Maria José Costa launches a book on the Tagus Estuary

MARE researcher Maria José Costa has just launched the book “The Tagus Estuary, where the river meets the sea”. The researcher is a retired full professor at the Faculty of Sciences of the University of Lisbon, and one of the 100 scientists honored by Ciência Viva's Women's Day in 2017.

The Tagus Estuary is an authentic natural laboratory for the study of climate change, which appeared around 80 million years ago at the end of the glacial period. Covering 320 square kilometers, the Tagus estuary is a biogeographical transition zone with fauna and flora from the Mediterranean, Subtropical Atlantic and Temperate Atlantic climates.

The characteristics of the estuary allow for the presence of carbon sequestering organisms that contribute to well-oxygenated waters. "Seagrasses, creeping plants in estuarine and coastal areas, ensure carbon sequestration. For example, the hedgerows and meadows on Samouco beach sequester the equivalent of the emissions of eight cars over the course of a year, making it the most productive ecosystem on the planet. The problem is that they are usually destroyed by human activity despite being protected by the Habitats Directive," says Maria José Costa in an interview with Green Efact.

According to the researcher, the estuary's water quality hasn't always been the best. It was only at the end of the 90s that there was an improvement due to the dismantling of certain industrial units, the cleaning up of the Trancão and the rehabilitation of the eastern zone with the advent of Expo 98. Despite this, the fish community only managed to recover 13 years after the removal of waste water from the estuary. “There was also greater environmental awareness on the part of the population, local authorities and the European Union's own rules,” says Maria José Costa.

“The problems facing the Tagus estuary today are still complex, such as the illegal capture of mussels, Japanese clams and corvina, as well as intense navigation that leads to the emergence of exotic species and also requires permanent dredging of the riverbed,” the researcher warns.

For Maria José Costa, “the most important thing today is to maintain the natural habitats for fauna and flora and the migratory corridor for birds from the North Atlantic”. As well as “taking care with the artificialization of the riverbanks”, so as not to destroy these habitats.