Port Isabel is located along the southwestern shore of the Laguna Madre and just north of the land mass delineated by the Rio Grande Delta. It is in the Gulf Prairies and Marshes eco-region and part of the Tamaulipas biotic province.
There is rich diversity of natural resources in the Port Isabel area and surrounding region, many of these supported by the Laguna Madre Coastal Bay. The Laguna Madre is one of the most unique natural features in South Texas and in the entire state. It is the only hypersaline coastal lagoon on the North American continent and one of only five worldwide. It is internationally recognized through its designation as a Western Hemisphere Shorebird Reserve Network site (meaning it hosts at least 100,000 shorebirds annually), and is the subject of much conservation effort and study by academic institutions and public interest organizations.
Port Isabel is located near prime birding sites (see Texas Parks & Wildlife Department’s Great Texas Coastal Birding Trail), both along Highway 48 and on South Padre Island. Two North American migratory flyways (Mississippi and Central) merge and pass through the region along the Texas Gulf Coast, funneling thousands of migrating songbirds, shorebirds, raptors, ducks and geese through the area. Supporting this bird diversity and other wildlife are the mosaic of habitats in the region, which include clay lomas, wind tidal flats, mudflats, mangroves, saline flats dominated by sea oxeye, gulf cordgrass and glasswort, tidal inlets, and wetlands like San Martin Lake and the Bahia Grande. Tamaulipas thorn scrub dominates some parts of the region, protecting other charismatic fauna like the endangered ocelot.
Less than 15 miles to the north from Port Isabel, Laguna Atascosa National Wildlife Refuge hosts some 50,000 visitors per year who come to enjoy this diverse mix of local flora and fauna. Many of these same visitors enjoy birding and wildlife-watching tours offered by Port-Isabel based outfits such as the Fins to Feathers bay tours and Dolphin watch cruises. To the northwest and west, outside the urban limits of Laguna Heights and Laguna Vista, Port Isabel is bordered by the publicly owned Bahia Grande unit of Laguna Atascosa National Wildlife Refuge (19,909 acres) The Port of Brownsville ship channel lies directly south, and immediately south of the channel, several units of the Lower Rio Grande Valley National Wildlife Refuge, totaling some 20,880 acres.
The Bahia Grande itself is the site of a major restoration effort in progress with the support of a number of conservation partners. This 6,000-acre wetland to the north of highway 48 was periodically flooded prior to dredging of the Port of Brownsville ship channel in the 1930′s. The ship channel, along with the construction of highway 48, effectively cut off tidal exchange to the Bahia, drying it up and creating a major source of dust in the surrounding area, including Port Isabel. The U.S. Fish & Wildlife Service acquired Bahia Grande in 1999 with the help of the Conservation Fund, thus galvanizing the effort to restore this long dried wetland. The entire scope of the restoration project contemplates the use of channels to route water to the Bahia and an additional 5,000 acres of adjacent wetlands, the purpose being to restore healthy functioning in the wetlands and re-energize its value as a shrimp, crab and finfish nursery area and native and migratory bird habitat. Additional benefits to the region include dust control and nature tourism.
Seagrass beds have often been described as the “cornerstone of life” in the lagoon, providing cover and forage for many juvenile shellfish and finfish. In fact, 26 of the 31 species of fish identified from Gulf of Mexico estuaries as having ecological, commercial, or recreational value have been found within the Laguna Madre. Texas Parks and Wildlife estimates the value of the Laguna Madre sport fishing industry to be around $180 million annually, supporting some 1,327 jobs. The offshore shrimping industry remains largely dependent on the Laguna Madre as a nursery ground for juvenile brown shrimp. The Port Isabel and Brownsville port together represent the third largest-volume shrimp port in the nation. The National Marine Fisheries Service data on offshore landings for shrimp from 1990-97 document average annual revenue of $57 million.
Seagrasses also provide the ecological structure sought by aquatic birds. About 38 different species of waterfowl have been documented along the lower Texas coast. At least 77% of the North American redhead duck population overwinters on the Lower Laguna Madre. The redhead is entirely dependent on the rhizomes of one particular type of seagrass called shoalgrass, found within seagrass meadows. Natural and human-created spoil islands provide nesting grounds and rookeries for thousands of colonial waterbirds (heron, egret, ibis, and spoonbill) – including the threatened reddish egret, as well as gulls and terns. It also provides the essential shallow water habitat for the fish and invertebrates important to wading birds. Washover passes (storm and hurricane-induced openings in the dune structure along South Padre Island) provide nesting sites for snowy plovers, and the Barrier Island and associated tidal flats are essential habitat for the threatened piping plover.
Altogether some 30 species of shorebirds (willet, dunlin, plover, sandpiper, dowitcher, sanderling, curlew, turnstone, avocet, yellowlegs, stilt, phalarope, oystercatcher, killdeer, whimbrel, red knot) use the barrier island beaches, exposed tidal flats, washover passes, and mudflats associated with the Laguna Madre. Some of these species can periodically be seen on the few undeveloped mudflats within Port Isabel.
In short, the fact that Port Isabel is surrounded by such diversity of wildlife and habitats that will be protected on public land for the foreseeable future is of great value to the community. The natural resources are a valuable asset lending additional reasons for tourists, winter residents or businesses to want to visit and/or locate there. At the same time, that development should be carried out in such a manner as to protect the natural assets the city enjoys to the greatest extent possible.