Search Results (164)

The European catfish (Silurus glanis Linnaeus, 1758) was introduced into the Ebro Basin in Spain in 1974 for recreational fishing. Since then, the species has spread throughout the country’s river basins, reaching the Iznájar Reservoir (Guadalquivir River Basin) in 2011. This area is of great ecological and economic relevance, especially as it includes the Doñana National Park, one of the most important nature reserves in Europe. Recently, the presence of catfish has been reported in the lower reaches of the river. In this work, we used non-invasive vertical and horizontal hydroacoustic surveys and environmental DNA river sampling to unravel the actual distribution and dispersal pattern of the species in the lower Guadalquivir River. The hydroacoustic profiles and the species-specific detections by real-time PCR (qPCR) and droplet digital PCR (ddPCR) showed that these non-invasive methods allow the detection and quantification of catfish and provide valuable information on the species’ presence. We have confirmed the presence of catfish in most of the study area, including downstream areas of the Guadalquivir Basin. The results suggest the possibility of other isolated introductions and/or human-mediated movements of specimens, and imply that a coordinated catfish prevention and mitigation strategy is therefore urgently needed. Full article

Data on the interactions between the order Psittaciformes and the anthropogenic environment are still insufficient and have not been systematized, especially in the Neotropical region. As a consequence of this coexistence, the volume of accumulated knowledge is probably significantly greater than the formal scientific contributions on the subject. In this survey, information was compiled on the wild parrots inhabiting cities in the Southern Cone of South America, based on surveys with key informants. The results obtained highlighted the presence of a large number of parrot species that form part of the urban avifauna of the region, between 67% and 90% of the total number of species of the order cited for each territory evaluated. The greatest species richness and the number of breeding species were associated with the large cities located in middle and low latitudes. We confirmed breeding within the cities for more than 40% of the species mentioned. Seventy-five percent of the species reported are native to the study area, the rest originating from other regions of South America or other continents. A quarter of the reported species are considered threatened and almost 50% have declining populations. Urban parrots represent a challenge in the search for urban models compatible with biodiversity conservation, and in the designing of innovative conservation strategies that respond to the new challenges posed by a constantly growing human population. Full article

Reliable soil moisture information is essential for accurate irrigation scheduling. A wide range of soil moisture sensors are currently available on the market, but their performance needs to be evaluated as most sensors are calibrated under limited laboratory conditions. The aim of this study was to evaluate the performance of six commercially available moisture sensors (HydraProbe, Teros 10, Teros 11, EnviroPro, CS616 and Drill & Drop) and three tensiometers (Irrometer RSU-C-34, Teros 32 and Teros 21) and to establish calibration equations for a typical sandy soil of the Doñana National Park (Huelva, Spain). The calibration process for soil moisture sensors indicated differences between factory and corrected equations. All tested sensors improved with adjustments made to the factory calibration, except for the HydraProbe sensor which had a more accurate factory equation for a sandy soil. Among the various sensors tested, the Teros 10, Teros 11, and HydraProbe were found to be the easiest to install, typically positioned with an auger to prevent preferential pathways and ensure adequate sensor-soil contact. For tensiometers, the Teros 32 sensor requires specialized labor for its correct installation, as it must be positioned at a specific angle and maintained with distilled water. All tensiometers need a stabilization period after installation. Full article

Decision trees are a widely used machine learning technique due to their ease of interpretation and construction. This method allows domain experts to learn from raw data, but they cannot include their prior knowledge in the analysis due to its automatic nature, which implies minimal human intervention in its computation. Conversely, interactive visualization methods have proven to be effective in gaining insights from data, as they incorporate the researcher’s criteria into the analysis process. In an effort to combine both methodologies, we have developed a tool to manually build decision trees according to subsequent visualizations of data mapping after applying linear discriminant analysis in combination with Star Coordinates in order to analyze the importance of each feature in the separation. The nodes’ information contains data about the features that can be used to split and their cut-off values, in order to select them in a guided manner. In this way, it is possible to produce simpler and more expertly driven decision trees than those obtained by automatic methods. The resulting decision trees reduces the tree size compared to those generated by automatic machine learning algorithms, obtaining a similar accuracy and therefore improving their understanding. The tool developed and presented here to manually create decision trees in a guided manner based on the subsequent visualizations of the data mapping facilitates the use of this method in real-world applications. The usefulness of this tool is demonstrated through a case study with a complex dataset used for motion recognition, where domain experts built their own decision trees by applying their prior knowledge and the visualizations provided by the tool in node construction. The resulting trees are more comprehensible and explainable, offering valuable insights into the data and confirming the relevance of upper body features and hand movements for motion recognition. Full article

