Comparison between satellite derived and ship based seafloor characteristic's in areas with complex seafloor morphology - A Baseline study for artificial reef deployment, Tenerife Island

Satellite-derived bathymetry is an essential tool for mapping shallow coastal areas with complex reef structures where ship-based surveys are either unsafe or inefficient. The focus of this study is to present a baseline study of the seabed morphology of a coastal region (0-130 m water depth) to support before-and-after analyses of an artificial reef deployment site under the OCEAN CITIZEN project.

OCEAN CITIZEN aims to develop a sustainable and innovative protocol for coastal restoration and biodiversity conservation. Adapted to specific ecozones, yet replicable across regions, this protocol emphasises the expansion of Marine Protected Areas (MPAs), the creation of ecological corridors to support ecosystem interactions, the restoration of biodiversity, the enhancement of blue carbon through innovative techniques, and the establishment of self-sustaining economic models for long-term sustainability.

In this context, the study investigates seafloor morphology using optical and acoustic methods to assess the suitability of satellite-derived data for mapping coastal habitats. Satellite data from Maxar's WorldView-2 satellite sensor were compared with ship-based data acquired with a Norbit iWBMS multibeam system (190 - 400 kHz) to assess their performance in water depths ranging from 10 to 20 m. Ground truthing was carried out using underwater video surveys to validate substrate, classification and biological observations.

Preliminary results show that satellite-derived data effectively capture broad-scale seafloor morphology, with contours closely matching multibeam data. However, small-scale and complex reef structures could only be resolved by ship-based surveys. Comparisons of seafloor reflectance (optical) and backscatter (acoustic) showed different sensitivities: as expected, backscatter distinguished sandy areas between hard outcropping substrate, whereas satellite reflectance is also sensitive to variations in substrate brightness. These differences highlight the need to be aware of the complementary nature of the two methods and their potential to provide additional insight into coastal restoration planning.