Overview

• Researchers analyzed organism counts from 200 coastal stations between Den Helder and Blåvand, using records dating back to 1900 and richer datasets since the 1970s.
• Populations of Atlantic cod, flatfish, seagrass, salt marshes and migratory or breeding birds have fallen sharply, with declines accelerating from the late 1990s onward.
• Species such as the Pacific oyster and American razor clam have increased markedly, signaling a major reorganization of the tidal ecosystem.
• Only a small fraction of native populations remained stable, underscoring widespread shifts in biodiversity composition.
• The team introduced a systematic early warning method for local species threats and plans targeted investigations into environmental and human drivers.