Salt Marsh

Influenced by tides, salinity and sun
The upper parts of salt marsh habitat are dominated by grasses and sedges that are rarely flooded by tides/Photo Courtesy of Suzy Whittey

Salt marshes are one of the most dynamic and productive habitats on earth. They are coastal wetlands that are flooded by tides. Salt marsh habitat occurs in the estuary where the ground is high enough to support herbaceous plants, but too low and wet to support shrubs and trees (they are not flooded too deeply for too long). The amount of submersion, salinity, and temperature changes on the plants that live there is extreme. Moving away from the water a few inches can change which plants will thrive and which will not. Salt-loving plants (halophytes) grow higher on the beach in a paradoxical twist. These plants face extremes in saltiness because there is less water movement to flush dried salts away. Most of these plants are succulent or waxy to maintain water, such as pickleweed, sea arrow grass, and sea plantain. Lush fields of grasses and sedges grow in the high salt marsh where they are only covered by very high tides. These areas are dominated by seashore salt grass and Lyngby’s sedge. Currents make it hard for annual plants to establish from seed. Therefore most salt marsh plants are perennial and grow each year from established roots, or clone by breaking off from parent plant to root in a new location. These plants protect shorelines from erosion by buffering wave action and trapping sediments in their stems and roots.

Although animals do eat the bounty of fresh vegetation in salt marshes, the real food chain engine is the high volume of dead and decomposing materials that are moved in and out with the tides. This nutrient rich material forms the foundation of the broad web of invertebrates, fish, shellfish, birds and mammals found in and near Willapa Bay.

As salt marshes were diked, drained and filled during the early part of the 1900s to create farmlands, this dynamic ecosystem was altered affecting a wide range of species. It is believed that Willapa Bay once contained approx. 14,600 acres (5,909 hectares) of salt marsh habitat. Now there are a little more than 5,000 acres (2,024 hectares) remaining. Restoration efforts undertaken in the last few decades have removed dikes and restored tidal action in many places, including areas at Willapa National Wildlife Refuge. Some aspects of restoration happen quickly, others more slowly.

Facts About Salt Marsh

Occur worldwide, including every coast of the U.S.

Are essential food, refuge and nursery habitat for fish and shellfish