The Natural Park of Ria Formosa (PNRF) is situated in the Algarve’s leeward area, based on the important lagoon area there, covering an area of about 18,000 ha, including the submerged area encompassing the counties of Faro, Loulé, Olhão, Tavira and Vila Real of Sto António.
The lagoon area of the Eastern Algarve has an obvious ecological and scientific, economic and social value and has long been subject to pressures of the most varied order or the Algarve was not the most important tourist destination in Portugal.
Decree-Law no. 373/87, of December 9, created the Ria Formosa Natural Park, which has as its primary objectives the protection and conservation of the lagoon system, namely its flora and fauna, including migratory species, and its habitats.
The need to reconcile the protection of natural and cultural heritage and sustainable socioeconomic development also included objectives related to: support for traditional and other economic activities as long as they are compatible with the rational use of resources; with the promotion of recreational, leisure and tourism activities, taking into account the particularities of the protected area and its carrying capacity; and not least with the implementation of infrastructure aimed at environmental education, in order to sensitize the resident population and visitors to the need to preserve natural and cultural values and that the Marim Environmental Education Center is a excellent exemple.
The Ria Formosa Natural Park is characterized by the presence of a coastal sand dune belt (beaches and dunes) that protects a lagoon area. A part of the lagoon system is permanently submerged, while a significant percentage emerges during low tide. The average depth of the lagoon is 2 m.
This large lagoon system extends from the Ancão to the Manta Rota – it includes a wide variety of habitats: barrier islands, marshes, sandbanks and dams, dunes, salt marshes, freshwater and brackish lagoons, courses of water, agricultural areas and forests, a situation that immediately indicates an evident floristic and faunistic diversity.
The presence of the men accompanies the Ria in all its extension materializing, mainly, in urban nuclei, isolated constructions and tourist villages.
Fishing and defense needs are two of the reasons men joined in this Eastern Algarve: Cacela, dominated by its eighteenth-century fortress; Tavira, which was once Roman and Arab; the Fuzeta, which originated in a camp of marauders; Olhão, a city that seems transposed from any North Africa; Faro, probably the Ossonoba spoken of by the ancients.
Geology | Hydrology | Climate
The Ria Formosa Natural Park is characterized by the presence of marine anamorphic littoral (beaches, barrier littoral or estuaries, coastline of sapal), anamorphic wind coastlines (dunes) and fluvial anamorphic littoral.
The Ria Formosa confronts the north with alluvial deposits of the Faro plain and with plio-plistocenic formations (sands and sandstones), Tertiary (sandstones and limestone) and Jurassic (limestone) formations. Further north lies the schist formation of the Cauldron. These are the same formations that are found in the basins of reception of the water courses that flow into it. To the south it is bounded by a set of barrier islands of the sandy coastal cordon, which separates it from the Atlantic Ocean, and that from Quarteira, it takes the direction NO-SE until the cape of Santa Maria. To the east of this cable, it curves, fluttering in the direction of SO-NE to Cacela.
The barrier islands (from west to east) are known as Ancão peninsula (Faro beach), Barreta islands, Culatra, Armona, Tavira, Cabanas and Cacela peninsula.
The six tidal bars that separate them have different characteristics, depending on whether they are west or east of Cape Santa Maria, and are called Ancão or S. Luís, Faro-Olhão, Armona, Fuzeta, Tavira and Lacém .
With an average depth of 2 m, and an irregular layout of the bottoms, the lagoon is characterized by an extensive intertidal area occupied by tide spreads and bars, which significantly interfere with the tidal current system. About 14% of the lagoon surface is permanently submerged, and about 80% of the bottoms emerge during the low tide under high tide conditions.
The water courses that flow into the Ria Formosa lagoon system (Seco, Gilão, Almargem rivers, Lacém, Cacela, and others) are seasonal, with a torrential regime, given the poor local rainfall. Thus, the Ria Formosa is fed almost exclusively by oceanic water.
The Ria Formosa Natural Park is part of a semi-arid Mediterranean climate with a prolonged dry season during the summer months and mild winter due to the influence of the Atlantic flow of the west and far from the regions of origin of continental polar air masses.
Inserted in the south of Portugal, it has transitional climatic characteristics for subtropics, where precipitations are weak and irregular, temperatures are mild, with rare occurrences of negative values, and insolation is high, whose average values are respectively 450 mm, 18 ° C and 3150 hours.
Coastal dunes and, in this case, the advanced dune strand are formed in the part immediately following the tides domain, especially during the ebbing, when the dry sands of the exposed beach are mobilized and carried by the wind and deposited later . In many places the crest dunar was cut by the action of constant winds already with certain intensity, being vestigios of remobilization of the sands, which results in the formation of incipient corridors of wind and sketches of small dunes parabolic. These are characteristic of transgressive periods, which correspond to sea level rise and during which the arrival of sediments to the beach is poor.
Sapal in front of Old Cacela
On sheltered sections of the coast, orlando estuaries, lagoons or bays, and protected from the impact of the waves of the open sea by a barrier of islands or sandy tips, at the level of entremarés, platforms arise where dense cover of a very peculiar vegetation is installed; are submerged during high tide and are exposed at low tide. It’s the marshes.
Although it does not appear, the marsh is among the most productive areas of the biosphere. Regarding the production of live matter or biomass, it is several times more profitable than the best corn fields, except that they need to be mechanically worked, sown, fertilized and treated with weeds. The marsh is not. The nutrients come naturally to it, carried by the constant flow and ebb of the tides, by the sediments coming from the continental zone, by the living beings that are fixed therein, and, dying, decompose there. Even by the inopportune human action that, not infrequently, of it dumps. As for weeds, there is usually no, as the survival conditions in the marsh are extremely difficult for plants that are not suitably adapted.
The waters of the salt marshes contain a great amount of nutrients. The small depth not only maintains a favorable temperature to the development of marine organisms as it allows a good penetration of the light, guaranteeing an intense and almost continuous photosynthetic activity. Because they are calm, they are a good place to shelter and stay for many animal species, of which the navies are particularly important, many of which spawn and pass through the larval and juvenile stages until the time comes to migrate to the sea, where they complete the biological activity. The marsh therefore functions as a nursery or nursery for these species, many of them with an interest in human food. The abundance of fish, mollusks and crustaceans depends on the conservation of marsh and maternity in the coastal waters where human populations seek and from which they derive part of their subsistence.
The productivity of the marsh also supports its scientific value. It conditions the number of species of sedentary birds that inhabit and nest in it; the number of migrants who need it for stopping, resting and feeding, before resuming their long journeys; and finally, the number of invertebrates, small vertebrates or plant species capable of sustaining others in this intricate web of food.
Finally, a relevant aspect of the “living” marsh is that its vegetation has a strong purifying action due to the great capacity of absorption and fixation of heavy metals, many of which are toxic