Feeding Mechanisms of Mixotrohpic nanoflagellates (Haptophytes)
| Autor: | Wei-Xin Chen, 陳維信 |
|---|---|
| Rok vydání: | 2017 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 105 Mixotrophic nanoflagellates (MNF), combining phototrophy and phagotrophy within a single cell, are important for fundamental nutrient regeneration and primary production in different ecosystems. Most haptophytes are MNF. Many studies have confirmed that the mixotrophic haptophytes have significant contribution to control the abundance of bacteria in the marine environment. The purpose of phagotrophy in MNF is considered as a supplement for phototrophy. The phagotrophy of MNF supplies nutrition or energy for necessary growth under light or nutrient deficiencies. However, a recent study suggested that” The roles of photo- and phagotrophy are more likely linked to synergy in energy and nutrient supply routes”. So far, this scenario has not been proved either by laboratory or field experiments. In this study, we estimated the ingestion rates of mixotrophic haptophytes in the East China Sea under different nutrient and prey conditions to confirm this hypothesis. The phagotrophy (expressed by ingestion rates) of the haptophytes is mainly controlled by the prey abundance, which was confirmed by our bacteria-added experiments. The ingestion rates were significantly and positively related with the abundance of bacteria. The ingestion rates of mixotrophic haptophytes were not different in our experiments with NO3-added in surface water. Furthermore, in our f/2-added experiments, the ingestion rates increased significantly (13.78 to 26.15 Bac Hap-1 h-1) at the surface but remained unchanged in the low and no light layers (20m and 30m). These results indicated that the photosynthesis would not inhibit the phagotrophy, but rather enhance it. The abundance of bacteria was also increased only at the surface in the f/2-added experiments. We suggested that the photosynthesis might release the DOC to support the bacteria growth, and consequently caused the increasing ingestion rates of mixotrophic haptophytes. This study, therefore, supports the known hypothesis that the photosynthesis and phagotrophy mutually cooperate with each other. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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