1666 / 2019-08-26 11:16:03

The response of Synechococcus to ocean acidification under iron limited conditions

6、海洋地球科学 > 专题2：海洋微量金属及其同位素地球化学循环：现代过程与地质记录

The response of Synechococcus to ocean acidification under iron limited conditions
Wanghuan Guo, Haizheng Hong, Dalin Shi
Since the industrial revolution a large amount of anthropogenic carbon dioxide has dissolved in the ocean, resulting in ocean acidification. Iron (Fe) is an essential element that limits primary productivity in many parts of the ocean such as the high-nutrient low-chlorophyll (HNLC) regions. Previous studies have shown that ocean acidification can affect Fe availability and requirement of phytoplankton and thus will likely affect Fe-limited phytoplankton in particular. Synechococcus are one of the most ubiquitous phytoplankton in the ocean, and the strategies for coastal and oceanic Synechococcus to cope with Fe stress are different. To investigate how coastal and oceanic Synechococcus will respond to ocean acidification under Fe limitation, we chose the coastal strain Synechococcus sp. CCMP 1333 and the oceanic strain Synechococcu sp. CCMP 2370 to compare their growth, photophysiology and key genes expression involved in carbon fixation and iron utilization. The preliminary results showed that acidification promoted the growth of both strains especially under Fe-limited conditions, but the underlying mechanisms were different for the two stains. Acidification led to higher Fe uptake rate in CCMP1333, whereas it resulted in higher Fe use efficiency for CCMP 2370, to alleviate Fe limitation. In addition, the different expressions levels of psbA, psaC, rbcL and atpB also indicated that the response to acidification were different between the two strains. Coastal and oceanic Synechococcus may thus play different roles in Fe and carbon biogeochemical cycles in the future oceans.

Key words: iron limitation, Synechococcus, ocean acidification, photosynthesis