胶州湾表层沉积颗石藻Gephyrocapsa oceanica的分布模式及其与环境的关系

对胶州湾和邻近海域表层沉积中颗石藻Gephyrocapsa oceanica的分布进行初步研究，并提出胶州湾内这个种的分布模式，研究结果表明，该种在胶州湾和邻近海域表层沉积颗石藻组合占绝对优势，几个从属种类Braarodosphaera bigelowill,Syracosphaera histrica,S.lamina和Acantholithus sp.等，在一些样品中稀少，在胶州湾，依据Gephyrocapsa oceanica丰度的变化，自岸向海可以划分三个分布带：向岸常见带，浅水丰富带和深水富集带，这一分布模式与海湾水下地貌有密切的关系，在湾外的近岸海域，该种的分布呈现出与湾内相似的特征。

DISTRIBUTION PATTERNS OF NANNOFOSSIL GEPHYROCAPSA OCEANICA IN SURFICIAL SEDIMENTS OF JIAOZHOU BAY, SOUTHERN SHANDONG PENINSULA,CHINA

Surficial sediment samples were collected from the Jiaozhou Bay and adjoining seawaters to study the spatial distribution patterns of calcareous nannofossils within the embayment. The result shows that Gephyrocapsa oceanica monopolized the nannofossil assemblage, whilst some subordinate taxa Braarudosphaera bigelowii, Syracosphaera histrica, S. lamina and Acantholithus sp. etc. scarcely occur in some samples. Three zones for the distribution of Gephyrocapsa oceanica are recognized, according to variations in its abundance value: They are the onshore common zone, shallow water rich zone and deep water accumulation zone, from the coastline to deep waters. Geomorphologically, these zones successively correspond to silty clay tidal flat, sub tidal erosional channels and submarine erosional highlands. The same nannofossil assemblage with an analogous distribution pattern is also observed on the adjacent continental shelf. It is well known that Emiliania huxleyi is one of the most common species in the ocean and Florisphaera profunda is a marker of deep water environments. However, these two species were not found in the study area, which may be explained by ecological controls related to water fertility and quality, and to water depth.