By Marc Durà
To protect life at seas, we often neglect the importance of ensuring the health of rivers. Rivers provide freshwater, sediment, organic matter, and in many cases pollution as well.
Rivermouths are usually the scene of a very important and delicate biological exchange, especially in places where there are wetlands and deltas.
Wetlands represent 6% of the planet’s surface, but they are the habitat of innumerable threatened species, from aquatic birds to Eurihalin fish such as the eel (Anguilla anguilla).
The Ebro Delta is one of the most important wetlands in Europe and the third-largest in the Mediterranean. With an area of 320Km2 where human activities coexist with protected habitats and more than 300 species of birds, the Ebro Delta faces its greatest threat: regression.
The Ebro basin has more than 100 reservoirs that retain all the sediment that would naturally reach the mouth, a process that over several millennia gave rise to the current delta as we know it. Without the contribution of sediment, the delta’s flooded plains suffer the onslaught of storms and gradually give way to the sea, a process known as litoral regression, which in some of the most vulnerable areas is estimated to be about 15 meters per year.
The years 2020 and 2021 will be remembered for two particularly virulent Levante storms that have fatally wounded one of the most fragile areas of the Delta. The waves of storms Gloria and Filomena have destroyed the Trabucador bar; the isthmus that connects the southern part of the delta with the Banya peninsula. It is a 6 km long sand bar that separates the Mediterranean Sea from the Alfaques bay.
Both storms, separated by exactly 12 months, sank the bar under the sea and despite efforts by local authorities to replace sand artificially, the damage is irreparable.
The regression causes the salinization of the lagoons, the loss of habitats, such as the shallow waters of bays or the mobile dunes, and in general the disappearance of an environment of extreme ecological value.
If the forecasts about global warming and sea level rise are correct, the regression will accelerate and we will be facing a biological catastrophe in the Mediterranean.
There is hope with the Platform in defense of the Ebro and the Campanya pels Sediments that advocate for a release of the sediments, trapped in some of the main reservoirs in the lower section of the river so that they are deposited in the delta in a natural way, which constitutes the only viable way to fight regression.
Marc Durà is a freelance photographer based in Barcelona, an ocean lover and passionate about the marine biodiversity of the Mediterranean.