Spatial variability in distribution and prevalence of skeletal eroding band and brown band disease in Faafu Atoll, Maldives

Indo-Pacific coral diseases are currently considered one of the 15 globally important threats requiring conservation attention. The coral reefs of the Maldives are experiencing a local decline, with the presence of some coral diseases reported only recently. We investigated the spatial variability in prevalence and distribution of two protozoan diseases, skeletal eroding band (SEB) and brown band disease (BrB), in three islands in the Faafu Atoll: an inhabited island (Magoodhoo), an uninhabited island (Adanga) and a resort island (Filitheyo). Our study revealed a low level of mean disease prevalence for both diseases (<1 %), with Magoodhoo and Adanga being the most affected by BrB and SEB, respectively. However, our preliminary temporal investigations revealed an increment of both coral diseases in Adanga during the last 4 years. Furthermore, we observed different spatial patterns between the two diseases, with SEB positively correlated to dead coral coverage. Finally, Acropora was the most affected coral genus, hosting both coral diseases. Considering that Acropora is the most abundant genus in the archipelago and many other areas in the Indo-Pacific, this finding highlights the need for particular conservation efforts for this genus. These results represent just a first step in the assessment of Maldivian coral disease epidemiology, and more detailed analyses of regional differences in diseases prevalence are needed to further explore their impacts on Maldivian coral reefs.