| 摘要: |
| 为查明冲绳海槽北部浮游有孔虫动物群的分布特征与海洋环境之间的关系, 对1992年6月和1999年6月两次采自冲绳海槽北部111个表层沉积物中的浮游有孔虫进行了鉴定和统计, 并利用Q型因子分析方法对其群落组合特征进行了分析。结果表明, 冲绳海槽北部浮游有孔虫主要有3个因子组合。以Globigerinita glutinata (Egger)为代表的主因子1主要分布在东南侧的黑潮主干和对马暖流控制区内, 同时受西侧陆架冷水影响的部分站位也
显示了较高的载荷值。G. glutinata的种群特征显示, 黑潮主干和对马暖流控制区以大个体分子为主, 而小个体分子主要集中在受冷水影响的陆架浅水区。因此, G. glutinata很可能是30°N以北海域黑潮及其分支流系的优势种, 而其小个体分子在陆架浅水的存在可能与东海冷涡沉积动力环境相关。以浅生种Globigerinoides ruber (d'Orbigny)为代表的主因子2主要分布在研究区西侧和北侧水深100—150m之间的陆架浅水区。以Neogloboquadrina dutertrei (d'Orbigny)和Pulleniatina obliquiloculata (Parker & Jones)为代表的主因子3, 主要分布在研究区中部的黑潮和对马暖流与陆架水的混合区内。因此, 冲绳海槽北部浮游有孔虫动物群的分布受到海流、水团、水深等多种海洋环境因素的影响。
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| 关键词: 浮游有孔虫,Q型因子分析,海洋环境,冲绳海槽北部 |
| DOI：10.11693/hyhz200305006006 |
| 分类号: |
| 基金项目:国家自然科学基金项目,49736210、40176019号和中国科学院院知识创新工程项目,KZCX3-SW-220号 |
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| PLANKTONIC FORAMINIFERA DISTRIBUTIONS IN SURFACE SEDIMENTS OF THE NORTHERN OKINAWA TROUGH AND THEIR MARINE ENVIRONMENT INTERPRETATION |
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SUN Rong-Tao1, LI Tie-Gang1, CAO Qi-Yuan1, XIANG Rong2
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1.Institute of Oceanology, The Chinese Academy of Sciences;2.Ocean University of China
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| Abstract: |
| Surficial sediment samples collected from the northern Okinawa Trough (water depths 100—1000m) were analyzed to reveal the relationship between the distributional pattern of recent planktonic foraminifera and marine environment. 33 species were identified from > 150μm portions of dry samples, with 6 of them having a percentage abundance exceeding 5%. The sites with abundance higher than 1000ind/g are mainly distributed in the southeast region influenced by the warm Tsushima Current and the main track of the Kuroshio. Planktonic foraminiferal abundances of the northeast part of the region controlled by the Tsushima Current range from 400ind/g to 1000ind/g, whereas the abundance in the western shelf region influenced by the Yellow Sea cold watermass andthe coastal current isbelow400ind/g. The distribution of the simple diversity and the complex diversity show similar trend that the sites with species more than 20 and the complex diversity higher than 2.1 are mainly distributed in the southeast part.
Q-mode factor analysis was carried out for the census data; 3 factors were recognized and accounted for 91.1% of the variance for G. glutinata, G. ruber, N. dutertrei and P. obliquiloculata. High loadings on factor 1 characterized
by G. glutinata are distributed mainly in the southeast, under the main track of the Kuroshio Current or controlled by the warm Tsushima Current. Some sites in the west also showed high negative loadings onfactor 1, but the G. glutinata individuals were all small-size ones possibly caused by the East China Sea cold cyclonic eddy water dynamics environment. High loadings on factor 2 are mainly distributed in the western and the northern parts (water depth < 150m). Corresponding foraminiferal assemblage characterized by G. ruber, a typical “shallow water species”, dominated the area where the abundances of other foraminifera dropped dramatically; apparently, the most evident influencing factor is water depth, rather than water mass or sea current. High positive loadings on factor 3 are mainly distributed in the middle part, a commix region influenced by the Kuroshio/Tsushima Current water and cold shelf water. Generally, they spread out along the 200m isobath from the southwest to the northeast, where there is a front of Tsushima current water and cold shelf water. The strong turbulence and fitting temperature provided the best living condition for N. dutertrei. Another dominant species of factor 3 is P. obliquiloculata, an indicating species of the Kuroshio recognized by previous studies, changed into the main component of fauna in the commix front in the northern Okinawa Trough. With the increasing latitude the water temperature and structure of Kuroshio had changed, which led to reduction of the relative abundance of P. obliquiloculata. The distribution of planktonic foraminifera in the northern Okinawa Trough was primarily affected by the Kuroshio and its anabranches. The biocoenosis structure and its distribution showed a diffusing trend from the warm current to the shallow shelf water.
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| Key words: Planktonic foraminifera, Q-model factor analysis, Marine environment, The northern Okinawa Trough |
