217 research outputs found
Permanent and temporary ponds in Doñana National Park (SW Spain) are threatened by desiccation
In Doñana National Park, most aquatic habitats are temporary. Ponds dry up during the summer, and are filled again when
phreatic levels rise after heavy rains. Permanent and semipermanent ponds, and a chain of long-hydroperiod ponds are formed
in an area of the park where discharges of the dune and regional aquifers coincide.
Over the last few decades, groundwater abstractions have severely affected the park. Using Landsat images (1975-2014), we
estimated the variation in the inundated areas of the park’s largest ponds. All ponds have increased their dependency on annual
rainfall in recent decades. Two seasonal ponds located close to urban pumping stations are currently dry. We found that other
seasonal ponds have tended to have shorter hydroperiod and have dried up in the summer in recent years, including in very
rainy years. The largest permanent pond had not such wide interannual fluctuations in its inundated area in the 1970s as those
experienced recently. During the last decades, its inundated area is strongly correlated with annual rainfall, and the pond is
close to desiccation in years of low rainfall.
These results show that this pond network is severely threatened by desiccation. It is urgent to control groundwater extraction
in the area to preserve the integrity of this important wetlandEn Doñana, la mayorÃa de los hábitats acuáticos son temporales. Las lagunas se desecan en verano y vuelven a inundarse con
la elevación del nivel freático que se produce tras las abundantes lluvias otoñales o invernales. En la zona central del parque
se localizan las lagunas permanentes y semipermanentes, que junto con otras de largo hidroperiodo forman una cadena de
lagunas donde coinciden las descargas del acuÃfero dunar y el gran acuÃfero regional.
En las últimas décadas, se han realizado extracciones de agua del acuÃfero que han afectado seriamente al parque. En
este estudio, usando imágenes del satélite Landsat (1975-2014), hemos estimado la variación de la superficie inundada de
las mayores lagunas del parque. En todas se observa un incremento en las últimas décadas de su dependencia de las lluvias
anuales. Dos lagunas estacionales, situadas en las proximidades de estaciones de bombeo de aguas se consideran actualmente
secas. En algunas lagunas, se observa una tendencia a acortar su periodo de inundación, secándose en los veranos de los años
más recientes, incluso en años lluviosos. La laguna más permanente no sufrÃa tan amplias variaciones en la superficie que
mantenÃa inundada en verano en los años 70, como las que observan en la actualidad, cuando su inundación en verano está
estrechamente correlacionada con las lluvias anuales, llegando en los últimos veranos a niveles muy próximos a la desecación.
Estos resultados indican que la red de lagunas está severamente amenazada de desecación. Para preservar la integridad de
este importante humedal, es urgente controlar las extracciones de agua del acuÃferoPeer reviewe
Relationships between hydroperiod length, and seasonal and spatial patterns of beta-diversity of the microcrustacean assemblages in Mediterranean ponds
Temporary ponds are unpredictable habitats that exhibit inundation periods of variable duration (hydroperiods). We hypothesised that changes in microcrustacean assemblages, namely among ponds (spatial variation) and within ponds at a monthly scale (intra-annual variation), would differ according to hydroperiod length. We found that the microcrustacean assemblages of the study ponds demonstrated distinctive individual patterns that were dependent on monthly variation. During pond filling, species turnover was particularly high in short-hydroperiod ponds, probably due to the fast hatching of the initial pool of species, which seemed to determine subsequent species succession. Some of the long-hydroperiod ponds were able to hold water during the summer, which meant that they could harbour adult microcrustaceans in the early autumn, in contrast to the recently filled ponds; species turnover could thus increase at the onset of the inundation cycle. In the summer, species turnover decreased (while the contribution of nestedness to β-diversity increased) because only a few tolerant species were able to withstand the poor water quality found in drying ponds. We suggest that preserving the broader hydroperiod gradient, by protecting ponds with different environmental conditions within each hydroperiod category, would safeguard the ecological dynamics of the microcrustacean assemblages found in temporary pondsPeer reviewe
Galápago leproso – Mauremys leprosa (Schweigger, 1812)
Reptiles - Orden Quelonios - Familia Geoemydidae en la Enciclopedia Virtual de Vertebrados Españoles, http://www.vertebradosibericos.org/.A comprehensive review of the natural history of the Mediterranean stripe-necked terrapin Mauremys leprosa in Spain.Peer reviewe
Spatio-temporal nested patterns in macroinvertebrate assemblages across a pond network with a wide hydroperiod range
Nestedness has been widely used to measure the structure of biological communities and occurs when species-poor sites contain subsets of species-rich ones. Here, we examine nested patterns across the macroinvertebrate assemblages of 91 ponds in Doñana National Park, Spain, and explore temporal variation of nestedness and species richness in 19 temporary ponds over 2 years with differing rainfall. Macroinvertebrate assemblages were significantly nested; both pond spatial arrangement and environmental variation being important in driving nested patterns. Despite the nested structure observed, a number of taxa and ponds deviate from this pattern (termed idiosyncratic), by occurring more frequently than expected in species-poor sites, or having assemblages dominated by species largely absent from species-rich sites. Aquatic adults of winged insects, capable of dispersal, were more highly nested than non-dispersing taxa and life-history stages. Idiosyncratic taxa were found in ponds spanning a wide range of hydroperiods, although nestedness was higher in more permanent waterbodies. Monthly sampling demonstrated a gradual increase of species richness and nestedness from pond filling to April-May, when the most temporary ponds started to dry. Although the degree of nestedness of individual pond assemblages varied from month to month, the overall degree of nestedness in the two study years was practically identical despite marked differences in hydroperiod. Our results suggest that differential colonization and environmental variation are key processes driving the nested structure of Doñana ponds, that macroinvertebrate assemblages change in a predictable manner each year in response to cycles of pond wetting and drying, and that connectivity and environmental variability maintain biodiversity in pond networks. © 2010 Springer-Verlag.Peer Reviewe
