Posidonia grows 1 cm/year; recovery takes decades. Leaf production drops 20% in the first year after a spill. Dredging: invertebrates take 2-5 years to recolonise. BOE 2025 environmental impact declaration Valencia.
Beach replenishment processes through artificial sand nourishment generate debate about their impact on underwater benthic life. Divers observe how sand dumping alters Posidonia seagrass meadows, invertebrate communities, and the behavior of fish that depend on specific rocky structures. Discussions cover whether seabed recovery after these interventions is possible and within what timeframe.
Posidonia oceanica meadows are particularly vulnerable because they grow barely one centimeter per year and their recovery can take decades. Scientific studies document that leaf production can be reduced by 20% during the first year after dumping. Sand extraction from the seabed creates a second impact at the dredging point, where benthic invertebrate communities take between two and five years to recolonize. In March 2025, the BOE published the environmental impact declaration for the deep-water sand extraction project off Valencia.