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The Balearic Archipelago (western Mediterranean) is an area of great ecological interest due to the combination of complex geomorphology, highly oligotrophic waters and low fishing pressure. Sponges play a key role in benthic habitats, providing structural complexity and significantly contributing to their diversity and biomass. Here, we present an insight into the sponge communities of this archipelago from the analysis of samples collected during several scientific research surveys carried out on bottom trawl fishing grounds around the Balearic Islands and on sedimentary and rocky bottoms of the Mallorca Channel seamounts. Sampling was carried out with experimental bottom trawl, beam trawl, rock dredge and remotely operated vehicle (ROV). We analyzed species presence/absence data using multivariate methods in order to identify assemblages. Once identified, we characterized their biodiversity, biomass and taxonomic composition. A dbRDA analysis was conducted to test the influence of environmental variables and fishing pressure on the sponge communities. Up to 350 species are reported: 220 at bottom trawl fishing grounds and 189 at seamounts. Communities were structured by depth, temperature, currents, substrate and fishing pressure with sponge presence/absense, biomass and diversity also linked to the presence of deep algae beds. Taxonomic composition differed between bottom trawl fishing grounds and the seamounts, where this fishing activity is almost negligible, pointing to different sensitivity to this fishing impact among the different orders, particularly for Tetractinellida, which was much more diverse and abundant at seamounts.

Flamenco, recognized by UNESCO as part of the Intangible Cultural Heritage of Humanity, is a profound expression of cultural identity rooted in Andalusia, Spain. However, there is a lack of quantitative studies that help identify characteristic patterns in this long-lived music tradition. In this work, we present a computational analysis of Flamenco lyrics, employing natural language processing and machine learning to categorize over 2000 lyrics into their respective Flamenco genres, termed as $\textit{palos}$. Using a Multinomial Naive Bayes classifier, we find that lexical variation across styles enables to accurately identify distinct $\textit{palos}$. More importantly, from an automatic method of word usage, we obtain the semantic fields that characterize each style. Further, applying a metric that quantifies the inter-genre distance we perform a network analysis that sheds light on the relationship between Flamenco styles. Remarkably, our results suggest historical connections and $\textit{palo}$ evolutions. Overall, our work illuminates the intricate relationships and cultural significance embedded within Flamenco lyrics, complementing previous qualitative discussions with quantitative analyses and sparking new discussions on the origin and development of traditional music genres.

In this work we analyzed 18 years (2003–2021) of MODIS-Aqua daily images and multi-annual monthly mean turbidity maps to provide a comprehensive characterization of seasonal patterns of turbidity in the transitional area between the mouth of the Bahía Blanca Estuary and the adjacent inner shelf (El Rincón coastal system, Argentina). Field measurements collected in the study area were combined with MODIS data processed under different schemes of atmospheric correction before turbidity retrieval. Then, an Empirical Orthogonal function (EOF) analysis was used to assess the temporal patterns of turbidity and their regional variability over the inner shelf. Through a Generalized Linear Model (GLM), changes in the turbidity plume were further associated with environmental forcing (i.e. tides, winds and precipitation) controlling the seasonal dynamics. A strong gradient of decreasing turbidity from the northeast (close to the estuarine region) to the southwest (coastal region) was detected, while a major spatial pattern of annual variability, characterized by decreasing seasonality from northwest to southeast was defined. According to our results, the frequency of northwest wind direction and the impact of the wind mixing are considered as primary factors that shape the seasonal variability of turbidity with a strong winter dominance of largest plume events. The results found in this study are key to understanding the general dynamics of biological activity in the regional waters and the implications that climate variability might have on this complex ecosystem.

Decreasing the dependence on external inputs to crop yield maximization is one of the main objectives of agricultural breeding programs. For this reason, new crop varieties once highly dependent on pollinators have been developed to be self-fertile and are now cultivated as pollinator-independent. However, the contribution of pollinators to these varieties remains unknown. In this study, we evaluated pollinators’ contribution to two self-fertile almond varieties (Marta and Marinada) and the density of pollinators needed to ensure adequate pollination. We measured the effects of pollinators on fruit set, seed yield, and pollination limitation at the tree level. Managed honeybees and wild bumblebees were the main floral visitors in both varieties. Both fruit set and seed yield were ~ 50% higher in pollinated trees than in excluded ones in the two varieties. We found no evidence of pollination limitation, suggesting that pollinators’ abundance was sufficient for adequate pollination. We recommend that almond growers actively manage pollinators to maximize seed yield and profits in these self-fertile varieties.

Submarine Groundwater Discharge (SGD) delivers nutrients to the coastal sea triggering phytoplankton blooms, eutrophication, and can also serve as a pathway for contaminants. Wastewater treatment plants (WWTP) including injection wells in coastal areas influence coastal aquifers and might impact the composition and magnitude of SGD fluxes. In tourist areas, wastewater treatment may be less efficient and larger in volume during high seasons, potentially impacting nutrient fluxes from SGD and exacerbating environmental impacts. This study analyzes the nutrient transfer from treated wastewater injection in karstic aquifers to the coastal sea via SGD, considering the impacts of tourism seasonality. This study is conducted in Cala Deià, a small cove in the Balearic Islands, a Mediterranean tourist destination. The findings suggest that the seasonality of tourism, leading to variations in the volume of wastewater treated in the WWTP, influences the dynamics of the coastal aquifer. This leads to increased SGD water and nutrient fluxes to the sea in summer, i.e. the peak tourist season. The measured DIN, DIP, and DSi inventories in the cove are much larger in August than in April (3, 10, and 1.5 times higher, respectively) due to higher input of nutrients in summer due to SGD impacted by the WWTP. These elevated nutrient flows can support algal blooms in the cove, compromising water quality for local swimmers and tourists. Indeed, in August, shoreline stations exhibited eutrophic Chl-a concentrations, with peaks reaching approximately 4 mg Chl-a L−1. These elevated levels suggest the presence of an algal bloom during the survey. The anthropogenic origin of SGD-driven nutrients is traced in seawater and seagrass meadows, as evidenced by high ∂15N signatures indicative of polluted areas. Thus, the high pressure exerted on coastal areas by tourism activities increased the magnitude of SGD nutrient fluxes, thereby threatening coastal ecosystems and the services they provide.

