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23 páginas.-- 10 figuras.-- 4 tablas.-- 53 referencias.-- Se puede descargar en https://www.mapama.gob.es/en/red-parques-nacionales/programa-investigacion/3-sistemalagunas38-60_tcm38-66005.pdf, [ES]: El sistema de lagunas temporales de Doñana contiene una alta riqueza en flora y fauna, que incluye unconsiderable número de especies amenazadas. La biodiversidad del sistema se mantiene gracias a lagran abundancia y heterogeneidad de lagunas y a su amplio gradiente de hidroperiodo, así como porla diferenciación geomorfológica del parque. Las principales amenazas para la conservación del sistema son la desecación y la introducción de es-pecies invasoras, como el cangrejo rojo americano (Procambarus clarkii). Se detectan tendencias impor-tantes de desecación asociadas a la sobreexplotación del acuífero en los alrededores del parque, queafecta también a las mayores lagunas del parque. Como consecuencia de los descensos del acuífero, seestá produciendo el acortamiento del hidroperiodo de las lagunas y la pérdida de las especies propiasde los medios más permanentes. Entre ellas destacan algunas con alto valor de conservación, que ac-tualmente restringen su distribución a lagunas profundizadas artificialmente (denominadas localmentezacallones), ya que son los únicos medios que actualmente se pueden considerar permanentes. Mientrasque no se solucionen los graves problemas que conllevan los descensos del acuífero, los zacallones tie-nen en la actualidad un importante valor para mantener la diversidad del sistema, por lo que requierenun plan de mantenimiento y gestión, [EN]: The Doñana temporary pond network is characterized by a high flora and fauna species richness, in-cluding a high number of rare and threatened species. This high biodiversity is due to the high abun-dance of ponds of different size across a broad hydroperiod range. The different geomorphologicalareas within the park contribute to increase the heterogeneity of the whole pond network. Two main problems are currently threatening the conservation of the pond network: the observed trendsof pond desiccation and the introduction of invasive species, such as the swamp crayfish (Procambarusclarkii). Desiccation trends are currently detected associated with groundwater overexploitation in agri-cultural and urban areas around the park. As a consequence, we detect a tendency to pond hydroperiodshortening that involves the loss of aquatic species requiring longer inundation cycles, being some ofthem threatened species. These species are presently only found in ponds that have been artificiallydeepened (“zacallones”) so they offer available water during summer or in dry periods. These semiar-tificial ponds have an important role for preservation of aquatic communities and should be includedinto a management plan for conservation of the biodiversity of the pond network.

Póster presentado en el 7th European Pond Conservation Network Workshop + LIFE Charco Seminar 1st May – 4th May 2017 Universidade do Algarve, Faro, Portugal, The pond network in the Doñana National Park, in SW Spain, is composed of more than 3000 temporary ponds that are usually dry during summer. This network is complemented with approximately 200 artificially deepened ponds that were transformed for old human uses (i. e., cattle drinking, farm irrigation, charcoal production). They are locally known as “zacallones”. We have recorded plant and animal species present in zacallones in order to assess their value for conservation. These water bodies act as permanent ponds; they are the reproductive habitats of those species with long larval phases, and the summer refuges of many coleopterans and heteropterans. They are also the habitats of plants that do not resist long dry phases. Some of these ponds are subject to occasional restoration tasks that mainly consist in the removal of thick bottom layers of mud. We have analysed and compared the water quality, and also animal and plant species richness of these ponds during two subsequent years after these tasks. Water quality was generally better in restored zacallones, and vegetation cover as well as animal and plant richness also increased. In unrestored zacallones, the concentration of total-P in the water was significantly higher than in recently restored sites. Additionally, the P-adsorption capacity of the sediment (estimated as the ratio between iron-hydroxides and P-inorganic fractions) was significantly higher in the restored sites. The removal of the bottom layer did not prevent the development of a rich community of aquatic macrophytes, including some threatened species. Our results suggest that zacallones can provide refuge to some significant species, particularly in recent years as the Doñana temporary ponds are being reduced in number and wet-phase duration (or hydroperiod). However, the water quality of these transformed ponds can deteriorate very rapidly (due to their small size and intensive use for wild fauna and cattle drinking), and hence they require periodical monitoring and management.

