Wave exposure shapes reef community composition and recovery trajectories at a remote coral atoll

Lange, Ines D., Benkwitt, Cassandra E., McDevitt-Irwin, Jamie M., Tietjen, Kristina L., Taylor, Brett, Chinkin, Mark, Gunn, Rachel L., Palmisciano, Melissa, Steyaert, Margaux, Wilson, Bry, East, Holly K., Turner, John, Graham, Nicholas A. J. and Perry, Chris T. (2021) Wave exposure shapes reef community composition and recovery trajectories at a remote coral atoll. Coral Reefs. ISSN 0722-4028 (In Press)

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Official URL: https://doi.org/10.1007/s00338-021-02184-w

Abstract

In a time of unprecedented ecological change, understanding natural biophysical relationships between reef resilience and physical drivers is of increasing importance. This study evaluates how wave forcing structures coral reef benthic community composition and recovery trajectories after the major 2015/2016 bleaching event in the remote Chagos Archipelago, Indian Ocean. Benthic cover and substrate rugosity were quantified from digital imagery at 23 fore reef sites around a small coral atoll (Salomon) in 2020 and compared to data from a similar survey in 2006 and opportunistic surveys in intermediate years. Cluster analysis and principal component analysis show strong separation of community composition between exposed (modelled wave exposure > 1000 J m−3) and sheltered sites (< 1000 J m−3) in 2020. This difference is driven by relatively high cover of Porites sp., other massive corals, encrusting corals, soft corals, rubble and dead table corals at sheltered sites versus high cover of pavement and sponges at exposed sites. Total coral cover and rugosity were also higher at sheltered sites. Adding data from previous years shows benthic community shifts from distinct exposure-driven assemblages and high live coral cover in 2006 towards bare pavement, dead Acropora tables and rubble after the 2015/2016 bleaching event. The subsequent recovery trajectories at sheltered and exposed sites are surprisingly parallel and lead communities towards their respective pre-bleaching communities. These results demonstrate that in the absence of human stressors, community patterns on fore reefs are strongly controlled by wave exposure, even during and after widespread coral loss from bleaching events.

Item Type: Article
Additional Information: Funding Information: This research was funded by the Bertarelli Foundation as part of the Bertarelli Programme in Marine Science and was conducted under permit number 0003SE20. We thank Rachel Jones, Heather Koldewey and Emma Levy as well as the captain and crew of the support vessel for logistical help and for bringing us home during a global pandemic.
Uncontrolled Keywords: Community composition, Biophysical coupling, Wave exposure, Recovery trajectory, Remote coral reef
Subjects: F700 Ocean Sciences
F800 Physical and Terrestrial Geographical and Environmental Sciences
Department: Faculties > Engineering and Environment > Geography and Environmental Sciences
Depositing User: John Coen
Date Deposited: 18 Oct 2021 13:14
Last Modified: 18 Oct 2021 13:15
URI: http://nrl.northumbria.ac.uk/id/eprint/47506

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