Prior to the arrival of European explorers in the Americas in 1492, it is estimated that the population of the continent was around sixty million people. Over the next two centuries, most scholars agree that the indigenous population fell to just ten percent of its pre-colonization level, primarily due to the Old World diseases (namely smallpox) brought to the New World by Europeans and African slaves, as well as through violence and famine.

Distribution

It is thought that the most densely populated region of the Americas was in the fertile Mexican valley, home to over one third of the entire continent, including several Mesoamerican civilizations such as the Aztec empire. While the mid-estimate shows a population of over 21 million before European arrival, one estimate suggests that there were just 730,000 people of indigenous descent in Mexico in 1620, just one hundred years after Cortes' arrival. Estimates also suggest that the Andes, home to the Incas, was the second most-populous region in the Americas, while North America (in this case, the region north of the Rio Grande river) may have been the most sparsely populated region. There is some contention as to the size of the pre-Columbian populations in the Caribbean, as the mass genocides, forced relocation, and pandemics that followed in the early stages of Spanish colonization make it difficult to predict these numbers.

Varying estimates Estimating the indigenous populations of the Americas has proven to be a challenge and point of contention for modern historians. Totals from reputable sources range from 8.4 million people to 112.55 million, and while both of these totals were published in the 1930s and 1960s respectively, their continued citation proves the ambiguity surrounding this topic. European settlers' records from the 15th to 17th centuries have also created challenges, due to their unrealistic population predictions and inaccurate methodologies (for example, many early settlers only counted the number of warriors in each civilization). Nonetheless, most modern historians use figures close to those given in the "Middle estimate" shown here, with similar distributions by region.

This dataset (in Excel format) represents in-situ information on the percentage of benthic cover collected at 714 stations. Seven field campaigns were conducted (2010-2016), in shallow waters (up to 25 m depth) along the coast of the Yucatan Peninsula in Mexico, from Cabo Catoche to Xcalak, as part of the Mesoamerican Reef System. The biotopes of reef lagoon, back reef, reef crest, rocky terrace, and the spur and grooves of the fore reef, were studied. The percentages of benthic cover were estimated through visual surveys and the use of underwater photographs for later analysis in the laboratory, establishing 12 classification categories. The data obtained have been used as a reference for the calibration of benthic cover classifications derived from the processing of 23 WorldView-2 satellite images (2009-2015). This product is the result of the ArrecifeSAM project, coordinated by CONABIO as part of the Marine-Coastal Information and Analysis System (SIMAR) (https://simar.conabio.gob.mx). Acknowledgement:The authors acknowledge the logistical and technical support provided by National Financial Trust Fund for Biodiversity and National Commission for the Knowledge and Use of Biodiversity (CONABIO), National Commission of Natural Protected Areas Mexico (CONANP), National Autonomous University of Mexico, UNAM (UASA Marine Science and Limnology Institute, Institute of Geography, Science Faculty - Academic Unit Sisal), and Center for Research and Advanced Studies of the National Polytechnic Institute (CINVESTAV-Mérida, IPN).