The relationships between environmental conditions and parallel ecosystems on the coastal dunes of the Mexican Caribbean

Abstract

Coastal dunes are very important, for both their ecosystem services and their ecological importance. A quantification of the area occupied by dunes was made for all of the Mexican Caribbean coast, and a qualification was assigned, according to the type of dune, its height and condition. 4981 ha of coastal dunes were identified on the coast, with heights of 1 to more than 10 m above mean sea level. Offshore wave climate was evaluated, showing relatively constant characteristics all along the coast. Aeolian drift potential was calculated and was found to be unrelated to the height of the dunes. The empirical relationship between coastal ecosystems (coral reefs and sea pastures) and the characteristic of the dunes are promising. The interconnectivity of ecosystems adjacent to coastal dunes, such as seagrass, coral reef and mangroves, affects the conditions of incident wave energy and/or the transport and availability of marine sediment. In the Mexican Caribbean, these ecosystems often exist parallel to one another, and their interrelationships could explain the variability of coastal dune height. It was observed that where the coast is protected by a coral barrier reef (less than 1000 m from the shore, with a crest at less than 2 m depth) and seagrasses, the foredunes are lower (under 2 m height) than those in more exposed areas, without coral reef protection (foredune height more than 10 m). A conceptual model was proposed to explain the size of the dunes in the study area, based on the characteristics of adjacent ecosystems (presence, distance from coastline, height of water column above corals and/or seagrasses) and the submerged morphology of the area.