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Multi-scale variations in invertebrate and fish megafauna in the mid-eastern Clarion Clipperton Zone

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posted on 27.01.2021, 22:55 authored by E Simon-Lledó, C Pomee, A Ahokava, JC Drazen, AB Leitner, Adrian FlynnAdrian Flynn, J Parianos, DOB Jones
© 2020 The Authors The abyssal seafloor of the Clarion Clipperton Zone (CCZ) in the central Pacific has the largest known deposits of polymetallic nodules and associated benthic faunal communities with high biodiversity. The environmental factors that structure these communities, both at regional and local scales, are not well understood. In this study, seabed image surveys were used to assess distribution patterns in invertebrate and fish megafauna (>1 cm) at multiple scales in relation to key environmental factors: food supply to the seabed varying at the regional scale (hundreds of km), seabed geomorphological variations varying at the broad local scale (tens of km), and seabed nodule cover varying at the fine local scale (tens of meters). We found significant differences in megafaunal density and community composition between all study areas. Variations in faunal density did not appear to match with regional productivity gradients, although faunal density generally decreased with increasing water depth (from E to W). In contrast, geomorphology and particularly nodule cover appeared to exert strong control on local faunal abundance and community composition, but not in species richness. Local variations in faunal density and beta-diversity, particularly those driven by nodule presence (within study areas), were of comparable magnitude to those observed at a regional level (between study areas). However, regional comparisons of megabenthic assemblages showed clear shifts in dominance between taxonomic groups (perceivable even at Phylum levels) across the mid-eastern CCZ seabed, suggesting a higher regional heterogeneity than was previously thought.


We would like to thank Nautilus Minerals Inc., for providing the data for scientific study, and the Ministry of Lands, Survey & Natural Resources, and the Ministry of Meteorology, Energy, Information, Disaster Management, Environment, Climate Change & Communications of the Kingdom of Tonga, particularly to Ms Mafileo Masi and Mr Taaniela Kula, for their support of the project. This work was supported by the United Kingdom Government through the Commonwealth Marine Economies Program, which aims to enable safe and sustainable marine economies across Commonwealth Small Island Developing States. DJ also received support from NERC through National Capability funding to NOC as part of the Climate Linked Atlantic Section Science (CLASS) program, grant number NE/R015953/1. The funders had no role in the study data processing and analysis, decision to publish, or preparation of the manuscript. We would also like to thank the scientific party and crew of the Research Vessel Yuzhmorgeologiya for their excellent work during marine operations.


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Progress in Oceanography



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