What is Happening to the Ebro Delta?

A hoard of flamingoes, half obscured by the haze rising from the warm waters, lounge and preen in the afternoon sun. Purple herons stalk through swathes of tall grass. Great crested grebes, cormorants and several species of duck and other waterfowl compete for space on the water, dipping with the steady ebb and occasionally disappearing beneath the surface to dive for weeds and fish. The sky is alive with murmurations and birds of prey. On one side the wetlands stretch for miles, uninterrupted save for a few small stone huts and old, twisted trees until they reach the Mediterranean sea. On the other looms the pale blue shadow of the mountains. It’s a beautiful scene, but sadly, one that is under threat.

Pink greater flamingoes roosting in the marhses of the Ebro Delta, surrounded by reeds.
A large colony of Greater Flamingoes calls the Delta home and is one of very few breeding in the Medeterranean.

This is the Ebro Delta (or Delta del Ebro). The largest wetland in Catalonia. At an impressive 320 square kilometres, this incredible landscape is an important habitat for many resident and migratory species. Declared a National Park in 1983, the Ebro Delta supports hundreds of species, including plants, fish, turtles, and, most famously, around 300 species of birds. It’s importance as a breeding ground and migratory stop-over for these birds, around 60% of species found in Europe, is internationally recognised.

The charcteristic lay of the delta was formed over hundreds of years by shifting sediments and changes in the flow of the Ebro River which drains down from the Iberian Penninsula. These nutrient-rich waters made the area ideal for both wildlife and human agriculture. In particular, rice is grown in abundance. The flooded paddies stretch out for miles, lush and green. However, in recent years the pressure put on the area, by increasing the amount of land used for agriculture and redirecting water, has begun to take its toll on the wildlife.

There are now more than 180 dams on the Ebro River, implemented by the
Spanish National Hydrological Plan (NHP). The NHP was first adopted in 2001, with the intention to build around 120 dams and redirect water from the Ebro and Rhône rivers to other areas of Spain. Those advocating for the NHP maintain that these measures are being taken to ensure that urban areas are not impacted by seasonal water shortages.

A view over the reed beds and an estuary of the Ebro River, towards a mountain range. At the base of the range is a small city and to one side of the estuary is a small group of greater flamingoes.
The Ebro River brings sediment down from the mountains into the sea, forming the Delta wetlands.

The dams now trap the sediment which once shaped the delta, preventing them from passing through the wetlands and into the sea. This is causing changes to the geographical composition of the area as the river mouth recedes, reshaping the marshes and dykes that provide habitat for many species. Paired with the rising sea levels seen globally, which threaten to submerge around 40 percent of the wetlands by 2100, some species are already disappearing from the area. The once large colony of pipistrelle bats that called the delta home have sharply declined, as have populations of sturgeon, turtles and various frogs.

In 2015, the resident colony of greater flamingoes did not breed. Even though this species is considered of Least Concern by the IUCN (International Union for Conservation of Nature), this is the only known breeding colony in Catalonia and one of very few in the Mediterranean, making the failure to breed worrying. Thankfully the birds did resume breeding, but it’s thought that the interruption may have been due to redistribution of populations of interacting birds and predatory mammals. Monitoring of these populations was increased in following years.

A close up visual of a juvenille great crested grebe on calm water.
Great Crested Grebes, like this juvenille, are just one of the many species found in the Delta.

The impacts of changes to this delicate landscape are not just felt by wildlife though. Agriculture in the area will also be affected. Rice farming has been well suited to the wetlands due to the plant’s resilience to the high salinity of the waters and its need for flooding. Soon, however, even this will become unsustainable as damage caused by redirections and dams on the Ebro River under the NHP, threaten to restrict water and sediment flow even further.

Scientists, political parties and environmental NGOs have strongly opposed the NHP over the years, due to its conflict with sustainable development goals. Several reports by academics outline the potential impacts continued construction of dams could have on the delta. Many also refute the need to redirect water to those areas which have been highlighted as vulnerable to seasonal water variations. As a result, the plan has been raised and dropped repeatedly since 2001, perhaps buying vital time for the people and wildlife the Ebro Delta supports.

Published by OwenL

Natural sciences communicator.

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