Effect of Rising Temperature and Carbon Dioxide on the Growth, Photophysiology, and Elemental Ratios of Marine Synechococcus : A Multistressor Approach

• Published in: Sustainability
• Main Authors: Samarpita Basu, Katherine R. M. Mackey
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2022
• Subjects: picocyanobacteria; ocean acidification; Synechococcus; specific growth rate; Environmental effects of industries and plants; TD194-195; Renewable energy sources; TJ807-830; Environmental sciences; GE1-350; Ocean acidification
• Online Access: https://doi.org/10.3390/su14159508; https://doaj.org/article/e0cc043ce307410a90c1f576e260df25

Marine picocyanobacteria belonging to the genus Synechococcus are one of the most abundant photosynthetic organisms on Earth. They are often exposed to large fluctuations in temperature and CO 2 concentrations in the ocean, which are expected to further change in the coming decades due to ocean acidification and warming resulting from rising atmospheric CO 2 levels. To decipher the effect of changing temperature and CO 2 levels on Synechococcus , six Synechococcus strains previously isolated from various coastal and open ocean sites were exposed to a matrix of three different temperatures (22 °C, 24 °C and 26 °C) and CO 2 levels (400 ppm, 600 ppm and 800 ppm). Thereafter, the specific growth rates, photophysiological parameters ( σ PSII and F v /F m ), C/N (mol/mol) ratios and the nitrogen stable isotopic composition (δ 15 N (‰)) of the strains were measured. Temperature was found to be a stronger driver of the changes in specific growth rates and photophysiology in the Synechococcus strains. Carbon-concentrating mechanisms (CCM) operational in these strains that shield the photosynthetic machinery from directly sensing ambient changes in CO 2 possibly played a major role in causing minimal changes in the specific growth rates under the varying CO 2 levels.