The bottom of the river is also a house
Vive Cabeceiras · Ocorrência referida no documento ambiental

The river mussel depends on more than surface water.

The municipal environmental document refers Margaritifera margaritifera in the municipality. The ICNF chart explains why the background matters: young people live buried in the substrate and need oxygen. The species prefers running water and avoids poor oxygen conditions. Feeding is done by filtration of water particles. Protecting this life involves looking at the bed, water and fish associated with reproduction. The municipal reference does not indicate a current observation point. There's a difference between having water and having the environment this animal needs. The chart distinguishes running water from standing water and describes how river change and habitat fragmentation can harm the species. Filtering particles to feed does not make the mussel resistant to pollution: oxygen availability and background conditions remain essential.

Sources and context
PDM — Environmental Assessment, p. 50
https://cabeceirasdebasto.pt/pdm/Acompanham_plano/0304_Avaliacao_Ambiental_Estrategica_RA.pdf
Accessed: 2026-11-06
ICNF — Margaritifera margaritifera, ecology, reproduction and threats, pp. 2–3
https://www.icnf.pt/api/file/doc/325a153f524d834a#page=2
Accessed: 2026-11-07

Editorial summary. The date of consultation is not the date of the facts.
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https://vivecabeceiras.pt/en/descobrir/terra-viva/?leitura=mexilhao#mexilhao