Approximate numerical methods are one of the most used strategies to extract information from many-interacting-agents systems. In particular, numerical approximations are of extended use to deal with epidemic, ecological and biological models, since unbiased methods like the Gillespie algorithm can become unpractical due to high CPU time usage required. However, the use of approximations has been debated and there is no clear consensus about whether unbiased methods or biased approach is the best option. In this work, we derive scaling relations for the errors in approximations based on binomial extractions. This finding allows us to build rules to compute the optimal values of both the discretization time and number of realizations needed to compute averages with the biased method with a target precision and minimum CPU-time usage. Furthermore, we also present another rule to discern whether the unbiased method or biased approach is more efficient. Ultimately, we will show that the choice of the method should depend on the desired precision for the estimation of averages.

Automated positioning devices can generate large datasets with information on the movement of humans, animals and objects, revealing patterns of movement, hot spots and overlaps among others. However, in the case of Automated Information Systems (AIS), attached to vessels, observed strange behaviors in the tracking datasets may come from intentional manipulation of the electronic devices. Thus, the analysis of anomalies can provide valuable information on suspicious behavior. Here, we analyze anomalies of fishing vessel trajectories obtained with the Automatic Identification System. The map of silent anomalies, those that occur when positioning data are absent for more than 24 hours, shows that they are most likely to occur closer to land, with 87.1% of anomalies observed within 100 km of the coast. This behavior suggests the potential of identifying silence anomalies as a proxy for illegal activities. With the increasing availability of high-resolution positioning of vessels and the development of powerful statistical analytical tools, we provide hints on the automatic detection of illegal activities that may help optimize the management of fishing resources., With funding from the Spanish government through the ‘María de Maeztu Unit of Excelence’ accreditation (CEX2021-001201-M; CEX2021-001164-M).

Like terrestrial animals, wild fish exhibit individual differences in daily activity patterns, known as chronotypes. However, monitoring free-living fish has posed challenges in studying chronotypes and their plasticity in response to the environment. To address this issue, we utilized high-throughput telemetry to measure daily activity in a large group of free-living pearly razorfish, Xyrichtys novacula, while also monitoring fine-scale environmental variables. Using hidden Markov models for behavioural segmentation, we quantified four circadian-related traits (awakening time, rest onset, activity duration relative to the daytime and rest midpoint relative to middle of the night) during two biological contexts (prespawning and spawning). We then used linear mixed-effects models to decompose the variation of these traits into individual, ecological (contextual environment) and population components. Our findings revealed the presence of chronotypes in both sexes, with greater between-individual variation in behaviour during spawning. Males exhibited longer activity duration due to an earlier awakening time than females, and temperature, waves and light significantly influenced daily activity behaviours. However, there was considerable individual variation in response to environmental changes, indicating the emergence of behavioural reaction norms (i.e. plasticity), with females showing greater plasticity in rest onset and relative rest midpoint. Our study also identified significant correlations among traits, suggesting that the activity duration continuum defines the pearly razorfish chronotype. Overall, our work represents the most comprehensive description of individual and ecological contextual variation in chronotypes within a wild marine fish population. It underscores the importance of environmental fluctuations in shaping the expression of internal clocks.

[Aim] Intraspecific variation in species relative abundance is shaped by a complex interplay of abiotic and biotic factors, making it both necessary and challenging to assess their combined relative importance in explaining variations across space and time. We used two congeneric butterfly species for which extensive count data and a deep understanding of their natural history is available to test three hypotheses explaining intraspecific variation in their abundance: (H1) seasonal dispersal behaviour driven by climate, (H2) resource availability and (H3) apparent competition mediated via shared parasitoids., [Taxon] Gonepteryx rhamni (Brimstone) and G. cleopatra (Cleopatra)., [Location] NE Iberian Peninsula, where both species coexist, and a nearby archipelago (Balearic Islands), where only Cleopatra occurs., [Methods] We analysed spatial abundance variations for both species in the mainland and island–mainland differences in the abundance of Cleopatra. Abiotic and biotic factors, including temperature, host plant and overwintering habitat availability, larval parasitism and density dependence, were tested to explain the observed variations., [Results] H1 can explain variation in butterfly abundance between mainland regions since in warmer summers populations increased in cooler areas but decreased in warmer areas. H2 explains the variation within mainland climate regions with a strong positive relationship between resource availability and abundance but is unlikely to explain the island–mainland variation in the abundance of Cleopatra. H3 could neither explain biogeographical variation in abundance because although richer parasitoid communities were found on the mainland, larval mortality rates were similar or lower on the mainland than in the islands., [Main Conclusions] Climate and resource availability jointly account for variation in butterfly abundance across the mainland, but neither these factors nor parasitism can explain island–mainland differences. Both coexisting butterfly species and their larval parasitoids may have undergone evolutionary processes, resulting in spatial segregation that promotes the coexistence of the two butterfly species on the mainland.

Continuous gravitational-wave (CW) signals are long-lasting quasi-monochromatic gravitational-wave signals expected to be emitted by rapidly rotating non-axisymmetric neutron stars. Depending on the rotational frequency and sky location of the source, certain CW signals may behave in a similar manner to narrow-band artifacts present in ground-based interferometric detectors. Part of the detector characterization tasks in the current generation of interferometric detectors (Advanced LIGO, Advanced Virgo, and KAGRA) aim at understanding the origin of these narrow artifacts, commonly known as "spectral lines". It is expected that similar tasks will continue after the arrival of next-generation detectors (e.g., Einstein Telescope and Cosmic Explorer). Typically, a fraction of the observed lines in a given detector can be associated to one or more instrumental causes; others, however, have an unknown origin. In this work, we assess the similarity of CW signals to spectral lines in order to understand whether a CW signal may be mistaken for a noise artifact. Albeit astrophysically unlikely, our results do not rule out the possibility of a CW signal being visible in the detector’s power spectrum.

This data set includes data collected from ICMAN-CSIC (Spain), consisting of measurements of the size and number of the statoliths present in newly released Rhizostoma pulmo ephirae under conditions of oceanic warming and acidification (IPCC SSP5-8.5 scenario). From each ephyra, three of its eight statocysts were randomly selected and all the statoliths inside were counted and measured.

