碩士 / 國立臺灣海洋大學 / 海洋生物研究所 / 92 / Due to the close connection between phytoplankton size distribution and marine carbon cycle, the goal of this study is to understand whether competition of nutrients, as compared with predation and cell sinking, also controls the size distribution. Experimentally, a diatom (Skeletonema costatum CH0128) and a cyanobacteria (Synechococcus spp. CH0129) were isolated from costal area of Keelung, and were used in a series of incubations with different nutrient concentrations. The population growth of these two phytoplankton was monitored when they were incubated separately, jointly, or with the existence of predators. Using Monod’s equation as a regression model, the Ks’s of S. costatum and Synechococcus spp. were estimated as 0.02f and 0.002f (the relative nutrient concentration is expressed as a fraction of the f-media); the µµax’s were estimated 1.62 and 1.04 day-1, respectively.By the comparison of maximum growth rate and carrying capacity between incubations with and without the competitor, a growth rate competition ratio (µcomp%) and a carrying capacity competition ration (Kcomp%) were constructed to judge their mutual influences in the same environment. In both lab-prepared media and natural seawater, S. costatum became more dominant with the decrease of nutrient concentration, and its µcomp% was close to 100%. Synechococcus spp. CH0129 dominated high nutrient environment and has higher µcomp%. Synechococcus spp. CH0129 also has better Kcomp% ratio at high nutrient concentrations. However, S. costatum did not feel the influences from Synechococcus spp. in all incubations, and almost all Kcomp% ratio of S. costatum were higher than 95%. The only exception was observed in the f/20 media, in which Kcomp% of S. costatum decreased to 1%. In conclusion, the competitive ability of S. costatum is better than that of Synechococcus spp. at low nutrient concentrations, and the existence of predator can effectively decrease the abundance of Synechococcus spp. Based these results, predation apparently controls Synechococcos spp. biomass in high nutrient environment, which let diatoms dominate in such locations. On the other hand, although nutrient competition still occurs in the oligotrophic open ocean, the dominance of Synechococcos spp. is due to cell sinking of diatoms which prevented diatoms to accumulate in the euphotic zone.
| Identifer | oai:union.ndltd.org:TW/092NTOU5270006 |
| Date | January 2004 |
| Creators | Liu Hung-Chun, 劉虹君 |
| Contributors | Chang Jeng, 張 正 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 55 |
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