Reef morphotype characterization as an effective tool for benthic habitat description: a case study from the Red Sea.

Remote sensing studies based on satellite and aerial imagery have generated a good understanding of the distribution of several shallow reefs found along the Arabian coast (Bruckner et al., 2011, Rowlands et al., 2012, Rowlands et al., 2016). However, data concerning the deeper benthic assemblages' spatial distribution, type, and conditions are missing, especially in the central Red Sea. Using high-resolution MBES and video collection, we aim to map, describe and classify the reefs found in Thuwal's coastal area, filling the information gap by producing the first benthic habitat map of this area.

High-resolution bathymetric data were collected using the Norbit iWBMS Multibeam Echosounder, which allowed us to classify the reefs in 12 morphotypes. From those morphotypes, 28 areas were selected for ground-truthing examination using a BlueROV2 equipped with a 4K camera and USBL positioning system to characterize the benthic community.

With the information obtained from the bathymetry data and the ROV video transects, a benthic habitat map for Thuwal's reefs was created, where 23 benthic habitat types were observed.

This research uncovered previously poorly studied reef morphologies in the Red Sea and their benthic composition, demonstrating how different reef communities express a different three-dimensional morphological structure. Moreover, this work will help us improve the understanding of the spatial distribution and condition of benthic communities located on Thuwal's coastline, giving a baseline with the potential to provide fundamental information that can be used for management, conservation, and future research in Saudi Arabia.