|The Laguna Madre is a large body of shallow
water separating Padre Island from the South Texas mainland. It covers
609 square miles of estuarine and coastal marine systems. The boundary
of Padre Island National Seashore encompasses approximately 20,000 acres
of the Laguna Madre. The Laguna Madre is located in parts of Cameron,
Willacy, Kenedy, Kleberg, and Nueces counties.
Laguna Madre, the only lagoon in the United States saltier than the
ocean, is part of the South Texas Coastal Plain, which extends inland
from the western Gulf of Mexico as a gently sloping prairie of short
grasses, mesquite trees, thorny brush and prickly pear cactus. Much of
the plain is used as rangeland, with some cropland and improved pasture.
The Nueces and Rio Grande river systems encircle this semi-arid region,
providing the only year-round sources of surface fresh water for the
cities and estuarine systems of South Texas.
Laguna Madre, formed between the mainland and Padre Island, is the
longest barrier island in the United States. Tidal currents in the
lagoon are weak, circulation is sluggish, and residence times of water
masses are long. During exceptionally dry periods, high salinity may
cause fish and other animals to leave or die. The lagoon also suffers
natural, periodic large fish kills due to severe freezes.
The South Texas Coastal Plain supports unique ecosystems and wildlife,
including barrier island dunes and beaches, Tamaulipan brushlands,
Laguna Madre seagrasses, intertidal wind flats, and the Baffin Bay and
Rio Grande delta. These habitat contain remarkable biological diversity:
Island's beaches serve as nesting grounds for endangered Kemp's
ridley sea turtles and threatened green sea turtles.
- Tamaulipan brushland is home to more than 600 vertebrate animal
species and 1,100 plant species, including an oily oak tree found
- The banks of the Arroyo Colorado and nearby uplands shelter
unusual animals like ocelot, jaguarundi, indigo snakes, horned
lizards, chachalaca, green jays, kiskadee flycatchers, and other
Laguna Madre accounts for three quarters of Texas's seagrass
habitat, which supports many rare and endangered species and
provides vital nursery grounds for fish and shellfish.