The evolution of the Maya coastal landscape in the Mexican Caribbean during the last 6200 years

The modern configuration of tropical coastlines is a result of changes in sea level and regional hydroclimates during the Holocene. In some regions, such as the Yucatan Peninsula, human occupation has also played an important role in defining coastal dynamics. We use a multiproxy analysis of a 6200-year-long sedimentary record from La Encantada lagoon, located near the Bay of Chetumal, Mexican Caribbean, to reconstruct local and regional environmental dynamics. By characterizing the record in terms of pollen and charcoal content, and geochemical composition, we aim to determine the relative importance of sea level rise, long term trends of moisture availability, and anthropic influences in the evolution of the Mayan coastal landscape. Our findings indicate a dominance of marine influences between ∼6200 and 5000 cal yr. BP, probably resulting from the rapidly rising sea level. During this time, whereas the water column was brackish, fluvial dynamics seem characterized by high erosion and the development of riparian mangroves. The geochemical record indicates a millennial-scale trend towards drier conditions, likely associated with the southward migration of the Intertropical Convergence Zone through the Holocene. This trend is also reflected in a progressive increase in the abundance of deciduous taxa in the vegetation. Centennial-scale climatic dynamics, on the other hand, seem associated with variability of the North Atlantic Subtropical High. Anthropogenic influence is evident around ∼5000 cal yr. BP, when local fires became more frequent and riparian mangroves were depleted. Taxa associated with human influence substantially increased at ∼3600 cal yr. BP, coinciding with an erosion increase indicated by the geochemical record. At ∼2200 cal yr. BP, anthropic disturbance indicators decrease, suggesting a potential role of modified agricultural practices to control soil erosion. The last ∼1000 years have been characterized by a decline of agricultural activity and a recovery of the riparian mangroves, suggesting modern vegetation is a result of forest recovery during the last millennium. Overall, our results show that sea level rise and changes in the regional hydroclimate modulate the evolution of the regional landscape, particularly through influences on the sedimentation rates. However, human occupation represents an overpowering influence that can modulate processes associated with natural forcings.