The Clarion-Clipperton Zone (CCZ) is an abyssal region of the tropical eastern Pacific Ocean where deep-sea mining may take place in the near future (Ramirez-Llodra et al. 2011, Wedding et al. 2013; Fig. 1). High-grade polymetallic nodules, which could provide a commercial source of copper, cobalt, nickel, and manganese (among other metals), are abundant in this six million km² region that lies in Areas Beyond National Jurisdiction (ABNJ), and thus falls under the legal mandate of the International Seabed Authority (ISA) (Wedding et al. 2013). Thus far, there have been 16 exploration leases (each up to 75,000 km² in area) granted by the International Seabed Authority in the CCZ, with those for exploitation expected to soon follow (https://www.isa.org.jm/).

Figure 1.  

Locations of megafaunal surveys during the ABYSSLINE cruises, AB01 and AB02, in the Clarion-Clipperton Zone. (a) The location of the UKSRL exploration contract area (UK-1) in the eastern Pacific Ocean. (b) The locations of the 30x30-km survey areas, UK-1 Stratum A and UK-1 Stratum B, in relation to the UK-1 exploration contract area and the AB01 ROV dive site, EPIRB, which was approximately 250 km east of the UK-1 contract area. (c) The locations of ROV dives within UK-1 Stratum A, indicated by purple tracklines labelled with the dive number (e.g. RV01). Stations where samples were collected with a Brenke epibenthic sled (EB04) and megacorer (MC10) are also indicated. (d) The locations of AUV dives within UK-1 Stratum B, indicated by purple tracklines labelled with the dive number (e.g. AV01). Stations where samples were collected with a Brenke epibenthic sled (EB02), box corer (BC02, BC19) and megacorer (MC17, MC25) are also indicated, as well as where imagery was collected with a baited camera (CA02). All maps were created by Seafloor Investigations Ltd for the ABYSSLINE Project using ArcGIS software (https://www.arcgis.com/features/).

The ABYSSLINE (ABYSSal BaseLINE) Project was designed to undertake benthic biological baseline studies in accordance with ISA environmental guidelines within the UK Seabed Resources Ltd (UKSRL) exploration contract area (UK-1) (Amon et al. 2016b). The UK-1 exploration contract area is one of the easternmost contract areas in the CCZ and encompasses ~58,000 km² of seafloor (Fig. 1). 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. 2016a, Amon et al. 2016b, Dahlgren et al. 2016, Glover et al. 2015, Glover et al. 2016, Shulse et al. 2016). No faunal studies had been undertaken in the UK-1 contract area prior to licensing in 2013.

It is expected that nodule mining will drastically alter this unique deep-sea habitat with recovery expected to be slow (Amon et al. 2016b, Vanreusel et al. 2016, Ramirez-Llodra et al. 2011, Oebius et al. 2001) and yet, despite increases in technology and the number of expeditions to the area, very little is known about the ecology and biogeography of the fauna inhabiting the region (Amon et al. 2016a, Amon et al. 2016b, Dahlgren et al. 2016, Foell and Pawson 1986, Bluhm and Gebruk 1999, Glover et al. 2016, Martinez-Arbizu et al. 2013, Pawson 1983, Pawson and Foell 1986, Roux 2004, Roux and Pawson 1999, Shulse et al. 2016, Tilot 2006, Vanreusel et al. 2016). The megafauna constitute an important component of the biodiversity in the abyssal deep sea and play a significant role in deep-sea ecosystem function (Amon et al. 2016a, Amon et al. 2016b, Smith et al. 2008, Vanreusel et al. 2016). It has also been suggested that echinoderms may act as indicators of physical disturbance of the seabed, such as that caused by deep-sea polymetallic-nodule mining (Bluhm and Gebruk 1999). Glover et al. 2016 reported that a search of OBIS listed 698 echinoderm species recorded at abyssal depths worldwide between 3000m and 6000m, but only 50 species within the CCZ. Amon et al. 2016b was able to confirm that there were no echinoderm or megafauna records for the UK-1 exploration contract area in OBIS. This is likely the result of lack of sampling, taxonomy and/or ensuring data are publicly available, especially as an abundant and diverse echinoderm fauna is already known from the tropical Pacific Ocean from photographic and video survey (Amon et al. 2016a, Amon et al. 2016b, Dahlgren et al. 2016, Foell and Pawson 1986, Glover et al. 2016, Martinez-Arbizu et al. 2013, Pawson 1983, Pawson and Foell 1986, Roux and Pawson 1999, Tilot 2006, Vanreusel et al. 2016). In order to predict and manage the environmental impacts of mining in the CCZ and within the UK-1 exploration contract area, baseline knowledge of the megafauna is essential and allows for a complete taxonomic and biogeographic synthesis of the fauna of the CCZ (Wedding et al. 2015).

Here, we present the first section (Echinodermata) of an image atlas of benthic megafauna that inhabit the UK-1 exploration contract area based on ROV and AUV surveys and samples collected during two cruises of the ABYSSLINE project. This section will be supported by the following sections in the near future: 1) Cnidaria, 2) Porifera, and 3) All Other Phyla (Annelida, Arthropoda, Bryozoa, Chordata, Ctenophora, and Mollusca). This atlas was crucial during the ABYSSLINE quantitative megafaunal analyses (Amon et al. 2016b) and we hope that it will facilitate the standardization of the putative morphospecies and be useful to other scientists and stakeholders undertaking research in the CCZ in the future.

Sample collection

Megafaunal image surveys and analyes