2023-08-10 11:53:25
It has happened again. Santa Olalla, the largest permanent lagoon in Doñana, has completely dried up. The Singular Scientific and Technical Infrastructure (ICTS) – Doñana Biological Reserve, dependent on the Doñana Biological Station (EBD-CSIC), of the Higher Council for Scientific Research (CSIC), updated its monitoring camera of the lagoon a few weeks ago to see its evolution.
Finally, yesterday its complete desiccation was verified. Since the research center began to collect data on the natural space half a century ago, this image had never been repeated for two consecutive years, which attests to the serious situation in which the Doñana lagoon system finds itself and, with it, all the biodiversity that depends on it.
The Doñana National Park was declared a World Heritage Site in 1994 due to its variety of ecosystems and the great diversity of species that inhabit them, making it a unique enclave in Europe.
Since the research center began to take data on the natural space half a century ago, never before has this image been repeated for two consecutive years.
One of these ecosystems is represented by the lagoon system, which is home to great biodiversity and is refuge for various endemic and endangered species. However, in recent years, the Doñana lagoons have suffered serious deterioration, their flooding period lasts less and less and many of them no longer flood, which is seriously affecting the biodiversity they support. The desiccation of Santa Olalla in summer is one of the greatest evidences of the deterioration of the lagoon system, indicating the absence of summer aquatic refuges for the aquatic fauna and flora of the Doñana wind mantle.
What the latest scientific data reveals
The ICTS – Doñana Biological Reserve, through the Monitoring Program, has verified that the 2021 to 2022 hydrological cycle has been the year with the lowest levels of precipitation in the last ten years (283mm), which has not improved much the current year, in which the rainfall has been similar (337mm until August). In addition, in both years they are registering very high maximum temperatures and the highest average annual temperature (18.53°C) recorded.
But these factors are not the only causes of deterioration of the lagoon system. In a study by the Doñana Biological Station published this same year, with data collected for 40 years, it was found that 59% of the largest lagoons in Doñana have already disappeared.
It is also worrying that 19% of the lagoons that are still maintained have more than half of their basin invaded by scrub and pine trees.
This phenomenon is significantly related to the high temperatures and the long period of low rainfall that Doñana is suffering; but also with the overexploitation of the aquifer that feeds this lagoon system. 80% of these gaps they dried up sooner than expected with the levels of temperature and precipitation registered and 84% were flooded less than expected, which shows that human activity is altering the natural balance of the lagoons and is aggravating the problem.
In addition, it is also worrying that 19% of the lagoons that are still maintained have more than half of their basin invaded by scrub and pine trees and only 10%, mainly located on the vera, remain in good condition.
In another recently published study, the Doñana Biological Station concludes that the invasion of the lagoon basins by terrestrial vegetation is a good indicator to detect their progressive deterioration and their imminent disappearance. These symptoms are especially detected in the northwestern area of the national park and in the lagoons closest to Matalascañas, including Santa Olalla, where they are already observed. dense reeds in the middle of its floodplain and masses of shrubs that have colonized its current shores and islets.
An ecosystem in danger
Most of the lagoons in Doñana are temporary, and they flood thanks to the water from the aquifer which, when it is recharged with the rains, reaches the surface level, filling its basins and flooding the reserve with life.
In the last decade there have not been years of heavy rainfall, reducing the recharge of the aquifer, which has not been enough to counteract the excessive withdrawal of water for consumption in the tourist town of Matalascañas in the summer period and for intensive strawberry crops. located in the surroundings of the park, which have increased their surface by more than 30% in the last 10 years. All this has contributed to reduce aquifer levelswhich prevents many lagoons from flooding or reducing the period that they remain flooded, affecting the life cycles of the species that live in these aquatic environments.
Until a few years ago, only three lagoons were considered permanent: Santa Olalla, the Dulce lagoon and the Sopetón lagoon. The only one that could continue like this until now was the first
Permanent lagoons, which hold water all year round, are very rare in the park, so in this temporary system they act as a refuge for many species. Until a few years ago, only three lagoons were considered permanent: Santa Olalla, the Dulce lagoon and the Sopetón lagoon. The only one that could continue to be considered permanent was Santa Olalla, although it reached little flooded area and high concentrations of salts in summer. Its complete desiccation prevents, for example, the presence of fish. When it dried up in 2022, we watched the death of the remaining eels, one of the currently threatened species. We are also seeing its Galapagos population decline.
The recommendations of the scientific community
From the Doñana Biological Station, the urgent reduction of the total amount of water that is extracted from the aquifer is demanded to levels that allow the recovery of the lagoon system and stop the degradation of the natural space. also suggests update the aquifer status assessment system and carry out annual evaluations of water availability to define the maximum amounts of extraction allowed and the saving measures that must be adopted.
The scientists demand to urgently restore the governance of water management and the planning of the territory of Doñana so that they are within the current legality
Another of his proposals is to urgently restore the governance of water management and territorial planning in the Doñana region so that they are within the current legality and, of course, protect the agricultural sector that operates under legality facing the loss of brand value of their products, facing unfair competition from illegal producers and facing the uncertainty that threatens them for the future.
They also consider important the establishment of the Doñana 2030 Work Commissionapproved by the Doñana Participation Council, to advance quickly and in a coordinated manner in solving all the problems that Doñana faces, not only those related to the aquifer, but also, among others, water contamination or the intense overgrazing, which is also affecting the natural enclave.
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