Characterization of deep-sea macrobenthos in the Korea exploration claim area in the Clarion-Clipperton Fracture Zone, Northeastern Pacific

Abstract

Macrobenthos in the Clarion-Clipperton Fracture Zone remains poorly understood, due both to gross undersampling and to the fact that most species collected from the area are new to science. Evaluation of the diversity and species distribution of the benthic fauna in this area is critical to predicting and managing the impacts of manganese nodule mining. In this study, we investigated the distribution of macrobenthos to understand the natural variability in the macrobenthic community and, by extension, to establish a baseline for environmental risk assessment. Samples were collected from KR5 block of the Korea Contract Area, within the abyssal area of the Clarion-Clipperton Fracture Zone in the northeastern Pacific Ocean, by the RV Onnuri from 2012-2014. A total of 36 core samples were examined in the survey, from which we identified 183 macrobenthic species in 25 faunal groups with a mean density of 257 ind/m2. Not taking into acount meiofaunal groups such as nematodes and harpacticoid copepods, the highest percentage of individuals was represented by Arthropoda. The dominant species (>1% of total density) were the tanaids Typhlotanais sp.1, and Akanthophoreus spp. and Stenotanais sp., the isopod Macrostylis sp.1, and the polychaetes, Cirratulidae spp. and Levinsenia uncinata. The abundances of two dominant species, the tanaid Typhlotanais sp1. and isopod Macrostylis sp.1., were positively correlated with total organon of the benthic fauna in this area is critical to predicting and managing the impacts of manganese nodule mining. In this study, we investigated the distribution of macrobenthos to understand the natural variability in the macrobenthic community and, by extension, to establish a baseline for environmental risk assessment. Samples were collected from KR5 block of the Korea Contract Area, within the abyssal area of the Clarion-Clipperton Fracture Zone in the northeastern Pacific Ocean, by the RV Onnuri from 2012-2014. A total of 36 core samples were examined in the survey, from which we identified 183 macrobenthic species in 25 faunal groups with a mean density of 257 ind/m2. Not taking into acount meiofaunal groups such as nematodes and harpacticoid copepods, the highest percentage of individuals was represented by Arthropoda. The dominant species (>1% of total density) were the tanaids Typhlotanais sp.1, and Akanthophoreus spp. and Stenotanais sp., the isopod Macrostylis sp.1, and the polychaetes, Cirratulidae spp. and Levinsenia uncinata. The abundances of two dominant species, the tanaid Typhlotanais sp1. and isopod Macrostylis sp.1., were positively correlated with total organ