DOI: 10.5061/dryad.pzgmsbcs8
title: Light and temperature drive the distribution of mesophotic benthic communities in the Central Indian Ocean

description: Aim: Research on Mesophotic Coral Ecosystems (MCEs) has increased
 exponentially in recent decades, and the significance of this ecosystem
 has been recognised both in terms of biodiversity and distribution.
 However, this research has mostly focussed on corals and is globally
 sporadic, with the Indian Ocean remaining largely unexplored and overall
 MCEs under protected. Hence, baseline data on MCE benthic communities is
 lacking, but nonetheless essential for developing adequate management
 strategies. Here, we assess the variation in diversity and community
 structure of MCEs along the depth gradient and among sites in the Indian
 Ocean and the environmental parameters that are potentially driving these
 differences. Location: Egmont Atoll, Chagos Archipelago, central Indian
 Ocean. Time period: Present. Major taxa studied: Marine benthic
 invertebrates, plants. Methods: Using a Remotely Operated Vehicle, we
 collected video transects between 15 and 160 m. We analysed the diversity
 and composition of benthic communities and used DistLM analysis to
 determine the environmental drivers of the community structure over the
 depth gradient and between sites.   Results: We observed
 distinct benthic communities along the depth gradient, with a strong
 community break observed at ~60 m. We also identified a clear zonation of
 the benthic taxa with depth. This zonation was primarily driven by
 downward irradiance and temperature, with additional environmental
 processes playing a minor role in structuring the benthic communities.
 Main conclusions: We show that MCEs in the Chagos Archipelago are distinct
 communities, and their distribution is driven primarily by irradiance and
 temperature. Our results highlight the variability in benthic community
 structure of MCEs, both along the depth gradient and at local geographical
 scales for the study region. This study showcases the uniqueness of MCEs
 and will aid in predicting their distribution, potential refugia for
 shallow reefs, and in developing evidence-based protection for MCEs, to
 maintain overall marine biodiversity.
description: Data collection methods can be found in the main manuscript,
 under the methods section.
description: Title: Light and temperature drive the distribution of mesophotic benthic
 communities in the Central Indian Ocean Short title: Drivers of mesophotic
 reef distribution Author list: Clara Diaz<sup>1†</sup>; Kerry
 L. Howell<sup>1</sup>; Edward
 Robinson<sup>1</sup>; Philip Hosegood<sup>1</sup>;
 Adam Bolton<sup>1</sup>; Peter
 Ganderton<sup>1</sup>; Peter Arber<sup>1</sup>;
 Martin J. Attrill<sup> 1</sup>; Nicola L.
 Foster<sup>1</sup> <sup>1</sup> School of
 Biological and Marine Sciences, University of Plymouth, Drake Circus,
 Plymouth, PL4 8AA, United Kingdom. <sup>† </sup>Corresponding
 author: Clara Diaz,
 [clara.diaz@plymouth.ac.uk](mailto:clara.diaz@plymouth.ac.uk),
 6<sup>th</sup> floor Davy building, School of Biological and
 Marine Sciences, University of Plymouth, Drake Circus, Plymouth, PL4 8AA,
 United Kingdom Raw data files are provided at this DOI:
 doi:10.5061/dryad.pzgmsbcs8 and is composed of 2 excel documents:
 Final\_meso\_data\_with\_metada is the annotated morphospecies abundance
 per image. The second sheet called "metadata" provide the
 abbreviations meaning and general information about the morphospecies
 abundance data. The collection and annotation methods can be found in the
 main manuscript under the methods section.
 Final\_env\_data\_with\_metadata is the document containing the
 environmental variables associated with each image. The second sheet
 called "metadata" provide the units; abbreviations meaning; and
 general information about the environmental data. The collection methods
 can be found in the main manuscript under the methods section. A benthic
 species catalogue is currently published: Diaz C, Foster NL, Howell KL.
 Shallow and mesophotic benthos reference image database for the Chagos
 Archipelago, central Indian Ocean. Zenodo. 2023.
 DOI:10.5281/zenodo.7948517