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Spanish Lakes Get New Life as Minnows Vanish
4 Oct
Summary
- Scientists removed minnows from two Spanish mountain lakes.
- Amphibians and aquatic invertebrates returned after ten months.
- Rotenone, a biodegradable piscicide, was used in the lake treatment.
Mountain lakes in Spain's Alt Pirineu Natural Park are experiencing a remarkable ecological recovery. Scientists from CEAB-CSIC treated two lakes, Tres Estanys del Mig and Tres Estanys de Baix, using rotenone, a biodegradable piscicide, to eliminate invasive minnows.
Ten months following the September 2025 treatment, the lakes have shown significant signs of life. Amphibians and aquatic invertebrates, absent since monitoring began in 2014, have returned. The water clarity has also improved considerably.
This initiative, part of the European project LIFE RESQUE ALPYR, aims to restore ecological balance. Initial findings suggest varied recovery paces among treated lakes, possibly influenced by prior conservation efforts and the presence of dormant species in lakebeds.
Researchers confirmed the rotenone's safe degradation, with a half-life of 10 to 20 days and no traces found downstream. This underscores the method's minimal ecological footprint. Previous studies also indicate that removing invasive species can lead to swift recovery of native biodiversity.
