Scientists monitoring New Zealand’s waters for ten years have tracked changes in ocean acidification that pose a threat to marine life in a warming climate.
A stocktake of ocean acidification – caused by rising CO2 levels – was published in the New Zealand Journal of Marine and Freshwater Research. Niwa marine biogeochemist Professor Cliff Law said while the overall picture was complicated, “what we know is that New Zealand waters are already exposed to ocean acidification and will be subject to further pH stress in the future”.
He said monitoring aimed to understand whether different life stages of key species like green-lipped mussels, pāua and snapper were affected by lower pH and whether measures such as selective breeding of shellfish could help build resilient communities.
Study co-author Dr Chris Hepburn from the University of Otago told Radio NZ “it’s certainly very clear that declining pH has major impacts on the ability of particularly calcifying organisms to do what they do, to lay down skeletons”.
“But also things you might not expect, like squid – things with high metabolic rates can be impacted by higher CO2.”
He said pāua relies on a particular calcifying organism, which its larvae settle on. “If that’s damaged or the community structure changes, perhaps they won’t settle there anymore; they have to build shell structures, if we have lower pH it becomes more difficult.”
“Already those fisheries are starting to take some pretty heavy knocks, from stuff like the Kaikōura earthquake, overfishing, poaching…I don’t want to sound negative but there are problems and we need to start thinking about how we can mitigate against change.”
The report has been covered by local media, including:
NZ Herald: How will climate change hurt our ocean species? Scientists investigate
Radio NZ: Ocean acidification threatening marine species
Newshub: Climate change could affect New Zealand seafood – scientists
Newstalk ZB: Ocean acidification may lead to smaller shellfish