ConnectFish: a project to restore the health of the Iberian rivers

Rivers are the planet's vital arteries: they transport not only water, but also energy, nutrients and life. Although they cover only 1% of the earth's surface, they are home to about 10% of the world's biodiversity. In addition to being the cradle of civilizations, source of water, food, culture and recreation, today they are seriously threatened. Overexploitation, pollution, deforestation and climate change are just some of the threats to their health.

But there is a less visible, yet widespread threat: dams. These infrastructures are extremely useful for managing water, supplying people, industry and agriculture, as well as generating hydroelectric power, providing recreational opportunities and contributing to the landscape and cultural identity of many areas. However, they alter riverbeds, putting at risk both their biological richness and the essential services they provide to society.

Aware of this problem, the Biodiversity and Environment Institute BIOMA of the University of Navarra, in partnership with the Instituto Hidráulico de Cantabria, is conducting ConnectFishamultidisciplinary research project that seeks to generate useful tools to guide the Administration's decisions on the construction or elimination of dams, favoring a more sustainable management of rivers. "If rivers are the veins and arteries of the planet, dams can act as thrombi that prevent them from flowing and affect planetary health. It is our duty to find a balance between the benefits that dams can provide and healthier, more resilient rivers," says Ana Sanchez, researcher at the ConnectFish project .

Spain is one of the countries with the highest density of dams per square kilometer. Many of them are abandoned or in disuse, but they continue to profoundly alter our rivers and their biodiversity. Upstream, the water becomes stagnant, its temperature increases, it loses oxygen and retains sediments and nutrients, altering the chemical balance and favoring the accumulation of pollutants. Downstream, the flow and sediments decrease, affecting the fertility of the environment, the supply of nutrients or the frequency of natural flooding, even affecting coastal areas as there is not enough sediment to regenerate the beaches.

These alterations seriously affect aquatic fauna, fragmenting populations such as trout or salmon and favoring the appearance of invasive species. In the case of Spain , these threats pose a great risk, since it is one of the countries with the highest percentage of endemic freshwater fish species in Europe (more than 70%). For this reason, the ConnectFis team, made up of more than 15 researchers and technicians from different disciplines, is preparing a database with all the existing barriers in Iberian rivers, modeling scenarios of dam removal or construction and evaluating their ecological impacts.

"A healthy and resilient river also provides numerous advantages to humans: it financial aid us financial aid to better adapt to climate change by acting as a flood regulator or climate refuge, maintains the fertility of nearby agricultural soils, sustains biodiversity that controls pests and pollinates crops, offers recreational spaces and cultural, spiritual and educationalvalue... among many other ecosystem services," says Ana. "In addition, the project also has an important social component, as we seek to know the perception that citizens have about the dams in their environment and the value they attach to them, in order to continue moving towards better management of natural areas and species conservation without neglecting the people who live and live in the territory every day," she adds.

ConnectFish is funded by the Biodiversity Foundation of the Ministry for Ecological Transition and Demographic challenge (MITECO) and by the European Union through the Recovery, Transformation and Resilience Plan (PRTR) - NextGenerationEU, ConnectFish has been studying for nearly three years how river barriers affect freshwater fish and what decisions can be made to balance human needs with ecosystem health.