The Benthic Megafaunal Assemblages of the CCZ (Eastern Pacific) and an Approach to their Management in the Face of Threatened Anthropogenic Impacts

Virginie Tilot,Teresa S Catalá,Rupert Ormond,Juan Moreno Navas

doi:10.3389/fmars.2018.00007

Abstract

We present here the results of a comprehensive UNESCO/IOC baseline study of the megafaunal assemblages of the metallic nodule ecosystem of 5 areas within the Clarion Clipperton Fracture Zone (CCFZ) of the eastern Pacific Ocean. The work was undertaken with a view to interpreting the structure of the epifaunal populations associated with the benthic biotopes being targeted for mining and developing an appropriate set of management tools and options. The general characteristics of the nodule ecosystem and its sensitivity to deep-sea mining are discussed in relation to water masses, ocean circulation from the surface to the seabed, the nepheloid layer and processes taking place at the sediment interface. Management tools considered include species diversity, vulnerability indexes, GIS systems, zoning, and 3D rapid environmental assessment (REA). These monitoring strategies are developed for application on one of the UNESCO/IOC baseline study sites.

Highlights

Knowledge of the structure of its megafaunal assemblages is essential to understanding the functioning of any deep-sea ecosystem (Rex and Etter, 2010)
The benthic fauna plays an important role in carbon cycling and mineralization within the epibenthos. It contributes to the genesis of polymetallic nodules, bioturbation along with bottom currents playing a role in allowing nodules to remain on the seafloor (Dugolinsky et al, 1977; Du Castel, 1985; Mullineaux, 1987; Thiel et al, 1993; Veillette et al, 2007a,b)
The study areas, data from which were used during the UNESCO/Intergovernmental Oceanographic Commission (IOC) baseline study (Tilot, 2006a,b, 2010a), were the NORIA region, within which lie the NIXO 45 and NIXO 41 sites, the American site ECHO 1, and the consortium site Interoceanmetal Joint Organization (IOM) BIE (Russia, Bulgaria, Cuba, Poland, Czech Republic, Slovakia) (Figure 2); the most detailed and recent work focussed on NIXO 45, a well explored and sampled site within Ifremer’s marine geosciences programmes

Summary

Introduction

Knowledge of the structure of its megafaunal assemblages is essential to understanding the functioning of any deep-sea ecosystem (Rex and Etter, 2010). This faunal component includes a significant fraction (17–50%) of benthic abyssal biomass (Haedrich and Rowe, 1977). Since the megafauna is one of the principal agents of bioturbation at the depositional interface of the deep-sea benthos (Mauviel and Sibuet, 1985; Levin et al, 1986), it can influence many other biological and geochemical components of the deep ocean, in particular concerning the nodule ecosystem (Sharma and Rao, 1992) (Figure 1). It contributes to the genesis of polymetallic nodules, bioturbation along with bottom currents playing a role in allowing nodules to remain on the seafloor (Dugolinsky et al, 1977; Du Castel, 1985; Mullineaux, 1987; Thiel et al, 1993; Veillette et al, 2007a,b).

Methods

Results

Conclusion