Cu is a vital micronutrient, but free Cu ions (Cu2+) in seawater, even at subnanomolar concentrations, can impede phytoplankton growth. Natural Cu complexation with organic ligands regulates Cu acquisition and, in most instances, reduces Cu2+ concentrations below toxic thresholds. Along the Antarctic coast, the sources and sinks of Cu and its associated ligands remain poorly defined. Despite the high productivity in the area, there are no studies on the role of trophic transfer in Cu cycling. This study explores penguin guano release of Cu and Cu ligands and its potential in neutralizing copper toxicity along the Antarctic coast. We collected guano in a Chinstrap penguin nesting location in the West coast of Deception Island and extracted its components into aqueous solution imitating natural processes. Copper concentration in guano was 0.4 mg (dry weight g)−1 constituting a potential toxic threat and showed biomagnification with respect to krill. Surface seawater samples collected from various locations varying in penguin activity, were analyzed to assess the potential influence of guano on the area. Visual examination and elevated levels of Al suggested that a substantial portion of guano was lithogenic. Consequently, only a modest 16 % of the total Cu present in guano could be extracted using mechanical methods. Notably, the concentrations of the extracted organic ligands were approximately 23 times higher than the concentrations of the extracted Cu. This significant presence of ligands effectively nullifies any potential toxicity that could have arisen from free Cu2+ ions. Guano ligands' conditional stability constants were lower than those in surface seawater suggesting phytoplankton exudation was the main ligand source in the area. Overall, guano acts as a key node for Cu cycling in coastal Antarctic waters but its deleterious potential is neutralized by ligands from krill digestion and the high background concentration of phytoplankton exudates.

This study is aimed at identifying and comparing microplastics and floating marine litter along the sea surface in the marine protected area of Cabrera Archipelago Maritime Terrestrial National Park (Cabrera MPA) in the Balearic Islands. A total of 52 net surveys and 22 visual surveys were carried out between July and August in 2019 and 2020. The abundance of microplastic (MP) items was highest in the southern and eastern regions, with an average of 381,244.4 ± 1,031,082.8 items/km2 weighing an average of 927.1 ± 2731.4 g/km2. Most of these items were < 5 mm (81%) in size and were mainly composed of polyethylene and polypropylene (98%). In terms of floating marine macro litter (ML) from visual surveys, an average of 2028 ± 2084 items/km2 were observed. In this case, the majority of the ML items were plastic pieces (69%) measuring 2.5 to 50 cm. Furthermore, ML quantified by visual surveys was an order of magnitude higher than in similar studies carried out on large vessels, highlighting the importance of vessel height and speed for identifying the smallest size fractions (81%). The results of this study document the intensity of MPs and ML, primarily plastic, in coastal waters, and provide a baseline for management efforts to mitigate floating litter, in addition to raising awareness of the transferability of marine litter from other regions.

We theoretically discuss electronic transport via Majorana states in magnetic topological insulator-superconductor junctions with an asymmetric split of the applied bias voltage. We study normal-superconductor-normal (NSN) junctions made of narrow (wire-like) or wide (film-like) magnetic topological insulator slabs with a central proximitized superconducting sector. The occurrence of charge non-conserving Andreev processes entails a nonzero conductance related to an electric current flowing to ground from the proximitized sector of the NSN junction. We show that topologically-protected Majorana modes require an antisymmetry of this conductance with respect to the point of equally split bias voltage across the junction.

[EN] Blache’s flounder, Arnoglossus blachei Stauch, 1965, is redescribed from the eastern Atlantic (Morocco south to Namibia, including the Canary Islands, larvae reaching South Africa) and distinguished from the imperial flounder A. imperialis (Rafinesque, 1810) by having a live colouration of the lower side of males which is bright red (whitish in A. imperialis), the caudal fin with lateral-line scales 52-57 (vs. 58-63), and the dorsal-fin filaments in male light grey, with black margins, distally yellowish (vs. plain white). A lectotype is selected for Arnoglossus blachei. The species is compared with similar species. The externally similar species Arnoglossus imperialis is also redescribed; its distibution range is restricted to the Mediterranean and northeastern Atlantic, including Madeira and the Azores. Neotypes are selected to stabilize the usage of the names Bothus imperialis Rafinesque, 1810, Bothus punctatus Rafinesque, 1814, Rhombus cristatus Lowe, 1839 and Charybdia rhomdoidichthys Facciolà, 1885. Molecular analyses based on two mitochondrial fragments (12s rRNA and COI) clearly support the validity of A. blachei. Moreover, though A. blachei is morphologically close to A. imperialis, the two species show the highest genetic distances among all Arnoglossus species compared (including A. capensis, A. imperialis, A. laterna, A. rueppelii and A. thori). A key to the eastern Atlantic and Mediterranean species of Arnoglossus is presented., [ES] Se vuelve a describir el pez plano de Blache’s Arnoglossus blachei Stauch, 1965 del Atlántico oriental (desde el sur de Marruecos a Namibia incluido las Islas Canarias, pudiendo sus larvas llegar a Sudáfrica), y se distingue del pez plano imperial A. imperialis (Rafinesque, 1810) por tener, en fresco, una coloración rojo brillante en la parte inferior de los machos (blanquecina en A. imperialis), la aleta caudal con escamas en la línea lateral 52-57 (vs. 58-63), y en los machos, los filamentos de la aleta dorsal son de color gris claro, con márgenes negros y en su parte distal amarillenta (vs. blanco liso). La especie se compara con especies similares. Asimismo, la especie externamente similar Arnoglossus imperialis, se vuelve a describir, cuya área de distribución está restringida al Mediterráneo y Atlántico nororiental, incluidas Madeira y Azores. Además, se seleccionan neotipos para estabilizar el uso de los nombres Bothus imperialis Rafinesque, 1810, Bothus punctatus Rafinesque, 1814, Rhombus cristatus Lowe, 1839 y Charybdia rhomdoidichthys Facciolà, 1885. Los análisis moleculares basados en dos fragmentos mitocondriales (12s rRNA y COI) respaldan claramente la validez de A. blachei. Por otra parte, a pesar de que A. blachei es morfológicamente más cercano a A. imperialis, ambas especies muestran las distancias genéticas más largas entre todas las especies de Arnoglossus comparadas (A. capensis, A. imperialis, A. laterna, A. rueppelii y A. thori). Se presenta una clave para las especies de Arnoglossus del Atlántico oriental y Mediterráneo.

