Imagine yourself enjoying the comforts of your home when you feel a sudden change in the atmosphere, and before you find out why, your skin starts to burn and you can hardly breathe. That’s when you realise that the place you have been living since ages has suddenly become a living hell. Welcome to the world of marine animals!
Oceans have been such comfortable homes to approximately 2.2 million species since hundreds of thousands of years. Thanks to overfishing, warming, pollution, plastics and other human pressures, now they are turning inhospitable. Apart from all these, there is another major threat to the marine life called the ‘ocean acidification’. It refers to the decreasing pH of ocean water due to the conversion of absorbed CO2 into carbonic acid.
The potential of hydrogen, or the ‘pH’, is a logarithmic scale representing the acidity of a solution and ranges from 0 to 14. Anything less than 7 is considered acidic, and more than 7 is basic. The pH of oceans has decreased from 8.25 to 8.14 since the beginning of the industrial revolution—a 30% increase in acidity. There is more bad news; the acidification rate is higher than what it had been in the past 35 million years and the pH of oceans is expected to increase by 150% by the end of this century!
The first victims of ocean acidification are the marine calcifying organisms with shells. Coral reefs, which cradle almost a quarter of marine biodiversity, are also severely affected by acidification. These reefs are formed by the accumulation of calcium carbonate skeletons secreted by the colonies of corals over time over which algae and protozoans grow, imparting beautiful colours to the coral reefs. Due to increased acidification and other reasons, these symbiotic organisms are expelled by the corals, revealing their white calcium carbonate skeleton underneath. This phenomenon is called coral bleaching.
Scientists are warning us about the irreversible impacts of acidification on the marine life and it is time to act. Reducing emissions holds the key. It would be unfortunate if we are looking for life in far-away planets, while losing it in our own oceans where life, as we know it, originated.