235
© Springer International Publishing AG 2017
M. Kumar, P. Ralph (eds.), Systems Biology of Marine Ecosystems,
DOI 10.1007/978-3-319-62094-7_12
Chapter 12
Effects of Ocean Acidification and UV
Radiation on Marine Photosynthetic
Carbon Fixation
Kunshan Gao and Donat-P. Häder
Abstract The oceans absorb anthropogenically released CO 2 at a rate of more than
one million tons per hour, which causes a pH decrease of seawater and results in ocean
acidification (OA). The effect of OA and absorption of CO 2 via the biological carbon
pump driven by marine photosynthesis has drawn increasing attentions. As a consequence, there are numerous studies on influences of OA on primary producers, and the
effects on photosynthetic carbon fixation are still under debate. OA can promote
the growth of diatoms at low PAR irradiances and inhibit it at high PAR. Besides, OA
may influence metabolic pathways of phytoplankton, upregulating β-oxidation, and
the tricarboxylic acid cycle, resulting in increased accumulation of toxic phenolic
compounds. In parallel, phytoplankton cells in the upper mixed layer are affected by
intense PAR and UV radiation (UVR). The calcareous layers of calcified algae, which
have been shown to shield the organisms from UVR, are thinned due to OA, exposing
the cells to increased UVR and further inhibiting the calcification. Therefore, effects
of OA and UV on marine photosynthetic carbon fixation could be compounded. While
the photosynthetic carbon fixation is controlled by other environmental stressors in
addition to OA and UV, such as nutrients limitation and warming, combined effects of
OA and UV have been less considered. In this review, we synthesize and analyze
recent advances on effects of OA and UV and their combined effects, implying that
future studies should pay special attentions to ecological and physiological effects of
OA in the presence of solar UV irradiance to reflect more realistic implications.
The ecophysiological effects of OA and/or UV and their mechanisms in complex
environments should be further explored.
Keywords CO 2 • Ocean acidification • Photosynthesis • Primary producers • Solar UV
radiation
K. Gao (*)
State Key Laboratory of Marine Environmental Science, College of Ocean and Earth
Sciences, Xiamen University, Xiang-An Campus, Xiamen 361102, China
e-mail: ksgao@xmu.edu.cn
D.-P. Häder
Department of Biology, Friedrich-Alexander University Erlangen-Nürnberg,
Neue Str. 9, Erlangen 91096, Germany
© Springer International Publishing AG 2017
M. Kumar, P. Ralph (eds.), Systems Biology of Marine Ecosystems,
DOI 10.1007/978-3-319-62094-7_12
Chapter 12
Effects of Ocean Acidification and UV
Radiation on Marine Photosynthetic
Carbon Fixation
Kunshan Gao and Donat-P. Häder
Abstract The oceans absorb anthropogenically released CO 2 at a rate of more than
one million tons per hour, which causes a pH decrease of seawater and results in ocean
acidification (OA). The effect of OA and absorption of CO 2 via the biological carbon
pump driven by marine photosynthesis has drawn increasing attentions. As a consequence, there are numerous studies on influences of OA on primary producers, and the
effects on photosynthetic carbon fixation are still under debate. OA can promote
the growth of diatoms at low PAR irradiances and inhibit it at high PAR. Besides, OA
may influence metabolic pathways of phytoplankton, upregulating β-oxidation, and
the tricarboxylic acid cycle, resulting in increased accumulation of toxic phenolic
compounds. In parallel, phytoplankton cells in the upper mixed layer are affected by
intense PAR and UV radiation (UVR). The calcareous layers of calcified algae, which
have been shown to shield the organisms from UVR, are thinned due to OA, exposing
the cells to increased UVR and further inhibiting the calcification. Therefore, effects
of OA and UV on marine photosynthetic carbon fixation could be compounded. While
the photosynthetic carbon fixation is controlled by other environmental stressors in
addition to OA and UV, such as nutrients limitation and warming, combined effects of
OA and UV have been less considered. In this review, we synthesize and analyze
recent advances on effects of OA and UV and their combined effects, implying that
future studies should pay special attentions to ecological and physiological effects of
OA in the presence of solar UV irradiance to reflect more realistic implications.
The ecophysiological effects of OA and/or UV and their mechanisms in complex
environments should be further explored.
Keywords CO 2 • Ocean acidification • Photosynthesis • Primary producers • Solar UV
radiation
K. Gao (*)
State Key Laboratory of Marine Environmental Science, College of Ocean and Earth
Sciences, Xiamen University, Xiang-An Campus, Xiamen 361102, China
e-mail: ksgao@xmu.edu.cn
D.-P. Häder
Department of Biology, Friedrich-Alexander University Erlangen-Nürnberg,
Neue Str. 9, Erlangen 91096, Germany