Estuarine Wetlands 



Estuarine wetlands are found along the U.S. coastline 

 and are associated with estuaries or brackish tidal waters. 

 They are represented by three major types: ( 1 ) emergent 

 wetland, (2) intertidal flat, and (3) scrub-shrub wetland. 

 Other coastal wetlands include intertidal coral and mol- 

 lusk reefs, rocky shores, and beaches. 



Estuarine Emergent Wetlands 



Estuarine emergent wetlands are dominated by grass or 

 grass-like plants (Figure 5). They are commonly called 

 "salt marshes" and "brackish tidal marshes". 



Salt marshes characteristically lie behind barrier is- 

 lands and beaches along all coasts in relatively high salin- 

 ity waters. They are best represented along the Alaskan, 

 Atlantic and Gulf coasts. Salt marshes are flooded by 

 tides for varying periods depending on elevation and tidal 

 amplitude. Two distinct zones can be observed based on 

 differences in frequency and duration of flooding and 

 associated vegetation: ( 1 ) regularly flooded marsh and (2) 

 irregularly flooded marsh (Figure 6). The regularly 

 flooded marsh is flooded and exposed at least once daily 

 by the tides. In New England, this marsh is generally 

 limited to tidal creek banks, while in the Southeast, it is 

 the dominant coastal wetland type covering vast acre- 

 ages. Along the Atlantic and Gulf coasts, smooth cord- 

 grass dominates the regularly flooded marsh, while on the 

 West coast, California cordgrass prevails. These grasses 

 are among the most productive marsh plants. Lying 

 above the regularly flooded zone, the irregularly flooded 



marsh is exposed to air for long periods and flooded only 

 at irregular intervals, usually monthly during spring and 

 storm tides. Vegetation in this zone is more varied, in- 

 cluding salt hay cordgrass, spikegrass, black grass, alka- 

 ligrass, Baltic rush, black needlerush, glassworts, 

 saltworts, sea ox-eye, high-tide bush, reed, bulrushes, 

 asters and switchgrass. On the West coast, Lyngbye's 

 sedge, hairgrass and jaumea are other important species. 

 Salt marshes along the Beaufort Sea in Alaska are domi- 

 nated by alkaligrass and sedges. 



Moving upstream in coastal rivers where seawater is 

 diluted by freshwater, the brackish tidal marshes can b = 

 found. Salinity here fluctuates greatly with the tides, river 

 flow and the seasons. Nearest the salt marshes, black 

 needlerush dominates brackish marshes along the South 

 Atlantic and Gulf coasts, while big cordgrass, narrow- 

 leaved cattail and bulrushes are important in more north- 

 em areas. As the upstream limit of salt water influence is 

 approached, a highly diverse assemblage of emergent 

 plants characterizes these marshes, including big cord- 

 grass, narrow-leaved cattail, pickerelweed, wild rice, gi- 

 ant cutgrass, marsh mallow, arrowheads, smartweeds, 

 sedges, bulrushes, beggar" s-ticks and reed. Most of these 

 plants, however, reach their maximum abundance in the 

 Nation's inland wetlands. 



Estuarine Intertidal Flats 



Intertidal flats often lie seaward of tidal marshes and 

 mangroves, at river mouths or along rocky coasts. They 

 also occur as barren areas within the hieh marsh in high 



