**3. Importance**

Mexico is among the five countries in the world with the largest extension of mangroves distributed; by 2015, 7,75,555 ha of mangroves have been registered in both coasts of the country covering at least 60% of the coastline [61].

In 2005, the National Commission for the Knowledge and Use of Biodiversity (CONABIO) initiated the bases for what is now called the Mangrove Monitoring System of Mexico. The aim of the SMMM is to generate information about changes in the mangrove ecosystem through the evaluation of its spatial distribution and condition over time. From this information, we also look for the identification of existing, latent threats and trends of changes (loss, deterioration, or recovery), in such a way as to support their conservation, understanding, and management. Based on the information generated, the threats and trends of change that through analysis have been incorporated into the conservation of this ecosystem have been identified. The results show a strong occurrence of both natural processes and human activities, which influence the loss of coverage or disturbance of the mangrove. Of these, those of anthropic origin stand out for their importance. In this category, two classes are presented: the agricultural-livestock and a pattern of occupation of land use derived from development. The first one is related to primary economic activities, that is to say agriculture (both irrigation and seasonal), livestock, and forestry. The second class encompasses land uses, such as rural areas, urban areas, industrial zones, aquaculture farms, ports, tourist infrastructure, and so on [61].

The tendency of loss of coverage occurred mainly in the period from 1970 to 2005 (up to 27,557 ha), there being a drastic change from 2005 to 2015, with the last period reported from 2010 to 2015 with a loss of 1090 ha but a profit of 1296 ha. Within the categories identified by the SMMM as threats in the loss of mangrove are the areas under construction, aquaculture farms and artificial ponds, hydraulic infrastructure (canals or dams), industrial zones (oil wells, salt pans, thermoelectric plants, complexes), and communication routes [61].

In Mexico, 6 of the world's 70 mangrove species (8.5%) have been reported [50] and contribute 5.4% of the total mangrove area, after Indonesia with 22.6%, Australia with 7.1%, and Brazil with 7% [60].

Its biological importance lies in being places of rest and nesting of birds (*Egretta caerulea, E. rufescens, E. tricolor, Ardea herodias, Aramides cajaneus, Sula leucogaster, Phalacrocorax auritus, Fregata magnificens, Ajaia ajaja,* among others). They represent an important habitat for species with some risk category (NOM-059-SEMARNAT-2010) such as Mexican *Tamandua mexicana, Buteogallus anthracinus, Rostrhamus sociabilis, Mycteria americana, Vireo pallens, Megascops cooperi, Crocodylus acutus, C. moreletii, Ctenosaura pectinata, C quinquecarinata, C. similis, C. acanthura, C. hemilopha,* and *Iguana iguana* [50].

The biological and ecological importance of mangroves has led CONABIO to establish 81 priority sites, determined by specialists in the subject; of these 29 are located on the Pacific coast, 27 in the Gulf of Mexico, and 25 in the Yucatan Peninsula. Each of these sites of interest has a characterization sheet with information on site location, physical characteristics, socioeconomic, uses, importance, impacts, and threats and transformation processes [13].
