Mudflats

Mudflats are expansive, flat stretches of soft sediment found in sheltered coastal areas, estuaries, and tidal rivers. They form where sediments such as silt, clay, and organic matter accumulate in the intertidal zone, and are periodically exposed at low tide while being submerged at high tide. Their extent and elevation are controlled by tidal range, sediment supply, wave energy, and anthropogenic changes in coastal hydrology.

Physical and biological characteristics: The sediments are often waterlogged and anaerobic, supporting microbial activity and a diverse assemblage of invertebrates including polychaete worms, bivalves, crustaceans, and burrowing species. The daily tides drive feeding opportunities for shorebirds and waders, which probe the surface or excavate the mud for prey. Mudflats are a key component of estuarine productivity and serve as nurseries and food resources for many species.

Ecological importance and threats: Mudflats provide feeding and roosting habitat for migratory shorebirds along flyways such as the East Asian-Australasian Flyway and the Americas. They are threatened by coastal development, dredging, pollution, sediment starvation from damming, sea-level rise, and erosion. Restoration and conservation measures include protected areas, sediment replenishment, managed retreat of infrastructure, and restoration of natural tidal flow.

Examples and other notes: Notable mudflat regions include the Wadden Sea in Europe, the San Francisco Bay mudflats in the United States, and mudflats along the Yellow and Yangtze rivers in Asia. They are valued for biodiversity, fisheries support, and as indicators of coastal ecosystem health.