The zonations of trees and marine associated fauna of two mangrove areas of the Pacific coast of Colombia, Malaga and Buenaventura bays, are compared. These bays are exposed to huge terrigeneous inputs, abundant rainfall, high tidal range and, for the later, to deforestation, urban and industrial pollution. Vertical distribution of the macrofaunal assemblages is under the influences of wetness and tidal gradients. These assemblages are associated with the various substrates (mangal substrates: canopy, trunks and roots; associated soil substrates: more or less clogged and muddy sands; litter) and with the tidal features. As their specific composition is more dependent on the ethology of each species (air-exposure, feeding, reproduction...), the zonation appears more quantitative than qualitative, the same species occurring frequently in different zones or subzones. Basically, similar assemblages are observed in the two bays. They can be locally enriched by species restricted to particular edaphic conditions such as gravelly muddy flats and rocks at Malaga, and intertidal creeks and running waters at Buenaventura, where they are relatively less influenced by moderate human impacts.
