Text by IICG-URJC and photograph by Michele Spairani
Every March 22nd, World Water Day is celebrated, an opportunity to remember that rivers, lakes, and wetlands not only provide us with water but also harbor extraordinary biodiversity. However, many of these ecosystems are among the most threatened on the planet.
The Mediterranean basin, in particular, is a true hotspot of freshwater biodiversity: it is home to numerous endemic species, that is, species that only live in this region of the world. But this uniqueness also implies fragility, since many of these species have very small distributions and are extremely sensitive to environmental changes.
A little-known example: a Mediterranean river lamprey
Dr. Simone Guareschi, a researcher at the Global Change Research Institute (IICG-URJC), in collaboration with the University of Turin (Italy), participated in a recent study, published in the journal Aquatic Conservation: Marine and Freshwater Ecosystems, which analysed the future of one of the lamprey species (Lampetra zanandreai), a primitive freshwater fish endemic to northern Italy and primarily associated with the Po River basin. Although little known, this species aptly represents the situation of many freshwater species: it lives in small, relatively cold rivers, depends on very specific sediments and habitats, and has limited dispersal capacity. These characteristics make it especially vulnerable to human pressures.
What will happen in the future?
Dr. Guareschi and the rest of the team collected data and used species distribution models to predict how suitable habitat—that which meets the necessary conditions for the organism’s survival, reproduction, and development—might change in the future under different climate scenarios. The result is worrying: a significant reduction in suitable habitat area is projected by 2050. Suitable areas could shift to higher altitudes, following colder temperatures, and the areas that remain suitable will be few and fragmented. In other words, a species that is already rare today could become even rarer in the future.
Climate change adds to other pressures
Climate change doesn’t act alone. The study shows that many of the areas that would still be suitable for the species coincide with areas under high human pressure: dams, river alterations, pollution, or changes in land use. This means that the species is caught between two major forces of global change: on the one hand, landscape and river transformations, and on the other, climate change. Furthermore, the study indicates that the Natura 2000 network of protected areas does not adequately cover either current populations or potential future habitats of this lamprey.
A global problem for freshwater ecosystems
Although the study, in which the IICG-URJC researcher participated, focuses on a single species, its message reflects a much broader problem. Freshwater ecosystems occupy less than 3% of the planet’s surface, but they harbour an enormous proportion of biodiversity and provide key ecosystem services for human populations. Despite this, they are among the most degraded ecosystems in the world.
Globally, recent studies estimate that around a quarter of freshwater fauna species are threatened with extinction, due to factors such as pollution, dams, water extraction, invasive species, and climate change.
The Mediterranean on the front lines of global change
The case of Lampetra zanandreai illustrates a very common pattern in the Mediterranean: species with small ranges, rivers highly fragmented by infrastructure, intense agricultural and urban pressure, and a rapidly warming and drying climate. In this context, the conservation of freshwater biodiversity requires measures that go beyond protecting isolated stretches of river. It is necessary to restore river connectivity, rehabilitate habitats, and anticipate the effects of climate change.
Looking to the future
The main message of this study, published last February, is clear: protecting freshwater species requires thinking about the future of both the climate and the land simultaneously. On World Water Day, remembering the importance of these ecosystems also means recognizing that conservation shouldn’t be solely about protecting iconic species. Often, as in the case of this small lamprey, it’s about protecting discreet and little-known species that are key to the functioning of rivers. Because when rare species disappear from our rivers, an essential part of the biodiversity that sustains life on the planet also disappears.
Reference:
Abbà, M., T.Cancellario, S.Fenoglio, A.Candiotto, M.Spairani, and S.Guareschi. 2026. “Rare Now and Rarer in the Future? Future Potential Distributions of the Endemic Lampetra zanandreai Showed Contractions in Its Suitable Areas.” Aquatic Conservation: Marine and Freshwater Ecosystems 36, no. 2: e70335. https://doi.org/10.1002/aqc.70335