Rivers are the lifelines of our planet. For thousands of years, people have settled along rivers and benefited from the advantages they offer, such as clean drinking water, energy, food, transportation, and recreation. However, human intervention has significantly damaged the diversity of flora and fauna in around 50 percent of the world’s rivers. Densely populated regions in East Asia, Europe, and North America are particularly affected, as are arid and tropical regions. The discharge of wastewater, the use of fertilizers and pesticides on nearby fields, the extraction of water, river channelization, and the introduction of alien species are just some of the causes of the poor condition of rivers.

In order to reduce this strain, numerous countries and regions have passed laws aimed at reducing river pollution, protecting species and habitats, and restoring ecosystems. These include the Clean Water Act in the USA, the European Water Framework Directive, and the Kunming-Montreal Convention on Global Biodiversity. As a result, numerous protective measures have been implemented worldwide to preserve or improve biodiversity in rivers – for example through renaturation, wastewater treatment, or reducing the use of fertilizers. In a new study, an international research team led by Prof. Dr. Peter Haase from the Senckenberg Research Institute and Natural History Museum Frankfurt has now taken a close look at the effectiveness of these measures and has initially come to sobering conclusions.

“In many places, the protection and renaturation measures are not enough to compensate for the strain on our rivers,” reports Haase. 

“The loss of biodiversity in rivers is far greater than in terrestrial or marine ecosystems: 88 percent of the megafauna such as river dolphins, turtles, and sturgeons are threatened with extinction.” The research team evaluated a total of 7,195 projects in 26 regions of the world, spread across different continents, countries, and river basins, with regard to their effectiveness in conserving biodiversity in rivers. “The vast majority of these conservation measures achieved either only minor improvements in biodiversity or none at all,” summarizes Haase

In their global analysis, the researchers examined nine different categories of conservation measures, including the restoration of habitats, the reduction of pollutant input, and the control of invasive species. The fact that many of the measures taken to date have only led to minor improvements for biodiversity does not necessarily mean that the individual measures are without benefit. Rather, there is often a lack of a comprehensive approach that addresses several stress factors simultaneously. “Local measures such as the renaturation of channelized rivers are an important step but are often not sufficient if the main causes such as diffuse pollution or invasive species are not taken into account,” continues Haase. “The proper geographical scale and long-term monitoring are also crucial. Rivers and their ecosystems often extend across national borders. Holistic, river basin-wide planning that incorporates both ecological and social aspects could bring about the urgently needed turnaround.”

The study’s authors advocate continuous monitoring and evaluation of the effectiveness of conservation measures and the involvement of all relevant social actors. “A key to successfully and effectively protecting the biodiversity of our rivers is the so-called ‘co-production’ – the joint development of solutions by researchers, policymakers, Indigenous communities, and other local groups that benefit directly from river use,” explains Haase. “This approach combines scientific findings with local knowledge and considers both ecological and social needs. This can reduce conflicts and increase the acceptance of measures. In addition, co-production enables flexible, site-specific solutions that can be dynamically adapted to new challenges. Rivers are complex ecosystems that are closely linked to their catchment area. Saving them therefore requires coordinated, large-scale efforts. The combination of science, political will, and social commitment can make the decisive difference in the future.”