Rapport scientifique de la campagne CALADU‐2021 sur le N/O Thalassa (avec le ROV Ariane)

• Main Authors: Fabri, Marie-claire, Arnaud-haond, Sophie
• Format: Text
• Language: French
• Subjects: envir; geo; Duthiers; Lacaze-Duthiers; Norway; Iceland; Lophelia pertusa
• Online Access: https://doi.org/10.13155/84585; https://archimer.ifremer.fr/doc/00734/84585/89676.pdf; https://archimer.ifremer.fr/doc/00734/84585/

The CALADU-2021 oceanographic cruise (http://dx.doi.org/10.17600/18001575) was dedicated to the study of the distribution of cold water corals at different scales. These corals are known for their status of Vulnerable Marine Ecosystems - VMEs - due to their life history traits (very slow growth) and their vulnerability to anthropogenic impacts (particularly to fishing). Two independent working scales will be considered, firstly the distribution at the scale of the Lacaze-Duthiers canyon to carry out the population mapping, but also at a larger scale which is that of understanding the evolution of the distribution over the course of geological times and different ice ages, between the Mediterranean and the Atlantic. The objective was therefore twofold: (1) The main objective was to carry out detailed mapping of all VME populations with the aim of quantifying their status. For this a methodical and exhaustive acquisition was necessary. In addition to the mapping of structuring species (two species of corals Madrepora oculata and Lophelia pertusa (syn. Desmophyllum pertusum) which form three-dimensional colonies that serve as shelter and breeding ground for other species) and the census anthropogenic impacts (lost fishing gear), a census of the associated diversity will be carried out using photos in order to measure the state of the ecosystem. This objective supports Public Policies (in particular within the framework of the Framework Directive for the Strategy on the Marine Environment - MSFD). (2) The second objective of this campaign was to take samples of corals in order to enrich the available data on the distribution of their clonal and genomic diversity along their range from the Mediterranean to Norway and Iceland. A first cruise took place in 2019, with the HROV Ariane on R/V L'Europe, but bad weather conditions did not allow the expected program to be carried out: insufficient sampling for the genetic part of the populations, and not enough data for the part "study of the distribution on the scale of the ...