Chronotypes, the individual differences in daily activity timing, have profound associations with numerous physiological processes. Despite this, the covariance between chronotypes and other aspects of an individual's behaviour has been infrequently explored in non-human animals. This study delves into individual's variation across four axes of personality in a controlled environment, utilising the pearly razorfish, a model species for fish chronotype studies. We identified behavioural types across the aggressiveness continuum and established behavioural syndromes amongst exploration, activity, and boldness, irrespective of body size and condition. Subsequent to this, the experimental subjects were reintroduced to their natural habitat and individually tracked using high-resolution technology to ascertain their chronotypes. Our results revealed that whilst the exploration-activity-boldness syndrome bore no correlation with chronotypes, a significant association was observed between aggressiveness and chronotype. Hence, individuals with later awakening times and rest onsets were more aggressive than their counterparts with earlier awakening times and rest onsets. This study provides pioneering evidence linking fish chronotypes with other behavioural traits, such as aggressiveness, suggesting that behavioural variation could be potentially linked to the individuals' variation in internal clocks and the environmental variables influencing their expression.

Quantum reservoir computing is a neuro-inspired machine learning approach harnessing the rich dynamics of quantum systems to solve temporal tasks. It has gathered attention for its suitability for NISQ devices, for easy and fast trainability, and for potential quantum advantage. Although several types of systems have been proposed as quantum reservoirs, differences arising from particle statistics have not been established yet. In this work, we assess and compare the ability of bosons, fermions, and qubits to store information from past inputs by measuring linear and nonlinear memory capacity. While, in general, the performance of the system improves with the Hilbert space size, we show that also the information spreading capability is a key factor. For the simplest reservoir Hamiltonian choice, and for each boson limited to at most one excitation, fermions provide the best reservoir due to their intrinsic nonlocal properties. On the other hand, a tailored input injection strategy allows the exploitation of the abundance of degrees of freedom of the Hilbert space for bosonic quantum reservoir computing and enhances the computational power compared to both qubits and fermions.

Cultural areas represent a useful concept that cross-fertilizes diverse fields in social sciences. Knowledge of how humans organize and relate their ideas and behavior within a society can help us to understand our actions and attitudes toward different issues. However, the selection of common traits that shape a cultural area is somewhat arbitrary. What is needed is a method that can leverage the massive amounts of data coming online, especially through social media, to identify cultural regions without ad-hoc assumptions, biases, or prejudices. This work takes a crucial step in this direction by introducing a method to infer cultural regions based on the automatic analysis of large datasets from microblogging posts. The approach presented here is based on the principle that cultural affiliation can be inferred from the topics that people discuss among themselves. Specifically, regional variations in written discourse are measured in American social media. From the frequency distributions of content words in geotagged tweets, the regional hotspots of words’ usage are found, and from there, principal components of regional variation are derived. Through a hierarchical clustering of the data in this lower-dimensional space, this method yields clear cultural areas and the topics of discussion that define them. It uncovers a manifest North–South separation, which is primarily influenced by the African American culture, and further contiguous (East–West) and non-contiguous divisions that provide a comprehensive picture of modern American cultural areas.

Twenty-three rocky shores along approximately 225 km on the southwest coast of the Bay of Biscay were sampled during the springs of 2014 and 2021, to explore changes in the distribution and abundance of four non-indigenous species (NIS) macroalgae (i.e., Asparagopsis armata, Grateloupia turuturu, Sargassum muticum, and Undaria pinnatifida) by using a semi-quantitative scale. Results showed relevant changes in the distribution and abundance of NIS. The kelp U. pinnatifida was recorded in 2021 for the first time on two shores. The distribution of G. turuturu showed an extension in its range of distribution of 200 km to the east. The other two target species S. muticum and A. armata were widely distributed along the whole 225 km of the studied area in 2014 and 2021, with higher abundance in 2021. Therefore, we strongly advise the necessity of future monitoring programs for these four NIS species. These monitoring programs will explore the progress of invasion and resilience of native species.

The strong interaction between the Brazil Current and the adjacent shelf is clearly visible in satellite-derived products (sea surface temperature, salinity, and chlorophyll-a concentration). Assessments of circulation features and cross-shelf exchanges from these products are, however, limited to the surface layer. Here we analyze the regional circulation and dynamics using the results of a suite of process-oriented, high-resolution numerical experiments. Passive tracers and Lagrangian floats characterize the exchanges between the shelf and the open ocean, identifying regions of high variability, and assessing the contribution of small-scale eddies to the cross-shelf mass exchanges. We estimate that 0.2–0.4 Sv of the shelf transport variability between 34°S and 25°S comes from ocean internal variability which represents ∼50%–70% of the total variability. Between 25°S and 21°S, internal ocean variability represents more than 90% of the shelf transport variability. We find that generation of cyclonic eddies is more frequent (>15% of the time) at the shelfbreak bights. The core of these eddies contains fresher, colder, and more nutrient-rich shelf waters. Maps of satellite chlorophyll-a concentration suggest that the horizontal and vertical exchanges of mass associated with these eddies are a critical element of the primary production cycle.

Seagrasses provide multiple ecosystem services and act as intense carbon sinks in coastal regions around the globe but are threatened by multiple anthropogenic pressures, leading to enhanced seagrass mortality that reflects in the spatial self-organization of the meadows. Spontaneous spatial vegetation patterns appear in such different ecosystems as drylands, peatlands, salt marshes, or seagrass meadows, and the mechanisms behind this phenomenon are still an open question in many cases. Here, we report on the formation of vegetation traveling pulses creating complex spatiotemporal patterns and rings in Mediterranean seagrass meadows. We show that these structures emerge due to an excitable behavior resulting from the coupled dynamics of vegetation and porewater hydrogen sulfide, toxic to seagrass, in the sediment. The resulting spatiotemporal patterns resemble those formed in other physical, chemical, and biological excitable media, but on a much larger scale. Based on theory, we derive a model that reproduces the observed seascapes and predicts the annihilation of these circular structures as they collide, a distinctive feature of excitable pulses. We show also that the patterns in field images and the empirically resolved radial profiles of vegetation density and sediment sulfide concentration across the structures are consistent with predictions from the theoretical model, which shows these structures to have diagnostic value, acting as a harbinger of the terminal state of the seagrass meadows prior to their collapse.

