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Nadine Le Bris, LECOB CNRS UPMC Sorbonne Universités, Observatoire océanologique de Banyuls, France
Pierre Galand, LECOB CNRS UPMC Sorbonne Universités, Observatoire océanologique de Banyuls, France
Dimitri Kalenitcheko, LECOB CNRS UPMC Sorbonne Universités, Observatoire océanologique de Banyuls, France
Franck Lartaud, LECOB CNRS UPMC Sorbonne Universités, Observatoire océanologique de Banyuls, France
Anne Leila Meistertzheim, LECOB CNRS UPMC Sorbonne Universités, Observatoire océanologique de Banyuls, France
Jadwiga Orignac, LECOB CNRS UPMC Sorbonne Universités, Observatoire océanologique de Banyuls, France
Erwan Peru, LECOB CNRS UPMC Sorbonne Universités, Observatoire océanologique de Banyuls, France
Audrey Pruski, LECOB CNRS UPMC Sorbonne Universités, Observatoire océanologique de Banyuls, France
Béatrice Rivière, LECOB CNRS UPMC Sorbonne Universités, Observatoire océanologique de Banyuls, Franceé
Gilles Vetion, LECOB CNRS UPMC Sorbonne Universités, Observatoire océanologique de Banyuls, France
The Lacaze-Duthiers canyon: a natural laboratory to study deep-sea ecosystem dynamics and functions in a climate change context
Submarine canyons are ecological hotspots on continental margins sustaining a variety of services to marine ecosystems and human societies. Canyon ecosystems are exposed to cumulative climatic and direct anthropogenic pressures, particularly at places where extreme events propagate disturbances of the meteorological-hydrological regime down to hundreds or thousands meters depth (e.g.: through deep water convection or export of material during storms). The complex links between environmental fluctuations and ecological responses however remains largely undescribed in the deep-sea due to limited access. There are thus many critical gaps to fill in order to understand how climate forcing may challenge ecosystem resilience.

In this perspective, we established a multiannual integrated ecological study in the Lacaze-Duthiers submarine canyon (Western Mediterranean Sea), which aimed at investigating key ecosystem functions and their dynamic features in natural conditions. This canyon hosts abundant populations of deep-water corals, whose sensitivity to warming and acidification may further enhance ecosystem vulnerability.  A first objective of our experimental approach was the study of the in situ growth dynamics of the two dominant coral species,  M. oculata and L. Pertusa, in combination with changes in associated microbial communities. We also focused on microbial and animal plant macrodebris colonization, to examine the role of canyon in transferring energy from land to deep-sea and supporting deep-sea faunal diversity.

The first outcomes of this programme reveal unexpected rapid dynamics of key ecological processes, potentially reflecting the environmental instability at seasonal or event scales, resulting of atmospheric forcings in this area. While providing clues to explore the underlying mechanisms, these results set the basis for a long-term integrated study of a climate-sensitive deep-sea ecosystem, supporting the implementation of effective monitoring strategies by the Marine Protected Area of the Gulf of Lion (Parc Naturel Marin du Golfe du Lion).

Theme 3: Biological patterns in submarine canyons: role of scale and heterogeneity
Oral Presentation
wood falls, cold-water corals, dense water cascading, Mediterannean deep-sea, Marine protected area