236
12.1 Introduction
Global environmental change has become a key factor influencing the sustainable
development of humans, and increasing atmospheric CO 2 concentration is causing
ocean acidification (OA), global warming, sea level rise, and altering water mixing
dynamics. As a CO 2 sink, the oceans continuously absorb CO 2 , playing an important
role in mitigating global warming. Therefore, the oceanic absorption of CO 2 and its
mechanism are key to study and predict the global environmental changes.
Photosynthesis is the basic driver of the biological CO 2 pump. As a result, it is necessary to understand the relationship between photosynthesis and the change of
marine chemical and physical environments to assess CO 2 uptake capacities in different regions.
Global warming caused by increasing atmospheric CO 2 concentrations results in
rise of seawater temperature and shoaling of the upper mixed layer (UML) above
the thermocline, which exposes the phytoplankton within this layer to higher integrated levels of UVR irradiances (Gao et al. 2012a). Meanwhile, the increased temperature on the ground and the decreased heat reflection from the Earth’s surface
through the atmosphere to the outer space lowers the temperature of the stratosphere
and accelerates the depletion of stratospheric ozone. The release of CFCs (chlorofluorocarbons) has been reduced since the Montreal Protocol Agreement was
signed; however, due to their long lifetimes (on the order of a century) in the stratosphere, these substances are still harmful for the stratospheric ozone (Bais et al.
2015). Besides, several new gases, harmful to the stratospheric ozone, are rapidly
accumulating in the atmosphere (Laube et al. 2014). Thus, the ecophysiological
effects of the enhanced UV-B radiation (280–315 nm) still gain much attention
(Häder and Gao 2015).
In short, OA and increased UVR exposure negatively affect the efficiency of the
marine biological CO 2 pump by influencing the physiological performance of
marine primary producers in the UML. Therefore, their respective and combined
effects on the photosynthetic carbon fixation should be examined in a context of
marine environmental changing biology.
Contents
12.1 Introduction .................................................................................................................
236
12.2 Ocean Acidification and Its Effect on Photosynthetic Organisms ..............................
237
12.2.1 Ocean acidification .......................................................................................
237
12.2.2 Responses of photosynthetic organisms to ocean acidification ....................
239
12.3 UV and Its Effect on Marine Photosynthetic Carbon Fixation ...................................
242
12.3.1 UV radiation .................................................................................................
242
12.3.2 The effect of UV on photosynthetic carbon fixation ....................................
244
12.4 The combined effects of OA and UV radiation ..........................................................
244
12.5 Conclusion ..................................................................................................................
246
References ............................................................................................................................
247
K. Gao and D.-P. Häder
12.1 Introduction
Global environmental change has become a key factor influencing the sustainable
development of humans, and increasing atmospheric CO 2 concentration is causing
ocean acidification (OA), global warming, sea level rise, and altering water mixing
dynamics. As a CO 2 sink, the oceans continuously absorb CO 2 , playing an important
role in mitigating global warming. Therefore, the oceanic absorption of CO 2 and its
mechanism are key to study and predict the global environmental changes.
Photosynthesis is the basic driver of the biological CO 2 pump. As a result, it is necessary to understand the relationship between photosynthesis and the change of
marine chemical and physical environments to assess CO 2 uptake capacities in different regions.
Global warming caused by increasing atmospheric CO 2 concentrations results in
rise of seawater temperature and shoaling of the upper mixed layer (UML) above
the thermocline, which exposes the phytoplankton within this layer to higher integrated levels of UVR irradiances (Gao et al. 2012a). Meanwhile, the increased temperature on the ground and the decreased heat reflection from the Earth’s surface
through the atmosphere to the outer space lowers the temperature of the stratosphere
and accelerates the depletion of stratospheric ozone. The release of CFCs (chlorofluorocarbons) has been reduced since the Montreal Protocol Agreement was
signed; however, due to their long lifetimes (on the order of a century) in the stratosphere, these substances are still harmful for the stratospheric ozone (Bais et al.
2015). Besides, several new gases, harmful to the stratospheric ozone, are rapidly
accumulating in the atmosphere (Laube et al. 2014). Thus, the ecophysiological
effects of the enhanced UV-B radiation (280–315 nm) still gain much attention
(Häder and Gao 2015).
In short, OA and increased UVR exposure negatively affect the efficiency of the
marine biological CO 2 pump by influencing the physiological performance of
marine primary producers in the UML. Therefore, their respective and combined
effects on the photosynthetic carbon fixation should be examined in a context of
marine environmental changing biology.
Contents
12.1 Introduction .................................................................................................................
236
12.2 Ocean Acidification and Its Effect on Photosynthetic Organisms ..............................
237
12.2.1 Ocean acidification .......................................................................................
237
12.2.2 Responses of photosynthetic organisms to ocean acidification ....................
239
12.3 UV and Its Effect on Marine Photosynthetic Carbon Fixation ...................................
242
12.3.1 UV radiation .................................................................................................
242
12.3.2 The effect of UV on photosynthetic carbon fixation ....................................
244
12.4 The combined effects of OA and UV radiation ..........................................................
244
12.5 Conclusion ..................................................................................................................
246
References ............................................................................................................................
247
K. Gao and D.-P. Häder