Supplementary Information
relatively evenly during the year (Kjerfve 1990; Blasco 1984; Snedaker 1984). Notable exceptions are the northern coast of Peru, portions of the Caribbean coasts of Colombia and Venezuela, the coast of Ceará in Brazil and most of the smaller islands in the Caribbean, where the most extensive and best developed mangrove systems are in regions with ample freshwater. Rainfall by itself apparently does not limit the growth of mangrove wetlands, as these exist in arid as well as wet climates (Galloway 1982). However, rainfall does serve an important role as a primary control in leaching residual salts from mangrove soils, and thus acts to reduce soil salinity. In arid areas or regions with a strongly seasonal rainfall pattern, a barren salt flat often develops as a rim landward of the mangroves. (Kjerfve 1990). Other factors being equal, coasts with a great tidal range can be expected to have more extensive mangrove wetlands because of a greater potential for tidal flooding. Such conditions are encountered along the humid Pacific coast of Colombia with spring tides reaching 3.9 metres, and also along the humid coasts of northern Brazil where semidiurnal spring tides exceed 7 metres. On the other hand, in the inner part of Baja California, Mexico, where the climate is arid, mangroves are poorly developed in spite of daily tides with a range of more than 7 metres. In contrast, all of the Gulf of Mexico and the Caribbean Sea is microtidal, sometimes diurnal and sometimes mixed, with a range of less than 0.5 metres (Kjerfve 1981). Here, the tide is of little consequence in terms of affecting mangrove distribution.
With the flow of water to the mangroves comes a steady supply of nutrients from the surrounding land. The organic silts and sediments settle and, warmed by the sun, provide ideal conditions for the growth of microscopic plants and animals, the base of aquatic food chains. The abundance of food materials leads to some mangroves being one of the most productive systems on Earth. The contribution of plant material to regulate climate and water source is one reason to consider and protect mangroves since the movement of water from the Earth to the sea to the air and back to the Earth is fundamental in the water cycle. Evaporation occurs with higher temperatures, where mangroves ecosystems are located. On one side, mangroves can absorb the water
through their leaves or roots through groundwater, and they also lose water vapour through their leaves into the atmosphere. As the water vapour in the atmosphere increases, clouds are formed and eventually water droplets form causing rain events to occur in other areas, this means that evaporated water, after being condensed, falls into rivers and streams and eventually into the ocean where the water cycle begins again.
There is growing concern about the state of mangroves in LAC.
In several countries, mangroves are being cut and replaced by other biological or engineered structures, such as large scale mariculture (shrimp farming) in Ecuador, Brazil and Central America, tourism in Mexico, Central America and South Eastern Brazil, and harbours and industrial complexes almost everywhere (Lugo 2002; Lacerda et al. 1993, MMA- Brazil 2010). According to a recent GEF Project report “Conservaçao e uso sustentável efetivo de ecossistemas manguezais no Brasil” (ICMBio e IBAMA, 2014) Brazil still has 1 398 966 hectares of mangroves, 76% of them inside reserves.
22. Water quality in beaches in touristic destinations
Marine water pollution can have negative effects on coastal ecosystems and on human health. Regarding the latter, the most common problems are related to bathing in contaminated waters, which lead to gastrointestinal illness, skin rush and eye and ear infections.
In Mexico, marine water quality standards are established by a series of official norms. Among different parameters, pathogens, particularly faecal coliforms and enterococci (commonly associated with municipal wastewater), are analyzed given their capacity to generate infectious diseases (Larrea-Murrell et al. 2013; James 1979 in Wong and Barrera 1996).
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