Effects of temperature change on seasonal variations in bacterial growth and loss rates in the northeast of Taiwan

• Main Authors: Hsiao, Wei, 蕭崴
• Other Authors: 蔡安益
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/24600123566292325479

碩士 === 國立臺灣海洋大學 === 海洋環境化學與生態研究所 === 103 === The word is steadily warming and induced global change in 21th century, in turn; the Earth’s climatic system and oceanic water circulation will be affected by global change. However, how global warming will affect the ecosystem of marine food chain and structure is under debate. It is well established that a significant fraction of the total carbon flux in marine food webs passes through heterotrophic bacteria. Thus, the fate of bacterial production has important implications for the ecology of microbial food webs and biogeochemical cycling in these systems. The relative contribution of viruses and grazers to bacterial mortality has important consequences for the processing and transfer of organic matter in the ocean. When bacterial cells are grazed, energy is made available to higher trophic levels, whereas when they are lysed, viruses redirect matter and energy away from higher trophic levels and generate substrates for non-infected bacteria. The goal of this study investigated the effect of rising temperatures on bacterial growth and mortality in coastal waters of the western subtropical Pacific Ocean. To do this, water samples were incubated for 24 h at ambient and experimentally increased temperatures (averages 3℃ higher than in situ values) and analyzed for bacterial growth, grazing and viral lysis using a modified dilution method. The experimental warming conditions were found to cause the ranged from 27 to 200% and 8 to 22% increase in bacterial growth rates compared with in situ situations that above and below 25℃, respectively. Furthermore, the experimental warming conditions also caused a 13-250% increase at which bacteria were being grazed, and showed grazing would increase in parallel with bacterial growth rate in this study. However, there was no significant effect of viral lysis as the temperature increased, under grazing pressure; grazers may preferentially graze virus-infected bacteria possibly changing viral mortality response. Furthermore, under grazing pressure, changes in the bacterial community structure may include the selection of virus-resistant bacteria species. These findings suggest that short-term warming changed the function of the microbial food web by increasing the rates of bacterial production and the bacterial carbon flux to predators in our study environment.