The Distribution of Epifaunal Megabenthos Varies with Deep-sea Sediment Conditions in the Korea Deep Ocean Study Area (KODOS) of the North-eastern Pacific

Abstract

In August, 2013, we collected epifaunal megabenthos using a deep sea camera (DSC) around a benthic impact study (BIS) site. This was located in the KR5 block of the Korea Deep Ocean Study (KODOS) area in the Northeastern Pacific. The DSC was positioned at 6.8 ± 2.9 m (SD) from the sea bottom and was operated from a position at 131 o 56.85' -131 o 55.02'W for 2.3 h at a speed of 1-2 knot. The geographical features of the study area consisted of two structures; a trough in the middle and hills at the east and west sides. Sediment conditions were consistent within six blocks and were affected by slope and polymetallic nodule deposits. We analyzed 226 megafaunal species. Sipunculida comprised the highest percentage of individuals (39%), and the dominant epifaunal megabenthos were Hormathiidae sp., Primnoidae sp., Hexactinellida sp., Hyphalaster inermis, Freyella benthophila, Paelopatides confundens, Psychropotes longicauda, and Peniagone leander. More than 80% of the total density of megafauna occurred on sea plain (D-and E-blocks). We found two distinct groups in the community, one located on sea plains and the other along both sides of the sea slop. Our results suggest that geographical features such as slope and polymetalic nodule deposits are important in controlling the distribution of the epifaunal megabenthos around the KODOS area.

Distribution of Rare Earth Elements and Yttrium in Sediments From the Clarion‐Clipperton Fracture Zone, Northeastern Pacific Ocean

“…Surface sediments were acquired from one of the valleys using a multiple corer on the R/V Onnuri during the KODOS13-02 cruise in July-August 2013 and the KODOS14-02 cruise in August-September 2014 (Table 1 and Figure 1c). The seafloor in the sampled area is commonly covered by numerous polymetallic nodules of different sizes, with nodule abundance varying from several to 10 kg/m 2 (Yu et al, 2014(Yu et al, , 2018.…”