Assessment of Deep-Sea Faunal Communities-Indicators of Environmental Impact

Abstract

Our assessment of deep-sea faunal communities is based on the results of a comprehensive UNESCO/IOC baseline study of the megafaunal assemblages of the metallic nodule ecosystem of five areas within the Clarion Clipperton Zone (CCZ) of the eastern Pacific Ocean. This study serves as benchmark to interpret the structure of megafaunal populations associated with benthic biotopes in areas targeted for mining. It identifies on a large scale the variability of nodule and sediment facies and their associations with specific megafaunal communities. An appropriate set of management tools and options have been developed, in particular indicators of sensitivity to environmental changes anthropogenically or naturally induced. The general characteristics of the nodule ecosystem in the CCZ and its sensitivity to deep-sea mining are discussed from the surface to the seabed in relation to recent research on the description of water masses and dynamics and an assessment of their vulnerability. A tridimensional multiparametric rapid environmental assessment (REA) has been applied on one pilot site of the French contract area using GIS zoning, ecohydrodynamics, and sensitivity indexes.