The Ria de Aveiro

The Ria de Aveiro is a broad estuarine zone resulting of the river Vouga and one of the most important wetlands of the Portuguese northern coast. It is located on the limits of the city of Aveiro and the growing human pressure put on it impose it threats such as contamination, hunting and the loss of habitat. Despite all that, the area still has a variety and abundance of wild birds. Its main habitats are banks of vasa and sand, areas with estuarine vegetation, coastal meadows and old salines, most of which is still abandoned or remade into tanks. There are also areas of cane thickets and rice fields. In the Ria de Aveiro you can also find the Natural Reserve of the Dunes of São Jacinto.

This lagoon system and contiguous wetland not only is a coastal wetland with a large socio-economical relevance but also possesses an invaluable Natural Patrimony that is recognized nationwide and internationally for the several protection statutes from which it was targeted. At a national level it is classified both as a Natural Ecological Reserve (Reserva Ecológica Nacional or REN) and a National Agricultural Reserve (Reserva Agrícula Nacional or RAN). On the other hand, at an international level it was declared a Protection Zone especially for birds (Zona de Proteção Especial para as Aves) under the Diretiva Aves and incorporated in the Rede Natura 2000, Important Bird Area (IBA) by Birdlife International and by SPEA (Portuguese Society for Bird Studying) and inventoried as a biotype CORINE. Other protection statutes of the Ria de Aveiro were originated in the Bern Convention and the Bona Convention and RAMSAR. These protection statutes have as a main goal to give the Ria de Aveiro an international visibility.

All the statutes mentioned above find themselves perfectly justified as the RIa de Aveiro is one of the most remarkable ecosystems of the Portuguese coastline, making it one of the most relevant wetlands located in national territory, not only in extension but also in biodiversity (Moreira, 1992).

The strong maritime influence that characterizes it allowed the development and consolidation of a remarkable diversity of biotypes of great ecological importance, whether it be in the heart of the lagoon or around it, according to the salt gradient, to a larger or shorter proximity to the water courses as well as the frequency and degree of immersion in the locations. You can highlight from among the existing biotype diversity, the marshes, bogs, dunes, islands with vegetation, vasa and slime beaches and the agricultural fields (particularly the rice fields and the “bocage”) (Matos, 1994).

It is still important to mention that some of these habitats of anthropogenic origin make some of the most important cores of biological wealth of this ecosystem, those that urge to recover and revitalize, particularly the salines, the rice fields and the “bocage”. This last one is a habitat so rare that in Portugal it is almost exclusive of this region of the Baixo Vouga Lagunar.

All of these habitats are occupied by various living being communities that maintain close relations among each other, making it a complex food web which sustains an enormous biological diversity. The Ria is in reality owner of elevated faunistic and floristic wealths, accommodating emblematic species of the Portuguese biodiversity, especially in the mammal category such as the otter and the common buttonquail; important species of icthyofauna including migratory species of elevated market value such as the eel, the branzino and the sole, and over 15% of the aquatic birds that spend their winter in Portugal, putting it as one of the most significant zones for wintering of birds at a national level (Neto, 1998). The Ria takes on an international importance in some species of willows. ( Loureiro, 2001). The rich floristic diversity is proven by its own biotype variety with halophilous and sub-halophilous marsh, bog, and “bocage” zones. It is due to this whole biodiversity and to the close interdependence relations between the environment and the humans and to its cultural and historical wealth developed along centuries of coexistence that the Ria became what it is today.

These centuries old traditions of sustained coexistence that are important to retrieve, maintain or recreate, allowing this way an active and effective conservation of nature, a desired growth and socio-economic development, heading towards the intended ecological balance and following sustainability.