Preliminary Studies On The Benthos From Deep-sea Hydrothermal Fields In Indian Ocean And East Pacific Rise

Studies on deep-sea hydrothermal activities and hydrothermal lives have been one of themost interesting topics in international marine researches, and in order to explore the deepsea mineral and biological resources, COMRA (China Ocean Mineral Resources R&DAssociation) successfully organized many deep-sea hydrothermal survey voyages. During2009~2010，many great achievements were obtained in the deep-sea hydrothermal survey ofChinese DY115-21expedition, finding an inactive hydrothermal vent and an inferred activehydrothermal vent in Southwest Indian Ridge, and a confirmed active hydrothermal vent fieldin East Pacific Rise. This paper analysed the sediment and fauna samples of15sites collectedfrom the hydrothermal fields both in Indian Ocean and East Pacific Rise (EPR) during theChinese DY115-21expedition to preliminarily study the ecology and taxonomy of thesebenthic communities. The main results are as followed:1. Six meiobenthos groups were distinguished for samples from sites of Indian Ocean(four stations). Nematode and copepoda were the dominant group in the communities, with88.93%and8.28%of the total benthos in individuals, respectively, but the other groups arefew. Average abundance, biomass (dry weight), and production of meiobenthos is43.02±43.24ind/10cm2、35.76±25.22μg/10cm2and321.86±226.99μg/10cm2/a,respectively. Our results showed that abundance, biomass and biodiversity of21V-S25-TVMC1station was significantly different from those of the other three sites,and we speculated that hydrothermal activites may be reponsible for it.2. Seventeen benthos groups were distinguished for samples from sites of EPR (elevenstations), in which meiobenthos had nine groups, macrobenthos seven groups, andmegabenthos eleven groups. The diversity of meiobenthos community was low (the mean ofH ’ is0.3977) and the meiobenthos community was mainly dominated by nematode, andfollowed by copepoda. The abundance of the other groups was extremely low, accounting forbelow1%of of total benthos in terms of abudance. Site of21III-S18-TVG14was aconfirmed hydrothermal vent found by China and biodiversity index was higher thanthose in the other sites.3. We identified several megabenthic groups sampled from a new hydrothermal vent of EPR based on the morphological traits, including Bathymodiolus thermophilus Kenk&Wilson1985, Calyptogena magnific Boss&Turner1980and pycnogonids of genusSericosura, and discussed the taxonomy in the level of genus and species. On the basis, weprelimarily concluded that Sericosura sp. I and Sericosura sp. II are new species.