Morpho-socio-ecological characterisation of shoreline development in Mayotte since 1950.
Supervisor: David Lecchini (U Perpignan)
The shoreline is at the interface of many physical, ecological, and socio-economical issues. The study of shoreline development is therefore crucial to understand these issues, all the more on an island such as Mayotte. Mayotte is a French department and a volcanic island in the Indian Ocean. The analysis of a time series of aerial photographs from 1950 to 2016 revealed that the shoreline urbanisation of Mayotte is still low (6%) compared with the worldwide trend, but has increased rapidly recently (from 3% in 1989 to 6% in 2016) due to the recent strong demographic increase and socio-economic development. The vulnerability, level of anthropogenic pressures, and suitability as nursery of four study sites (representative of beaches with fringing reefs in Mayotte with different levels of urbanisation) were assessed. The vulnerability of Bandrélé is lower than in the other sites, probably due to the presence of the mangrove behind the beach, playing a role of buffer between land and sea. M’tsamboro is the site with the highest anthropogenic pressure, but is also the one displaying the best nursery score on the fore-reef among the four sites (although the difference is not significant), suggesting that urbanisation of the shoreline is not the main factor driving the suitability as a nursery of the fore-reef. Overall, as most of the shoreline is still natural, a sound management advice would be to put in place conservation measures to preserve natural coastal habitats, such as beaches, mangroves, seagrass beds, and coral reefs.