Estuarys

An estuary is a coastal ecosystem where freshwater from rivers and streams mixes with seawater from the ocean, creating a semi-enclosed body of water that experiences regular tidal influence. Estuaries are typically shallow, with gradients in salinity and temperature, and they accumulate nutrients from upstream, making them among the most productive environments on Earth.

Estuaries form where rivers meet the sea, and their hydrology is shaped by discharge, tides, wind, and the surrounding topography. They can be classified by salinity regimes into well-mixed, moderately mixed, and salt-wedge types, and by geography into drowned river valleys, estuarine bays, lagoons, and fjords.

Ecologically, estuaries support diverse communities and serve as nurseries for many fish and crustaceans. Their nutrient-rich waters sustain high primary production, while sediment deposition creates productive benthic habitats. They also provide feeding and breeding grounds for birds and act as natural filters, trapping pollutants and sediments.

Humans rely on estuaries for fisheries, shipping, recreation, and energy. They face pressures from pollution, habitat loss, dredging, damming of rivers, and land reclamation, as well as climate-change related sea-level rise and altered flood regimes that can degrade or relocate habitats.

Management emphasizes integrated coastal zone planning and restoration, including marsh creation, sediment management, pollution control, and sustainable watershed practices. Notable estuaries include Chesapeake Bay, the Thames Estuary, the Yangtze Estuary, the Amazon River Estuary, and the Rio de la Plata.

Note: estuarys is a common misspelling of estuaries.