The first video, titled “How to Eradicate Fish from High-Mountain Lakes,” presents the project’s main goals, focusing on the conservation and restoration of these lake ecosystems. High-mountain lakes are traditionally isolated from valley rivers by natural barriers that prevent the arrival of fish. However, many of these lakes now host fish species introduced through historical interventions, which have disrupted the natural ecological balance. These introduced species have become invasive, negatively affecting native fauna and the ecological quality of the habitat.

The video also highlights the collaboration with the FishME project, which uses a multidisciplinary approach to analyze the impact of fish and pollution, and to develop practical tools for managing and restoring mountain lakes.

In the second video, “Mountain Lake Rewilding Works!” Dr. Ventura explains how, after removing the introduced fish species, the original fauna of these lakes begins to recover. This rewilding has led to the return of native species, especially amphibians and macroinvertebrates, and has facilitated the recolonization of small mammals such as the Pyrenean desman, a rodent that relies on aquatic insects for food.

These videos emphasize the importance of conserving and restoring mountain ecosystems and demonstrate essential tools for effective, evidence-based management of these unique natural environments.

Under the motto “Multiple perspectives for studying landscape evolution: Pyrenees 2024” various itineraries were proposed to explore the natural values of Alt Pirineu, including its habitats, species, geodiversity, and human influence on the landscape over time. These routes took place within the Alt Pirineu Natural Park and the Aigüestortes i Estany de Sant Maurici National Park, as well as their surrounding areas.

Actions for permanent and temporary exclusion of livestock in peat bogs

The first outing, in which we participated, took place on June 25th at the Estanyeres peat bogs. This visit provided a firsthand opportunity to observe the effects of livestock exclusion enclosure experiments. Such experiments are invaluable for understanding how herbivore pressure affects plant communities and soil dynamics.

By completely or partially eliminating herbivore activity, we witnessed significant changes in plant growth conditions. This approach mirrors other experiments manipulating biological communities, such as removing trout from ponds to observe their impact on aquatic ecosystem dynamics.

One of the primary conservation goals in these areas is the restoration of superficial soil, often degraded by the trampling of cows and horses. While plant communities in these regions are adapted to moderate grazing, they are susceptible to overgrazing.

Therefore, efforts are underway to maintain an intermediate grazing regime within temporary enclosures, aimed at evaluating whether this management strategy is sufficient to sustain ecological balance and improve the stewardship of these spaces.

Muntanyó d’Àrreu Lake, a unique place

The second visit was to Muntanyó d’Àrreu Lake, located at the head of the Àrreu valley. This shallow lake (approximately 13 meters deep) has a small basin. Below Muntanyó Lake lies an ancient sediment-filled basin, now forming a series of extraordinary peat bogs, a rarity in the Pyrenees.

Situated in a limestone basin, Muntanyó d’Àrreu Lake stands out within our region for its exceptional characteristics among lakes. It boasts a rich macrophytic flora, with up to four different species of the Potamogeton genus thriving here.

Currently, actions are underway at the lake to eradicate the minnow, a small cyprinid introduced as live bait for trout fishing.

In flat areas, water flows through tortuous streams or forms small ponds, saturating the soil along the riverbanks. This creates a high mountain wetland environment known as a mire.

In this second publication, we elaborate the characteristics of these ecosystems and their significance. Furthermore, we delve into the primary threats they encounter and outline the key conservation efforts undertaken by the project.

The brochure is available on the project’s website and also at the tourist offices of the Alt Pirineu Natural Park and the Aigüestortes and Sant Maurici National Park, in Catalonia, and of the Mont Avic Natural Park and the Gran Paradiso National Park, in Italy.