DOI: 10.5061/dryad.rjdfn2zc7
title: Mesophotic coral ecosystems of French Polynesia are hotspots of alpha and beta generic diversity for scleractinian assemblages

description: Revealing how diversity varies across the depth gradient is key to
 understanding the role of mesophotic coral ecosystems in the functioning
 of coral reefs. We examined how alpha and beta generic diversity of
 scleractinian coral assemblages vary across a wide depth gradient for
 coral reefs. We studied generic diversity patterns of scleractinian corals
 at sixteen sites in eight islands of three archipelagos in French
 Polynesia, as derived from the analysis of photo-quadrats, across the
 seafloor from shallow to lower mesophotic depths (6 to 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. 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
 turnover of coral genera across islands (i.e., spatial beta diversity)
 increased steadily along the depth gradient. 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.
description: # Mesophotic coral ecosystems of French Polynesia are hotspots of alpha
 and beta generic diversity for scleractinian assemblages
 [https://doi.org/10.1111/ddi.13549](https://doi.org/10.1111/ddi.13549) The
 present data was uploaded for the submission of the manuscript to
 Diversity and Distributions (DDI-2021-0458). The data names and files are
 edited to be double-blind for peer review. ## The two main data files are:
 "photoquad_rndpts_DEEPHOPE.csv" random points of coral cover by
 genus "photoquad_sppcount_DEEPHOPE_genus_form.csv"
 presence/absence of coral genera Note:  * The units of depth are meters
 (m) * The meaning of DRRH is Deep Reef Refugia Hypotheses * Jaccard and
 Bray-Curtis are dissimilarity indexes. Jaccard works for presence-absence
 data and Bray-Curtis for abundance data.  * The cover represents the
 percentage of coral cover (1-100%). The unit is cover per surface area and
 the value was determined using photoquadrats.  ## The two main scripts
 are: Script_R_Diversity_Cover.R working on coral cover data
 Script_R_Diverstiy_PA_Occupancy.R working on presence/absence data If you
 have any requests, do not hesitate to contact:
 [gonzalo.prb@gmail.com](mailto:gonzalo.prb@gmail.com)