Heat shock proteins (HSPs) are essential to cellular protection against heat stress. However, the causes of inter-individual variation in HSP regulation remain unclear. This study aimed to test the impact of early-life conditions on the HSP response to heat in zebra finches. In this arid-adapted bird, incubating parents emit “heat-calls” at high temperatures, which adaptively alter offspring’s phenotypes. Embryos were exposed to heat-calls or control-calls, and at 13 days post-hatch nestlings were separated into two different experiments to test responses to either chronic nest temperature (“in-nest” experiment) or an acute “heat-challenge”. Blood samples were collected to measure levels of heat shock cognate 70, heat shock protein 90α, corticosterone and the heterophil-to-lymphocyte (H/L) ratio. In the in-nest experiment, both HSPs were upregulated in response to increasing nest temperatures only in control-calls nestlings (HSC70: p = 0.010, HSP90α: p = 0.050), which also had a marginally higher H/L ratio overall than heat-call birds (p = 0.066). These results point to a higher heat sensitivity in control-call nestlings. Furthermore, comparing across experiments, only the H/L ratio differed, being higher in heat-challenged than in in-nest nestlings (p = 0.009). Overall, this study shows for the first time that a prenatal acoustic signal of heat affects the nestling HSP response to postnatal temperature. Full article

Doñana (southern Spain), a region of notable biodiversity richness, is highly threatened by ongoing landscape transformation and climate change. We investigated the local effect of these anthropogenic factors on the temporal range dynamics of Lataste’s viper (Vipera latastei), an Iberian endemic Mediterranean reptile that has apparently become rare over the years in Doñana. Using ecological niche-based models, based on climatic and remote sensing variables, we analyzed historical (1959–1999) and contemporary (2000–2022) records of the species to assess range shifts and identify environmental factors that may influence them. Our results show that V. latastei is mostly restricted to the coastal region of Doñana and that one temperature variable is the most important factor explaining this distribution pattern in both periods. Additional climatic and vegetation variables play a role in its historical distribution, but they become less important in contemporary times, suggesting a niche simplification over time. We found 30.5% of reduction in the species suitable area from historical to contemporary conditions, a reduction that would be even greater (83.37%) in the absence of niche shift. These findings underscore the species’ heightened vulnerability to ongoing environmental changes and highlight the urgent need for targeted conservation strategies. Full article

Prescribed burns have recently become a widespread environmental management practice for biodiversity restoration to reduce fuel load, to provide forest fire suppression operational opportunities, to favor plant recruitment or to manage wild species. Prescribed fires were again applied in Doñana National Park (southern Spain) after decades of non-intervention regarding fire use. Here, we assessed their impacts on the soil CO₂ effluxes over two years after burning to test the hypothesis that if the ecosystem is resilient, soil respiration will have a rapid recovery to the conditions previous to the fire. Using soil automated CO₂ flux chambers to continuously measure respiration in burned and unburned sites, we showed that soil respiration varies among seasons but only showed significant differences between burned and unburned plots in the fall season one year after fire, which corresponded with the end of the dry season. Comparing soil respiration values from the burned plots in the three fall seasons studied, soil respiration increased significantly in the fall one year after fire, but decreased in the following fall to the values of the control plots. This study highlights the resilience of soil respiration after prescribed fire, showing the potential benefits of prescribed fire to reduce catastrophic wildfires, especially in protected areas subjected to non-intervention. Full article

Internal transport (endozoochory) and external transport (epizoochory) by migratory waterbirds are key mechanisms of long-distance dispersal for seeds and other diaspores of plants lacking a fleshy fruit. Beginning with Darwin in 1859, we review how opinions about the relative importance of epizoochory and endozoochory have changed repeatedly over time and how this allows us to reassess our modern understanding of plant dispersal. Darwin was mistaken in asserting that diaspores cannot survive passage through the gut of waterbirds or other granivorous birds. This “digestion myth” led him to underestimate endozoochory and overstate the importance of epizoochory, an approach which is echoed throughout the literature until the present day. Darwin also focused on aquatic plants, yet it is now clear that waterbirds are also major vectors of terrestrial plants. Based on their empirical observations and experiments, other less influential scientists (notably Hesselman in 1897, Guppy in 1906 and Proctor in the 1960s) argued that endozoochory is the more important mechanism for waterbirds. Modern field and experimental studies demonstrate the dominant role for endozoochory. Unfortunately, avian endozoochory of dry-fruited plants continues to be ignored as a dispersal mechanism by many plant ecologists, which we attribute to Darwin’s continuing influence. However, this endozoochory has major implications for plant biogeography and requires wider recognition and research. Full article

