Restoring freshwater ecosystems
National Science Challenges looks at old problems in new ways, and bring teams of scientists together from around the country, writes Andrea Byrom.
What springs to mind when you think about big environmental problems? Wasps – public enemy No 1. Weeds choking our forest remnants. Catastrophic pests and pathogens that could arrive at any moment to cripple our primary industries.
Invasive rats, stoats and possums munching their way through our native flora and fauna. Lakes and rivers we can’t swim in.
The New Zealand’s Biological Heritage National Science Challenge was created to tackle these environmental issues on land and freshwater, specifically focused on New Zealand’s native flora and fauna, as well as combating serious weed, pest and pathogen threats to our primary production and natural ecosystems.
The idea behind the science challenges is to break down institutional barriers, as science in New Zealand has been under a highly competitive model for decades. The new model is designed to bring teams of scientists together from different organisations and disciplines, and it also recognises matauranga Maori (Maori knowledge), and the role of ‘‘citizen scientists’’.
What’s in our groundwater?
The groundwater that fills the dark, underground spaces in rocks and gravel can be thousands of years old. Some of our highly productive alluvial plains are hundreds of metres deep, holding enormous volumes of water. Some of it gets trapped and cannot find its way to the sea, but much of it finds its way into lowland rivers and wetlands.
Most of the water from aquifers is high in quality for human uses and contains few harmful contaminants. This is largely due to a remarkable subterranean ecosystem of microbial slime layers and small invertebrates, some up to 25mm long. Specially adapted to living without sunlight, this ecosystem does a thorough job of filtering out and processing contaminants and many bacteria carried underground by the water.
A programme led by Niwa aims to identify the different populations of these important creatures that are present in three regions (Nelson, Canterbury and Hawke’s Bay), seven catchments, and varying land use situations. Although out of sight and out of mind, they are as much a part of our biodiversity as kiwi or kauri, and definitely have their role, as we are beginning to realise. We don’t yet know what we stand to lose, and how land use might be affecting them.
Many of these organisms will be new to science, and so this programme will create a reference database for conservation managers, local government, and anyone interested in the health of these neglected ecosystems. DNA profiling, led by Waikato University, will be used to identify, differentiate and characterise species. Maori communities and regional council staff will help with fieldwork and be closely involved in the interpretation of the resulting information.
The recent breach of the Havelock North water supply alerted New Zealanders to the vital importance of maintaining the health of our aquifers, which we tend to take for granted until something goes wrong. Some water drawn from aquifers for town supplies has chlorine routinely added to kill off any surviving bugs. In some places, here and around the world, groundwater is being used up faster than it can be replaced. It is an increasingly precious resource that must be managed carefully to sustain its valuable ‘‘ecosystem services’’ and groundwater quality.
Restoration of waterways
Enormous effort is going into the restoration of our waterways. Intriguingly, however, there is some resistance to restoration – not from people, but from the waterways themselves. Degraded waterways become dominated by species that preserve the degraded status quo. This determined default to an unhealthy state (called ‘‘negative resilience’’) is disheartening and needs to be understood, to ensure that restoration efforts are fully rewarded. If we can boost the resilience of our streams, we can roll out restoration efforts on a grand scale in future.
Ecosystems are complicated. A team from the University of Canterbury Freshwater Research Group, with help from Niwa, will conduct research that draws on a huge amount of information we already know about the interconnected web of freshwater organisms in our streams and rivers. Vital characteristics about individual insects and fish, such as when or how they feed or reproduce (called functional traits), will help the scientists figure out what needs to be present to restore healthy resilience.
For example, a tiny snail covers some stream bottoms and overwhelms other species found in agricultural waterways across Canterbury. The team will study various combinations of freshwater organisms and their functional traits, to see what community of individuals works best together, and whether these designer communities can overcome the negative resilience. And while planting riparian zones is still a great thing to do, we need to accept that stream life is complicated, and that this is a multi-generation job.
Dr Andrea Byrom is the director of the Science Challenge for New Zealand’s Biological Heritage, and is an expert in the management of predators such as possums, rats and stoats.