Bryozoan organisms feeding. Image: YouTube

Climate change is causing oceanic CO2 levels to rise due to increased absorption from the atmosphere — and as a result threaten calcified marine wildlife. 

A recent study published in The Proceedings of the Royal Society B analyzed the effect of acidified water on invertebrate exoskeletons. Ocean acidification is the process by which excess CO2 dissolves into the water and becomes the more ecologically harmful carbonic acid H2CO3.

Increased concentrations of acidity in seawater can attribute to the weakened exoskeletal structures of marine animals, including the shells of clams, oysters, urchins, and snails. Although the carbonic molecules can be broken down and raw carbon used in the construction of new shells, many animals are not capable of converting it to a usable form, and instead suffer from exoskeletal degradation.

The embedded photos below are pulled from another study, relaying the negative effects of CO2 on the exoskeletons of shrimp:

Daniel Swezey and his team based out of the University of California, Davis experimented with the bryozoan Jellyella tuberculata in the most recent study. Jellyellas are distinguished by their calcitic skeletal structures composed of transversely situated, lengthy spindles.

Jellyella tuberculata, also known as the ‘Gulf weed bryozoan’ grows on the floating alga, kelp, and other related seaweeds around the Cape Peninsula of South Africa and other warm waters around the world.

The team at Davis grew Jellyella tuberculata in a controlled environment, elevating levels of COthroughout the saltwater in addition to changing the water’s temperature. Lowered temperatures and increased gas levels caused physiological stress while those in warm water with a moderated food supply formed skeletons that dissolved rapidly when exposed to acidic conditions.

This research highlights the sensitivity of certain marine invertebrates to ocean acidification caused by the changing climate.