Microbiota in Brackish Ecosystems: From Water Quality to Ecological Processes

Brackish ecosystems include estuaries and coastal lagoons, the latter being the most abundant in the coasts of Mexico. These ecosystems are among the most productive of the marine environment and are characterized by high biodiversity, but they are also the most impacted by different anthropogenic activities. Different studies related to their biological diversity have been carried out in the estuarine ecosystems of Mexico; however, studies about macroorganisms have dominated the scientific interest, and very limited information is available about the ecological role of bacterial and archaeal communities in these habitats. Studies have focused on fecal pollution and water quality, type and number of indicator bacteria (coliforms), or presence of pathogens (Vibrio cholerae) because of the impact on human health and the quality of food resources, and these aspects influence the vulnerability of coastal areas. This chapter provides an overview of the microbiology of the estuary–coastal lagoon ecosystem in Mexico. This is a compilation of useful information regarding human health and the ecological role of microorganisms in the coasts of the Pacific and Mexican Caribbean, as well as in the Gulf of Mexico. The information will be put in perspective with what has been published for other tropical zones.