Unexpected high abyssal ophiuroid diversity in polymetallic nodule fields of the Northeast Pacific Ocean, and implications for conservation Magdalini Christodoulou1, Timothy O'Hara2, Andrew Hugall2, Sahar Khodami1, Clara F. Rodrigues3, Ana 5 Hilario3, Annemiek Vink4, Pedro Martinez Arbizu1 1German Centre for Marine Biodiversity Research (DZMB), Senckenberg am Meer, Wilhelmshaven, 26382, Germany 2Laboratory example, city, postal code, country Museums Victoria, Melbourne, 3001, Australia 3 Centre for Environmental and Marine Studies (CESAM), Department of Biology, University of Aveiro, Aveiro, 3810–193, Portugal 10 4Federal Institute for Geosciences and Natural Resources, Marine Geology, 30655, Hannover, Germany Correspondence to: Magdalini Christodoulou (
[email protected]) Abstract. The largest and commercially appealing mineral deposits can be found in the abyssal seafloor of the Clarion- Clipperton Zone (CCZ), a polymetallic nodule province, in the NE Pacific Ocean, where experimental mining is due to take 15 place. In anticipation of deep-sea mining impacts, it has become essential to rapidly and accurately assess biodiversity. For this reason, ophiuroid material collected during eight scientific cruises from five exploration license areas within CCZ, one area protected from mining (APEI3, Area of Particular Environmental Interest) in the periphery of CCZ and the DIS-turbance and re-COLonisation (DISCOL) Experimental Area (DEA), in the SE Pacific Ocean, was examined. Specimens were genetically analysed using a fragment of the mitochondrial cytochrome c oxidase subunit I (COI). Maximum Likelihood and 20 Neighbour Joining trees were constructed, while four tree-based and distance-based methods of species delineation (ABGD, BINs, GMYC, mPTP) were employed to propose Secondary Species Hypotheses (SSHs) within the ophiuroids collected.