TEXAS GEMS -LAGUNA MADRE
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 locatedin parts of Cameron, Willacy, Kenedy, Kleberg, and Nueces counties.
Area of Influence:
Watersheds: 12110203- North Laguna Madre, 12110207-
Middle Laguna Madre, and 12110208- South Laguna Madre (USGS Hydrologic
Units, Texas Maps).
4b- Estuarine Zone of Gulf Coast Prairies and Marshes (Ecoregions and Sub-regions of Texas)
Since no major rivers flow into the Laguna Madre, its salt content is quite high, about 35 parts per 1000 parts of water. This increases to 45 parts per 1000 parts of water in the Lower Laguna Madre and during periods of hot, dry weather.
The average water depth is about 2.5 feet, with some areas reaching a depth of 5 feet. Variable depths and salinity support different types of seagrasses, hyper-saline marshes, algal flats, and lomas.
Rare/endangered/threatened species and natural communities
with occurrence record on the Laguna Madre include:
lila de los llanos (Echeandia chandleri)
Piping Plover (Charadrius melodus)
Peregrine Falcon (Falco peregrinus)
Green Island Bird Rookery Port Isabel Spoil Rookery
Laguna Vista Spoil Rookery Three Island Spoil Rookery
South Three Islands Rookery East Rattlesnake Island Rookery
East Arroyo Spoil Rookery Green Island Cut Spoil Rookery
Green Hill Spoil Island Rookery SW Mansfield Rookery
NE Mansfield Intersection Rookery SE Mansfield Intersection Rookery
South Land Cut Rookery East Marker 265 spoil Rookery
East Flats Spoil Rookery
The Laguna Madre is an important breeding ground for many aquatic birds, as well as an important wintering and stopover area for numerous species. The extremely shallow areas provide excellent feeding grounds for winter duck populations which number in the thousands. Seagrasses are the main winter food source for Redhead ducks. The Laguna Madre is the summer nursery area for young brown shrimp. Skipjacks, pinfish, broad killifish and striped mullet forage in the shoalgrass areas. Mollusks and crustaceans, generally associated with the areas of underwater vegetation, are important as waterfowl food.
The Laguna Madre serves as a wintering area for 80% of the North American population of Redheads, Aythya americana. The fall season brings high numbers of ducks and geese on the lagoon. The lagoon is the end of the Central Flyway and many ducks find shelter in the southern refuges of Santa Ana and Laguna Atascosa National Wildlife Refuges. Redheads, Canada Geese, Snow Geese, Canvasbacks, Pintails, Mallards, Blue-winged Teal and many others can be observed inside the National Seashore in the freshwater ponds.
Mudflats, barrier islands, dunes, spoil islands, saline marsh, and coastal sand plains are the main geomorphic features of Laguna Madre.
Uniqueness of Natural Community:
Submerged land, marshes, spoil islands, variable salinity and depths, including the variety of seagrasses, make the Laguna Madre, a 110-mile long saltwater lagoon, a unique natural community. Shoal grass is the key species of the bay habitat, for it is the principal winter food for ducks, particularly redheads and is the spawning, foraging and nursery area for fish and shrimp.
Sport fishing is very rewarding in the Laguna Madre where redfish, black drum and flounder are caught. Texas General Land Office (GLO) operate fishing cabins as well as camping sites on the spoil islands.
Petroleum is still a large commercial activity in Laguna Madre area as well as commercial fishing. Brown shrimp make up a large part of the commercial shrimp catch taken from the Gulf of Mexico and brought into ports contiguous to the Laguna Madre.
The Laguna Madre is a large area and parts of it are owned by the public sector while other parts are owned by the private sector. The Texas General Land Office (GLO), Texas Parks and Wildlife, and the federal government own a large section of the area, while private entities like the Audubon Society, King Ranch, and others own other sections of the area.
The Laguna Madre itself has no specific designations while different parcels of barrier islands and mainland areas are designated as National Wildlife Refuges, Coastal Preserves, and Audubon sanctuaries.
Existing Monitoring Activities:
Ecology of migratory waterfowl
and their responses to long term shifts in wetland ecosystems
in the Laguna Madre;
Analysis of status and trends of seagrasses in Laguna Madre; Habitat analysis using Landsat Imagery.
Threats to Ecological Integrity:
The Lower Laguna Madre receives significant quantities of agricultural pesticides and other environmental contaminants from the Arroyo Colorado, an irrigation drainage of the Lower Rio Grande Valley. Oil spills from barges, discharge from the Mexican side of the Rio Grande, and hydrocarbon extraction are the threats posed by the high volume of commercial activities taking place on the Laguna Madre. Accidental release of exotic shrimp or effluent from commercial shrimp farms are also a concern.