Northwest Gulf of Mexico

This Guidebook was developed to assess the functions of tidal fringe wetlands in the northwestern Gulf of Mexico. For the purposes of this approach, the term “tidal fringe wetlands” applies only to vegetated habitats occupying the intertidal zone of marine, estuarine, or riverine systems. Specifically, these wetlands occur along the fringe of drowned river valleys, barrier islands, lagoons, and other coastal waterways, receive their water primarily from marine or estuarine sources, and are affected by astronomical tidal action. Included in this group are wetlands commonly known as intertidal marshes, salt marshes, forested riverine swamps, and mangrove swamps and correspond to the emergent, scrub-shrub, and forested wetland class designations used by Cowardin et al. (1979). The dominant hydrodynamic is bidirectional water flow generated by tidal action. Additional water sources may be riverine flow, groundwater discharge, and precipitation. Tidal fringe wetlands lose water by tidal exchange, by saturated overland flow to tidal creek channels, and by evapotranspiration. Organic matter normally accumulates in higher elevation marsh areas where flooding is less frequent and the wetlands are protected from shoreline wave erosion by intervening areas of low marsh. Spartina alterniflora salt marshes are a common example of tidal fringe wetlands.

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Web Date: October 1997
Updated: April 2008