UC ecologist leads urgent global call to save rivers

International experts, led by a Canterbury ecologist, are calling for urgent global change to how the world’s rivers are managed and modelled.

University of Canterbury Rutherford Discovery Fellow Dr Jonathan Tonkin and a range of international scientists contend we can no longer solely aim to restore river ecosystems to historical or ‘natural’ states, because often, and increasingly, those states are themselves changing.

He says we are ill equipped to tackle river management challenges because current tools no longer work amid increasing climatic uncertainty.

“The world is changing so fast that we risk losing the services that river ecosystems provide to society. We need to move on from traditional approaches to managing rivers, to tools that can anticipate future shocks and manage adaptively to protect valuable species and ecosystem services,” says Dr Tonkin, community ecologist and lead author of the new paper, ‘Prepare river ecosystems for an uncertain future’, published today in the leading international science journal Nature.

“We are losing freshwater biodiversity on our watch. The threats are stacking up, including from pollution, invasive species, and land-use change, and the amplifying effects of climate change,” says Dr Tonkin.

He argues that models of river management must be able to look into the future, where novel conditions are inevitable. Dr Tonkin is calling for rivers to be managed adaptively and for researchers to develop forecasting tools that move beyond simply monitoring the state of ecosystems to establishing the biological mechanisms that underpin their survival.

“The reason we want to look into the future is to anticipate future conditions and proactively manage against extremes to avoid collapses in populations or ecosystems,” he says.

“In New Zealand and around the world we know rivers are under extreme pressure. In times of such rapid environmental change, we must manage rivers for resilience. Large fish kills and droughts are increasingly frequent globally, including in Australia’s Murray-Darling Basin, Europe’s Rhine River, and across California.”

To limit the regularity of such events, Dr Tonkin and his colleagues want to see a greater uptake of adaptive approaches to managing river flows, and for greater emphasis to be placed on understanding the biological mechanisms by which species respond to rapid change. By understanding these mechanisms, he says, we will be better able to foresee how management interventions will play out in the future, as well as how species will respond to unprecedented change.

“This paper is a call for the uptake of these approaches, in order to allow for a scientifically robust basis for managing for resilience in rivers under climate change,” he says. “Rivers also need to be managed for people. So we have a major task ahead of us, requiring collaboration between scientists, conservationists, water managers, and policymakers.”

Joining Dr Tonkin as co-authors are scientists from Colorado State University, Oregon State University, the University of Washington, the University of California Berkeley, the University of Canberra, La Trobe University, the University of Melbourne, and the United States Forest Service.

DOI: 10.1038/d41586-019-01877-1 ‘Prepare river ecosystems for an uncertain future’, URL: https://www.nature.com/articles/d41586-019-01877-1

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