When rivers stop flowing, do we stop caring?

 

You may have seen signs on stormwater drains to remind us that rubbish in the streets can end up polluting our rivers and eventually our oceans.

Somewhat less obvious than street gutters are the ecological channels mapping most of our land masses — temporary rivers that only flow part-year, unlike their perennial counterparts that flow all year round.

In fact, more than 50 per cent of the world’s rivers are ‘temporary rivers’ — on every continent, many ecosystems from small headwaters to large lowland rivers sometimes stop flowing.

Surface waters can isolate into pools or may disappear completely, leaving a dry bed. This can happen naturally in response to climate and geology or, increasingly, due to human activities.

However, when waters start running, whatever was tossed onto the dry bed will flow downstream into bigger rivers and likely make its way into the ocean — just like trash through a stormwater drain.

Despite the prevalence and unique biodiversity of temporary rivers, they are among the most understudied and under-protected in the world.

We are familiar with perennial rivers which always flow, but do we care less about the part-timers?

Dr Catherine Leigh from the Queensland University of Technology (QUT) in Brisbane, Australia, investigated attitudes towards temporary and perennial rivers with colleagues from Centre College (USA), University of San Diego (USA), Nottingham Trent University (UK) and the University of Worcester (UK).

Despite the ecological importance of temporary rivers, the research was one of only two empirical studies available on attitudes towards temporary versus perennial rivers.

The researchers surveyed university students enrolled in undergraduate degrees in Australia, UK and USA at the start and end of courses in environmental education.

Even though students were likely aware of and interested in the environment, attitudes towards temporary rivers were not as positive as attitudes towards perennial rivers, especially when temporary rivers were not flowing.

“In particular, students tended to think that non-flowing temporary rivers had little aesthetic or recreational amenity,” Dr Leigh said.

“The good news is that attitudes towards these rivers improved after students finished courses of environmental education, even when those courses weren’t about rivers,” she said.

This finding is important because students’ attitudes towards rivers could affect their future work in environmental science and management.

The study also suggested that general education about the environment, if provided to the wider community, may improve attitudes towards temporary rivers and provide impetus to support protection and management.

“Temporary rivers contribute to local and global biodiversity and play important roles in our environment, even when they’re not flowing,” Dr Leigh said.

“They help to regulate climate, to filter, process and store materials, and they provide habitat for aquatic and terrestrial life.”

“When plastic and other rubbish on the streets and in the environment makes its way into streams and rivers by direct dumping or wind, that rubbish and the water that carries it can end up in our oceans,” Dr Leigh said.

“A dry creek might look at the time an unlikely candidate for a ‘downstream rubbish transporter’, but temporary rivers do flow sometimes, and this can happen very suddenly, especially during big downpours.”

“Most of the rivers in Australia are temporary, so they are an integral part of our water resources physically, chemically, biologically and ecologically.

“For example, here in the south-east Queensland region of Australia, once you get about 20 km from the coast, any river or stream you encounter is likely to be temporary. Even the Brisbane River, which supports Australia’s third-largest city, is temporary in its upper reaches.

“When we think of rivers, we tend to think of water. Temporary rivers don’t always have water in them, so this can make them a bit harder to notice at times, and people might not think about them as much as rivers that flow all year round.

“So it might at first seem odd to learn about dry riverbeds, isolated waters, and even land-based plants and animals when learning about rivers.

“This is something we need to change.”

Many perennial rivers are becoming temporary, with much of this change associated with changes in land and water use, as well as climate change that leads to greater intermittence of flow. These changes are driving increased consideration of temporary rivers in research, management and policy.

Management of temporary rivers differs around Australia and the world, according to Dr Leigh, who is an advocate for the wise management of temporary waterways.

In 2018 she was one of 17 science and management experts worldwide who called on United States President Donald Trump to ensure the protection of temporary waterways across the US.

“In our letter published in Science magazine, we called for the US to provide temporary waterways with a level of protection similar to that in other countries, such as Australia,” Dr Leigh said.

“Failure to protect and manage temporary rivers wisely risks costly and potentially irreversible harm to the ecosystem services supported by these ecosystems, including the provision of secure potable water.”

The need to protect and better manage temporary rivers has prompted Dr Leigh and other researchers to develop new or modified methods to monitor flow status, assess the ecological condition of these systems, and collate and curate temporary-river data.

“The problem for temporary rivers is that they are often ungauged and unmonitored, and therefore underrepresented in the data,” she said.

“This limits our ability to map, study, and protect these important ecosystems.

“We need to share our data and knowledge on temporary rivers to ensure greater understanding of the roles these ecosystems play, to better predict changing flow conditions, and better manage our water resources and the diversity of life that depends on them.”

It may seem an obscure passion, but a love of temporary rivers was something Dr Leigh fell in to.

“Temporary rivers are so diverse! They can range from tiny streams to huge rivers, and they are found on every continent on Earth.

“These rivers and the plants and animals that depend on them are also under a lot of pressure from human activities, including climate change.

“They also provide important ecosystems services for society and culture, and we’re only just beginning to scrape the surface on this topic.

“We know so little about them scientifically, relative to what we know about rivers that flow all year round, yet temporary rivers make up more than 50 per cent of the world’s flowing-water ecosystems.

“I study temporary rivers because they are fascinating, beautiful and deserving of our care and protection.”

Many of today’s youth get actively involved in conservation efforts like ‘Clean Up Australia’ — a national-cum-global campaign to inspire and empower communities to clean up, fix up and conserve the environment. As a youngster, a love of outdoor play and a passionate mentor paved the way for Dr Leigh’s interest in ecology.

“When I found out how common these types of streams and rivers were, yet there was so little research done on them, I was hooked!”

“I had spent a lot of time as a kid playing in creeks that would often be dry; there were lots of them around my and friends’ places in Buderim on the Sunshine Coast.

“I got really interested in studying temporary rivers during my undergraduate Ecology degree — I was inspired by a great teacher who later became my PhD supervisor, Dr Fran Sheldon.

“She had done a lot of work on Australia’s inland river systems like Cooper Creek, which is huge.

“It seldom flows but, when it does, the waters eventually make their way into Lake Eyre in the middle of Australia, leading to booms in wildlife.

In April, the NASA Earth Observatory reported that Cooper Creek started flowing again this year after several record storm systems including Cyclone Trevor in Queensland between February and April, filling Lake Eyre in South Australia, which typically only fills once per decade.

Dr Leigh teaches Honours students studying Earth, Environmental and Biological Sciences at QUT in Brisbane, Australia. She is also a senior research fellow investigating water quality and emerging technologies with Dr Erin Peterson and Distinguished Professor Kerrie Mengersen at the Australian Research Council Centre of Excellence for Mathematical and Statistical Frontiers (ACEMS).

Read full study:
Leigh, C, Boersma, K, Galatowitsch, M, Milner, V, Stubbington, R. Are all rivers equal? The role of education in attitudes towards temporary and perennial rivers. People Nat. 2019;00:1–10. DOI:10.1002/pan3.22

People and Nature is a new open access journal published by the British Ecological Society. All articles can be viewed here.

Media contact:
Novella Moncrieff, Queensland University of Technology, Email: novella.moncrieff@qut.edu.au, Tel: :+61 73 138 7675