The Doñana wetlands in SW Spain constitute what remains of the original 180,000 ha of marshland in the Guadalquivir delta. The natural wetlands are protected in the National Park and World Heritage Site (54,252 ha), and include more than 3,000 temporary dune ponds fed mainly from groundwater and 30,000 ha of seasonal marshes dependent on surface flows. They are particularly famous for their avifauna, and hold more wintering waterfowl than any other European wetland. Wading birds exploit surrounding ricefields and fishfarms, and their breeding numbers are increasing. Doñana holds a high diversity of herpetofauna, mammals, invertebrates and plants, with several endemic species. The wetlands have high value for ecotourism and are the setting for the El Rocío pilgrimage. Alien fish and crayfish have had a significant impact. The quantity and quality of water entering the wetlands is under threat from groundwater extraction and other effects of agricultural and urban development.

La importancia del sistema de lagunas de Doñana radica en la gran cantidad de lagunas y su elevada heterogeneidad, lo que le permite albergar a un gran número de especies, muchas de ellas singulares, al ser exclusivas de este tipo de medios acuáticos, caracterizados por un periodo de desecadón recurrente. Esta compleja red de lagunas se ha ido conformando, a lo largo del tiempo, coroo consecuencia de la interacción de los aprovechamientos tradicionales del suelo sobre las coodiciones hidrogeolágicas del manto eólico litoral onubense, en un contexto donde fluctúan períodos dimaticamente húmedos y secos.

Azolla filiculoides es un helecho acuático invasor, que fue detectado por primera vez en la marisma Doñana en el año 2000. Aparece como cubierta dominante o por debajo de helófitos. En las zonas invadidas termina cubriendo totalmente la lámina de agua, modificando las características reflectivas de la superficie. La biología de esta especie (escaso tamaño y hábito flotante) junto con las características propias de la marisma (gran extensión y dificultad de acceso) no facilitan el seguimiento tradicional de la invasión ofreciéndose la teledetección como una herramienta eficaz para su seguimiento. En la primavera de 2007, Azolla experimentó una explosión demográfica desconocida hasta el momento. Para este periodo se poseen 4 imágenes Landsat entre marzo y junio y datos de campo próximos a tres de las fechas. El objetivo de este trabajo es estimar la superficie invadida por Azolla con un alto porcentaje de recubrimiento (“densa”) mediante clasificación de imágenes Landsat en la marisma del Parque Nacional de Doñana, tanto en el momento de máxima actividad fotosintética y en presencia de agua, como cuando la marisma se seca y Azolla muere. Se estima que la superficie invadida por Azolla “densa” en el año 2007 para la zona sur de la marisma del Parque Nacional de Doñana fue de 669 ha.

The Doñana National Park is given the highest degree of environmental protection in Spain as it has been designated as a Ramsar Site, a Biosphere Reserve, a Special Protection Area for birds, and a Natural World Heritage Site. Nevertheless, it is located in an area with a wide variety of pressures due to the exploitation of water resources. The intensification of agriculture, urban growth, and the development of tourist resorts on the fringe of this protected land has long threatened the conservation value of the Doñana National Park and has, consequently, added this park to the Montreux Record of Ramsar Sites under threat in 1990.

In 2001, Azolla filiculoides Lam., a floating pteridophyte native to the New World, was found in Do˜nana National Park (SW Spain), an European protected area well known for its high value from a conservation point of view and for its ecological vulnerability. Until that time, there had been no exotic aquatic macrophyte observations in the National Park. Since then, surfaces covered by Azolla filiculoides have increased explosively forming thick floating mats which eliminate submersed plants, and seriously threaten the aquatic ecosystems in this important protected area. En 2001, Azolla filiculoides Lam., una pteridofita acuática nativa del Nuevo Mundo, fue encontrada en el Parque Nacional de Doñana (SW España), un espacio protegido europeo bien conocido por su alto valor desde el punto de vista de la conservación y por su vulnerabilidad ecológica. Hasta ese momento, no se había observado ningún macrófito acuático exótico en el Parque Nacional; desde entonces, las superficies cubiertas por Azolla filiculoides se han incrementado de manera explosiva originando gruesas capas flotantes que eliminan las plantas acuáticas sumergidas y amenazan gravemente los ecosistemas acuáticos de este importante espacio protegido.