磷酸盐和硝酸盐浓度对海链藻Thalassiosira sp.沉降的影响

Effects of Phosphate and Nitrate Concentrations on the Sedimentation of the Marine Chain Alga Thalassiosira sp.

为了研究氮、磷营养盐比例变化对近海硅藻的生理效应及其对硅藻相关碳汇的影响,分别采用半连续培养和一次性培养的方式对海链藻(Thalassiosirasp.)在不同氮磷比及不同氮、磷营养盐浓度的条件下进行模拟培养实验。结果表明:在半连续培养中,营养盐限制明显降低海链藻的胞内叶绿素含量及蛋白质含量,增加了胞内生物硅含量和碳水化合物含量,藻细胞密度变大增加沉降速率;在一次性培养中,指数生长期的沉降速率最低,随着细胞生长逐步到达衰退期,沉降速率随之升高,而在最低营养盐浓度条件下最高。海链藻的沉降速率在低氮磷比的条件下显著升高。因此,近海氮、磷营养元素结构的变化也会对浮游植物相关的碳沉降产生重要影响,在富营养化的生态效应研究中不容忽视。

In order to study the physiological effects of changes in nitrogen and phosphorus nutrient ratio on offshore diatoms and their effects on diatom-associated carbon sinking,we carried out a series of semi-continuous incubation and batch culture on marine diatom Thalassiosira sp.under different nitrogen and phosphorus ratios and different nitrogen and phosphorus concentrations,respectively.The results showed that on the one hand in semi-continuous cultures,nutrient limitation significantly reduced the intracellular chlorophyll and protein contents,increased the intracellular biogenic silica and carbohydrate contents,and raised the sinking rate by increasing cell density.On the other hand,in the batch culture,the lowest sinking rate was observed in the exponential growth phase.As the cell growth gradually reached the stationary stage,the sinking rate significantly increased,and reached the highest under the condition of the lowest nutrient concentration.In general,our results indicated that the sinking of Thalassiosira sp.was significantly accelerated under low N/P ratio conditions.Therefore,changes in the structure of offshore nitrogen and phosphorus nutrients will also have important impacts on phytoplankton-related carbon sinking,which cannot be ignored in the study of the ecological effects of eutrophication.