SE Spain Research Articles

Eocene Stratigraphic Sequences in the Prebetic of Alicante (SE Spain) and Their Correlation with Global Sea-Level and Climatic Curves

The Onil and Ibi sections (Prebetic Zone, Betic Cordillera: Alicante, SE Spain) record a late Ypresian (Cuisian) to early Lutetian (~51 to ~43 Myr) carbonate platform succession, dated using larger benthic foraminifera (LBF) and planktonic foraminifera. Seven field lithofacies (L1 to L7) and five thin-section microfacies (Mf1–Mf5) were identified, indicating inner- to mid-ramp environments (from seagrass meadows to Maërl-LBF-dominated) in warm-water and low-latitude conditions. A distinctive feature of these platforms is their dominance by LBF in association with rhodophyceae, contrasting with typical coral reef factories. We propose a novel carbonate production model, “TC-factory”, to describe these warm-temperate systems. Integrated field logging, drone imagery, and microfacies data allowed us to define a sequence stratigraphic framework comprising five lower-frequency sequences (LFS: ~2 Myr average duration), each of them nesting various numbers of high-frequency sequences (HFS: ~0.25 to ~1 Myr). The LFSs belong to a higher-rank sequence bounded by regional unconformities. The five LFSs only broadly match the upper Ypresian and lower Lutetian cycles in global eustatic curves (~51 to ~43 Myr), indicating that other regional or local controls were important. The number of HFSs being fewer than expected also suggests additional controls, such as local tectonics, erosion during lowstands, or carbonate production feedback.

Temporal Changes in Fishing Yields, Trophic Dynamics, and Fisheries in Three Mediterranean Lagoons: Logarou and Rodia-Tsoukalio (Greece) and Mar Menor (Spain)

This study analyzes 1980–2020 landings data from three Mediterranean coastal lagoons—the Logarou and Rodia-Tsoukalio Lagoons (NW Greece) and the Mar Menor Lagoon (SE Spain)—to assess ecosystem changes and fishing pressure dynamics. The findings classify these systems as low-yielding, with productivity ranked as follows: Yield Logarou > Yield Rodia-Tsoukalio = Yield Mar Menor. Mean trophic level analysis (mTrL) revealed significant differences driven by the contribution of detritivorous and mid-level carnivorous species (TrL Mar Menor > TrL Rodia-Tsoukalio > TrL Logarou). The fishing pressure indices suggest reduced fishing intensity in the Greek lagoons, while in Mar Menor, a stable Fisheries in Balance (FiB) trend corresponded with stable yields despite eutrophication. Cluster analysis (CA) and principal component analysis (PCA) linked ecosystem differences to sediment characteristics and changes in habitat structure. These results underscore a transition of Mediterranean coastal lagoons toward new ecological states, highlighting the urgent need for habitat conservation and adaptive management strategies to ensure sustainable fisheries under increasing environmental pressures. These findings may be extrapolated to similar transitional coastal ecosystems facing comparable anthropogenic stressors worldwide, providing a broader framework for understanding and managing lagoon systems under changing environmental conditions.

Persistent metal and metalloid fluxes to the seafloor from an underlying mine tailings deposit 25years after disposal off Portmán Bay (SE Spain).

Persistent metal and metalloid fluxes to the seafloor from an underlying mine tailings deposit 25years after disposal off Portmán Bay (SE Spain).

Characterization and potential causes of a whiting event in the Mar Menor coastal lagoon (Mediterranean, SE Spain).

Characterization and potential causes of a whiting event in the Mar Menor coastal lagoon (Mediterranean, SE Spain).

Detecting Flooded Areas Using Sentinel-1 SAR Imagery

Floods are a major threat to human life and economic assets. Monitoring these events is therefore essential to quantify and minimize such losses. Remote sensing has been used to extract flooded areas, with SAR imagery being particularly useful as it is independent of weather conditions. This approach is more difficult when detecting flooded areas in semi-arid environments, without a reference permanent water body, than when monitoring the water level rise of permanent rivers or lakes. In this study, Random Forest is used to estimate flooded cells after 19 events in Campo de Cartagena, an agricultural area in SE Spain. Sentinel-1 SAR metrics are used as predictors and irrigation ponds as training areas. To minimize false positives, the pre- and post-event results are compared and only those pixels with a probability of water increase are considered as flooded areas. The ability of the RF model to detect water surfaces is demonstrated (mean accuracy = 0.941, standard deviation = 0.048) along the 19 events. Validating using optical imagery (Sentinel-2 MSI) reduces accuracy to 0.642. This form of validation can only be applied to a single event using a S2 image taken 3 days before the S1 image. A large number of false negatives is then expected. A procedure developed to correct for this error gives an accuracy of 0.886 for this single event. Another form of indirect validation consists in relating the area flooded in each event to the amount of rainfall recorded. An RF regression model using both rainfall metrics and season of the year gives a correlation coefficient of 0.451 and RMSE = 979 ha using LOO-CV. This result shows a clear relationship between flooded areas and rainfall metrics.

