A range of human activities and environmental changes along water courses and on adjacent wetland and farmland, alone or in combination, can influence the habitat and survival chances of both adult and juvenile mussel, in Irish rivers.
Research has shown that the decline in freshwater pearl mussel in Ireland can be related to three main causes:
- Changes in river and catchment flows, can mean that river channels dry up during periods of low flow, while erosion during high flood flows gives rise to sedimentation or scouring damage of the river bed;
- Artificially increased sediment losses from the land into rivers (known as sedimentation); and
- Low water quality due mainly to high nutrient run-off into rivers from organic and artificial sources. Pesticides and herbicides can also be toxic to aquatic life.
Any land use activity occurring within a freshwater pearl mussel catchment, that gives rise to the above effects, may impact negatively on the survival of juvenile or adult freshwater pearl mussels. Illustrated examples of how land use can cause an effect on catchment flow, sedimentation, and water quality within freshwater pearl mussel rivers are shown here.
