Maerl beds refer to the accumulation of unattached calcareous coralline algae. They are composed of living and dead thalii forming an ‘underwater carpet’. Considered as biodiversity “hotspot” sheltering many and varied marine species, they are an important carbon-storing habitat. Within the EU project JERICO-Next (VA) the new version of SpiArcBase (V2.0) (https://spiarcbase.epoc.u-bordeaux1.fr/) has been developed to assess maerl beds while measuring different features: mean and total maerl-water interface rugosity, total living maerl surface, total dead maerl surface, mean maerl bed thickness, vertical profiles of the surface proportion of living and dead maerl.
Within the JRAP 2 of JERICO-NEXT (WP4), the pertinence of those features has been studied and related to an abrasion disturbance gradient in the Bay of Brest induced by dredge-fishing activity. Preliminary results show among others that these features are appropriate to quantify the harmful effects of abrasion through a decrease in live maerl thalli, compaction of the maerl bed and the decrease in interstice surface and the rugosity of the surface.
Dr. Alicia Romero Raminez
Service Géomatique et analyse d’image
Université Bordeaux, France