New Zealand the first country to start investigating multiple human impacts on the health of estuaries

17 July 2017
Graduate students learning benthic sampling techniques in the Whangateau Estuary, North Island, New Zealand.
Graduate students learning benthic sampling techniques in the Whangateau Estuary, North Island, New Zealand.

In a world of escalating environmental change, it is critical we understand how natural ecosystems respond. 

This is especially important for our coasts and estuaries, because they are squeezed between the land and the sea and at the forefront of climate change.  Understanding how our coasts respond to change, and how this will affect the many ways we value these ecosystems, is a huge challenge. 

A large group of estuarine scientists and postgraduate students met at the University of Auckland’s Leigh Marine Laboratory in late June as part of the National Science Challenge - Sustainable Seas.

Called the Tipping Points workshop, participants included senior scientists, postdoctoral research fellows, technicians, and postgraduate students from the University of Auckland, the University of Waikato, the University of Canterbury and the University of Otago, as well as the National Institute of Water and Atmospheric Research, and the Cawthron Institute.

This is the first project globally to investigate experimentally the impact of multiple human-induced stressors on the health and functioning of coastal ecosystems at sites spanning from Northland to Southland, and the workshop and brought these researchers together to discuss progress.

The focus for their work is exploring how estuaries respond to sediment and nutrient loading, two of the most important land-based stressors affecting our coasts. These stressors have intense localised effects; smothering shellfish beds, reducing water clarity and promoting blooms of nuisance algae, such as sea lettuce.

Dr Simon Thrush, Director, Institute of Marine Sciences from the University of Auckland says, “We know that small but cumulative changes can radically change how marine ecosystems work, but we do not yet know how to assess these risks. 

“This project is a first step towards understanding how estuaries respond to increasing inputs of these stressors and their capacity drive rapid and unexpected changes estuary health (i.e. exceed a tipping point).”

The project bridges the gap between scientific research and environmental policy through an ecosystem-based management approach – which includes humans as a crucial component of ecosystems and takes a holistic approach to managing marine resources.

The first Tipping Points field experiment will run until November. Teams of researchers will be working around the country to gather data that explains how the increasingly muddy waters of our estuaries is affecting the capacity of these systems to deal with nutrient runoff. 

This will provide hard evidence on how to best manage our coasts and ensure these precious ecosystems continue to clean up our coasts, help keep the water clear, provide food, provide medicine, provide oxygen for us to breath, and sequester carbon, among many other processes.