12 



Table 2. Salinity modifiers used in this classification system. 



Coastal modifiers 3 



Inland modifiers b 



Salinity (parts per thousand) 



Approximate 



specific 



conductance 



(/<Mhos at 25 °C) 



Hyperhaline 

 Euhaline 

 Mixohaline (brackish) 



Polyhaline 



Mesohaline 



Oligohaline 

 Fresh 



Hypersaline 



Eusaline 



Mixosaline 

 Polysaline 

 Mesosahne 

 Oligosaline 



Fresh 



>40 



30.0-40 



0.5-30 



18.0-30 



5.0-18 



0.5-5 



< 0.5 



> 60,000 



45.000-60,000 



800-45,000 



30,000-45,000 



8,000-30.000 



800- 8,000 



<800 



a Coastal modifiers are used in the Marine and Estuarine systems. 



b Inland modifiers are used in the Riverine, Lacustrine, and Palustrine systems. 



c The term Brackish should not be used for inland wetlands or deepwater habitats. 



sistent emergents, emergent mosses, or lichens. Lacus- 

 trine systems formed by damming a river channel are 

 bounded by a contour approximating the normal spill- 

 way elevation or normal pool elevation, except where 

 Palustrine wetlands extend lakeward of that bound- 

 ary. Where a river enters a lake, the extension of the 

 Lacustrine shoreline forms the Riverine-Lacustrine 

 boundary. 



Description. The Lacustrine System includes perma- 

 nently flooded lakes and reservoirs (e.g., Lake Supe- 

 rior), intermittent lakes (e.g., playa lakes), and tidal 

 lakes with ocean-derived salinities below 0.5°/oo (e.g., 

 Grand Lake, Louisiana). Typically, there are extensive 

 areas of deep water and there is considerable wave 

 action. Islands of Palustrine wetland may he within 

 the boundaries of the Lacustrine System. 



Subsystems. 



Limnetic. — All deepwater habitats within the 

 Lacustrine System; many small Lacustrine systems 

 have no Limnetic Subsystem. 



Littoral.— AH wetland habitats in the Lacustrine 

 System. Extends from the shoreward boundary of the 

 system to a depth of 2 m (6.6 feet) below low water or 

 to the maximum extent of nonpersistent emergents, if 

 these grow at depths greater than 2 m. 



Classes. Rock Bottom, Unconsolidated Bottom, 

 Aquatic Bed, Rocky Shore, Unconsolidated Shore, and 

 Emergent Wetland (nonpersistent). 



Palustrine System 



Definition. The Palustrine System (Fig. 6) includes 

 all nontidal wetlands dominated by trees, shrubs, per- 

 sistent emergents, emergent mosses or lichens, and all 

 such wetlands that occur in tidal areas where salinity 

 due to ocean-derived salts is below 0.5%o. It also in- 

 cludes wetlands lacking such vegetation, but with all 

 of the following four characteristics: (1) area less than 

 8 ha (20 acres); (2) active wave-formed or bedrock 

 shoreline features lacking; (3) water depth in the deep- 



est part of basin less than 2 m at low water; and (4) 

 salinity due to ocean-derived salts less than 0.5°/oo. 



Limits. The Palustrine System is bounded by upland 

 or by any of the other four systems. 



Description. The Palustrine System was developed 

 to group the vegetated wetlands traditionally called 

 by such names as marsh, swamp, bog, fen, and prairie, 

 which are found throughout the United States. It also 

 includes the small, shallow, permanent or intermittent 

 water bodies often called ponds. Palustrine wetlands 

 may be situated shoreward of lakes, river channels, or 

 estuaries; on river floodplains; in isolated catchments; 

 or on slopes. They may also occur as islands in lakes or 

 rivers. The erosive forces of wind and water are of 

 minor importance except during severe floods. 



The emergent vegetation adjacent to rivers and 

 lakes is often referred to as "the shore zone" or the 

 "zone of emergent vegetation" (Reid and Wood 1976), 

 and is generally considered separately from the river 

 itself. As an example, Hynes (1970:85) wrote in ref- 

 erence to riverine habitats, "We will not here consider 

 the long list of emergent plants which may occur along 

 the banks out of the current, as they do not belong, 

 strictly speaking, to the running water habitat." There 

 are often great similarities between wetlands lying 

 adjacent to lakes or rivers and isolated wetlands of the 

 same class in basins without open water. 



Subsystems. None. 



Classes. Rock Bottom, Unconsolidated Bottom, 

 Aquatic Bed, Unconsolidated Shore, Moss-Lichen 

 Wetland, Emergent Wetland, Scrub-Shrub Wetland, 

 and Forested Wetland. 



Classes, Subclasses, and Dominance Types 



The CLASS is the highest taxonomic unit below the 

 subsystem level. It describes the general appearance 

 of the habitat in terms of either the dominant life form 



