Automated Image Analysis to Map the Extent of Deep-Sea Mining Plumes Reveals a Larger Impacted Area Compared to Manual Analysis

Abstract

Deep sea mining for poly-metallic nodules impacts the environment in many ways. A key potential hazard is the creation of a sediment plume from resuspending sediment during seabed mining. The resuspended matter disperses with currents but eventually resettles on the seabed. Resettling causes a blanketing of the seafloor environment, potentially causing harm to in-, epi- and hyperbenthic communities with possible cascading effects into food webs of deep sea habitats. Mapping the extent of such blanketing is thus an important factor in quantifying potential impacts of deep-sea mining.One technology that can assess seabed blanketing is optical imaging with cameras at square-kilometre scale. To efficiently analyse the resulting Terabytes of image data with minimized bias, automated image analysis is required. Moreover, effective quantitative monitoring of the blanketing requires ground truthing of the image data. Here, we present results from a camera-based monitoring of a deep-sea mining simulation combined with automated image analysis using the CoMoNoD method and low-cost seabed sediment traps for quantification of the blanketing thickness. We found that the impacted area was about 50 percent larger than previously determined by manual image annotation.

Research Status of Deep-Sea Polymetallic Nodule Collection Technology

“…Therefore, there is still a need to focus on the impacts on organisms during the collection process [74,75]. In terms of sediment disturbance, Timm et al [76] assessed the coverage of the plume by optical imaging with a camera at the square-kilometer scale and processed the static images using the CoMoNoD method, which can quantify the macroscopic impact of the plume. However, there is still a lack of research related to the quantification of suspended plumes Future improvements in automated image analysis capacity may reveal an even larger impacted area with unknown effects to the deep-sea habitat.…”

Simulation Study on the Sediment Dispersion during Deep-Sea Nodule Harvesting

“…Therefore, it is essential to estimate the suspending time as well as the spreading area of the sediment particles before re-settling, in order to assess the environmental impact before the formal harvesting process is applied. Up to date, a number of works has been carried out to investigate the evolution of the sediment plume by field observation as well as numerical simulation [4][5][6][7][8][9][10]. However, more work needs to be done before an accurate and robust way to access the sediment plume impact is developed.…”