Wrack accumulations are a source of nutrients on sandy beaches and host invertebrate species, increasing local biodiversity. The distribution of these important accumulations varies in space and time depending on the environmental conditions and the composition of species that are in the wrack. Species composition and spatiotemporal variability in wrack accumulations remain poorly understood in some regions. In this study, we evaluated the spatiotemporal variability in wrack biomass and diversity on four sandy beaches in northern Portugal over the course of 1 year. The results revealed that both the diversity and biomass of wrack varied temporally depending on the beach and tidal level where it was collected. Wrack biomass was about 20 to 35 times greater at higher than at the low tide level and was more abundant (87%) and twice as diverse at the two northernmost beaches of the study, probably due to a greater proximity to rocky shores. Large brown temperate and boreal macroalgae species such as fucoids (Fucus spp., Cystoseira spp., and Ascophyllum nodosum) and the kelp Saccorhiza polyschides were the most abundant taxa in the wrack. Fucoids were in the wrack throughout the year, while kelps predominated in the warmer months, generating 8% more biomass than that produced by fucoids throughout the year. However, since large brown macroalgae species are reducing their size and recruitment due to global warming in the north of the Iberian Peninsula, the biomass and diversity of wrack in northern Portugal could be limited in the future, compromising crucial functions of wrack in ecosystems.

The Hunga Tonga-Hunga Ha'apai volcano eruption of January 15th 2022 generated a global atmospheric and oceanic response that was recorded by an unprecedented amount of sensors. The eruption caused an atmospheric perturbation that travelled as a Lamb wave surrounding the Earth at least 3 times, and was recorded by hundreds of barographs worldwide. The atmospheric wave showed complex patterns of amplitude and spectral energy content, although most of the energy was concentrated in the band (2-120 min). Simultaneously to each passage of the atmospheric wave and after, significant Sea Level Oscillations (SLOs) in the tsunami frequency band were recorded by tide gauges located all around the globe, in what it can be referred to as a global meteotsunami. The amplitude and dominant frequency of the recorded SLOs showed a high spatial heterogeneity. Our point is that the geometry of continental shelves and harbours acted as tuners for the surface waves generated by the atmospheric disturbance at open sea, amplifying the signal at the eigenmodes of each shelf and harbour.

The topological structure of interaction networks determines community dynamics and stability. Closeness centrality is a species-level attribute that measures the relative position and proximity of species in the interaction network. We assessed the link between closeness centrality of crops in plant-pollinator interaction networks and crop seed production. We worked with five crop species used for seed production distributed in 14 farms. At each farm we recorded pollinators’ interactions with the crop and with the co-flowering plants at crop edges and built quantitative plant-pollinator interaction networks. For each network, we calculated weighted closeness centrality of crops and related it to crop seed set by using generalized linear mixed models. Our results show that crop centrality is positively associated with crop seed production, and suggest that the use of ecological interaction network metrics in agricultural systems could be useful to design agronomic management plans and enhance crop yields.

To enrich spatio-temporal information on the distribution of alien, cryptogenic, and neonative species in the Mediterranean and the Black Sea, a collective effort by 173 marine scientists was made to provide unpublished records and make them open access to the scientific community. Through this effort, we collected and harmonized a dataset of 12,649 records. It includes 247 taxa, of which 217 are Animalia, 25 Plantae and 5 Chromista, from 23 countries surrounding the Mediterranean and the Black Sea. Chordata was the most abundant taxonomic group, followed by Arthropoda, Mollusca, and Annelida. In terms of species records, Siganus luridus, Siganus rivulatus, Saurida lessepsianus, Pterois miles, Upeneus moluccensis, Charybdis (Archias) longicollis, and Caulerpa cylindracea were the most numerous. The temporal distribution of the records ranges from 1973 to 2022, with 44% of the records in 2020–2021. Lethrinus borbonicus is reported for the first time in the Mediterranean Sea, while Pomatoschistus quagga, Caulerpa cylindracea, Grateloupia turuturu, and Misophria pallida are first records for the Black Sea; Kapraunia schneideri is recorded for the second time in the Mediterranean and for the first time in Israel; Prionospio depauperata and Pseudonereis anomala are reported for the first time from the Sea of Marmara. Many first country records are also included, namely: Amathia verticillata (Montenegro), Ampithoe valida (Italy), Antithamnion amphigeneum (Greece), Clavelina oblonga (Tunisia and Slovenia), Dendostrea cf. folium (Syria), Epinephelus fasciatus (Tunisia), Ganonema farinosum (Montenegro), Macrorhynchia philippina (Tunisia), Marenzelleria neglecta (Romania), Paratapes textilis (Tunisia), and Botrylloides diegensis (Tunisia).

Pollinator-mediated selection is supposed to influence floral integration. However, the potential pathway through which pollinators drive floral integration needs further investigations. We propose that pollinator proboscis length may play a key role in the evolution of floral integration. We first assessed the divergence of floral traits in 11 Lonicera species. Further, we detected the influence of pollinator proboscis length and eight floral traits on floral integration. We then used phylogenetic structural equation models (PSEMs) to illustrate the pathway through which pollinators drive the divergence of floral integration. Results of PCA indicated that species significantly differed in floral traits. Floral integration increased along with corolla tube length, stigma height, lip length, and the main pollinators' proboscis length. PSEMs revealed a potential pathway by which pollinator proboscis length directly selected on corolla tube length and stigma height, while lip length co-varied with stigma height. Compared to species with short corolla tubes, long-tube flowers may experience more intense pollinator-mediated selection due to more specialized pollination systems and thus reduce variation in the floral traits. Along elongation of corolla tube and stigma height, the covariation of other relevant traits might help to maintain pollination success. The direct and indirect pollinator-mediation selection collectively enhances floral integration.

