Effects of increased CO2 and temperature on the growth and photosynthesis in the marine macroalga Gracilaria lemaneiformis from the coastal waters of South China
Liu, L.; Zou, D.; Jiang, H.; Chen, B.; Zeng, X.
Journal of Applied Phycology 30(2): 1271-1280
ISSN/ISBN: 0921-8971 DOI: 10.1007/s10811-017-1316-y
The marine red macroalga Gracilaria lemaneiformis (Gracilariales, Rhodophyta) is one of the most important species for seaweed cultivation along the coastal waters of South China. In this study, G. lemaneiformis was incubated under present-day (390 ppm) or predicted-year CO2 levels (700 ppm), and under normal (20 degrees C) versus elevated temperatures (24 degrees C), to investigate possible effects of climate change conditions on the growth and photosynthesis. The chlorophyll a (Chl a), carotenoid (Car), and phycobiliprotein (PB) contents responded significantly to increased temperature under normal CO2 and high CO2 concentrations. However, CO2 enrichment in the culture had no significant impact on Chl a and Car but decreased the PB contents in G. lemanelformis. The growth rates of G. lemaneiformis were significantly improved by increasing temperature, especially under concurrent increasing CO2 levels. Additionally, shortterm exposure to high temperature stimulated the irradiance-saturated maximum photosynthetic rate (P-max), and this stimulation was preserved with exposure to the high temperature in long-term incubations, with such stimulation being much more pronounced under normal CO2 concentrations than high CO2 concentrations. Results suggest that increased temperature exerted more pronounced effects on the growth and photosynthesis of G. lemaneiformis than increased CO2 concentrations did. We proposed that the sea cultivation of G. lemaneiformis would benefit from the ongoing climate change (increasing atmospheric CO2 concentrations and sea surface temperatures) through enhanced growth and carbon sequestration.