The Tidal Symphony: Atlantic Ecosystems

The Atlantic coast's dramatic tides create unique habitats that pulse with twice-daily rhythms. The Bay of Mont-Saint-Michel, experiencing Europe's highest tidal ranges up to 15 meters, transforms from vast mudflat to shallow sea in hours. This dynamic environment supports specialized communities: lugworms that process tons of sediment, shore crabs that migrate with the tide, and millions of migrating birds that depend on exposed invertebrates for fuel.

These intertidal zones function as massive biological filters. Oysters alone can filter up to 200 liters of water daily, removing excess nutrients and particles. The salt marshes of the Baie de Somme and Marais Poitevin act as nurseries for commercial fish species, with juvenile bass, mullet, and sole finding protection among cordgrass and samphire. Scientists estimate that 80% of Atlantic commercial fish species depend on coastal habitats during some life stage.

The productivity of these systems amazes: mudflats can support 100,000 invertebrates per square meter, providing food for everything from small waders to humans harvesting cockles. Yet this productivity depends on delicate balances. Too many nutrients from agricultural runoff trigger algal blooms that suffocate bottom-dwelling creatures. Heavy metals from industrial sources accumulate in filter feeders. Plastic pollution entangles wildlife and enters food chains through microscopic particles.

Brittany's rocky shores present different challenges and opportunities. The zonation from splash zone to subtidal creates distinct bands of life, each adapted to specific exposure levels. Barnacles and limpets grip exposed rocks, while anemones and sponges flourish in permanent pools. The kelp forests offshore—some of Europe's most extensive—provide three-dimensional habitat comparable to terrestrial forests, supporting diverse fish communities and protecting shores from wave erosion.