Small vertebrates on islands are expected to attain a larger body size, and a greater survival than their mainland counterparts. Comparative studies have questioned whether lizards exhibit this set of adaptations, referred to as the 'island syndrome'. We collected data on 730 individuals the endemic Lilford's lizard Podarcis lilfordi throughout a 10-year period on a small island of the Balearic archipelago (Spain). We coupled a growth function with a capture-mark-recapture model to simultaneously estimate size- and sex-dependent growth rate and survival. To put our results into a wider context, we conducted a systematic review of growth, life span and age at maturity in different Podarcis species comparing insular and mainland populations. We found a low average growth coefficient (0.56 and 0.41 year-1 for males and females to reach an asymptotic size of 72.3 and 65.6 mm respectively), a high annual survival probability of 0.81 and 0.79 in males and females, and a large variability between individuals in growth parameters. Survival probability decreased with body size in both sexes, indicating a senescence pattern typical of long-lived species or in populations with a low extrinsic mortality. Assuming a constant survival after sexual maturity, at about 2 years old, the average life span was 6.18 years in males and 8.99 in females. The oldest animal was a male last captured at an estimated age of ≥13 years and still alive at the end of the study. Our results agree with the predictions of the 'island syndrome' for survival, life span and growth parameters. A comparative analysis of these values across 29 populations of 16 different species of Podarcis indicated that insular lizards grow slower and live longer than their mainland counterparts. However, our data differed from other island populations of the same species, suggesting that island-specific characteristics play an additional role to isolation. Within this study we developed an analytical approach to study th

Information on the distribution, population traits and conservation status of the endangered coral Cladocora caespitosa is still missing for most of its distribution area. As prompted throughout conservation assessments and red lists, obtaining such information is a priority in the current context of generalized decline of benthic communities in the Mediterranean Sea. We assessed these topics in the main C. caespitosa populations (n = 18) thriving throughout UNESCO's Menorca Biosphere Reserve (MBR), which includes the largest marine Biosphere Reserve in the Mediterranean Sea. The MBR harbours an arrange of C. caespitosa populations of great interest, with a good representation of the contrasted environmental conditions that this long-lived coral is able to thrive in. Although average coral cover falls into the lower range compared to other Mediterranean populations, it is the ubiquity of the species along Menorca's coastline that differentiates this location from others described to date. Warming-related mortality can be considered the main threat to this species in the MBR, showing an average colony necrosis of ∼30%. Nevertheless, special attention should also be paid to other potential threats derived from human activity, such as pollution and coastal development. This study should be used as a baseline to implement conservation and management actions in the MBR, including a long-term monitoring programme.

The irregular distribution of marinas along the coast together with the natural attraction of some specific sites is leading to an over-capacity in many popular anchoring Mediterranean destinations during the summer season. This study proposes a standard procedure to assess the physical, social and environmental nautical carrying capacity of anchoring areas. Based on legislative restrictions and homogenous criteria, the anchoring sites are identified and the physical, social and environmental nautical carrying capacity is computed, thus establishing a range of distances between boats. The daily potential carrying capacity, considering the physical, social or environmental perspective, is assessed using an analysis of how suitable or safe a particular site is for anchoring. The physical, social and environmental saturation risk on the sandy seabed of each anchoring area is computed considering the relation between demand and the estimated physical, social and environmental carrying capacity, respectively. Methods have been applied to 318 anchoring areas along the coast of the Balearic Islands, confirming its usefulness as an environmental management tool.

Climate change can impact regional and global biodiversity for multiple reasons. In sea turtles, changes in local climate at nesting beaches can affect egg and hatchling survival and primary sex ratios. Sea turtles could respond to climate change by occupying new nesting areas. The recent increase in sporadic nesting in the western Mediterranean may indicate colonization of new nesting beaches. We assessed the suitability of a western area, the Balearic Islands (∼1500 km from current nesting grounds) as climate refuge for loggerhead turtles (Caretta caretta) under current (2015–2017) and climate change scenarios to the mid (+40 years) and end (+80 years) of the 21st century. Using a correlative approach based on air and sand temperatures, we predicted nest temperatures and sex ratios for 19 beaches. Most beaches could provide viable temperatures and predominantly produce male hatchlings under all scenarios. Sex ratio projections were male-biased but with an increasing female ratio throughout time. Although mean sex ratio under the +80 years scenario was still male-biased, the warmest beaches could provide female-biased ratios, which are similar to those estimated for current nesting sites. The Balearic Islands could function as climate refuge for loggerhead turtles in the Mediterranean because temperatures could favor embryo viability and a male sex ratio. However, a nesting population may not be established until the percentage of female hatchlings increases and turtles return to nest as adults. Conditions at sea should also favor survival of hatchlings and juveniles. Because western Mediterranean beaches are popular tourist destinations, active management may be needed to protect nesting populations.

Land reclamation in the Maldives is widespread. Current land reclamation practices, however, lack a systematic approach to anticipate sea-level rise and do not account for local flood risk differences to inform location and design choices. To address these limitations, this paper applies two decision-support tools: a hazard threshold analysis, and a cost-benefit analysis. Both tools produce site-specific estimates of land elevations or flood defence heights but do so for different goals. The hazard threshold analysis identifies hazard-based solutions that meet an acceptable flood probability for an intended lifespan without follow-up actions by reliability optimisation. The cost-benefit analysis identifies risk-based solutions using dynamic programming. We apply both tools to two land reclamation sites, a newly reclaimed airport island and a land extension of an inhabited island, in the Maldives. We find that total hazard-based heights for long-term planning horizons are highly uncertain, with local height differences of up to 1.9 m across sea-level rise scenarios by 2100. Risk-based Island elevations, in contrast, differ much less across scenarios, offering a practical advantage for decision-making. However, land reclamation choices on location, land elevation and investment in flood protection are not only driven by hazard-related aspects, such as reef characteristics, swell exposure, and sea-level rise, but also by estimates of exposed assets, reclamation, and flood protection costs. Taken together, the two decision-support tools are helpful for improving adaptation decisions and are also applicable in other small island regions.

