Ocean acidification largely impacts on marine life

Cuts in global CO2 emissions are essential to limit further damage to coral reefs and kelp forests.

Corals, such as this table Acroporid, provide habitats for a wide range of fauna (photo: Marco Milazzo)
Corals, such as this table Acroporid, provide habitats for a wide range of fauna (photo: Marco Milazzo)

Carbon dioxide emissions are rising and causing a bad impact on marine life as heat waves and ocean acidification damage marine ecosystems. In a new study, scientists warned, with this rising levels of CO2 emissions, the seawater levels will soon have lower pH levels or even worse catastrophic impact.

The study was conducted by the University of Tsukuba in Japan, the University of Plymouth in the UK and the University of Palermo in Italy. During the study, scientists discovered volcanic CO2 seeps off Shikine Island, Japan, which is on the border of temperate and tropical climates.

They experienced ocean currents there, which suggests the naturally low level of surface water CO2. The volcanic seeps indicate how rising CO2 levels will affect future ecology.

Lead author Dr. Sylvain Agostini, Associate Professor at the University of Tsukuba Shimoda Marine Research Centre, said: “These CO2 seeps provide a vital window into the future. There was mass mortality of corals in the south of Japan last year, but many people cling to the hope that corals will be able to spread north. Therefore it is extremely worrying to find that tropical corals are so vulnerable to ocean acidification, as this will stop them from being able to spread further north and escape the damage caused by water that is too hot for them.”

Scientists studied underwater CO2 gradients created by volcanic seeps. They also identified how the fauna and flora respond to seawater acidification.

They found that while a couple of plant species profited from the evolving conditions, they turned into smaller weeds and algae that cover the seabed, choking corals and bringing down overall marine diversity.

These species and some smaller marine animals are thriving in light of the fact that they are more tolerant of the pressure postured by rising levels of CO2.

Jason Hall-Spencer, Professor of Marine Biology at the University of Plymouth, said:

“Our research site is like a time machine. In areas with pre-industrial levels of CO2, the coast has an impressive amount of calcified organisms such as corals and oysters. But in areas with present-day average levels of surface seawater CO2 we found far fewer corals and other calcified life, and so there was less biodiversity. It shows the extensive damage caused by humans due to CO2 emissions over the past 300 years and unless we can get a grip on reducing CO2 emissions we will undoubtedly see a major degradation of coastal systems worldwide.”

Professor Kazuo Inaba, former director of the Shimoda Marine Research Centre, added: “Local fishermen are keen to know how ocean acidification will affect their livelihoods. Currents flowing past Japan bring waters that have naturally low levels of CO2 and fish benefit from the array of calcified habitats around our islands. If we are able to meet the Paris Agreement targets to limit emissions we should be able to limit further damage to kelp forests, coral reefs, and all marine ecosystems.”

The full study is published in Scientific Reports.