Climate change: Research on how increasing CO2 is affecting the Waikato River

New research will study how increasing CO2 is changing the water quality of the Waikato River. Photo / Doug Sherring

The Waikato River is at the centre of a new multi-million-dollar programme aiming to reveal how increasing carbon dioxide (CO2) levels are affecting rivers and lakes – and what that means environmentally, economically and socially.

Lincoln Agritech is leading a new five-year, $10 million research programme funded by the Ministry of Business, Innovation and Employment, studying how increasing CO2 is changing the water quality of the Waikato River.

The aim is to develop a model that predicts harmful algal blooms in freshwater systems and the effectiveness of preventative measures.

“We know that increasing atmospheric carbon dioxide is making oceans more acidic,” said Lincoln Agritech principal environmental scientist Dr Roland Stenger. “But we don’t know the impact of atmospheric CO2 on freshwater.”

“We think freshwater is acidifying faster than the oceans in some places, and where this is most pronounced, CO2 could be driving other ecological changes.”

The research team will investigate the effects of atmospheric CO2 on algae, kākahi [freshwater mussels], and how nutrient availability affects the development of harmful algal blooms.

“We will deploy new methods to monitor water quality and predict future algal growth,” said science leader Dr Adam Hartland.

“We hope also to show the likely effectiveness of interventions to maintain freshwater quality.”

The Waikato River supplies drinking water to around one-third of New Zealand’s population, including Auckland and Hamilton.

Hartland said recent studies showed the increasing risk of harmful algal blooms as the climate changes.

“They affect ecosystem health, restrict water sports and mahinga kai gathering, and pose a contamination risk to drinking water.”

“We hope this research programme will develop monitoring techniques that provide advance warning of developing water quality problems, so treatment plants can take preventative action, lowering costs and reducing disruption.”

The team will also include researchers from the Waikato-Tainui, Ngāti Maniapoto and Ngāti Tahu – Ngāti Whaoa iwi, the Cawthron Institute, Waikato Regional Council, Lincoln and Victoria Universities, Otago and Waikato Universities and several overseas universities.

Stenger said rapidly increasing atmospheric CO2 was adding pressure to already degraded freshwater systems, such as the Waikato River.

“But freshwater management in general, and ambitious intergenerational restoration projects in particular, don’t take these impacts into account.

“Through the combined lenses of mātauranga and scientific knowledge, we will show the implications of climate change for restoration strategies.”