Nursery areas are essential fish habitats due to their relevance in the survival of early stages of fish populations. They are also considered as of high priority in marine conservation strategies. Here, we investigated the diet of white seabream [Diplodus sargus (Linnaeus, 1758)] settlers in six nursery areas located in the shallow waters of coves in Minorca Island (Balearic Islands, Spain). Our aim was to characterize the food sources at different stages of juvenile development and their site-related variability in order to discern the importance of trophic links in cove selection during settling. The gut contents of 101 juveniles captured at different coves, three to the north of the island (N), and three in the southern coast (S), revealed a marked preference for feeding on crustaceans and, in particular, on harpacticoid copepods (>90% of gut contents). Copepods represented the main food source (80 ±4.4%; mean ±S.E.) in younger seabream individuals (10 - 15 mm length). A higher diversity in prey items was observed in the larger size-classes (s2: 16 - 23 and S3: 24 - 30 mm, respectively), which incorporated other prey items such as amphipods, isopods, foraminiferans or ostracods. Diet composition did not vary between the two surveyed locations (North vs. South of the island), but it did show significant differences among the six coves (p<0.001). Comparison between cove sediment infaunal composition and gut contents revealed that predation on sediment communities was scarce. Instead, diet was typically of phytal origin. Our results highlight the importance of the algal component of shallow coastal areas as a foraging habitat. In particular, harpacticoid copepods were key for survival during early development phases. The potential use of harpacticoid copepods to track ontogenic shifts in habitat use by juvenile fish is discussed.

Abundance and trait-driven processes have both been identified as potential mechanisms in determining the occurrence of species interactions. However, little is known about how these two mechanisms interact to determine the relative frequencies of interactions between species, and thereby species-specific contributions to ecological functions. Here, we evaluate the effect of both species’ abundance and trait-matching on the occurrence of plant-bird seed dispersal interactions in the Cantabrian Range (northern Spain). For two years at fourteen plots, we independently sampled the abundance and diversity of fleshy-fruited plants and frugivores, as well as the consumption of fruits by birds. We quantified trait-matching by applying a food-web approach based on the log-ratios of species traits relevant to seed dispersal and traits related to fruit-handling and foraging-stratum. We fitted multi-level models incorporating phylogenetic relatedness to identify phylogenetically independent effects of species abundance and trait-matching on interaction frequencies. Fitted models showed that species abundances of both plants and birds always had strong positive effects on interaction frequencies. Trait-matching effects associated with fruit-handling were weak, but consistent across years, whereas those derived from foraging stratum varied across years, according to strong interannual changes in species abundance. Our findings reveal that both species abundance and functional traits are required for a mechanistic understanding of species interactions, as well as for predicting species roles in ecosystems under global change.

The endemic angiosperm Posidonia oceanica plays a remarkable role as marine habitat and ecosystem service provider in shallow waters in the Mediterranean Basin through their vertical growth, oxygenation of the water column and as a carbon sink storing allochthonous carbon and biomass underneath the meadows. Here we assess the capacity of a pristine meadow at 8m depth in the PMNT Cabrera (Mallorca, Spain) to oxygenate the water column in the coastal area through monitoring of oxygen concentrations and subsequent evaluation of the metabolic rates from these profiles in the benthic as well as pelagic compartment. Here we report dissolved oxygen (DO) measurements from a CT at 4m dept with continuous (hourly) measurements from October 2019 to October 2021 as well as DO measurements from multiparameteric sensors in the meadow (8m depth) during some weeks in the same period and 2 evalautions of DO with closed incubations.

Gymnesigobius medits is reported for the first time after a recent description recorded from the Balearic Islands and from the slope of the Gulf of Vera on the Iberian Peninsula coast. The record from the Emile Baudot seamount on the Balearic Islands represents the deepest positive benthic gobiiform species record in general. The presence of the membrane connection between the pelvic fins in Gymnesigobius medits, presumed on the damaged fin in the original description, was confirmed. The recently described Gobius xoriguer is the first record from the Pitiusas and Columbretes islands and from the Iberian Peninsula coast. It appears to be widely distributed in the circalittoral bottoms, preferentially in red algae beds. Morphological identification of both species was confirmed using molecular analyses based on the sequencing of the mitochondrial cytochrome c oxidase subunit I (DNA barcode) gene. The deepest records of gobiiform fishes in oceans and seas are reviewed. The European seas, a well-studied area with eight gobiid species recorded deeper than 200 m, show high bathyal gobiid species richness compared to other areas. The real worldwide diversity of bathyal gobies, although only a fraction of the shallow water species richness of this taxon, is probably much larger than presently known.

Phlebotomine sand flies are vectors of several diseases of importance for public health, including leishmaniosis, bartonellosis, and sand fly fevers. An entomological survey on blood-feeding Diptera was conducted in June–November 2020–2021 to know the diversity of insect vectors in Mallorca (Balearic Islands, Spain). Among the vectors collected, Phlebotomus (Larroussius) perfiliewi Parrot, 1930 was found being the first record of this species in Spain. Phlebotomus perfiliewi s.l. is one of the main vectors of Leishmania infantum in the Mediterranean Basin and Central Asia. The identification of this species was confirmed by both morphological features and DNA barcoding. Phylogenetic analyses showed that the specimens captured were Ph. perfiliewi s.s. (99.85–100% homologues from Italy and Algeria specimens), with a sequence divergence of 0.17%. The cytochrome c oxidase subunit I gene clearly separates the three species that make up the Ph. perfiliewi species complex. In addition, we also provide a brief discussion about their identification remarks, phylogenetic relationships, and vector status.

