Activities contributing to smothering and change in siltation in the Celtic Sea include dredging for shipping, disposal of materials to the seafloor, and commercial fishing. Maerl and aggregate extraction also occurred in the past.
Sediment accretion (land mass increases caused by water-borne sediment deposition) and sediment release issues associated
with the growth of new species such as cordgrass Spartina spp have been known to cause significant siltation problems in
coastal wetlands such as those in Cork Harbour.