南极罗斯海表层沉积物中的放射虫组合分布及与其他硅质生物关系和环境生态意义

BIOGENIC SILICA AND RADIOLARIAN ASSEMBLAGES IN THE SURFACE SEDIMENTS OF ROSS SEA, ANTARCTICA AND THEIR IMPLICATIONS ON MARINE ENVIRONMENT AND ECOLOGY

本文利用中国第31-33次南极科学考察在罗斯海陆架区采取的表层沉积物样品,研究了生物硅含量、硅质微体生物遗骸丰度分布特征和放射虫属种组合及其与海洋环境和生态的关系。研究显示,区域上生物硅含量是硅藻、放射虫和海绵骨针共同沉积的结果。其中,高的硅藻和放射虫丰度指示了罗斯海陆架区西部表层水初级生产力,而高的海绵骨针丰度可能与悬浮食物来源有关。主要放射虫属种的Q型因子分析将37个放射虫优势种归为四类属种组合。其中,以Antarctissa denticulata为优势种的组合代表寒冷的南极表层水;以Plectacantha oikiskos-Antarctissa(?)sp.1为优势种的组合指示水深和地形变化大、高初级生产力的近岸环境,代表罗斯海季节性海冰生成活跃的冰缘区;以Antarctissa strelkovi-Trisulcus borealis为优势种的组合中,A.strelkovi可能指示表层水硅酸盐浓度较高的浅水环境,而Trisulcus borealis和其它优势种可能受到多种环境因素的共同影响;以Lithomelissa setosa为优势种的组合主要受到上层冷暖水团混合的影响较大,可能指示侵入罗斯海陆架中部的变性绕极深层水。

Distribution patterns of biogenic silica content,siliceous microfossil abundances,radiolarian assemblages and their relation with marine environment and ecology are studied based on the box-core sediment samples collected from the Ross Sea continental shelf,Antarctica during the 31 st-33 rd Chinese National Antarctic Expedition.Biogenic silica content in the research area is contributed by diatoms,radiolarians and sponge spicules.High abundances of diatoms and radiolarians indicate primary productivity in surface water,while the abundance of sponge spicules may be relevant to source of suspending feed.Selected 37 dominant radiolarian species are divided into 4 assemblages by Q-factor analysis.Assemblage dominated by Antarctissa denticulata represents cold Antarctic Surface Water.Assemblage dominated by Plectacantha oikiskos and Antarctissa(?)sp.1 denotes neritic environment with various topography and high productivity,which represents marginal ice-zone with active seasonal sea ice in Ross Sea sector.In assemblage dominated by Antarctissa strelkovi-Trisulcus borealis,distribution of A.strelkovi implies high-silicate surface water from shallow water sites,Trisulcus borealis and other species are influenced by multiple environmental factors.Assemblage dominated by Lithomelissa setosa reflects warm and cold water mixing in upper water column,displaying intrusion of Modified Circumpolar Deep Water towards the central continental shelf.