Résumé
Coral recruitment is an essential demographic mechanism that underpins the community structure and dynamics of coral reefs and facilitates post-disturbance coral recovery. However, information on coral recruitment patterns in mesophotic coral ecosystems (MCEs) is globally scarce, and no study describes patterns in the lower mesophotic zone (> 60 m depth). We quantified spatial variability in coral recruitment at shallow (15 m), upper (45 m) and lower (75 m) mesophotic depths across three contrasted locations (nine stations) around Reunion Island in the southwestern Indian Ocean. This study, the first to assess coral recruitment patterns on lower mesophotic habitats, highlighted a marked decline in recruitment rate in MCEs consistently across locations. Recruit composition varied significantly with depth, with Pocilloporidae dominating shallow habitats, while lower MCEs exclusively harbored "other" coral family recruits (i.e., other than Acroporidae, Pocilloporidae and Poritidae). Coral recruitment rate on tile surface orientation varied significantly with depth, with an overall higher proportion of recruits recorded on top surfaces at lower mesophotic depths. The abundance of Pocilloporidae recruits was positively correlated with confamilial adult coral cover, suggesting stock-recruitment or recruitment-limitation models for the dynamic of dominant shallow corals over a broad depth gradient. Upper MCEs could constitute substantial refuges for Pocilloporidae corals, while lower MCEs are of paramount importance for "other" coral families. Interannual surveys are necessary to better understand the spatiotemporal variability of coral recruitment in shallow habitats and MCEs and the driving forces of early post-settlement processes.