As oceans acidify, it’s life or death for some marine animals

Scientist search for clues of climate change impacts in tidepools

By Tiffany Chen
Medill Reports

Since the beginning of the Industrial Revolution, the world’s oceans have been absorbing carbon dioxide caused by human activity.  Oceans act like a sponge to buffer the heating effects caused by excessive CO2 levels. Without it, the earth would be dangerously hot.

But there’s a catch. Ocean acidification is described as climate change’s “evil twin.” The dissolved form of carbon dioxide can sour the water and change the chemistry in marine environments. Scientists from the Bodega Marine Lab at the University of California, Davis, are fishing for clues to understand how ocean acidification affects the organisms that live in the sea.

“Ocean acidification is really concerning,” said Brittany Jellison, a Ph.D. Graduate Student at the Bodega Marine Laboratory. “Because we are starting to see that it can change how animals behave, and the behavior of animals dictates lots of interactions with other organisms.”

Jellison studies the predator and prey interaction between sea stars and sea snails. Sea snails are unable to “smell” their sea star predators in acidified water. Other animals like clownfish can’t find their way back home and sometimes swim right toward their predators instead of swimming away. These abnormal behaviors are caused by changes in ocean chemistry and biological responses.

“For animals living in the ocean, having the chemistry of the water around them change in really dramatic ways, in a short amount of time…can have a very large effect,” said Jordan Hollarsmith, a Ph.D. student at the Bodega Marine Laboratory.

For shellfish, such as crabs, oysters and mussels, the souring of the ocean water lowers the level of calcium carbonate, which is the main building block for their protective shells. Oyster farms near Bodega Bay have noticed that oysters did not grow as much in more acidified water.

“As water acidifies, calcifying organisms generally have a harder time creating their shells,” said Hollarsmith. “Whereas more carbon dioxide in the water can be something beneficial to organisms that photosynthesize.” Organisms like seaweed can neutralize the water by pulling out carbon dioxide.

Scientists are collaborating with oyster farms to grow oysters on seaweed beds. They hope the seaweed can neutralize the water to create a better environment for the oysters to grow in.

Photo at top: Scientist search for clues of climate change impact in tidepools. Feb. 14, 2018. (Tiffany Chen/MEDILL)