Beyond urban boundaries: the invasive ant Wasmannia auropunctata (Roger, 1863) (Hymenoptera, Formicidae) now reaching Iberian coastal habitats

The little fire ant (Wasmannia auropunctata), notable for its minute size and painful sting, has emerged as a significant threat in Mediterranean Europe. This widespread exotic species is well-known because of its invasive nature, impacting biodiversity, public health, and economic activities. Noted for the first time in Málaga (S Spain) in 2018, it has since expanded to other locations in the same province. Here we report the presence of W. auropunctata in La Marina (Alacant province, SE Spain), representing the fifth recorded population on the Iberian Peninsula and the first occurrence outside Málaga province. The species was found infesting a coastal area of approximately 5.1 hectares, with workers being observed in foraging trails across multiple surfaces and living in dense concentrations both indoors and outdoors. Exclusion of native ant species within the occupied area and direct engagement in combat with other species was observed. The population was discovered in September 2024; however, based on infestation density, spatial extent, and comparison with data of other Mediterranean exotic populations, the species likely established in the region prior to 2019. For the first time in Iberia, W. auropunctata was also detected in the coastal dunes adjacent to the infested urbanised area, highlighting its potential adaptability to dry Mediterranean habitats. The resilience of W. auropunctata, combined with its aggressive invasive traits and propensity to sting, underscores the urgent need for integrated management strategies to limit further expansion of the species in Iberia.

Estimation of soil properties using machine learning techniques to improve hydrological modeling in a semiarid environment: Campo de Cartagena (Spain)

Soils are a key element in the hydrological cycle through a number of soil properties that are complex to estimate and exhibit considerable spatial variability. Therefore, several techniques have been proposed for their estimation and mapping from point data along a given study area. In this work, four machine learning methods: Random Forest, Support Vector Machines, XGBoost and Multilayer Perceptrons, are used to predict and map the proportions of organic carbon, clay, silt and sand in the soils of the Campo de Cartagena (SE Spain). These models depend on a number of hyperparameters that need to be optimised to maximise accuracy, although this process can lead to overtraining, which affects the generalisability of the models. In this work it was found that neural networks gave the best results in validation, but on the test data the methods based on decision trees, random forest and xgboost were more accurate, although the differences were generally not significant. Accuracy values, as usual for soil variables, were not high. The RMSE values were 8.040 for SOC, 7.049 for clay, 10.227 for silt and 13.561 for loam. The layers obtained were then used to obtain annual curve number layers whose ability to reproduce runoff hydrographs was compared with the official CN layer. For high flow events, the CN layers obtained in this study gave better results (NSE=0.807, PBIAS=-4.7 and RMSE=0.4) than the official CN layers (NSE=-2.28, PBIAS=135.82 and RMSE=1.8).

Temporal dynamics of a trace fossil rocky coast assemblage: Insights into the development of a Middle Miocene transgressive episode (SE Spain)

A study of a Middle Miocene series (lower Langhian–Serravalian) in the El Bellical Basin (Almería) has revealed evidence of an ancient rocky coastline. This conclusion is supported by the discover of bioerosive structures on numerous boulders and pebbles from various conglomeratic beds. Four distinct ichnogenera have been identified: Entobia, Gastrochaenolites, Caulostrepsis, and Maeandropolydora, encompassing a total of eleven ichnospecies. These bioerosive structures were formed by clionaid sponges, lithophagous bivalves, and polychaete or spionid annelids, indicating they belong to the Entobia ichnofacies, typical of shallow, high-energy marine environments. A typical colonisation sequence was identified, beginning with clionaid sponges, followed by lithophagous bivalves, and then annelids, either contemporaneously or shortly thereafter. Additionally, some instances showed encrusting epilithozoan organisms. The conglomerate deposits further suggest the accumulation of large boulders and pebbles at the base of cliffs or as part of extensive, shallow, high-energy littoral environments with low sedimentation rates and abundant suspended nutrients. This evidence points to the existence of an ancient shoreline during the Lower Langhian–Serravalian (Middle Miocene) in this region, linked to the Mediterranean Neogene basins formed by the uplift of the Betic Cordillera and related to the extensional tectonic of this area.

Salt expulsion triggered by prograding clinoforms in the SW Valencia Trough (SE Spain)

Salt expulsion triggered by prograding clinoforms in the SW Valencia Trough (SE Spain)

Identifying surviving Pinna nobilis after the Mass Mortality Event (MME) in the Mediterranean: Proposal of a low-risk methodology for collecting genetic samples.

