Impacts of coral bleaching on reef fish abundance, biomass and assemblage structure at remote Aldabra Atoll, Seychelles: insights from two survey methods

Aldabra Atoll, a remote UNESCO World Heritage Site, experienced a 50% coral mortality due to the 2015/16 bleaching event. Research revealed contrasting impacts on reef fish communities depending on survey methods used. Indicator surveys showed no significant change in fish abundance or biomass post-bleaching, with increases mainly driven by herbivores and omnivores responding to elevated turf algae cover. However, extended surveys detected a 55–60% reduction in overall fish abundance and a 69% decrease in biomass on shallow reefs, highlighting the importance of comprehensive survey methods to capture ecological responses. Multivariate analysis confirmed immediate and lasting shifts in community composition, primarily affecting herbivorous, omnivorous, and piscivorous taxa. This study underscores the value of diverse survey techniques in understanding the delayed and nuanced impacts of coral bleaching on reef ecosystems.

Koester, A., Gordó−Vilaseca, C., Bunbury, N., Ferse, S. C. A., Ford, A., Haupt, P., A’Bear, L., Bielsa, M., Burt, A. J., Letori, J., Mederic, E., Nancy, E., Sanchez, C., Waller, M., & Wild, C. (2023). Impacts of coral bleaching on reef fish abundance, biomass and assemblage structure at remote Aldabra Atoll, Seychelles: insights from two survey methods. Frontiers in Marine Science, 10. https://doi.org/10.3389/fmars.2023.1230717