A marine scientist says shellfish are the canary in the mine when it comes to climate change - and that they're being severely affected by increasingly acidic oceans.
Sixty shellfish scientists from New Zealand and the United States attended a workshop in Nelson last week - where they looked at the destruction of oyster farming in the north-western United States caused by acidic water.
A researcher with the Cawthron Institute in Nelson, Dr Norman Ragg, says the oceans are becoming more acidic as they absorb more emissions.
Dr Ragg says shellfish can't form their shells once the water gets too acidic.
He says American oyster farmers - particularly those along the north Oregon and Washington State coasts, which focus mainly on the production of baby oysters - have learned this the hard way.
He says commercial production there declined by about 80%.
But, Dr Ragg says scientists have made some exciting research breakthroughs - which has helped get the shellfish hatcheries back on track.
In fact he says by monitoring the water and adding common chemicals similar to those that might be added to pasture, the growing environment for shellfish can be brought back to pre-industrial age levels of acidity.