LIFE IN THE MARSHES

Over 650 thousand acres of wetlands make up the Centla marshes of Tabasco, Mexico; an area declared an UNESCO World Heritage Site.

By Pilar Márquez

The Centla Marsh Biosphere Reserve is located on a strip of land between the Grijalva and Usumacinta rivers, the two longest rivers in Mexico. Originating in the southern mountains of Chiapas and Guatemala, the rivers roll to the sea collecting nutrients that break down and settle along the riverbanks, forming marshes and swamps.

    Wetland habitats are like great reservoirs that regulate the flow of water across the surface of the land, its subterranean rivers and estuaries. They keep water in the ecosystem long enough for the plants and animals to reproduce, and they act as giant filters for contaminants and toxic wastes. It is calculated that two and a half acres of swamp equal a $120,000-dollar water treatment plant.

    Mexico's marshes are among the country's most populated ecosystems. In Centla, scientists have identified 434 species of plants in 105 families-most of them aquatic.

    The hot humid environment of the marsh supports many life forms linked to many ecosystems. Far from the rough currents of the sea, fish and crustaceans use the tepid, nutrient-rich waters of the marsh to breed, and birds and mammals feed and nest in its trees and mangrove forests.

MARSH WILDLIFE

The most abundant animals are the water and shore birds: 237 species, 66 of which are migratory. Next come the reptiles and amphibians with 67 species, and finally the mammals with 56. The water is also rich with life, and while the fish outnumber the birds, they only number 60 species.

    Great flocks of migratory birds, exchanging the colder latitudes of Canada and the United States for the warmth of southeastern Mexico arrive in the fall. Other species present in autumn are in transit to South America. They touch down to rest and feed in the marsh before resuming their journey to Columbia, Brazil and Argentina. The marshes have everything these birds need to survive: warm weather, plenty of food and freedom from human predators.

    Twenty-five of Centla's bird species are threatened or in danger of extinction including the American Stork (Mycteria americana), Osprey (Pandion haliaetus), Blue-Winged Teal (Anas discors), Peregrine Falcon (Falco peregrinus), Great Blue Heron (Ardea herodias) and the Anas acuta duck. Nevertheless, of all the creatures at Centla, the crocodile is most at risk.

    Crocodiles (Crocodylus moreletti) have been a source of food and income for wetland cultures in Mexico for centuries, and those in Tabasco are no exception. Marsh inhabitants hunt the crocodile for its meat, and from its hide, they produce numerous handcrafted items. In the past, man instinctively limited his hunting to what the species could survive. Modern man apparently knows no limits and his demand for exotic leather-at whatever the cost to the environment-has left the crocodile so depleted in numbers that its very survival as a species is now at stake.

    The crocodile plays an important role in the ecosystem; it feeds on fish, mollusks, reptiles, amphibians and even the larger mammals of the environment, helping to keep these animal populations at acceptable levels.

    The manatee (Trichechus manatus) is another endangered resident inhabiting the rivers and lakes of the marshes. Manatees are herbivorous mammals that feed on the aquatic grasses and plants of their environment; and like whales, dolphins and other water-dwelling, mammals, they take their oxygen from the air, not the water and must surface every few minutes to breath.

    The manatee's body is large and ponderous, with powerful dorsal fins and a paddle-like tail to propel it through the water. Manatees can measure up to five meters long and weigh over a ton and a half.

    The marsh residents of Tabasco were familiar with the manatee very early on, hunting it as they did the crocodile. They ate the meat, processed the fat and made utensils and trinkets from its bones.

THE COMMUNITIES OF CENTLA

Forty percent of the state of Tabasco is marshland, and due to the ecosystem's unique ability to support life, the marshes have always been inhabited. The Chontal Maya occupied the region from A.D. 600 until the Spanish Conquest in the 1500s. They became savvy waterpeople, exploiting their wetland environment to a formidable degree. Over 250 Chontal sites-from ancient cities to temporary settlements-have been discovered in the area.

    Researchers believe the Chontal chose the marshes, not an easy existence by any means, for a very specific reason. Tabasco was a major commercial crossroads that witnessed the exchange of goods (and culture) from all over Mundo Maya, and the Chontal eventually controlled that vast network.

    Today, 15,000 people in 90 different communities live in the reserve, mostly by fishing and, to a far lesser degree by farming and animal husbandry. The towns rest on slender spits of land that separate the rivers from the marshes. Residential lots are usually perpendicular; the houses built on the edge overlooking the water, with a narrow garden at the back for raising corn and small livestock.

    Due to a lack of solid ground, large-scale agriculture is out of the question, but the marshes possess other treasures, such as a wide range of edible and medicinal plants, and commercial woods such as the red mangrove (Rhizophora mangle), dyewood (palo de tinte) and many others.

    The people of Centla are wise in the ways of the marsh; they live in harmony with an environment they understand and respect. They fish and plant as nature dictates just as their ancestors did 3,000 years before them. The Biosphere Reserve of Centla not only guarantees the survival of a delicate and complex ecosystem, it guarantees the continuance of a way of life that began centuries ago with the Chontal Maya of Tabasco.