustainability is linked to the interdependence between the ecosystem and the accompanying socio-system. For this reason, one of the key measures of the COP15-Biodiversity Summit in December 2022 focuses on the restoration of degraded natural environments.One of its objectives is to successfully restore habitats and ecosystem functionalities through human actions that combine scientific knowledge, local knowledge and technical expertise. However, the restoration of coral reefs does not always live up to these objectives.Focusing on so-called active ecological repair techniques, we are interested in the question of this effectiveness. We formulate the following hypotheses: (1) Assessment of the effectiveness of ecological repair takes little account of the social dimension, (2) The social effectiveness of ecological repair projects depends first and foremost on their social acceptance, which is the result of the perceptions and representations that stakeholders have of the ecosystem to be repaired, the uses they make of this ecosystem and the repair project, (3) this social effectiveness can be summarised in a few indicators that can be included in a dashboard of ecological repair management indicators, (4) this dashboard has a dual function: on the one hand, to estimate the capacity of the players, the physico-chemical environment, and the materials and know-how used to generate an effective ecological repair project, and on the other hand, to monitor the sustainability of this effectiveness.Our problematic of resarch is: how can the effectiveness of this ecological repair be improved by taking better account of its social dimensions? We take a multidisciplinary approach to this question, understanding coral reefs as a socio-ecosystem and addressing the socio-ecological dimension of this ecosystem. We mobilise several postulates around reef ecological engineering, social acceptance and governance.We analysed the effectiveness of 62 reef ecological engineering projects from 13 different territories in the Indian Ocean basin. The aim of this analysis was to deduce the various components of this effectiveness. At the same time, we identified project effectiveness criteria and highlighted the lack of consideration given to the social dimension of ecological engineering projects. This dimension was studied through the perceptions and representations of 247 stakeholders on the islands of Réunion and Mayotte. Finally, ecological and sociological indicators of reef ecological engineering were developed and applied.