The Doñana Protected Area, Western Europe’s largest protected wetland and UNESCO World Heritage Site, is of great importance for the Spanish biodiversity. Despite its ecological value, there is a noticeable scarcity of scientific and technical information about its hydrology and expected climate change effects, as highlighted by several authors. This article reviews the existing research on the Guadalquivir River and Doñana National Park, examining the interplay between hydrodynamics, climate change scenarios, and the potential impact of the removal of the current dike which was built to limit tidal flooding. In this context, the hydrodynamic changes predicted by a hydrodynamic model were examined under both present (including the current mean sea level and the presence of the dike) and predicted future conditions (encompassing a mean sea level rise of 0.84 m and the removal of the dike). These hydrodynamic changes were assessed in terms of the maximum predicted water levels, mean velocity, amplitude, and phase of M₂ and M₄ tidal constituents, tidal asymmetry, and tidal prims. The results reveal that the removal of the dike and a sea level rise will have a significant impact on the protected area, resulting in the complete flooding of the Doñana national marshes during spring tides. Such changes could have negative impacts, as increased environmental alterations would require more demanding adaptation measures. Full article

Restored wetlands should be closely monitored to fully evaluate the effectiveness of restoration efforts. However, regular post-restoration monitoring can be time-consuming and expensive, and is often absent or inadequate. Satellite and airborne remote sensing systems have proven to be cost-effective tools in many fields, but they have not been widely used to monitor ecological restoration. This study assessed the potential of airborne hyperspectral remote sensing to monitor water mass characteristics of experimental temporary ponds in the Mediterranean region. These ponds were created during marsh restoration in Doñana National Park (south-west Spain). We used hyperspectral images acquired by the CASI-1500 hyperspectral airborne sensor to estimate and map water depth, turbidity and chlorophyll a in a subset of the 96 new ponds. The high spatial and spectral resolution of the CASI sensor allowed us to detect differences between ponds in water depth, turbidity and chlorophyll a, providing accurate mapping of these three variables, and a useful method to assess restoration success. High levels of spatial variation were recorded between different ponds, which likely generates high diversity in the animal and plant species that they contain. These results highlight the great potential of hyperspectral sensors for the long-term monitoring of wetland complexes in the Mediterranean region and elsewhere. Full article

Buttonweed (Cotula coronopifolia) is native to South Africa but invasive in wetlands in Europe, North America, and Australasia, where it excludes native plants. Despite being dry-fruited, field studies suggest migratory waterbirds can disperse its seeds via gut passage (endozoochory), aiding its expansion. To explore the potential for endozoochory in different regions and habitats, we collected seeds from six populations in Spain, Sweden, and the UK. Germination was tested under different salinity levels (0, 5, 10, 15 g/L) and simulated gut passage treatments: scarification, acidification, or both. No germination occurred at 15 g/L. Higher salinity reduced and delayed germination, but full gut passage treatment (i.e., both scarification and acidification) increased germinability and accelerated germination. Scarification or acid treatment alone resulted in intermediate germination patterns. There were significant salinity × population and gut passage × population interactions on germinability. The acceleration effect of gut passage on germination was stronger at 5–10 g/L than at 0 g/L. This study highlights how migratory birds can facilitate the spread of alien plants introduced by humans. Endozoochory by waterbirds is an understudied mechanism for the long-distance dispersal of dry-fruited alien plants. Further research on C. coronopifolia, including population genetics, is necessary to understand dispersal mechanisms and facilitate management strategies. Full article

