Deep-sea metazoan Meiofauna from a Polymetallic nodule area in the Central Indian Ocean Basin

The metazoan meiofauna in the Central Indian Ocean Basin were collected at five deep sea stations (depths ranging 4738 to 5418 m) during the China Ocean Mineral Resources Research and Development Association (COMRA) 22nd Expedition Cruise in December, 2011. The sampling stations were in and around a potentially commercial important polymetallic nodule area. All together five meiofauna taxa were detected, including Nematoda, Harpacticoida copepoda, Polychaeta, Halacaroidea and Ostracoda. Average meiofaunal abundance (9.59 ± 5.44 ind./10cm2) was generally lower than the other meiofaunal abundance reported in the Central Indian Ocean and much lower than those reported from other deep-sea regions. The abundance pattern of vertical distribution corresponded well with those from other deep-sea regions. Biomass calculation with coefficients considering detailed size classes was done. Average total meiofaunal biomass was estimated as 4.64 ± 1.81 μg/10 cm2 (dry weight). The composition of meiofaunal assemblages from different stations differed substantially. Stations in the center of the polymetallic nodule area had similar meiofaunal abundance, biomass, as well as relatively high similarity. The present study could offer a baseline of the meiofauna and enrich the meiofauna data in the area, and could be helpful for future disturbance studies.