Texas Coast Salt and Brackish Tidal Marsh

Geology

Recent alluvial and eolian deposits along the coast.

Landform

Nearly level very gentle slopes, and flats influenced by tides.

Soils

Coastal sands and various Salt Marsh Ecological Sites.

Parent Description

These marshes occupy relatively low-lying, coastal situations on level landforms influenced by tidal fluctuations. Some sites are only influenced by storm tides, or tides resulting from extreme wind events. The composition of these marshes is primarily influenced by the frequency and duration of tidal inundation. Salinity on some marshes, particularly in the south, is maintained by salt spray from prevailing southeasterly winds. Low marshes are regularly flooded and representative examples are dominated by Spartina alterniflora (smooth cordgrass), Juncus roemerianus (blackrush), or Avicennia germinans (black mangrove). Significant areas of Avicennia germinans (black mangrove) become more frequent towards the south, while extensive areas of Spartina alterniflora (smooth cordgrass) become rare south of Corpus Christi Bay. Areas of decreased frequency and/or duration of tidal inundation are often referred to as high, or irregularly flooded, marsh. These marshes may be dominated by species such as Spartina patens (marshhay cordgrass), Distichlis spicata (saltgrass), Schoenoplectus robustus (sturdy bulrush), Schoenoplectus americanus (three-square bulrush), Sporobolus virginicus (seashore dropseed), Monanthochloe littoralis (shoregrass), and Spartina spartinae (Gulf cordgrass). Shrubs, subshrubs, and forbs, such as Batis maritima (saltwort), Borrichia frutescens (sea ox-eye daisy), Sesuvium portulacastrum (shoreline seapurslane), Salicornia spp. (glassworts), Suaeda linearis (annual seepweed), Limonium spp. (sea-lavenders), and Lycium carolinianum (Carolina wolfberry) are commonly encountered in these marshes. Some irregularly flooded sites may become shrub-dominated with species such as Iva frutescens (shrubby sumpweed) or Baccharis halimifolia (eastern baccharis). In the south, extensive areas are dominated by Borrichia frutescens (sea ox-eye daisy) and these often occur at very slightly lower elevations and higher salinities than nearby Spartina spartinae (Gulf cordgrass) salty prairie. These Borrichia flats may be very infrequently flooded, perhaps only under extreme storm tide conditions. Other species that may be encountered in these situations include Maytenus phyllanthoides (gutta-percha), Prosopis reptans (tornillo), Monanthochloe littoralis (shoregrass), Distichlis spicata (saltgrass), and Batis maritima (saltwort). The aspect dominant on these sites is clearly Borrichia frutescens (sea ox-eye daisy).