Humans in the Mangrove-Estuary zone of Eastern Soconusco

The intertidal environment of eastern Soconusco came into existence around 7000 years ago, as sea level stabilized along the Pacific coast of southern Mesoamerica, and an extensive system of mangrove forests and lagoons began to develop in sheltered settings behind barrier beaches. This low-energy wetland environment has acted as a trap for sediments washed down rivers and streams throughout the Middle and Late Holocene. As sediments accumulate in lagoons, open water gradually gives way to mangrove forest. Breaches in the barrier beaches and shifting river courses also contribute to geomorphological dynamics of the region. In recent times the mangrove zone has started to expand inland due to diversion of water from the Rio Suchiate for irrigation of bananas: irrigation water flowing out of the banana fields collects at the interior edge of the mangrove swamp, creating swampy conditions in what was formerly cattle pasture. Freshwater and mangrove swamps then gradually expand inland.

The mangrove-estuary zone is rich in fish, shellfish, crustaceans, reptiles, birds, and mammals. As documented by Barbara Voorhies’ investigations in the Acapetahua Estuary over the past 40 years, these rich biotic resources attracted people to the swamp as early as 7500 years ago. The Archaic period inhabitants were focused mainly on subsistence resources, the procurement and processing of marsh clams being one main activity. Technological innovations during the Early Formative period permitted exploitation of a broader range of estuarine subsistence resources; the first sedentary villages arguably appear at the inland edge of the swamp zone during this period. Following the Early Formative, a growing commitment to agricultural subsistence led to abandonment of the swamp. Human occupation of the swamp picked up again during the Late Formative, when mounds that apparently were the sites of pyro-industrial activities began to accumulate. Such industrial uses continued into historic times, when salt extraction by the sal cocida method is documented.

Currently, people live around the swamp, both on the beach and in communities just inland from the swamp. While they venture into the swamp to fish, collect oysters, hunt iguanas and alligators, and clear routes to archaeological sites, they do not live within the swamp. Workers on our project who have camped overnight in the swamp report that they easily obtain an abundance of gar pike and mojarra (fish) to eat. In addition, they report eerie noises, such as a snarling feline that may be a jaguar. Jaguars, unlike most felines, are good swimmers, and growing human population on the coastal plain may have pushed it into the most isolated local zone, namely the swamp.

Because of the isolation and relative impenetrability of the mangrove forest, archaeological resources within the swamp are remarkably well preserved. Whereas many archaeological sites on the coastal plain have been leveled and trenched for a succession of agricultural uses, the most recent of which is bananas, sites within the mangroves have never been affected by mechanized equipment, and are only infrequently even visited by people. People who do visit stay for an hour or so to hunt iguanas or other animals that sometimes live on the archaeological mounds. Even more rarely, fishermen and hunters may stay on the mounds for a couple of nights. Human damage to the archaeological deposits is mostly limited to shallow excavations into iguana burrows. Otherwise, burrowing animals and tree roots, especially from the fast-growing palms of the region, have the biggest impacts on deposit integrity.