Access the main highlights of Collection 7 on the Coastal Zone in Brazil

At 7491 kilometers, Brazil's coastline is one of the 20 countries with the longest coastlines in the world. With the help of satellite images and artificial intelligence resources, MapBiomas took an X-ray of this territory, which includes beaches, dunes, mangroves, apincus and aquaculture and salt farming areas. Municipalities in the interior of Brazil with large sandy areas were also mapped. The figures show relative stability in these natural formations, with some gains in mangroves and the same tendency to lose beaches and dunes.

The good news comes from the mangroves, which stretch all along the Brazilian coast from Amapá to Santa Catarina. Between 1985 and 2021, their total area expanded by 4%, from 970,000 hectares to more than one million hectares (1,011 Mha). Three states in the northern region - Amapá, Pará and Maranhão - account for 80% of the country's mangrove coverage and their configuration explains this good result. The mangroves in the north grow under a macrotidal regime, where the water level varies daily by more than 4 meters, and develop on a mud plain that is up to 30 km wide, occupied by trees up to 30 m high, says Pedro Walfir, from MapBiomas' coastal zone mapping team. This type of natural cover makes this ecosystem naturally resilient to anthropogenic changes. 

Mangroves are nurseries for countless marine species: 70 to 80% of the fish, crustaceans and molluscs that people consume need this biome at some stage in their lives. Several economically important fish species use the mangroves as a breeding ground and then return to the sea. Mangroves are also important for protecting the coast from marine erosion.

Among the natural formations over which the mangrove expands are the apicuns - dynamic, hypersaline surfaces associated with the tidal regime. Between 1985 and 2021, apicuns grew from 57,000 to 54,000 hectares in Brazil. Maranhão concentrates approximately 60% of the country's apicuns. 

Most of its area (70%) is within one of the 340 Conservation Units in the Brazilian Coastal Zone. Despite this, between 1985 and 2021, 1,300 hectares of apicuns were converted for aquaculture activities which, together with the 531 hectares lost to urban infrastructure, represents the main risk to this type of natural formation. "Apicuns, like mangroves, are locally dynamic, interspersing losses and gains of approximate magnitude throughout the time series. These are processes of natural transformation," explains César Diniz, from MapBiomas' coastal zone mapping team. "However, when there is a conversion to urban infrastructure or aquaculture, this dynamic is interrupted: there is no return to the original formation," he adds.

Aquaculture was the fastest-growing occupation of the Brazilian coastal zone over the last 37 years: it increased by 36% between 1985 and 2021, rising from 36,000 hectares to 56,000 hectares in the country. The activity expanded mainly on water surfaces (28%), agricultural or pasture mosaics (25%) and savannah formations (14%), with a clear preference for non-vegetated areas, such as apicuns or, when vegetated, shrubby areas. Two states (Rio Grande do Norte, with 67%, and Ceará, with 15.4%) account for 82% of the salt farming/aquaculture area in Brazil. Mossoró, in Rio Grande do Norte, has the largest aquaculture/saliculture area in the country: approximately 11,000 hectares - twice the urbanized area of the municipality. 

Beaches, dunes and sands lose 15% of their area

The scenario of sandy beaches and dunes without vegetation cover is different: 47% of their area is in conservation units, which have shrunk from 457,000 hectares in 1985 to 389,000 hectares in 2021 - a 15% drop. Among the vectors that led to this loss of 68,000 hectares is pressure from the real estate market and the consequent advance of urban infrastructures (11%), forestry (7.4%), pastures and mosaics of agriculture and livestock (10%).

"This loss is worrying because beaches and dunes play a strategic role in controlling coastal erosion and preserving biodiversity," explains César. "Beaches and dunes normally protect mangroves from the action of waves, creating a calm environment where mud can be deposited and colonized by mangrove vegetation," he says.

The Lençóis Maranhenses and the Cordão Dunar in Rio Grande do Sul are the two largest contiguous sandy features in Brazil. Together, they account for 51% of the country's beaches and dunes. However, there aren't just sandy beaches and dunes on the coast: according to MapBiomas, of the 10 municipalities with the greatest extent of this type of cover, two are in the interior of the country - Pilão Arcado and Xique-Xique, both in Bahia. The leading municipality is Barreirinhas, in Maranhão.