Characterisation of long-term evolution (1950–2016) and vulnerability of Mayotte’s shoreline using aerial photographs and a multidisciplinary vulnerability index
2022
Courteille, Marine | Jeanson, Matthieu | Collin, Antoine | James, Dorothée | Claverie, Thomas | Charpentier, Michel | Gairin, Emma | Trouillefou, Malika | Giraud-Renard, Eléa | Dolique, Franck | Lecchini, David
The shoreline is often at the interface of a combination of physical, ecological, and socio-economic forcing agents. Monitoring the shoreline changes across time is crucial to understand the causes of its evolution and put in place management measures. The analysis of aerial photographs from 1950 to 2016 at Mayotte Island (Indian Ocean) showed that the shoreline urbanisation is still low (6%) compared to the worldwide trend. However, a faster increase happened recently (from 3% in 1989 to 6% in 2016) owing to a strong demographic growth and socio-economic development. A multidisciplinary index was developed to assess the vulnerability of four study sites – Bandrélé, M’tsamboro, N’gouja, and Sakouli – (representative sites of beaches with fringing reefs throughout Mayotte with varying levels of urbanisation). The vulnerability of Bandrélé was lower than that of the other sites due to the presence of a mangrove at the back of the beach which plays a key role of buffer between the land and sea. M’tsamboro was the site with the highest anthropogenic pressure and highest vulnerability. Overall, as most of the shoreline is still natural at Mayotte, 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. The multidisciplinary vulnerability index developed in this study can be a useful tool to help coastal managers in the decision-making and prioritisation of actions to undertake on the shore.
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