Fig. 2 Distinguishing features and examples of habitats in the Marine System. EHWS 

 ELWS = extreme low water of spring tides. 



extreme high water of spring tides; 



tides, precipitation, freshwater runoff from land areas, 

 evaporation, and wind. Estuarine salinities range from 

 hyperhaline to oligohaline (Table 2). The salinity may 

 be variable, as in hyperhaline lagoons (e.g., Laguna 

 Madre, Texas) and most brackish estuaries (e.g., 

 Chesapeake Bay, Virginia-Maryland); or it may be 

 relatively stable, as in sheltered euhaline embayments 

 (e.g., Chincoteague Bay, Maryland) or brackish embay- 

 ments with partly obstructed access or small tidal 

 range (e.g., Pamlico Sound, North Carolina). (For an 

 extended discussion of estuaries and lagoons see Lauff 

 1967.) 



Subsystems. 



Subtidai— The substrate is continuously sub- 

 merged. 



Intertidal— The substrate is exposed and flooded 

 by tides; includes the associated splash zone. 



Classes. Rock Bottom, Unconsolidated Bottom, 

 Aquatic Bed, Reef, Streambed, Rocky Shore, Uncon- 

 solidated Shore, Emergent Wetland, Scrub-Shrub 

 Wetland, and Forested Wetland. 



Riverine System 



Definition. The Riverine System (Fig. 4) includes all 

 wetlands and deepwater habitats contained within a 

 channel, with two exceptions: (1) wetlands dominated 

 by trees, shrubs, persistent emergents, emergent 

 mosses, or lichens, and (2) habitats with water con- 

 taining ocean-derived salts in excess of 0.5°/oo. A 

 channel is "an open conduit either naturally or arti- 

 ficially created which periodically or continuously 

 contains moving water, or which forms a connecting 

 link between two bodies of standing water" (Langbein 

 and Iseri 1960:5). 



Limits. The Riverine System is bounded on the land- 

 ward side by upland, by the channel bank (including 

 natural and man-made levees), or by wetland domi- 

 nated by trees, shrubs, persistent emergents, 

 emergent mosses, or lichens. In braided streams, the 

 system is bounded by the banks forming the outer 

 limits of the depression within which the braiding 

 occurs. 



The Riverine System terminates at the downstream 



