EDITORIAL

Editorial: Biodiversity of the Clarion Clipperton Fracture Zone

Stefanie Kaiser1 & Craig R. Smith2& Pedro Martinez Arbizu1

Received: 5 May 2017 /Accepted: 6 May 2017 /Published online: 27 May 2017# Senckenberg Gesellschaft für Naturforschung and Springer-Verlag Berlin Heidelberg 2017

Background

Deep-sea areas (>200 m and beyond) support high biodiver-sity, but also hold economically important reservoirs of min-eral deposits, including polymetallic nodules (or manganesenodules), cobalt-rich ferromanganese crusts and polymetallicsulphides, among others. Regions of interest are often locatedin areas beyond jurisdiction, i.e. in ‘The Area,’ and any activ-ities there related to the exploration and exploitation of non-living resources are managed by the International SeabedAuthority (ISA). For polymetallic nodules, the ClarionClipperton Fracture Zone (CCZ), in the north-eastern equato-rial Pacific, is the area of greatest commercial interest (Fig. 1)(Wedding et al. 2015). The CCZ encompasses about six mil-lion square kilometres of abyssal (>3000 m) seafloor, an areanearly the size of Europe, and the region harbours among theworld’s most economically valuable deposits of polymetallicnodules (Figs 2 and 3) and is, thus, potentially a major sourceof copper, nickel, cobalt and other minerals.

The CCZ is also of great interest from an ecological pointof view. In fact, it displays a spatially very heterogeneousenvironment characterised by, for example, changes in nodulesizes and densities, large-scale productivity and depth gradi-ents, as well as a high abundance of topographic features, suchas seamounts, hills and channels (e.g. Wedding et al. 2013).

The variety of habitats has been thought to promote higherdiversity of associated benthic communities compared toabyssal areas elsewhere (Ramirez-Llodra et al. 2010; Janssenet al. 2015; Amon et al. 2016b; Vanreusel et al. 2016).

Nodules lie on the surface of the soft-sediment seafloorand, therefore, themselves represent important (micro-)habi-tats for the sessile biota (e.g. xenophyophores, antipathariancorals, sponges), as well as several meiofaunal and microbialtaxa found inside the sediment-filled nodule crevices (Fig. 3;Thiel et al. 1993; Veillette et al. 2007; Vanreusel et al. 2016). Arecent study by Amon et al. (2016b) suggested that more thanhalf of megafaunal species in the CCZ depend on nodules as ahard substrate. Furthermore, nodule areas seem to containhigher densities of mobile megafauna compared to those lack-ing nodules (Amon et al. 2016b; Vanreusel et al. 2016). Manyspecies appear have to have very limited geographic rangesconsistent with reproduction patterns; alternatively, these spe-cies may simply be rare and undersampled (Glover et al. 2002;Janssen et al. 2015;Wilson 2017). In addition, there are quite afew common species, in some cases broadcast spawners, oc-curring widely across the CCZ (e.g. Glover et al. 2002;Gooday et al. 2015; Wilson 2017).

The extraction of deep-sea minerals will alter the structureand functioning of ecosystems targeted for mining. Althoughbiological research on the nodule fauna began in the 1970s(Jones et al. 2017 and citations therein), many fundamentalecological questions (e.g. related to levels of biodiversity, spe-cies ranges, connectivity among populations and habitats) re-main unanswered, making the impacts of mining difficult topredict. It does seem to be clear, though, that nodules haveboth significant economic and ecological value (Fritz 2016).In particular, the removal or burial of nodules by mining ac-tivities will erase the biota that depend on nodules for habitat,and will also affect the soft-sediment fauna through sedimentcompression and disruption of near-surface sediment layers

* Stefanie Kaiserstefanie.kaiser@senckenberg.de

1 DZMB, German Centre for Marine Biodiversity Research,Senckenberg am Meer, Südstrand 44,26382 Wilhelmshaven, Germany

2 Department of Oceanography, University of Hawaii at Manoa, 1000Pope Road, Honolulu, HI 96822, USA

Mar Biodiv (2017) 47:259–264DOI 10.1007/s12526-017-0733-0

Fig. 1 Location of licence areas and Areas of Particular Environmental Interest (APEIs) across the Clarion Clipperton Fracture Zone [CCZ; mapcourtesy of the International Seabed Authority (ISA)]

