In Europe, many large nature reserves have been established or expanded in recent decades. Plants and animals in the protected land areas benefit from this. However, the protected areas have so far offered little protection for the river ecosystems within them, a new study shows. Because the waters outside their protected sections often continue to be polluted and overused. The researchers therefore advocate more comprehensive nature conservation that takes land and freshwater creatures equally into account.
Through their actions, humans are destroying habitats in many places and causing global mass extinction. In order to limit this loss of species, countries around the world have established several new nature reserves or expanded existing protected areas in recent decades. National laws and international agreements have been passed for this purpose, including, for example, the EU’s Fauna-Flora-Habitat Directive and the Kunming-Montreal Agreement for the Protection of Biodiversity. These regulations restrict human activities in national parks or nature reserves in order to preserve and restore biological diversity on land and in the sea. But how effective are these measures for the health of inland freshwater bodies of water, where biodiversity is currently declining most rapidly?
How well are the rivers in Europe?
Researchers led by James Sinclair from the Senckenberg Research Institute and Nature Museum Frankfurt am Main investigated this question by taking an inventory of rivers in Europe. They examined the status of rivers in ten European countries over a period of almost four decades. To do this, they took samples from 1,754 locations in protected and unprotected areas between 1986 and 2022 and examined which living creatures occur there. In particular, they analyzed the population of small aquatic invertebrates such as insect larvae and mussels. These so-called bioindicators show how healthy a river is overall.
The result: On most rivers, the biologists found no differences between protected and unprotected waters. This is not surprising for already very clean rivers, as the habitats of these waters were and are less polluted anyway. But even in moderately or slightly polluted rivers, water health could only be slightly improved by designating protected areas. Only the once heavily polluted rivers and their inhabitants benefited noticeably and measurably from the protection zones – provided that the protection also included large parts of the water catchment area.
The team concludes that existing protected areas only brought measurable improvements in a few cases over decades. “Our results show that existing protected areas in Europe for rivers and their species have limited effectiveness,” says Sinclair. “We were only able to see improvements in biodiversity and water quality where large parts of the river catchment area were protected. Small-scale protection measures directly on the banks are obviously not enough to really relieve pressure on rivers.”
Think about nature conservation holistically
But why do nature reserves not adequately protect aquatic life? According to the researchers, the existing concepts of protected areas simply ignored river ecosystems because they only focused on certain plants or animals on land – such as forests or rare birds and mammals. The protected areas have been designated and regulated accordingly to benefit these species. However, the rivers that flow through these zones continue to be polluted. Pollutants or agricultural inputs often continue to enter the waterways, just in other places, outside of the protected areas. “Rivers are not isolated habitats, but rather part of a network that extends far beyond the actual protection boundaries,” emphasizes senior author Peter Haase from the Senckenberg Research Institute and Nature Museum Frankfurt. “If we only protect individual sections but don’t think about the entire catchment area, the benefits will remain low.”
In order to protect rivers sustainably, protection concepts should be thought of and established more holistically in the future and then take land and water habitats equally into account, according to the researchers. The rivers would have to be protected from pollution and overuse from source to mouth, including the riparian zones, tributaries and adjacent landscapes. “We need to break down the boundaries between terrestrial and aquatic conservation,” said Sinclair. “This is the only way protected areas can develop their full impact on water bodies and their valuable communities.” This holistic approach could then better stop the loss of species in rivers, on land and in the sea. This would also make international agreements to protect biodiversity more effective and overall goals more realistically achievable, according to the team.
Source: Senckenberg Society for Natural Research; Specialist article: Nature Communications, doi: 10.1038/s41467-025-67125-5