Megafauna of the UKSRL exploration contract area and eastern Clarion-Clipperton Zone in the Pacific Ocean: Echinodermata

Abstract

BackgroundThere is growing interest in mining polymetallic nodules from the abyssal Clarion-Clipperton Zone (CCZ) in the tropical Pacific Ocean. Despite being the focus of environmental studies for decades, the benthic megafauna of the CCZ remain poorly known. In order to predict and manage the environmental impacts of mining in the CCZ, baseline knowledge of the megafauna is essential. The ABYSSLINE Project has conducted benthic biological baseline surveys in the UK Seabed Resources Ltd polymetallic-nodule exploration contract area (UK-1). Prior to these research cruises in 2013 and 2015, no biological studies had been done in this area of the eastern CCZ.New informationUsing a Remotely Operated Vehicle and Autonomous Underwater Vehicle, the megafauna within the UKSRL exploration contract area (UK-1) and at a site ~250 km east of the UK-1 area were surveyed, allowing us to make the first estimates of megafaunal morphospecies richness from the imagery collected. Here, we present an atlas of the abyssal echinoderm megafauna observed and collected during the ABYSSLINE cruises to the UK-1 polymetallic-nodule exploration contract area in the CCZ. There appear to be at least 62 distinct morphospecies (13 Asteroidea, 5 Crinoidea, 9 Echinoidea, 29 Holothuroidea and 6 Ophiuroidea) identified mostly by imagery but also using molecular barcoding for a limited number of animals that were collected. This atlas will aid the synthesis of megafaunal presence/absence data collected by contractors, scientists and other stakeholders undertaking work in the CCZ, ultimately helping to decipher the biogeography of the megafauna in this threatened habitat.

Unexpected high abyssal ophiuroid diversity in polymetallic nodule fields of the Northeast Pacific Ocean, and implications for conservation

“…The abyssal Eastern Pacific harbours a highly diverse ecosystem. The number of ophiuroid species reported from the polymetallic nodule fields of the Pacific has now increased by 433%, from 10 (Glover et al, 2016;Amon et al, 2017) to 43 in this paper. This is the largest collection of any megafaunal taxon in the CCZ and the only one that has been studied in such detail using a comprehensive combination of morphological and genetic evidence.…”

“…Our initial assumption was that ophiuroid diversity would be low (we expected around 10 species) based on the previous studies in the region (Glover et al, 2016;Amon et al, 2017) and on a recent review of global ophiuroid distribution, in which only 28 species were recorded for the whole tropical East Pacific at abyssal depths (Stöhr et al, 2012). Coupled with expectations of low diversity we assumed that connectivity would be high and that most beta diversity between sites would be composed of nestedness (high) rather than species turnover (low).…”

“…Studies describing the tropical abyssal Northeast Pacific ophiuroid fauna are scarce, including few historical studies resulting from the great expeditions of the late nineteenth and early twentieth centuries such as the HMS Challenger (Lyman, 1878(Lyman, , 1879(Lyman, , 1882Ludwig, 1898Ludwig, , 1899 and the Albatross (Clark, 1911;Clark, 1949). Limited recent studies exist (Amon et al, 2016(Amon et al, , 2017Glover et al, 2016), reporting only a small number of species. Consequently, the diversity of the deep-sea ophiuroid fauna in the CCZ is only poorly known.…”

Unexpected high abyssal ophiuroid diversity in polymetallic nodule fields of the northeast Pacific Ocean and implications for conservation

“…Chao1 uses the proportions of singletons and doubletons in the sample to estimate expected species richness, while ACE is an abundance-based coverage estimator. For the analysis of beta (regional) diversity, the total multiple-site beta diversity β SOR was calculated using the modified Sørensen index (Sørensen, 1948;Baselga and Orme, 2012), and β SOR was decomposed into its additive components "multiple-site species turnover" β SIM (Simpson index: Simpson, 1943) and "multiple-site nestedness" β SNE using the R package "betapart" (Baselga, 2010;Baselga and Orme, 2012). In order to explore the relative contribution of every area to species turnover and nestedness, these values were calculated taking one area out each time in a jackknife approach.…”

Megafauna of the UKSRL exploration contract area and eastern Clarion-Clipperton Zone in the Pacific Ocean: Annelida, Arthropoda, Bryozoa, Chordata, Ctenophora, Mollusca

“…The ABYSSLINE Project was led by scientists from the University of Hawai’i at Mānoa (USA), and included scientists from Hawai’i Pacific University (USA), the Natural History Museum, London (UK), the National Oceanography Centre, Southampton (UK), Senckenberg Gesellschaft für Naturforschung (Germany), Uni Research (Norway), and the International Research Institute of Stavanger (Norway). The ABYSSLINE Project aimed to evaluate baseline conditions of community structure and biodiversity for megafauna, macrofauna, meiofauna and microbes within the UK-1 contract area and across the CCZ ( Amon et al 2016 , Amon et al 2016 , Amon et al 2017 , Dahlgren et al 2016 , Glover et al 2016 , Glover et al 2015 , Leitner et al 2017 , Shulse et al 2016 ). No faunal studies had been undertaken in the UK-1 contract area prior to licensing by the ISA in 2013 and the commencement of the ABYSSLINE Project.…”