Native marine species threatened by climate change

New research led by Victoria University of Wellington has shown a significant threat to an organism crucial to the growth of many marine species including native New Zealand pāua and kina.

Empty paua shell on beach
Empty paua shell on beach

The organism—coralline algae—cements reefs together and acts as a foundation species and breeding ground for many species from poles to tropics, says Dr Chris Cornwall from the School of Biological Sciences. He says declines in coralline algae could lead to the loss of important marine species, including pāua and kina, which use the algae as a nursery.

“Our research shows that changing ocean chemistry and temperature, caused by climate change, will have negative consequences for coralline algae,” says Dr Cornwall, who worked with the French National Centre for Scientific Research (CNRS), and the ARC Centre of Excellence in Coral Reef Studies in Australia on the research.

“Declines in coralline algae could lead to the loss of many other marine species. In New Zealand declines in species of cultural significance like pāua and kina will have profound consequences. In coral reefs, the loss of this cementing algae will further reduce reef growth already impacted by reoccurring mass coral bleaching events.”

The research was published over two papers in Nature Climate Change and Frontiers in Marine Science. In the Nature paper, Dr Cornwall and his colleagues show that ocean acidification caused by climate change slows the calcification of coralline algae, which is a significant part of their development process. They also show that coralline algae cannot acclimatise to these effects over one lifetime. However, in Frontiers, the research team show that coralline algae are much more resistant to short-term ocean warming than other ecologically important species such as corals.

“Coralline algae may be able to resist short-term changes in ocean temperatures. However, once changes in ocean chemistry occur and cause acidification, their capacity to build and cement together reefs will be compromised,” Dr Cornwall says.

Dr Cornwall and his colleagues plan to further investigate the effects of marine heatwaves and warming on coralline algae and study possible epigenetic or genetic changes that could help these algae resist acidification.

“The temperate southern hemisphere has little to no data available on how ocean warming will specifically affect our local coralline algae. We also do not know whether over multiple lifetimes they can gain tolerance to either warming or acidification,” Dr Cornwall says.

Dr Cornwall was awarded a Rutherford Discovery Fellowship to continue researching how local species are specifically affected and can be done to protect them from climate change.