The Texas High School Coastal Monitoring Program Field Guides
Mustang Island Field Guide - Field Stop 4

This stop will be a quick look at wind-tidal flats. Wind-tidal flats are areas of very low relief that are slightly higher in elevation than the mean high water level of the adjacent bay. Wind-tidal flats (fig. 1) are so low lying that a tropical storm or sustained winter winds across the bay can drive water up onto the flats. As the winds die down, the water recedes to the bay and the remaining moisture evaporates creating high salinity conditions. The change in water level and especially the change from normal salinity to high salinity make it a difficult environment for most plants to live. The surface of a mostly dry tidal flat is bare sand and mud. One of the few successful plants in this environment is algae. Some wind-tidal flats comprise layers of algae, called algal mats (fig. 2), and grains of windblown sand and finer mud deposited during episodic inundation by muddy waters of the bay.

Dry wind-tidal flat on the bay side of Mustang Island.
Figure 1. Dry wind-tidal flat on the bay side of Mustang Island.
Algal mat on Mustang Island with mangroves along the edge of the tidal flat
Figure 2. Algal mat on Mustang Island with mangroves along the edge of the tidal flat. Photo by William White.