The contribution of dissolved organic nitrogen by nanoflagellate grazing in the subtropical coastal region in autumn

• Main Authors: Zhi-Ning Lin, 林芷寧
• Other Authors: Kuo-Ping Chiang
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/2k59wn

碩士 === 國立臺灣海洋大學 === 海洋環境與生態研究所 === 106 === Nanoflagellate (NF) is a major bacterial grazer. The process of NF ingestion releases dissolved organic matter (DOM) and support bacterial growth. However, there are many origins of DOM in oceans. In this study, the culture experiments of adding 15N labeled bacteria and ingestion experiments of adding fluorescence labeled bacteria were carry out at the coast of northeastern Taiwan in September 2017. In order to understand the contribution of releasing dissolved organic nitrogen (DON) during NF feeding. The results of the analysis showed that the number of NF increased from 962 cells ml-1 to 2526 cells ml-1, and the ingestion rate of HF increased from 7 bac HNF-1 h-1 to 10 bac HNF-1 h-1. The per milliliter average ingestion rate of 15N bacteria was 0.012 ± 0.006 ng N ml-1 h-1. We suppose that the released rate of DON of NF is 0.3, the rate of DON release by NF was about 0.004 ng N ml-1 h-1. However, the rate of total 15N release into water was 0.05 ng N ml-1 h-1, indicating that only 8% of the DON contributed to NF ingestion releasing. Moreover, in order to understand the reduced of PON in culture has become DON , we used IRMS (Isotope Ratio Mass Spectrometer) to measure the 15N-labelled total dissolved nitrogen(T15N = DO15N + 15NH4+ + 15NO3-) in the sample. The results showed that most the reduced PON does indeed translate into DON.