Mangroves Can Counter Ocean Acidification, Study Reveals

The researchers discovered that mangrove forests can buffer ocean acidification because they are known to increase the alkalinity of the waters surrounding these ecosystems. The alkaline solutions can counter acidification.

The study was printed in Global Biogeochemical Cycles on May 24, 2016. It was authored by James Z. Sippo, Douglas R. Tait, Damien T. Maher and Ceylena Holloway from Southern Cross University, School of Environment, Science and Engineering, Lismore and National Marine Science Centre, Coffs Harbour in New South Wales, Australia.

Ocean acidification can harm the ecosystem just like the "climate change." It is actually referred to as the evil twin of climate change. About one-quarter of the carbon dioxide (CO2) caused by the burning of fossil fuels such as oil, coal, and gas doesn't remain in the air, rather it disperses in the ocean. This decreases pH in a process called ocean acidification.

In the study, the researchers examined the magnitude to which the mangroves can buffer the ocean acidification. They evaluated the dissolved inorganic carbon (DIC) content, dissolved carbon dioxide in the waters and alkalinity in the waters of six unspoiled mangrove tidal creeks along the northern, eastern and southern coasts of Australia. They also gathered water samples from nearby coastal waters to know if the alkalinity of the mangroves' waters had an evident influence on the surrounding area.

The researchers then calculated the alkalinity in the mangrove forest waters using the titration. They computed the alkalinity, exchange of DIC and dissolved CO2 from the mangroves to the coastal ocean.

The results showed that the mangroves that were examined put out 59 millimoles of DIC per square meter in a day into the surrounding coastal waters. This will result in global exports of more than 2.5 X 10 the ninth power moles of carbon per year. They also computed that mangrove forests can export up to 4.2 teramoles of alkalinity yearly.

The study suggests that the effect of dissolved inorganic carbon and alkalinity exports from the mangroves caused neighboring ocean pH to increase. The researchers imply that this increase in pH from the mangroves could have a bigger effect in areas with large mangrove coverage. It could also have an effect in other tropical coastal ecosystem like coral reefs. The study also indicates that mangroves are one of the largest natural sources of alkalinity to tropical coastal oceans.