Preliminary Studies On The Benthos From Deep-sea Hydrothermal Fields In Lau Basin Of Southwest Pacific And Southwest Indian Ridge

Studies on deep-sea hydrothermal activities and hydrothermal lives have been one of the most interesting topics in international marine researches, and the deep-sea hydrothermal ecosystem is showing us a unique benthal picture about lives. This paper analyses the sediment and fauna samples of 45 sites collected during the Chinese DY115-19 and DY115-20 expeditions from the hydrothermal fields both in Lau Basin and in Southewest Indian Ridge (SWIR). Ecology and taxonomy preliminary researches about these benthic communities have been done, follows are the main results:1. Thirteen meiobenthos groups are detected in Lau Basin hydrothermal fields, nematode is the dominant one in individual amount, takes 45.29% of the total benthos, acari followed, 30.53%, and copepoda is the third one, 17.56%, the other groups are few. Average abundance, biomass, and production of meiobenthos is 18.67±10.12 ind/10cm2,34.79±23.57μg?dwt/10cm2 and 313.09±212.12μg?dwt/10cm2?a respectively.2. Twenty-two benthic groups are detected in twenty-nine sites in hydrothermal surveyed fields of SWIR, meiobenthos have eleven groups, macrobenthos have twelve groups, and megabenthos have fourteen groups. The meiobenthos community is mainly dominated by nematode in individual amount, followed by copepoda, but the amount of the other groups is low. In another side, amphipoda and tanaidacea are the dominated groups in a few sites while nematode is few. Comparing with the meiobenthos community of Lau Basin, amphipoda and tanaidacea are richer in individual amount in SWIR but acari are few correspondingly.3. In those surveyed sites of SWIR, only nematode and copepoda are detected in the sediment which containing much sulfides, showing the least groups number and diversity index. Copepoda and amphipoda dominate the benthic community in harder foraminifers'mud which has the highest groups number and diversity index. Tanaidacea, Isopoda and nematode take not low percentages in this community either. The community in softer foraminifers'mud which is dominated by nematode and copepoda, and nematode is the richest groups. Community in silidous mud with much opal is dominated by nematode-copepoda and followed by amphipoda-tanaidacea.4. Morphological taxon researches in several megabenthic groups from SWIR hydrothermal fields have been carried out, including scalpellomorpha, ischnochitonidae, mytilidae, squat lobster and some other lives related with hydrothermal activities: scaly-foot gastropod, thecosomata, et al. The preliminary studies on galathea'morphological taxons have been done too, and a table of abridged keys to families of Galatheoidea is presented.