Fig. 2 Seabed image (using ROV) of a nodule site in the CCZ. Polymetallic nodules cover large areas of abyssal seafloor in the north-eastern centralPacific, varying greatly in size and density, even at the kilometre scale (image courtesy of GEOMAR)

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(Miljutin et al. 2011; Vanreusel et al. 2016; Jones et al. 2017;Gollner et al. 2017). Due to the slow growth rates of nodules(ca. 10 mm/My) and overall very low sedimentation rates,short-term recovery is unlikely; the nodules and nodule-dependent fauna may take millions of years to recover, andeven the partial recovery of the motile sediment-dwelling fau-na may take hundreds to thousands of years (Smith et al.2008b; Miljutin et al. 2011; Wedding et al. 2013; Gollneret al. 2017). Additionally, mining impacts may be far-

reaching, beyond the actual mining block, that would affectbenthic and pelagic communities largely through the disper-sion of sediment plumes, as well as (potentially toxic) dis-charge water from mine tailings (ECORYS 2014; Gollneret al. 2017).

Recent biological findings have led to a plea to develop andimprove environmental regulations and agreements to betterbalance conservation and exploitation needs (e.g. Weddinget al. 2015; Fritz 2016; Le et al. 2017; Vanreusel et al.

Fig. 3 Examples of important planktonic and benthic organisms andhabitats present in the CCZ: a dinophysoid dinoflagellate, Phalacromafavus Kofoid & Michener, 1911; scale bar: 10 μm (image: C.Zinssmeister); b isopod, Ketosoma ruehlemanni Kaiser & Janssen,2017; scale bar: 500 μm (image: T.C. Kihara); c bivalve, Nuculaprofundorum E. A. Smith, 1885; specimens between 1 and 6 mm inlength (image: A. Glover, T. Dahlgren & H. Wiklund); d hexactinellidsponge, Saccocalyx pedunculatus Schulze, 1896; specimen about18.9 cm in length (image courtesy of GEOMAR); e nematode,Acantholaimus sp. (family Chromadoridae Filipjev, 1917); specimenabout 1.4–1.7 μm in length (image: R. Singh); f polymetallic nodulesrepresent important habitats for a diverse fauna inhabiting the surfaceand nodule crevices; the nodule pictured is about 8 cm in diameter

(image: S. Kaiser); g wood fall collected during the JPIO EcoResponse(SO239) expedition to the CCZ (image courtesy of GEOMAR); hxenophyophore, Psammina limbata Kamenskaya, Gooday & Tendal,2015, encrusting a manganese nodule; specimen about 2 cm in size(image: O. Kamenskaya); i seamount habitat in the CCZ (imagecourtesy of GEOMAR); j harpacticoid copepod, Pseudotachidiusbipartitus Montagna, 1980; scale bar: 500 μm (image: U. Raschka); kpolychaete, Bathyeliasona sp. nov., Polynoidae Kinberg, 1856; specimen9.86 mm in length (image: P. Bonifacio); l antipatharian (black) coral,Abyssopathes lyra (Brook, 1889); specimen about 8 cm in length (image:T. Molodtsova);m ophiuroid, Ophiomusium cf. glabrum, scale bar: 1 cm(image courtesy of A. Hilario & P. Ribeiro)

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2016). Following a precautionary approach, the ISA protecteda network of nine 160,000-km2 no-mining areas, now calledAreas of Particular Environmental Interest (APEIs), to safe-guard biodiversity and ecosystem function in the CCZ (Smithet al. 2008a;Wedding et al. 2013, 2015). Although the originalnetwork design included APEIs in the core of the CCZ (Smithet al. 2008a; Wedding et al. 2013), the APEIs are now locatedmainly in the outer regions of the CCZ and were selectedbased on environmental proxies; until 2015, no biologicalsampling had been undertaken in these areas to directly eval-uate the degree of connectivity between faunal assemblages ofAPEIs and areas targeted for mining (Martínez Arbizu andHaeckel 2015; Amon et al. 2016b; Vanreusel et al. 2016).Nevertheless, Vanreusel et al. (2016) concluded that APEIsare crucial to protect and preserve regional-scale diversity,but also recommended protected areas (i.e. preservation refer-ence areas, PRA) within each licence area using criteria (e.g.sufficient nodule coverage) to facilitate recolonisation of near-by impacted seafloor areas.

