Polymetallic nodules were discovered on the Pacific Ocean in 1891. They exist at the sediment surface, sometimes in upper layers of sediments, and cover more than 50% of the sea floor at Clarion鄄Clipperton fracture Zone ( CCFZ) in the north Pacific. The huge economic value from nodule mining has brought to many research programs dedicated to resource evaluation and design of collecting tools in the 1970s. China has carried out surveys on polymetallic nodules and sediment in the CCFZ for many years. Since the late 1980s, China has already got 75000 km 2 exclusive pioneer areas in COMRA忆s contracted area. One of the potential impacts of nodule mining is the destruction of the fauna attached to the partial covering of surrounding epifauna by sediment blanketing. Meiofauna, the important components of benthic ecosystem, are considered to be energetically important in benthic food web. as they play a critical role in the recycling of nutrients. In order to manage and mitigate these impacts, we need to better understand the composition and the distribution of meiofauna and its relationship to the environment.A quantitative study was carried out on " Dayang Yihao冶 in July 2005. The meiofauna samples were collected from 12

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An investigation of the distribution and size composition of chlorophyll a concentration was carried out in the Southwestern Indian Ocean (47-70毅E, 25-40毅S) in January 2011, and factors that might affect the distribution and size composition were discussed. Fluorometric method was used to obtain total and size鄄fractioned chlorophyll a concentrations. The survey was carried out during the austral summer, and there were 6 stations altogether, two of which located in the region of the south Indian Ocean Subtropical Gyre (IOSG) and the other four located in the subtropical convergence zone (SCZ). Water samples were collected from 13 layers in 0-200m column of each station and the vertical profiles of chlorophyll a, nutrients (NO-3 、PO 3-4 and SiO 2-3) , temperature and salinity were obtained. The objective of this study was to investigate the spatial distribution and size fraction of chlorophyll a concentration and to relate them to environmental factors. The results showed that the surface chlorophyll a concentration was low and did not exceed 0. 07mg / m 3 , and the depth of the subsurface chlorophyll a maximum was deep, at approximately 100m and sometimes reaching as deep as 150m in the region of IOSG; However, in the SCZ, the surface chlorophyll a concentration was higher (0. 164-0郾 247 mg / m 3) , and the subsurface chlorophyll a maximum layer occurred between 50-70m. In the region of IOSG, phytoplankton growth is limited by nutrients supply, while the frontal system formed by the Agulhas Return Current (ARC) and the Subtropical Convergence (STC) is a region of intense mesoscale activity presenting enhanced levels of biological production and

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