Identifying surviving Pinna nobilis after the Mass Mortality Event (MME) in the Mediterranean: Proposal of a low-risk methodology for collecting genetic samples.

Synthesis and Characterization of Na-X Zeolite Using a Natural Opaline Diatomite Rock from SE Spain

Synthesis and Characterization of Na-X Zeolite Using a Natural Opaline Diatomite Rock from SE Spain

Eocene Gravity Flows in the Internal Prebetic (Betic Cordillera, SE Spain): A Vestige of an Ilerdian Lost Carbonate Platform in the South Iberian Margin

In the Betic-Rif Cordilleras, recent works have evidenced the existence of well-developed Eocene (Ypresian-Bartonian) carbonate platforms rich in Larger Benthic Foraminifera (LBF). Contrarily to other sectors of the western Tethys, like the Pyrenean domain in the North Iberian Margin, where these platforms started in the early Ypresian (Ilerdian), in the Betic-Rif chains, the recorded Eocene platforms started in the late Ypresian (Cuisian) after a widespread gap of sedimentation including the Ilerdian time span. In this work, the Aspe-Terreros Prebetic section (External Betic Zone) is studied. An Eocene succession with gravity flow deposits consisting of terrigenous and bioclastic turbidites, as well as olistostromes with olistoliths, was detected. In one of these turbidites, we dated (with the inherent limitations when dating bioclasts contained by gravity flow deposits) the middle Ilerdian, on the basis of LBF, representing a vestige of a missing Illerdian carbonate platform. The microfacies of these turbidites and olistoliths rich in LBF have been described and documented in detail. The gap in the sedimentary record and absence of Ilerdian platforms in the Betic-Rif Cordillera have been related to the so-called Eo-Alpine tectonics (Cretaceous to Paleogene) and sea-level variations contemporarily with the establishment of shallow marine realms in the margins of the western Tethys.

The offshore Alicante Basin: late Neogene basin development at the Internal–External Zone Boundary of the eastern Betics, SE Spain

The offshore Alicante Basin: late Neogene basin development at the Internal–External Zone Boundary of the eastern Betics, SE Spain

Effect of runoff water supply on vegetation and soil response to increasing aridity in Mediterranean drylands

Effect of runoff water supply on vegetation and soil response to increasing aridity in Mediterranean drylands

Paleoenvironmental conditions and evolution of a muddy turbidite system: an integrated sedimentological and ichnological analysis

Abstract Recent advances in characterization of turbidite-fans have been achieved through various methodologies, including flume-tank experiments, numerical modeling, seismic analysis, and integrated core and outcrop studies. Ichnology has proven valuable for understanding turbidite systems by providing insights into paleoenvironmental conditions such as oxygen levels, nutrient availability, hydrodynamic energy, and sedimentation rates. Since the 1960s, the Nereites ichnofacies has been linked to flysch deposits, characterized by features such as graphoglyptids, shallow-tier ichnotaxa, complex grazing trails, and diverse, but low density, trace fossils. The aim of this study is to combine ichnological and sedimentological data to improve recognition of subenvironments in turbidite systems. Analysis of five sections in a late Miocene, muddy turbidite system in the Tabernas Basin (SE Spain) shows that: 1) the distal fan lobes are characterized by a high diversity and abundance of predepositional trace fossils linked to the Paleodictyon ichnosubfacies, indicating stable and oligotrophic conditions, and 2) the proximal fan lobes by a low diversity and abundance of postdepositional trace fossils with abundant Ophiomorpha rudis ichnosubfacies in areas close to the feeder channel.

The Transport of Sediments from the Cartagena-La Unión Mining District Leads to the Incorporation of Metal(loid)s into the Marine Environment

Extraction activities can have a significant impact on the environment due to the mobilization of trace elements. These elements can pose a risk to soils, biota, water, and human health when incorporated into nearby ecosystems. To evaluate the transfer of As, Cd, Pb, and Zn from mine areas to the marine environment, a study was conducted in the Cartagena-La Union mining district (SE Spain). The study area included the mouth of a stream affected by waste materials from tailing ponds. In addition, a maritime area without mining influence was selected as a control site. Sediment samples were collected (three transects with nine sampling points and three depths) at the El Gorguel shoreline, and analyzed for pH, electrical conductivity, total metal(loid)s content, water-soluble anions, and metal(loid)s in chemical fraction distribution. Water and biota samples (Paracentrotus lividus, Patella vulgata, Hexaplex trunculus, Anemonia viridis, and Trachinotus ovatus) were also collected for metal(loid) content analysis. The results showed that the metal(loid)s concentration in the sediment increased compared to the control site, which was not influenced by mining activities. The chemical composition of metal(loid)s in the sediments revealed that Cd is the most hazardous element due to its high concentration in the labile fractions (20%), suggesting easy transfer to the marine environment. However, transfer mechanisms should be studied in various scenarios with different climatic, wave, and tidal conditions. Marine biota metal(loid)s concentrations showed an increase in specimens collected under the influence of mining activities but without exceeding limits that would affect incorporation into the trophic chain. Consequently, bioaccumulation and biomagnification processes must be considered in a future biomonitoring program.