Located in the south of the Iberian Peninsula, the Doñana salt marshes occupy around half of Doñana National Park and are currently considered among the most important wetlands worldwide due to the importance of their ecosystem. In this research work, using a novel patented procedure, the effects of climate change on the study area between 2009 and 2020 were evaluated. For this reason, DEMs were downloaded from the 30-meter Shuttle Radar Topography Mission (SRTM). Furthermore, to check the depth of the flooded area, 792 satellite images (L5 TM, L7 ETM+, and L8 OLI) with a resolution of 30 m were analyzed. The results show how the combined use of geomatic techniques, such as radar, optical, and geographic information system (GIS) data, along with regression models and iterative processes, plays a key role in the prediction and analysis of the flooded area volume in the Doñana salt marshes. Another significant contribution of this work is the development of a new remote sensing index. In conclusion, given that the study area depends on its aquifers’ status, it would be advisable to implement policies aimed at eradicating illegal aquifer extraction, as well as recovery plans to avoid the complete clogging of this salt marsh. Full article

The Asian tiger mosquito (Aedes albopictus) is an invasive mosquito species with a global distribution. This species has populations established in most continents, being considered one of the 100 most dangerous invasive species. Invasions of mosquitoes such as Ae. albopictus could facilitate local transmission of pathogens, impacting the epidemiology of some mosquito-borne diseases. Aedes albopictus is a vector of several pathogens affecting humans, including viruses such as dengue virus, Zika virus and Chikungunya virus, as well as parasites such as Dirofilaria. However, information about its competence for the transmission of parasites affecting wildlife, such as avian malaria parasites, is limited. In this literature review, we aim to explore the current knowledge about the relationships between Ae. albopictus and avian Plasmodium to understand the role of this mosquito species in avian malaria transmission. The prevalence of avian Plasmodium in field-collected Ae. albopictus is generally low, although studies have been conducted in a small proportion of the affected countries. In addition, the competence of Ae. albopictus for the transmission of avian malaria parasites has been only proved for certain Plasmodium morphospecies under laboratory conditions. Therefore, Ae. albopictus may play a minor role in avian Plasmodium transmission in the wild, likely due to its mammal-biased blood-feeding pattern and its reduced competence for the development of different avian Plasmodium. However, further studies considering other avian Plasmodium species and lineages circulating under natural conditions should be carried out to properly assess the vectorial role of Ae. albopictus for the Plasmodium species naturally circulating in its distribution range. Full article

Doñana National Park is located in the southwest of the Iberian Peninsula, where water scarcity is recurrent, together with a high heterogeneity in species and ecosystems. Monitoring carbon assimilation is essential to improve knowledge of global change in natural vegetation cover. In this work, a light use efficiency (LUE) model was applied to estimate gross primary production (GPP) in two ecosystems of Doñana, xeric shrub (drought resistant) and seasonal marsh (with grasslands dependent on water hydroperiod) and validated with in situ data from eddy covariance (EC) towers installed in both ecosystems. The model was applied in two ways: (1) using the fraction of absorbed photosynthetically active radiation (FAPAR) from Sentinel-2 and meteorological data from reanalysis (ERA5), and (2) using Sentinel-2 FAPAR, reanalysis solar radiation (ERA5) and the Sentinel-2 land surface water index (LSWI). In both cases and for both ecosystems, the error values are acceptable (below 1 gC/m²) and in both ecosystems the model using the LSWI gave better results (R² of 0.8 in marshes and 0.51 in xeric shrubs). The results also show a greater influence of the water status of the system than of the meteorological variables in this area. Full article

Bird feathers have several functions, including flight, insulation, communication, and camouflage. Since feathers degrade over time, birds need to moult regularly to maintain these functions. However, environmental factors like food scarcity, stress, and parasite infections can affect feather quality and moult speed. This study examined the impact of avian haemosporidian infection and uropygial gland volume, as well as feather quality and feather growth rate in two migratory hirundine species captured in southwestern Spain—the house martin (Delichon urbicum) and sand martin (Riparia riparia). Our findings showed that the prevalence of infection varied among species, with house martins having the highest rates, possibly due to their larger colony size. Moreover, haemosporidian infection had a different impact on each species; infected house martins exhibited lower feather quality than healthy individuals, although this outcome was not observed in sand martins. Furthermore, no effect of infection on feather growth rate was observed in both hirundinids. Additionally, feather growth rate only correlated positively with feather quality in house martins. Finally, no link was observed between uropygial gland volume and feather quality or feather growth rate in any of the species in this study. These findings highlight the effect of haemosporidian infections on the plumage of migratory birds, marking, for the first time, how avian haemosporidian infection is shown to adversely impact feather quality. Even so, further research is needed to explore these relationships more deeply. Full article