Reconstruction of the Maërl habitat to better understand its ecological integrity.

Maërl habitats are composed of coralline red algae species that can live freely rolling on the seabed and forming nodules, the so-called rhodoliths, or incrusted forming coralligenous habitats. Maërl habitats are generally distributed in the Mediterranean at a depth of between 30 m and 70 m and are considered one of the most emblematic Mediterranean seabeds. In the present study, the complex structure of maërl habitats was investigated to i) characterise the relief features and classify the different sediments, ii) to estimate the abundance of the coralline red algae (both rhodoliths and encrusting ones) and iii) to analyse the biodiversity of the species inhabiting the habitat.

Distribution of rhodolith beds and their functional biodiversity characterisation using ROV images in the western Mediterranean Sea.

Underwater biogenic habitats composed of unattached calcified red algae, named as rhodolith or maërl beds, may extant either alive or dead, over the seabed. The accumulation of rhodoliths constitute three-dimensional structured biogenic habitats that harbour high diversity of benthic organisms. In the Mediterranean Sea, rhodolith beds can be found between ca.