Understanding Mn-nodule distribution and evaluation of related deep-sea mining impacts using AUV-based hydroacoustic and optical data

摘要: Abstract. In this study, ship- and autonomous underwater vehicle (AUV)-based multibeam data from the German ferromanganese-nodule (Mn-nodule) license area in the Clarion–Clipperton Zone (CCZ; eastern Pacific) are linked to ground-truth data optical imaging. Photographs obtained by an AUV enable semi-quantitative assessments of nodule coverage at a spatial resolution in the range meters. Together with high-resolution bathymetry, this revealed a correlation small-scale terrain variations (  5  m horizontally,  1  vertically) coverage. the presented data set, increased could be correlated slopes >  1.8 ∘ concave terrain. On a more regional scale, factors such as geological setting (existence horst graben structures, sediment thickness, outcropping basement) influence bottom currents seem to play essential role for spatial variation the related hard substrate habitat. imagery was also successfully employed map distribution of resettled sediment following a disturbance cloud generation during a sampling deployment epibenthic sledge. Data before after “disturbance” allow a direct assessment impact. Automated image processing analyzed seafloor, revealing nodule blanketing resettling suspended within 16 h after the disturbance. The visually detectable impact spatially limited a maximum 100  distance disturbance track, downstream water current. A correlation with high-resolution bathymetry reveals that blanketing pattern varies extent tens meters, strictly the bathymetry, even areas only slightly undulating seafloor ( 1  vertical change). These results highlight importance detailed knowledge when engaging resource studies abundance estimates defining mineable areas. At same time, it shows the mapping benthic habitat show a heterogeneity scales 10 to 100  . Terrain knowledge is needed determine the scale seafloor mining operations.