Calcareous Nannoplankton in Continental-Shelf Sediments, East China Sea

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Abstract
Calcareous nannoplankton have been investigated in 22 samples collected from the East China Sea continental shelf and 36 indigenous taxa identified. Nannoplankton abundance and diversity increase progressively in a seaward direction, reflecting changes in water temperature, salinity and terrigenous sediment input to the shelf. The chief environmental factors controlling the distribution of modern nannoplankton assemblages are the cold inshore Coastal Current flowing southward and the warm Kuroshio Current flowing northeastward over the southern middle and outer shelf. The continental shelf can be divided into three zones based on the nannoplankton assemblage: 1) an inner-shelf zone (Gephyrocapsa oceanica Zone) which is low in nannoplankton abundance and diversity and in which the species present are overwhelmingly dominated by G. oceanica; 2) a zone approximating the middle shelf (Gephyrocapsa oceanica-Emiliania huxleyi Zone) in which abundance and diversity are moderate-with G. oceanica and E. huxleyi the dominant species and G. oceanica predominating; and 3) an outer-shelf zone (Emiliania huxleyi-Gephyrocapsa oceanica Zone) of much abundance and diversity, with E. huxleyi predominant over G. oceanica.