2023-11-15 11:15:20
Freshwater ecosystems are one of the most vulnerable to biodiversity loss due to the pressures that humans have exerted on them throughout history. The measures that have been adopted to improve this situation – installation of treatment plants, removal of obstacles, etc. – have improved environmental quality and have promoted the recovery of freshwater biodiversity. But has this trend continued?
A recent study by a team led by Peter Haase of the University of Duisburg-Essen in Germany examined this last question.
Ecologists from 22 European countries collaborating in different initiatives, including the River Ecology research group of the University of the Basque Country (Euskal Herriko Unibertsitatea), have wanted to investigate the trend over time relative to the diversity and organization of invertebrates. in rivers and how they have responded to environmental pressures and changes. To do this, they have used 1,816 time series of data from invertebrates sampled in the river systems of those countries between 1968 and 2020. “1,816 points in Europe have been sampled for many years, from which we have deduced the evolution of these rivers and streams to over 40 years,” said Aitor Larrañaga, researcher and professor at the UPV/EHU.
The study concludes that, “in general, the biodiversity of rivers and streams has improved until the 2000s, with an increase in both species and populations. And that’s a good sign. But from then on, the improvement in biodiversity has stagnated: we no longer see the increases that occurred before, he says. This improvement observed in the 1990s and 2000s highlights the effectiveness of the measures implemented to improve water quality, as well as the recovery work, but the fact that this trend has slowed down in the 2010s of improvement suggests that the effectiveness of the measures currently applied has decreased,” says Larrañaga.
Renteria in Río Oiartzun. (Photo: Arturo Elosegi, UPV/EHU)
Importance of monitoring river ecosystems
The researcher points out that signs of complacency must be put aside: “To a certain extent, it is evident that highly polluted areas have improved and that as the number of highly polluted streams is reduced, it is more difficult to substantially improve the ecological state. since even the simplest solutions in highly contaminated areas generate important improvements. However, there are still black holes on Europe’s water quality map. There are quite contaminated places, not everything is done.”
Researchers emphasize that there are new and long-lasting pressures that damage freshwater ecosystems, such as new pollutants, climate change and invasive species, which require redoubling efforts to continue recovering the biodiversity of these ecosystems. “New pollutants are continually being produced. It is very difficult to deduce causality, that is, what this stagnation of the last decade could be due to. But it is likely a consequence of the appearance of new contaminants. The study of the impact of each of these new pollutants must be undertaken with caution, a topic on which numerous works have been appearing in recent years. In any case, this is an issue of special relevance from the point of view of the state of ecosystems, since new contaminants appear at a very rapid rate and the interactions between them can be very complex. We ask for more research and, at the same time, caution,” says Larrañaga.
The study is titled “The recovery of European freshwater biodiversity has come to a halt”. And it has been published in the academic journal Nature. (Source: UPV/EHU)
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