Mesophotic coral ecosystems of French Polynesia are hotspots of alpha and beta generic diversity for scleractinian assemblages

Type : ACL
Nature : Production scientifique
Au bénéfice du Laboratoire : Non
Statut de publication : Publié
Année de publication : 2022
Auteurs (11) : PÉREZ-ROSALES Gonzalo PICHON M ROUZE Heloise VILLÉGER Sébastien TORDA G BONGAERTS Pim CARLOT Jeremy CONSORTIUM Under, the, pole PARRAVICINI Valeriano HÉDOUIN Laetitia (EMBL) European, molecular, biology, laboratory
Revue scientifique : Diversity and Distributions
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DOI : 10.1111/ddi.13549
URL : https://onlinelibrary.wiley.com/doi/full/10.1111/ddi.13549
Abstract : Aim
Revealing how diversity varies across the depth gradient is key for understanding the role of mesophotic coral ecosystems in the functioning of coral reefs. We quantitatively examined how alpha and beta generic diversity of scleractinian coral assemblages vary across a wide depth gradient for coral reefs.

Location
Sixteen sites in eight islands of three archipelagos in French Polynesia.

Methods
We studied generic diversity patterns of scleractinian corals, as derived from the analysis of photo-quadrats, across the seafloor from shallow to lower mesophotic depths (6–120 m) and on a wide geographic scale. Our sampling considered quantitative coral cover to explore the patterns of alpha and beta components of diversity across depth and horizontal space.

Results
We show that in French Polynesia, mesophotic coral ecosystems host higher alpha and beta generic diversity than shallow reefs despite decreasing coral cover with depth. The variation of coral genus richness across the depth gradient is mainly driven by a mid-domain effect with a peak at 40 m depth. At the same time, we found that the differences in coral genera across islands (spatial beta-diversity) increased steadily along the depth gradient.

Main conclusions
Our findings report the first quantitative results of coral cover and diversity from mesophotic coral ecosystems in French Polynesia and also present one of the few existing studies to examine the broad breadth of the mesophotic depth gradient. We demonstrate that mesophotic depths can host unexpectedly high generic richness of scleractinian coral assemblages. At the same time, we showed that increasing depth increases the differences in generic diversity composition across islands, whereas shallow reefs are similar in between. While a single island could conserve shallow regional biodiversity, mesophotic depths containing the richest diversity require site-specific measures, suggesting that considering these mesophotic depths in conservation is necessary to maintain regional diversity.
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Citation :
Pérez-Rosales G, Pichon M, Rouze H, Villéger S, Torda G, Bongaerts P, Carlot J, Consortium U , Parravicini V, Hédouin L, (EMBL) E (2022) Mesophotic coral ecosystems of French Polynesia are hotspots of alpha and beta generic diversity for scleractinian assemblages. Divers Distrib | doi: 10.1111/ddi.13549