| Summary: | 碩士 === 國立臺灣海洋大學 === 海洋環境化學與生態研究所 === 98 === To explore inorganic nutrients effects on the relationship between dissolved organic carbon (DOC) and heterotrophic bacteria production, field survey on 13 stations along the shelf of the South China Sea was conducted in June, 2009. Diel investigation (sampling every 3 hrs for 24 hrs) was conducted at the stations outside Dong-Sha Atoll (i.e. DSA station) and Pearl River mouth (i.e. PR station), at which inorganic nutrient supply was dominated by river discharge and internal tide, respectively. In term of spatial variation, bacterial production (BP; 1.7~9.8 mgC m-3 d-1) and biomass (BB; 10.7~29.0 mgC m-3) showed higher values at near-shore areas, and then decreased off-shore. Diel variations at the two anchored sampling stations were obvious, but with distinct BP-DOC relationships. At the PR station, there was a significant positive correlation between DOC and BP (r=+0.80, p<0.01, n=33). The coupling between DOC and BP might be resulted from the abundant inorganic nutrient supply from Pearl River. Further analysis suggested that phytoplankton, rather than river discharge, served as the major source of DOC. At the DSA station, high DOC and low BP were recorded at the day-time, ebb-tide period; low DOC and high BP were observed during the night-time, flood-tide period. It is proposed that the decoupling of BP vs. DOC at the DSA station could be explained by the periodic change of inorganic nutrient supply, which was a function of internal tide.
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