Characterization of the CO 2 system in a Coral Reef, a seagrass meadow, and a mangrove forest in the central Red Sea

• Published in: Journal of Geophysical Research: Oceans
• Main Authors: Saderne, V, Baldry, K, Anton, A, Agusti, S, Duarte, CM
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley-Blackwell Publishing Inc. 2019
• Subjects: Earth Sciences; Oceanography; Chemical Oceanography; Ocean acidification
• Online Access: https://doi.org/10.1029/2019JC015266; http://ecite.utas.edu.au/137768

The Red Sea is characterized by its high seawater temperature and salinity, and the resilience of its coastal ecosystems to global warming is of growing interest. This high salinity and temperature might also render the Red Sea a favorable ecosystem for calcification and therefore resistant to ocean acidification. However, there is a lack of survey data on the CO 2 system of Red Sea coastal ecosystems. A 1‐year survey of the CO 2 system was performed in a seagrass lagoon, a mangrove forest, and a coral reef in the central Red Sea, including fortnight seawater sampling and high‐frequency pH T monitoring. In the coral reef, the CO 2 system mean and variability over the measurement period are within the range of other world's reefs with pH T , dissolved inorganic carbon (DIC), total alkalinity (TA), p CO 2, and Ω arag of 8.0160.077, 206158 μmol/kg, 241534 μmol/kg, 46139 μatm, and 3.90.4, respectively. Here, comparisons with an offshore site highlight dominance of calcification and photosynthesis in summer‐autumn, and dissolution and heterotrophy in winter‐spring. In the seagrass meadow, the pH T , DIC, TA, p CO 2 , and Ω arag were 8.000.09, 198668 μmol/kg, 235249 μmol/kg, 41166 μatm, and 4.00.3, respectively. The seagrass meadow TA and DIC were consistently lower than offshore water. The mangrove forest showed the highest amplitudes of variation, with pH T , DIC, TA, p CO 2 , and Ω arag , were 7.950.26, 2069132 μmol/kg, 243891 μmol/kg, 493178 μatm, and 4.10.6, respectively. We highlight the need for more research on sources and sinks of DIC and TA in coastal ecosystems.