Tide Pools
Estuaries are transition zones between land and sea. They are found in sheltered bays, inlets, and lagoons where freshwater rivers and streams meet and mix with the salt water, forming a melting pot of organic and mineral nutrients. The nutrient-rich soup of the estuary nourishes plankton and plants which in turn, nourish oysters, clams, crabs, salmon, and birds.  
What Estuaries Provide  
  • Habitat
    Estuaries create a rich nursery environment for salmon and other species. Tens of thousands of birds, mammals, fish, and other wildlife rely on estuarine habitats to live, feed, and reproduce.  
  • Productive
    Acre for acre, estuaries are among the most biologically productive ecosystems on earth.  
  • Erosion & Flood Control
    Estuaries serve as buffers, protecting shorelines from erosion and flooding.  
  • Pollutant Filter
    Estuaries filter pollutants, improving water quality.
    Black Brant feed on estuary eelgrass, Nisqually River estuary.

    Flyway For The Birds

    The entire estuarine environment - shallow waters, mudflats, and salt marshes - serves as a major resting and refueling station for thousands of ducks, geese and shorebirds. Pintails, brant, teals, mallards, Canada Geese, and trumpeter swans are a few of the species that stop here to graze on seeds, grasses, and small invertebrates.

    Estuary Habitats: A Mosaic

  • Higher Up The Beach
    Gumweed and salt grass intermingle to form low dense mats dissected by shallow drainage channels. Beyond the reach of tidal waters, less salt-tolerant plants appear; tufted hairgrass, marsh aster, and red fescue.
  • Intertidal Zone
    An area of broad sloping mudflats fringed with salt marsh vegetation. The plants here are tough and tolerant of saltwater; pickleweed, sand spurry, and arrowgrass. Shorebirds, herons, and raccoons forage for food here.
  • Shallow Water, Subtidal
    Seals, waterfowl, and many species of fish graze on the rich and abundant food sources found in estuary waters. This zone is important for salmon: Young salmon travel downstream to estuaries where they feed and grow rapidly. Here is where young salmon adjust to salt water and get ready for an ocean journey.
  • Deep Water, Subtidal
    Pacific oysters can thrive where the estuary floor is hard gravel. A sandy floor can host sand dollars, snails, and several species of clams. A muddy floor can support clams, shrimp, and worms.

    Protecting Estuaries

    • In eleven major Puget Sound estuaries, only 52 percent of the original salt marsh and mudflat habitat remains. In urban areas such as Seattle and Tacoma, the loss of salt marsh habitat is close to 100 percent.
    • Along Puget Sound, a few estuaries are protected as refuges; Skagit Bay, Nisqually Delta, and Padilla Bay.

    Related Links

    Puget Sound Nearshore Environments, Nearshore Processes, King County. Educational graphics help explain nearshore physical and biological workings and stressors to the nearshore system.

    Nisqually National Wildlife Refuge, U.S. Fish & Wildlife. General information, trail map, and species list.

    Padilla Bay, National Estuarine Research Reserve System. Facilities, educational programs, estuary habitats, geology, and history.

    About Estuaries, US EPA. Estuaries, their biological components, and their importance.

    Estuaries and Your Coastal Watershed, US EPA Fact sheet (1998). Fact sheet on estuaries and their function within a coastal watershed.  

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