Oceanic Acidification Ruining Digestion of Sea Urchins

Researchers from Sweden and Germany have found that climate change and ocean acidification is ruining the digestive systems of marine animals.

They conducted the study on a larval stage of green sea urchins Strongylocentrotus droebachiensis. The research shows that marine animals can't digest food in acidic environment.

Ocean acidification is an unfortunate consequence of the industrial revolution. Burning fossil fuels has resulted in the release of a billion tons of carbon dioxide in the environment. This has led to a drop in the sea-surface pH. The increase of carbonic acid in the oceans inhibits growth and development of marine life.

The study was conducted by researchers at the Helmholtz Centre for Ocean Research Kiel (GEOMAR) and colleagues.

Dr. Meike Stumpp, an author of the study, found that sea urchin larvae can't digest food in acidic environment. The team used novel pH micro-electrode techniques and latest assay methods to understand the digestive system of larvae in normal and acidic waters.

"My measurements demonstrated a very strong pH dependency," Stumpp explained in a news release. "The enzymes in the sea urchins' stomachs are optimized to function at very high pH - which is different from the situation in mammals, where stomach pH is acidic and enzymes work best at low pH."

Larvae exposed to acidic conditions have to spend more energy to regulate internal pH levels.

"The energetic demands to maintain the stomach pH increase," says Dr. Marian Hu, co-first author of the study.

The study is published in the journal Nature Climate Change.

Researchers found high concentrations of cells that regulate pH in the stomachs of these larvae. These cells require a lot of energy, meaning that the organism needs to feed more often to compensate for the energy loss.

"If the organisms are unable to compensate for extra costs caused by ocean acidification, by eating more, they suffer negative consequences in the form of reduced growth and fertility and in extreme cases death," Dr. Sam Dupont, a study author, said in a news release.