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Estimates of virus- vs. grazing induced mortality of bacteria and Synechococcus spp. in the Danshui River Estuary
|Authors: ||Huang, Yu-Wen|
|Issue Date: ||2017-11-15T08:45:38Z
|Abstract: ||據先前的研究已知，病毒裂解與微細鞭毛蟲攝食是主要控制細菌與藍綠細菌數量變化的生物因子。至此本研究即利用修正後的稀釋培養法來量測淡水河河內及河口水域細菌與藍綠細菌成長率，被攝食率與被裂解率的季節變化，以期了解淡水河河內及河口水域細菌與藍綠細菌季節數量的變動原因。本實驗於2012年10月，2013年1月，4月及7月各採樣一次並進行培養實驗。由培養實驗結果顯示，淡水河河內及河口水域細菌成長的季節變化各在0.11~0.201 h-1與0.11~0.17 h-1之間，其最高值出現在2013的7月。此外藍綠細菌在淡水河河內及河口水域之季節成長變化各在0.14~0.18 h-1與0.11~0.14 h-1之間。另由細菌與藍綠細菌之被攝食率與被裂解率的季節變化來看，除了2013年1月的採樣外，細菌在河內與河口環境主要皆是微細鞭毛蟲攝食會超過病毒裂解影響。相反的對於藍綠細菌而言，則發現病毒裂解會超過微細鞭毛蟲攝食影響。由此培養結果可推測在淡水河河內及河口水域微細鞭毛蟲主要的餌料來源應是利用細菌而成長。|
Viruses and nanoflagellates are known to exert an important control on picoplankton (bacteria and Synechococcus spp.). In parallel with the study of picoplankton dynamics (abundance and distribution) in surface waters of upriver and estuary of the Danshui River, we used a modified dilution technique during different seasonal periods (October, 2012 and January, April and July, 2013) in order to assess nanoflagellate- versus virus-induced mortality of bacteria and Synechococcus spp. In this study, abundance of bacteria and viruses in the upriver region was significantly higher than that at the river estuary. However, Synechococcus spp. did not follow the spatial pattern with bacteria and viruses, abundance of Synechococcus spp. were relatively low during the whole sampling period in the upriver region. Furthermore, seasonal variations of bacterial growth rates varied between 0.11 and 0.201 h-1 and 0.11 and 0.17 h-1 at upriver and estuary site, respectively, with higher growth rates of bacteria detected in July 2013. Synechococcus spp. growth rates ranged from 0.14 to 0.18 h-1 in the upriver region and from 0.11 to 0.14 h-1 in the estuary. These results suggest that seasonal temperature might control seasonal variations in bacterial and Synechococcus spp. growth. Bacterial carbon losses generated by nanoflagellate grazing were generally higher than those caused by viral lysis in the upriver region during the study periods. Looking specifically at the Synechococcus spp., viral lysis appeared to be the main factor in removing Synechococcus spp. in the upriver and estuary region of Danshui River. The results of our dilution experiments suggest that nanoflagellates largely depend on bacteria as an important energy source in the Danshui River.
|Appears in Collections:||[海洋環境與生態研究所] 博碩士論文|
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