Quality of science
Professor Emerita Carolyn Burns has dedicated her career to understanding – and helping to protect – New Zealand's freshwater ecosystems. This lifetime of outstanding service to science has recently been recognised with the Marsden Medal.
After a lifetime of distinguished research into freshwater ecology, Professor Emerita Carolyn Burns (Zoology) is well qualified to judge the health of our lakes and rivers.
It's not good news. Just as climate change has only recently become a hot topic – despite decades of dire warnings from scientists – our freshwater resources have been allowed to decline in quality because years of far-sighted predictions from experts like Burns have been ignored.
“We're sitting on a slow-ticking time bomb in places like Taupo and many other parts of New Zealand,” says Burns, “waiting to inherit the legacy of farm practice from 50 years ago. Now, no matter what we do, some of these lakes are unlikely to recover for a long time.”
Burns has recently been honoured by her peers, being awarded the prestigious 2017 Marsden Medal by the New Zealand Association of Scientists, not just for her stellar academic career, but also for her support for up-and-coming science leaders and her ability to communicate the importance of what science is and does, now and in the future, to a wide range of audiences.
The medal is the latest in a long line of accolades, including the world's top award for the study of inland waters – the Naumann-Thienemann Medal – and high-level involvement with a range of influential organisations spanning academia, government and conservation.
Her expertise has benefited the World Conservation Union, the Department of Conservation, the Nature Conservation Council, the National Parks and Reserves Authority, the National Institute of Water and Atmospheric Research (NIWA) and Antarctica New Zealand. She has served on Performance-Based Research Fund panels, advised the Marsden Fund, chaired academic audits and supported the promotion of science on panels selecting a diverse array of prizes, awards and fellowships.
She became a Fellow of the Royal Society of New Zealand in 1993 and was subsequently the first woman to chair the society's Academy Council.
Having selected worthy recipients of awards for so many years, receiving the Marsden Medal was a surprise.
“Acknowledgement by one's peers in science is the ultimate accolade and I feel enormously privileged to be honoured in this way. It's really nice to be recognised, but I still worry about science in New Zealand not being acknowledged and thought of as highly as it is in other countries.”
Time has brought some progress, says Burns. “There's been more recognition that science is expensive to do and needs resources and funding and time. There are no immediate answers, especially in ecological areas where research can take years rather than months or weeks to get answers.
“But at least it's acknowledged that it really does cost thousands just to get a multi-measurement probe into a lake. It's also good that now teams of scientists work on things rather than just one person, which is how it used to be.”
Burns' career began with her childhood fascination with tiny organisms she found living in a ditch close to the family home in Lincoln, near Christchurch. That early exposure led to university field trips to ponds, lakes, rivers, estuaries and seashores – and then a difficult decision: whether to study planktonic organisms in fresh or marine environments.
She decided inland waterways were more accessible and would give her more control over her research. She also realised early on that the growth of New Zealand's population and agricultural economy would see freshwater quality become increasingly important.
“New Zealand's freshwater ecosystems have a strong aesthetic and cultural appeal for many people and, for me, our lakes, wetlands, rivers and streams are part of what it is to be a New Zealander. So, I've always felt privileged to be able to work in these dynamic ecosystems."
“I love the way they are constantly changing physically and biologically in response to internal and external drivers – weather, land development, seasons etcetera – and, increasingly also now, to climate change and invasive species. Every answer in freshwater ecology raises new questions and new challenges.
“In particular, I love the challenges raised by the microscopic organisms in the plankton, whose role in freshwater ecosystems worldwide has largely been overlooked until relatively recently, yet they underpin open water food chains and often have significant effects on water quality.”
Burns understands tourism campaigns promoting New Zealand's clean green image, but the scientist in her can only report the facts.
“We have never been 100 per cent pure since human settlement. We are in the happy situation that we have a good image only because we have so few people that we have just not caused much impact. Europe has done a lot to clean up its act, but we have done very little to ensure our environment really is 'clean and green' and it will take considerable time and money to change our practices. We have just been lucky so far.”
Now our luck is running out.
“Our lakes have become increasingly low in quality and there are more algal blooms that cause problems. Water clarity has decreased. Intensification of dairy farming is having an increasing impact.”
Farming has always influenced water quality.
“In New Zealand in the '70s we knew that lakes such as Rotorua were in a very bad state because of high levels of phosphorus and nitrogen causing algal blooms. More than 40 lakes were in trouble and farming, in general, was a major contributor.
“I've come to realise that, in situations like this, people, governments and countries may acknowledge the problem, but only pay lip service to it until they are really up against it. They don't take early action, which would save money and time in the long term. We can see that happening again now with climate change.
“In retrospect I'm not that surprised – but if action had been taken back then, we would have saved millions of dollars on improving water quality in lakes like Rotorua and Taupo, where we have recently spent more than $150 million. And, even when we remove direct sewage inflows from lakes like Rotorua and Lake Horowhenua, we still have run-off from the land. Waste goes into fast flowing rivers or into the sea from developments on the coast.”
Science can identify the problems, and science may be able to provide some solutions.
“Recent research has been looking at the use of slow-release fertilisers, applied appropriately, to mitigate the effects of artificial fertiliser put on to the land.
“For years we didn't apply nitrogen fertiliser because we used clovers and other legumes that fix nitrogen in the soil. Now we do. We also have an intensification of dairying. Cows' urine and dung contain more nitrogen than that of most other livestock, which they expel – in large volumes – onto pasture, concentrated in small areas so that it quickly percolates deeply in the soil and may reach the groundwater. Where these underground aquifers discharge into lakes and inflowing streams it can take 50 or 60 years for the additional nitrogen to reach the lake and the effects seen.
“Years of neglect and poor practice have led to nitrogen and phosphorus building up in lake sediments. When you have nutrient-rich organic sediments, oxygen is lost from the bottom waters of the lake, which has happened in Lake Hayes, near Queenstown."
“In the absence of oxygen, nitrogen and phosphorus are released from the sediments and are carried into the upper waters where they promote algal growth and blooms. When these algae die and sink, they add to the organic material breaking down on the lake bottom, a process that uses more oxygen, so that increasingly more bottom water becomes anoxic – and fish can't live without oxygen. It's a vicious cycle that is very hard to break.”
NIWA is looking at ways to break the cycle, from using chemicals to installing plastic sheeting to physically isolate lake sediments from the overlying water.
Burns has been investigating using more natural mechanisms in the form of shrimp-like Daphnia species that eat algae that cause blooms. But recently the bloom-forming algae have tended to be larger species – too big to be eaten by the Daphnia.
The microscopic world remains one of multiple mysteries and Burns is far from done with it.
“Although I am now a professor emerita it doesn't mean it's the end of my career. I'm still active in research and I'm still going to be working in science. There are so many things I would still love to do, but there is not enough time in the rest of my life to do them all.”
Burns is also working on her bucket list, travelling widely to explore the problems, pressures and other mysteries in the rest of the world.
“It's a horrifying thought that one day I might be confined to a rocking chair regretting that I know so little about the rest of our planet, so I want to get things done while I can, travelling to see different countries and different cultures and learn from them. It's astonishing what people achieved as long ago as 5000 years BC – but what happened to all that knowledge?”
Burns' passion for life and science is infectious, something generations of students and colleagues have appreciated.
“For me, a university academic position has provided an ideal opportunity to pursue my love of scientific research while at the same time passing on my enthusiasm, knowledge and curiosity about aspects of Earth's ecosystems and biota to students and staff through my teaching. I couldn't have chosen a better career.”