Researchers from James Cook University have found that ocean acidification may not be all bad news for one important sea-dwelling plant. A JCU team led by Dr Catherine Collier studied seagrass growing near underwater volcanic vents in PNG. Carbon dioxide from the vents increases the acidity of nearby water.

The researchers found that the more acidic the water was, the more the plant grew.

"The increased growth has nothing to do with the acidified water as such, but increased acidification means more carbon, which means the seagrass photosynthesises quicker," said Dr Collier.

Seagrass provides food and habitat to many species and is a significant carbon sink - soaking up 15 percent of the carbon stored in the ocean every year. But pollution and development mean the plants are declining at a rate of seven per cent a year.

Dr Collier said every one of the ten varieties of seagrass so far tested had done better in acidified water. But there were still questions over whether other aspects of climate change would adversely affect them.

"On the one hand, if acidification increases seagrass growth, they will be able to absorb more carbon from the ocean, which may slow the acidification. On the other hand, acidification is bad for coral, and erosion of the reef and rising sea levels could have detrimental effects on the seagrass meadows it protects," said Dr Collier.

She said more investigation, incorporating other variables in the seagrass environment, needed to be done.