Laminaria hyperborea, how explain and what happen when the canopy desappeared from some areas?

Martial Laurans¹, Sandrine Derrien², Touria Bajjouk¹, Fernando Tempera³, Benoit Quéguiner⁴, Simon Dittami⁵, Jean Charles Leclerc⁵, Claire Laspougeas⁶,

¹Ifremer, France - ²MNHN, France - ³OFB, France - ⁴Algaia, France - ⁵CNRS, France - ⁶PNMI, France

Kelps are the main algae species in Brittany if we have a biomass point of view. The different species (list) considering their biotic range are presents all along the brittany coast from +1 meter to minus 30 meters depth. Nevertheless, knowing some changes in the environmental conditions, the spatial distribution fluctuate a lot for more than 20 years as well as the size structure of the population. Here, we are going to focus on Laminaria hyperborea using a big sample to define what parameters characterize their presence at brittany coast level. Then, we describe some recents situation where the canapy has completely disappeared in some places in fews weeks. From these degraded situations, we have started to explore what parameters could explained what’s happened. In paralell, in these areas we have followed how the population of the Laminaria hyperborea has reacted after 1, 2 years and more time following the canopy disappeared. We are questionning the resilience of this species in changing conditions.