Mediterranean temporary ponds as amphibian breeding habitats: The importance of preserving pond networks
We describe the spatial and temporal variation in the main characteristics of amphibian breeding habitats in Doñana National Park (south of Spain), during two hydrologic cycles with different rainfall amounts and timing (2002-2003 and 2005-2006). We also evaluate amphibian habitat requirements following a model selection approach based on Akaike's Information Criterion. Our results evidenced large spatial variability in all pond characteristics and inter-annual differences in pond hydroperiod, depth, and most water-chemistry characteristics. We observed a remarkable independence of pond characteristics at different sampling dates, suggesting that a pond description based on a single survey may not be representative. Eight of nine amphibian species attempted breeding in both years in spite of the marked inter-annual variability. Habitat models were species-specific and year-specific, as we found inter-annual differences in the pond characteristics relevant for species richness or for the relative abundance of particular species. All these results suggest that this large and diverse network of ponds provides different habitat opportunities each year, favouring the long-term persistence of the whole amphibian community. © Springer Science+Business Media B.V. 2009.Peer Reviewe
Use of water soluble extracts from ulva sp. by probiotics and fish bacterial pathogens
BACKGROUNDS The potential of seaweeds as dietary components is considered for a wide range of cultured fish species. In this context, Ulva is investigated as a good source of protein, minerals and vitamins. In addition, of probiotics are used to improve fish growth and modulate immune system and intestinal microbiota. To promote probiotics colonization and maintenance in the intestine, prebiotics are included in fish diets. Prebiotics are indigestible substrates used as energy sources for gastrointestinal microbiota, with a positive effect on the nutrition and health status of the host.
In the present work, ability of selected probiotic and fish pathogen strains to use water soluble extracts from Ulva as nutrient source has been evaluated. MATERIALS AND METHODS Water-soluble extracts from Ulva sp. prepared by sonication of dehydrated samples were used to supplement minimum medium (M9). Probiotics and pathogens growth was evaluated based on the optical densities measured with a microplate reader.
RESULTS AND CONCLUSIONS
Probiotics were able to grow in minimum medium using water soluble extracts as nutrient source. On the other hand, P. damselae subsp. piscicida and V. harveyistrains were also able to grow with Ulvaextracts as nutrient source. However, incubation time to reach maximum growth was longer.
Although Ulva extract may support growth of both probiotics and pathogen bacteria, faster growth of probiotics may help for the establishment of probiotic populations in the intestinal environment. In addition, beneficial effects on growth performance, gut microbiota, immunity and disease resistance of Ulva for Solea senegalensisare being studied.
This work was funded by INIA, Ministerio de EconomÃa y Competitividad and FEDER (RTA201400023 C0202).This work was funded by INIA, Ministerio de EconomÃa y Competitividad and FEDER (RTA201400023 C0202).Universidad de Málaga. Campus de Excelencia Internacional AndalucÃa Tech
Doñana wetlands
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 RocÃo 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.Peer reviewe
Salmonella in free-living exotic and native turtles and in pet exotic turtles from SW Spain
We screened 78 native and 94 exotic turtles from natural ponds and 39 exotic pet turtles for presence of Salmonella, resulting with infection rates of 6.61%, 6.4%, and 5.1%, respectively. Concurrent shedding of multiple serotypes of the bacteria was only detected in one pet turtle. Eleven isolates were obtained in free-living turtles, including serotypes commonly found in reptiles and also the serotype Typhimurium, which is commonly related to human infections. In pet turtles, the five serotypes isolated were different to those isolated in free-living turtles and had been reported to cause reptile-associated salmonellosis in humans. These results confirm the risk of transmission of Salmonella from free-living and pet turtles to humans, demanding the necessity of regulation of pet turtle trade in Europe. © 2008 Elsevier Ltd. All rights reserved.Peer Reviewe
The influence of geomorphology on the composition of aquatic flora and fauna withim a temporary pond network
Geomorphological and hydrological features can provide a sound basis for global wetland classification. Temporary ponds
located on the sandy area of Doñana can be classified into five different geomorphological areas. We hypothesised that these
ponds would differ in soil characteristics, which may also explain differences in the composition of their macroinvertebrate,
amphibian, and aquatic plant species assemblages. The study ponds were significantly segregated into southern and northern
geomorphological areas based on the depth to the water table. The results of the multivariate ordination of soil variables were
consistent with a north-south segregation, which was explained by the carbonate and other main ion concentrations in the
pond basins. The ponds located in ecotones (marsh-sand and stable-mobile dunes) were particularly rich in amphibians and
macroinvertebrates. This result may be explained because the ponds with the longest permanence of water were located in
these areas, which represented the only flooded ponds during droughts. In addition, they also contained a high number of
temporary ponds, thus favouring connectivity and environmental heterogeneity in these areas
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