REMOTS monitoring of dredging, disposal, sand mining, and organic enrichment on the Hong Kong shelf

The territorial waters of Hong Kong encompass extensive areas of shallow continental shelf affected by many activities including sand dredging for reclamation fill, disposal of dredged mud, disposal of sewage sludge, commercial fishing, and mariculture. The REMOTS sediment profile imaging camera has been used successfully since 1993 for rapid seafloor assessment to define baseline conditions and impacts on sediment duality during both wet (typhoon) and dry seasons. Several hundred stations have been occupied in a two week survey. Analysis of sediment profile images has allowed assessment of dredging and disposal effects and organic enrichment "hot spots". It appears that tropical storms may have a large effect on mobilization of soft sediments during the wet season, while anthropogenic factors (dredging, disposal, and seabed fishing activities) may assume greater relative importance in some areas during the dry season when severe storms are less common. The soft bottom benthic community consists of a few species of small invertebrates adapted to physical disturbance.