GALIMOS Monitoring the interaction between Oceanographic elements and Sedimentary seabed structures at the GALIcian margin - Cruise No. M110 - September 15 - September 30, 2014 - Vigo (Spain) - Cádiz (Spain) (English)

The cruise M110 GALIMOS aimed at monitoring the relationship between oceanography and seabed at the continental margin off the NW-Iberian Peninsula. The expedition focused on the two areas of most intense interaction between the hydrographic and sedimentary regimes: a) the mid-shelf muddy depocenter and b) the Galician deeper shelf edge with two spectacular morphological terraces. We applied PARASOUND PHF (18 kHz)/SADCP water-column imaging for both lateral profiling and monitoring. The profiles showed internal interfaces with wave trains and cloudy features. We collected 58 CTD profiles (42 stations) to collect physical water-column properties. ParCa imaging (8 stations) and water sampling (78) at selected water depths will help to evaluate the observed water-column features. Twenty-eight Rumohr cores, 18 grab samples, and 7 gravity cores provided sediment surface and subbottom information. For bottom-near observations on the continental shelf, a lander mooring was equipped with 3 ECM/CTD/OBS sensors, an upward looking ADCP 300 kHz, a downward looking ADCP 1200 kHz, and a LISST. It was deployed in a sandy area (73 m water depth) off the Douro River mouth and in the center of the Galician mud depocenter (125 m) off the Ría de Vigo. The first deployment lasted 104 h and recorded a passing storm. The latter run for 109 h until a dredging incident. The data illustrate the bottom current, tidal currents, and storm wave activity leading to different degrees of resuspension. The ROV provided additional information on the seabed characteristics. For bottom-near information on the upper continental slope, we ran 4 ROV surveys. These visualized how the slope-parallel bottom current controls sediment distribution.