[Giant protists (xenophyophores and komokiaceans) from the Clarion-Clipperton ferromanganese nodule field (Eastern Pacific)].

Our previous investigations showed that giant protists (xenophyophores and komokiaceans) are one of the key groups in the deep-sea mega- and macrobenthos, dominating in density and biomass in some areas of the World Ocean. Analyses of 38600 seafloor photographs and fauna from 30 box-corers taken in the Russian Exploratory area at the Clarion-Clipperton Fracture Zone ferromanganese nodule field revealed a diverse and abundant fauna of these organisms. Xenophyophores were found on 70% of seafloor photographs. Their abundance averaged 1600 specimens per hectare, whereas abundance of the next common group, Actiniaria, did not exceed 170 specimens per hectare. The maximum abundance of xenophyophores was 12 specimens per m2 (equal to 120000 specimens per hectare). In the box-corers, xenophyophores were found in 30% of samples. The most common group in these samples was Komokiacea. They occurred in 100% of samples. It was shown earlier that abundance and species diversity of macro- and meiobenthos increased when xenophyophores and komokiaceans were present. On the Russian exploratory area, the giant protists structure benthic communities. Study of these protists is especially important in the light of mining planned in the deep sea and for understanding of recovery of benthic communities after mining. We have found 6 species of xenophyophores, 4 of them were new and 25 species of komokiaceans, most part of part of them was not known earlier.