JERICObet-5 is composed of two LEGs which aim to realize a synoptic map of the extension of the West Gironde Mud Patch (WGMP) with a reliability and a resolution better than the one obtained until now. In fact, our first research cruise (JERICObent-1, Oct.-Nov. 2016) clearly indicated that the mapping recently proposed by Cirac et al (2016) was more representative of the maximum expansion of WGMP over the last 35 years recent years rather than its current surface.

The first LEG on the R/V Thalia aims to obtain a "medium-resolution" mapping by coupling acoustic mapping methods and geophysical methods of seismic reflection THR with a chirp "Peskavel". The acoustic and geophysical data thus acquired are calibrated by sedimentology data collected during this second LEG on the R/V 'Côtes de la Manche'. For this purpose, surface sediment samples were taken using a Uwitec interface corer, and photographs of the sedimentary structure were taken in situ using a Sediment Imaging Profiler (SPI). The spatial variability of the main surface sediment properties (grain size, porosity, specific surface area), biogeochemical characteristics of the sediment (particulate Mn, Fe and P), sedimentary organic matter (isotopy, bulk, qualitative descriptors) as well as the activity of the benthic fauna (SPI) will be characterized in the current expansion of the WGMP.

This work is part of the EU JERICO-NEXT project (2015-2018) and the joint project LEFE (2018-2020) and DRIL-EC2CO (2018-2019).