The first 15-year licences to explore polymetallic noduleoccurrences in the CCZ were issued in 2001 and, since then,ISA has approved 15 exploration contracts (by March 2017,http://www.isa.org.jm), of which six expired or were extendedin 2016. The ISA is currently framing regulations for theexploitation of deep-seabed minerals in ABNJ. At the sametime, the UN is developing recommendations for ecosystem-based management of mining activities in ‘The Area’ to betterprotect its biodiversity (ISA and ITLOS PreparatoryCommission 1990; Danovaro et al. 2017). Thus, it is timelyto improve the characterisation of the biodiversity of theCCZ and the understanding of underlying processes, includ-ing taxonomic analyses and inventories, to provide a soundbasis to address crucial ecological and biogeographicquestions.

Highlights in this special issue

This special issue of Marine Biodiversity presents a series ofpapers illustrating different facets of the biodiversity of theCCZ region, encompassing a wide range of taxonomicgroups, size classes and habitats (see Fig. 3). New speciesdescriptions, in particular for previously neglected groups,illustrate a taxonomically more balanced view and representone of many smaller steps for diversity estimations(Kamenskaya et al. 2016; Markhaseva et al. 2017;Molodtsova and Opresko 2017; Zinssmeister et al. 2017). Insitu observations from video and still imagery using mannedand unmanned (ROV, AUV) submersibles have led to discov-eries of new habitats and also yielded valuable biogeographicinformation (Amon et al. 2016a; Durden et al. 2017;Vecchione 2016), while community analyses provideimportant insights into the patterns and processes driving

(macro-)faunal diversity and turnover at local to regionalscales (Wilson 2017).

Dinoflagellate protists are a common and diversecomponent of the marine plankton and, yet, the study ofZinssmeister et al. (2017) represents the first on the diversityof dinophysoid dinoflagellates in the CCZ. The authors couldidentify 66 species and 11 genera, which greatly exceedsnumbers previously reported from elsewhere in the easternPacific. The sample collection contained a number of speciesnew to the area, some of which may represent undescribedspecies.

Kamenskaya et al. (2016) report novel data onxenophyophores, a group of large, agglutinated foraminif-erans that are typically among the most dominant megafaunaltaxa in the CCZ. Xenophyophores also appear to be particu-larly diverse in nodule areas of the eastern Pacific (Goodayet al. 2017) and Kamenskaya and co-authors (2016) add to thisdiversity by describing three new species from the Russianlicence area of the CCZ. This is likely reflects just a fractionof the species present, because there are still severalxenophyophore species awaiting formal description(Kamenskaya et al. 2016).

Until now, there has been a paucity of data onbenthopelagic calanoids from abyssal waters of the CCZ.Markhaseva et al. (2017) provide a description of a new spe-cies within the cosmopolitan family Aetideidae, which iscomplemented by biogeographic information. While this isthe first record of the genus Pseudeuchaeta from the equato-rial Pacific, the few records of benthopelagic calanoid taxa ingeneral points towards great undersampling of the deepbenthopelagic realm (Markhaseva et al. 2017).

Antipatharian corals, or black corals, are commonly foundin nodule areas of the abyss, while they are absent fromnodule-poor sites, making them potentially very susceptibleto mining impact (Vanreusel et al. 2016; Molodtsova andOpresko 2017). In their study, Molodtsova and Opresko(2017) present a checklist of abyssal antipatharian species,as well as a morphological assessment of all species knownfrom the CCZ. Furthermore, they describe a new genus andspecies from the CCZ, both of which were previously record-ed from the Indian Ocean and, thus, have rather broaddistributions.