Captive-introduced tortoises in wild populations: can we identify them by shell morphology?

Direct exploitation and wildlife trade pose significant threats to global biodiversity, particularly impacting reptiles, such as tortoises, which are highly vulnerable. Moreover, the releases of captive-held animals into the wild can lead to potential negative consequences, including genetic introgression, disease transmission, and parasite spread. Therefore, diagnostic assessments are essential to evaluate the impact of release practices. In this study, we analyzed the shell morphology of Testudo graeca tortoises to assess the effectiveness of morphological analysis in identifying captive-introduced tortoises and quantifying tortoise releases in SE Spain. Despite being illegal, the cultural tradition of keeping and breeding tortoises at home persists in this region. Principal component analyses identified significant morphological differences between captive and wild tortoises. Captive tortoises generally exhibited larger shell sizes and greater morphological variability compared to wild tortoises. Accordingly, linear discriminant analyses accurately identified approximately 99% of wild tortoises, but the identification of captive tortoises was only 50% accurate because some captive tortoises show shell morphologies identical to wild ones. These results likely reflect the diverse origins and growth conditions of captive tortoises. Although this is likely an underestimation, our approach classified 7% of 125 wildlife tortoises across 13 natural sites such as captive-introduced tortoises. These findings highlight the potential impact of tortoise releases in wild populations and underscore the value of morphological analyses as an initial tool for diagnosing such impacts. Furthermore, integrating genetic and isotopic methods could further enhance the precision of these assessments.

Foraging strategies, prey selection and size- and microhabitat-related diet variation in Buthus montanus (Scorpiones: Buthidae) in an arid area of SE Spain

Foraging strategies, prey selection and size- and microhabitat-related diet variation in Buthus montanus (Scorpiones: Buthidae) in an arid area of SE Spain

Drought affects biocrust more than increased rainfall in the Tabernas Desert (SE Spain)

Abstract Composed of poikilohydric organisms, biocrusts have the ability to survive during periods of drought, making them particularly important in arid and semi-arid areas. However, despite recent research into climate change, the limits of this tolerance to desiccation and the effects of increased water availability, are not very well known. Our objectives were to analyze the effect of prolonged droughts on the cover and metabolism of various crust types, as well as the effect of increased precipitation. Five types of crusts representative of hypothetic successional stages were studied (Physical, Incipient, Cyanobacteria, Squamarina and Lepraria). Two representative areas were selected for each crust type. Nine plots were established in each area, delimited by a 10-cm-diameter ring, and distributed in sets of three plots. In each set, three treatments were applied (control, watering and rain exclusion), and changes in cover, CO2 fluxes and chlorophyll a fluorescence were analyzed. Rain exclusion led to cover losses due to respiration, although this effect differed among successional stages. However, increased precipitation did not increase biocrust cover, because both photosynthesis and respiration rates increased. Chlorophyll a fluorescence was higher in lichens; under watering, it was not different from the control but decreased under rain exclusion.

Underlying Causes of Long-Term Environmental Pollution by Waste from an Abandoned Metal Mining District: When Legislative and Remediation Measures Are Ineffective

Since ancient times, mining activities have been recognised as having a strong environmental impact. Due to the extraordinary amount of waste and impacts on the landscape, environmental concerns caused by mining can be found worldwide. The risks associated with mining waste are of great concern, especially when these residues come from metal mining and its associated potentially toxic elements that can be released into the environment. The reality of many of these metal mining areas is that, despite the extensive regulatory frameworks and remediation techniques applied, they continue to have high levels of contamination, posing a source of environmental and public health risk to their surroundings. The issues underlying this situation are details that can only be detected by experience in the management and thorough knowledge of the dynamics of these tailings in the long term. And in many cases, the key is in the details. For this purpose, the case of the former metal mining district of Cartagena-La Unión (SE Spain), one of the most affected areas in the European continent by these metal mining wastes, has been analyzed. In conclusion, it has been shown that the legal status of these waste and mining operations and the lack of control and effectiveness of rehabilitation activities are behind the worrying environmental situation of these areas. The interaction between the legal framework and the environmental and technical knowledge of these tailings and mining areas reveals practical issues beyond the scope of general analysis. This case study, conducted in the main Spanish metal mining area, concerns waste volume, and its findings offer the potential to improve the safety and environmental quality of metal mining regions elsewhere.