两种海洋硅藻透明胞外聚合颗粒物的产生及其生态学意义

透明胞外聚合颗粒物（transparent exopolymer particles，TEP）是一类由胞外多糖组成的透明胶状颗粒物质，对海洋生态系统碳循环具有重要意义。本研究以两种海洋硅藻布氏双尾藻（Ditylume brightwelii）和窄隙角毛藻（Chaetoceros affinis）为研究对象，研究了其在不同生长时期的TEP含量、TEP与叶绿素a（Chlorophyll a，Chl a）的关系及TEP的C:N。结果表明:两种硅藻在整个生长时期均产生TEP，且在不同生长时期的TEP含量不同。布氏双尾藻和窄隙角毛藻最大TEP产量分别在指数期、衰亡期。窄隙角毛藻单位细胞体积和单位Chl a所产最大TEP含量分别是184.91±14.03 fg Xeq./μm3、38.06±4.96 μg Xeq./μg Chl a，高出布氏双尾藻相应单位TEP含量的16倍和5倍。对两种硅藻的Chl a与TEP关系分析表明，在指数期会呈现TEP=α（Chl a）β的函数关系（布氏双尾藻:R2=0.98；窄隙角毛藻:R2=0.80）。两种硅藻TEP的C:N均高于Redfield比值（C:N=106:16）。说明TEP的产生具有种间差异性，且生长时期显著影响TEP产生效率。TEP的高含碳量对海洋碳循环有直接贡献。

Production of transparent exopolymer particles from two marine diatoms and its ecological significance

The transparent exopolymer particles (TEP), a kind of transparent colloidal particulate matter, consists of extracellular polysaccharides.TEP is of great significance to the carbon cycle of marine ecosystems.In this study, two marine diatoms, Ditylume brightwelii and Chaetoceros affinis, were studied.The TEP concentration, the relationship between TEP and Chlorophyll a (Chl a) and the C:N ratio of TEP were studied at different growth phases.The results showed that TEP was produced by both species during the whole growth phases, and TEP concentration was different in different growth phase.The maximum TEP concentration of D.brightwelii and C.affinis was produced in the exponential phase and the decline phase, respectively.The maximum TEP concentration per cell volume and per Chl a of C.affinis was 184.91±14.03 fg Xeq/μm3 and 38.06±4.96 μg Xeq./μg Chl a, and were 16 and 5 times higher than the values obtained from the D.brightwelii.The analysis of the relationship between Chl a and TEP in two diatoms showed that the function relationship between TEP=α (Chl a) β was presented in the exponential phase (D.brightwelii:R2=0.98; C.affinis:R2=0.80).The TEP C:N ratio of both diatoms was higher than the Redfield ratio (C:N=106:16).It indicates that the generation of TEP was difference between species, and the growth phase significantly affects the efficiency of TEP production.The high carbon concentration of TEP show that TEP production contributes significantly to the ocean carbon cycle.