Paleodictyon nodosum represents a trace fossil found indeep-sea areas of the Atlantic and Pacific oceans. Durdenet al. (2017) provide the first in situ observation from theCCZ. Although Paleodictyon nodosum creates a distinct sym-metric pattern and is commonly found on the abyssal seabed,its origin and function remains elusive. Therefore, Durdenet al. (2017) discuss the potential use of time-lapse imagery,among other techniques, to elucidate unresolved questions.

Cirrate (finned) octopods are confined to the deep sea,where they are distributed globally. In the CCZ, they belongto the larger, potentially rarer megafauna, and data on their

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distribution are scarce. Vecchione (2016) reports records oftwo families of cirrate octopods, based on identification fromvideo images, from the French licence areas. It is likely thatother cephalopod taxa are present in the CCZ, such as big-finsquid and incirrate octopods (Vecchione 2016; see also Purseret al. 2016).

Organic falls, such as wood and whale carcasses, are asignificant source of habitat heterogeneity in the deep sea.On the seafloor, they represent an important hard-substrateand organic-rich habitat, supporting unique microbial andfaunal communities. Amon et al. (2016a) present the firststudy of wood falls and associated faunal assemblages exam-ined from different licence areas and APEIs in the CCZ. Theirfindings suggest that wood falls are, despite the great distancefrom land, a common phenomenon in the CCZ, with the po-tential to enhance local and regional diversity.

Understanding of the drivers that constrain speciesdistributions and the degree of connectivity betweencommunities is important to assess ecosystem resilience tomining impacts. Wilson (2017) analysed variation in macro-faunal community composition and diversity under differentproductivity regimes in the CCZ and in relation to reproduc-tive mode. He found contrasting patterns in diversity and dis-tributional ranges among the taxa investigated. This leads tothe assumption that diversity patterns should not be inferredfrom a single taxon, but should include a large array of taxarepresentative for the CCZ that encompass a variety of life-history traits and functions.

Summary of highlights

This special issue of Marine Biodiversity includes:

& Among the first biological data from APEIs (Amon et al.2016a; Durden et al. 2017)

& The first study of dinophysoid dinoflagellates from theCCZ (Zinssmeister et al. 2017)

& The first record of wood falls from the CCZ (Amon et al.2016a)

& The first record of Paleodictyon nodosum from the easternequatorial Pacific (Durden et al. 2017)

& New species and/or new distributional records ofxenophyophores, benthopelagic calanoids, antipathariancorals and cirrate octopods (Kamenskaya et al. 2016;Markhaseva et al. 2017; Molodtsova and Opresko 2017;Vecchione 2016)

Acknowledgements We are grateful to the authors for their contribu-tions to this special issue, the publisher who agreed to its compilation andthe referees for their time and effort to improve manuscripts related to thebiodiversity of the Clarion Clipperton Fracture Zone (CCZ). Thanks arealso due to the ship personnel and numerous colleagues for their logisticand scientific support to collect samples during various expeditions to the

CCZ. Furthermore, we would like to thank Diva Amon (SOEST), PauloBonifacio (Ifremer), Thomas Dahlgren (Uni ResearchMiljø), Ana Hilario(U Aveiro), Olga Kamenskaya (IO RAS), Daniel Kersken (SGN),Thomas Kuhn (BGR), Tina Molodtsova (IO RAS), Uwe Raschka(SGN), Ravail Singh (NIO) and Carmen Zinssmeister (SGN) for provid-ing images. The research leading to these results has received fundingfrom the German Ministry of Education and Science (BMBF) as a con-tribution to the European project JPI Oceans BEcological Aspects ofDeep-Sea Mining^, the European Union Seventh FrameworkProgramme (FP7/2007-2013) under the MIDAS project, grant agreementno. 603418, and fromUK Seabed Resources Ltd. to University of Hawaiiin support of the ABYSSLINE Project.

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