海洋酸化对颗石藻生理特性的影响

Effects of Ocean Acidification on Physiological Characteristics of Coccolithophores

中文关键词: 海洋酸化  颗石藻  特异性  生物多样性

英文关键词: Ocean acidification  Coccolithophores  Specific  Biodiversity

中文摘要:

      CO2浓度升高引起的海洋酸化对海洋生物尤其是钙化生物颗石藻产生了很大的影响。然而，有关颗石藻对CO2浓度升高响应的研究多集中在单一的品系上，并且在种内或者种间产生了差异甚至相互矛盾的结果。本研究中，分别以赫氏颗石藻(Emiliania huxleyi)和大洋球石藻(Gephyrocapsa oceanica) 2种颗石藻的钙化和非钙化的4个品系藻种为研究对象，设置了400、750、1000、2000 µatm共4个CO2浓度梯度，同时进行分批充气培养，系统研究了海洋酸化对颗石藻的生长光合、氮源吸收、元素组成和钙化效率等生理影响。结果显示，随着CO2浓度升高至2000 µatm，不同的颗石藻并未有一致的反应。除了非钙化的E. huxleyi (N-E)外，其他3个品系颗石藻的生长和颗粒有机碳产率都对CO2增加表现出积极的响应；随着CO2浓度的升高，4种品系颗石藻的光合参数Fv/Fm、Y(Ⅱ)和叶绿素含量呈整体下降趋势；E. huxleyi CS369 (C-E)和G. oceanica (C-G)在第7天的钙化效率分别下降了35.4%和68.9%；此外，4种品系颗石藻的颗粒有机氮产率都出现增加趋势，而POC/PON和PIC/POC均呈现下降趋势。本研究确定了海洋酸化对颗石藻的不同生理影响，这种差异影响可能会导致未来海洋生物多样性的改变和其他生态系统进程的变化。

英文摘要:

      Ocean acidification caused by increasing amounts of carbon dioxide has a great impact on marine organisms, especially calcified coccolithophores. However, culture experiments examining the response of coccolithophores to elevated CO2 pa have mostly been based on investigations of a single strain and have yielded differences and even contradictory results from experiments between and even within species. Here, four strains of the coccolithophores, which contained naked and calcifying strains, were investigated simultaneously for the first time. Four carbon dioxide concentration gradients (400 µatm, 750 µatm, 1000 µatm, and 2000 µatm) were set up to systematically study the effects of ocean acidification on growth, photosynthesis, nitrogen source absorption, element composition and calcification efficiency of four coccolithophore species by batch aeration culture. The results did not show a uniform response from the different strains to elevated CO2 concentrations up to 2000 µatm, and the naked strain Emiliania huxleyi (N-E) was seriously suppressed, which was in sharp contrast to the positive response of the other three algae to the different levels. On the other hand, photosynthetic parameters Fv/Fm, Y(II) and pigment show overall downward trend for all four strains, and calcification efficiency of C-E and C-G decrease 35.4% and 68.9% respectively, on the seventh day. In addition, the four coccolithophore strains of particulate organic nitrogen production show an increasing trend and the resulting POC/PON and PIC/POC declin. We determined that the responses of coccolithophores to ocean acidification are specific, and this variation may cause changes to biodiversity and other ecosystem processes in the ocean of the future.