Fresh evidence signals at dangers of ocean acidification

Increased carbon dioxide emissions lead to increase in CO2 concentrations in oceans causing ocean acidification and this is becoming a major threat to marine animals, a new study has said.

According to researchers, marine animals along California’s rocky coastline specifically those that develop shells or skeletons from calcium carbonate are at a greater risk from ocean acidification for the increased CO2 levels cause the water to corrosive to calcium carbonate shells and skeletons.

Researchers Ken Caldeira and Lester Kwiatkowski demonstrated through their study of water in tide pools along California’s rocky coast that the rate at which shells and skeletons of marine animals are dissolved because of increase CO2 levels in water during nighttime periods. They explain that increase in levels of CO2 in ocean waters bring about a change in seawater chemistry and makes it more acidic and this process is called “ocean acidification.”

Tide pools along California’s rocky coast are isolated from the open ocean during low tides. During the daytime, photosynthesis–the mechanism by which plants convert the Sun’s energy and atmospheric carbon dioxide into sugar, giving off oxygen in the process–takes up carbon dioxide from the seawater and acts to reverse ocean acidification’s effects. However, at night, plants and animals respire just like we do, taking up oxygen and releasing carbon dioxide. This adds carbon dioxide to the seawater and exacerbates effects of ocean acidification, causing the increasing risk to calcifying organisms.

One of the problems with increased acidity in water is that it makes it difficult for organisms that construct their shells and exoskeletons out of calcium carbonate, such as mussels and oysters, to continue to build these protective layers. In high enough concentrations, carbon dioxide can even cause these shells and skeletons to dissolve entirely.

“Unless carbon dioxide emissions are rapidly curtailed, we expect ocean acidification to continue to lower the pH of seawater,” said Kwiatkowski, the study’s lead author. “This work highlights that even in today’s temperate coastal oceans, calcifying species, such as mussels and coralline algae, can dissolve during the night due to the more-acidic conditions caused by community respiration.”

Caldeira added: “If what we see happening along California’s coast today is indicative of what will continue in the coming decades, by the year 2050 there will likely be twice as much nighttime dissolution as there is today. Nobody really knows how our coastal ecosystems will respond to these corrosive waters, but it certainly won’t be well.”

Ravi Mandalia, Dispatch Tribunal, 21 March 2016. Article.


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