Research led by the University of Otago suggests the impact of ocean acidification has been underestimated.
Ocean acidification is a side-effect of climate change. Increased carbon dioxide in the atmosphere dissolves into seawater where it forms carbonic acid.
A team led by Otago PhD student Chris Cornwall has discovered acidity can be boosted even further by the natural effects of dense kelp forests.
Mr Cornwall says the increased acidity slows the growth of smaller seaweeds, which form the foundation of the ecosystem on rocky reefs.
He carried out his experiments using kelp forests in Otago and says similar forests can be found all around the world.