A team of Spanish scientists from a variety of fields has analysed the effects of human activity on the peridunal lagoons in the Doņana National Park. Results show that the lagoons are in the process of regressing, largely due to the extraction of underground water for the Matalascaņas tourist resort (Huelva). Moreover, the natural effects of the ecosystem itself are further aggravating the situation.
Botanists, limnologists and climatologists from the University of Seville (US) have developed a botanical monitoring methodology which combines botanical studies with documents from past centuries, historical maps, data on the use of the land, microrelief and recent climate trends. The aim of the study, which was published in the ICES Journal of Marine Science, was to investigate the changes in the perilagoonal vegetation in Doņana and ascertain their impact.
Arturo Sousa, the main author of the study and a researcher from the Department of Plant Biology and Ecology at the US explained the main conclusion of the study to SINC: "The lagoons are in the process of regressing, particularly due to the extraction of underground water for the Matalascaņas tourist resort, a coastal development complex that is right on the edge of the Doņana National Park, a short distance from the lagoons".
The surface and morphology of the lagoons in Doņana has changed over the last two centuries, according to the analyses of perilagoonal vegetation. The research confirms that the lagoons were reduced by 70.7% between 1920 and 1987.
The new methodology is based on the changes in perilagoonal vegetation and allows researchers to study the anthropological impact on the lagoons practically in real time, "and the possible negative effect that Global Warming may have on them in the future," the botanist adds.
Natural Effects also Negative
In the past, climate trends also had a negative impact on the lagoons in Doņana. "Before human activity in the area escalated, the lagoons had already begun a slow process of regression and desiccation linked to the advance of dunes, coinciding with the driest phases of the climate period known as the "Little Ice Age" (from the beginning of the 14th century to halfway through the 19th century), and probably also due to the start of the current process of global warming", Sousa says.
The coastal lagoons in Doņana have always been at the centre of public opinion and their conservation is of great interest. After reconstructing their evolution, the researchers confirm that the reactivation of mobile dune fronts is responsible for blocking and filling the original lagoons with sea sand. According to the experts, this could have occurred during the driest periods of the Little Ice Age in Andalusia. "If the frequency and duration of dry periods increases, together with droughts in general, the desiccation and disappearance of lagoons could become more widespread, not only in south western Europe, but also in other Mediterranean coastal ecosystems," Sousa warns.
Sousa, Arturo; García-Murillo, Pablo; Morales, Julia; García-Barrķn, Leoncio. "Anthropogenic and natural effects on the coastal lagoons in the southwest of Spain (Doņana National Park)" Ices Journal of Marine Science 66(7): 1508-1514 agosto de 2009.
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