[PROJECT] REBIOMA-3D: pilot study for the improvement of Mayotte reef biodiversity management
Créocéan
3D structure of Reefs, pilot study for the improvement of Mayotte reef biodiversity
Coral reefs represent emblematic ecosystems in terms of local natural heritage in the Indian Ocean.
However, according to UNESCO, 50% of coral reefs could disappear by 2030 due to natural factors and increasinganthropogenic pressures (coastal development, pollution, global warming, etc.). In addition to their key role for biodiversity, they provide numerous ecosystem services to more than 500 million people around the world (tourism, fishing, coastal protection in particular).
The structural complexity of coral reefs, along with other three-dimensional characteristics (refuge capacity, fractal dimension, slope), are fundamental aspects of the functioning of a reef. Despite their importance, few monitoring programs take these descriptors into account to determine the health of reefs.
Underwater photogrammetry allows the creation of 3D reef models at different spatial scales, ranging from colony to coral landscapes. 3D reconstruction by photogrammetry also allows precise temporal monitoring of coral communities. In addition to the calculation of the indicators traditionally used (percentages of coverage, diversity, etc.), photogrammetry makes it possible to define new descriptors of the 3D physical characteristics of the reef such as structural complexity, the volume of coral colonies, the capacity of refuge or the roughness.
Mayotte's Most Accurate Reef Monitoring Program (GCRMN) uses standard descriptors, but does not take into account their three-dimensional nature. The application of underwater photogrammetry and the calculation of 3D descriptors will thus make it possible to complete the assessment of the state of health of the reefs. Thanks to the high
precision of models and 3D analysis, this technique is the most suitable for quantifying the possible impacts on the structure of reefs.
It is therefore relevant for monitoring reefs at risk of being disturbed by coastal development projects or tourist activities.
REBIOMA-3D offers, thanks to a pilot study of underwater photogrammetry, a physical and morphobiological analysis of 6 study sites in Mayotte:
3 sites located in the reserve area, 3 sites subject to possible impacts linked to urban development.
The objective is to achieve a "zero state" and to highlight any degradation linked to human activities, as well as to recommend management measures adapted to preserve the biodiversity of these reefs.
The specific objectives of the project are as follows:
Objective 1: Apply the technique of underwater photogrammetry on the coral reefs of Mayotte to study their 3D characteristics and calculate new habitat descriptors,
Objective 2: Identify the anthropogenic impacts on the reef structure (physical destruction, loss of structural complexity, macro-waste),
Objective 3: Propose conservation measures and recommend management measures, in consultation with managers,
Objective 4: Make the local population aware of the importance of preserving coral reefs.
Finally, the project will establish a future time monitoring.