A preliminary evaluation of some elements for designation of preservation and impact reference zones in deep sea in the Clarion-Clipperton Zone: A case study of the China ocean mineral resources association contract area

Abstract

At present, the enthusiasm for deep-sea mining is increasing in major countries worldwide. However, the impact of deep-sea mining on the environment is not clearly understood. The International Seabed Authority (ISA) has issued a series of regulations on mining environmental management. Environmental baseline data collection, impact reference zones (IRZs) and preservation reference zones (PRZs) designation, and an Environmental Impact Assessment (EIA) for test mining are required during the exploration period, which also provides support for environmental management during exploitation periods in the future. This study presents a process based on some environmental and biological elements that can be used to guide the preliminary designation of Reference Zones (RZs) (IRZ and PRZ) in the Clarion-Clipperton Zone, using the COMRA contract area as a case study. Based on the monitoring results in the initial RZs of the COMRA contract area, we compare the similarities of hydrological, chemical and biological communities feature between 3 RZs. And finally, we give suggestions on the key elements in designing the RZs. These findings provide evidence for the future development of environmental management plans for deep-sea mining by the ISA.