Further investigation is needed to improve the identification and classification of fish in underwater images using artificial intelligence, specifically deep learning. Questions that need to be explored include the importance of using diverse backgrounds, the effect of (not) labeling small fish on precision, the number of images needed for successful classification, and whether they should be randomly selected. To address these questions, a new labeled dataset was created with over 18,400 recorded Mediterranean fish from 20 species from over 1,600 underwater images with different backgrounds. Two state-of-the-art object detectors/classifiers, YOLOv5m and Faster RCNN, were compared for the detection of the ‘fish’ category in different datasets. YOLOv5m performed better and was thus selected for classifying an increasing number of species in six combinations of labeled datasets varying in background types, balanced or unbalanced number of fishes per background, number of labeled fish, and quality of labeling. Results showed that i) it is cost-efficient to work with a reduced labeled set (a few hundred labeled objects per category) if images are carefully selected, ii) the usefulness of the trained model for classifying unseen datasets improves with the use of different backgrounds in the training dataset, and iii) avoiding training with low-quality labels (e.g., small relative size or incomplete silhouettes) yields better classification metrics. These results and dataset will help select and label images in the most effective way to improve the use of deep learning in studying underwater organisms

We conducted one of the first studies to integrate the quantification and characterization of microplastics (MPs), including fibers, in different habitats (sea surface, seafloor and beach sediments) of a coastal Mediterranean marine protected area, analyzing their ingestion in several marine species. The objectives of the study were to evaluate the distribution of MPs according to shape and polymer, to assess the contribution of fibers to local plastic pollution and to evaluate their ingestion in fish and invertebrates species that inhabit the study area (Pagrus pagrus, Serranus scriba, Spondyliosoma cantharus, Diplodus vulgaris, Oblada melanura, Holothuria forskalii, Holothuria tubularis, Holothuria polis, Arbacia lixula, Paracentrotus lividus, Modiolus barbatus, Mytilus galloprovincialis and Arca noae). A total of 111 environmental samples were analyzed. The mean abundance of MPs (excluding fibers) quantified in beach sediments (13,418.86 ± 28,787.99 MPs/m2) was two orders of magnitude higher than that found in seafloor sediments (76.92 ± 108.84 MPs/m2), which in turn was two orders of magnitude higher than sea surface samples (0.17 ± 0.39 MPs/m2). The fibers were the most abundant shape of MPs identified in all habitats. Variability in MPs ingestion was detected between species, with ingestion rates ranging from 43 % to 100 % for general MPs and ranging from 7 % to 100 % for fibers. The highest ingestion was observed in Holoturians, representing suitable bioindicators for plastic pollution. The composition of the polymer varies weakly depending on habitats and biota, but the result is strongly correlated with the morphology of the plastic. Fibers were mainly composed of cellulose acetate (29 %), styrofoam of polystyrene (18 %), and filaments, films and fragments of polyethylene and polypropylene. The results highlighted the need to expand integrated approaches to effectively study marine plastic pollution and to undertake efficient actions to limit the input of p

Dispersal shapes population connectivity and plays a critical role in marine metacommunities. Prominent species for coastal socioecological systems, such as jellyfish and spiny lobsters, feature long pelagic dispersal phases (LPDPs), which have long been overlooked. Here, we use a cross-scale approach combining field surveys of these species with a high-resolution hydrodynamic model to decipher the underlying mechanisms of LPDP patterns in northwestern Mediterranean shores. We identified basin-scale prevailing dispersal routes and synchronic year-to-year patterns tightly linked to prominent circulation features typical of marginal seas and semienclosed basins, with an outstanding role of a retentive source area replenishing shores and potentially acting as a pelagic nursery area. We show how the atmospheric forcing of the ocean, a marked hydrological driver of the Mediterranean Sea, modulates dispersal routes and sources of LPDP at interannual scales. These findings represent a crucial advance in our understanding of the functioning of metapopulations of species with LPDP in marginal seas and may contribute to the effective management of coastal ecosystem services in the face of climate change.

Fisheries management requires the best scientific knowledge on the exploitation and conservation status of stocks. This is challenging for by-catch species, for which necessary data for their assessment is more limited than for target ones. That is the case for the thornback ray, Raja clavata, in the Balearic Islands (western Mediterranean), whose exploitation and conservation status are addressed here for the first time, in an integrative approach, by using innovative assessment methods and genetic diversity analysis. The time series of fishing landings from 1964 and MEDITS trawl survey data from 2004 were used to apply CMSY++ and Bayesian state-space Schaefer production models. We also estimated the genetic diversity of the Cytochrome C Oxidase subunit I mitochondrial gene from 31 individuals collected during MEDITS surveys. The species showed overexploitation with a current fishing mortality (F) below that producing maximum sustainable yield (FMSY), but with a current stock biomass (B) lower than BMSY. Despite the fact that the exploitation status is stable or even has improved in the last decades, the overexploitation period since the late 1970s seems to have reduced levels of genetic diversity, below those of related species and other populations of R. clavata. This low genetic diversity may entail the loss of adaptive potential, making the species more vulnerable to fishing and the current climate change.

In this paper, measurements of 2.012 bone remains from four different domestic species (sheep, goats, cattle and pigs) originating from 33 Bronze Age archaeological sites from the Balearic Islands, mainland Iberia, southern France and Sardinia, and spanning about 2500 years (3700-700 cal. BCE) have been compared. The results show that a decrease in animal size occurred in the Balearic Islands during the Bronze Age. It was not a local phenomenon but rather was a general pattern that happened in different territories. Yet it was more marked on the islands. The evidence shows that the four analyzed species were not affected in the same way and it was a nonlinear phenomenon. Indeed, during the Late Bronze Age some archaeological sites from the Balearics had taller caprines compared with the other contemporaneous places, also on the continent. A multi-factor explanation for these fluctuations is proposed in this paper, showing that animal sizes generally decreased during late prehistory -especially cattle- and this process could reflect different factors such as a combination of limited feeding, increased human pressure and endogamy.

Improved observational constraints on the orbital parameters of the low-mass X-ray binary Scorpius X-1 were recently published in Killestein et al. In the process, errors were corrected in previous orbital ephemerides, which have been used in searches for continuous gravitational waves from Sco X-1 using data from the Advanced LIGO detectors. We present the results of a reanalysis of LIGO detector data from the third observing run of Advanced LIGO and Advanced Virgo using a model-based cross-correlation search. The corrected region of parameter space, which was not covered by previous searches, was about 1/3 as large as the region searched in the original O3 analysis, reducing the required computing time. We have confirmed that no detectable signal is present over a range of gravitational-wave frequencies from 25 to 1600 Hz, analogous to the null result of Abbott et al. Our search sensitivity is comparable to that of Abbott et al., who set upper limits corresponding, between 100 and 200 Hz, to an amplitude h0 of about 10−25 when marginalized isotropically over the unknown inclination angle of the neutron star's rotation axis, or less than 4 × 10−26 assuming the optimal orientation.

Low-enthalpy geothermal energy (LEGE) is a carbon-free and renewable source to provide cooling and heating to infrastructures (e.g. buildings) by exchanging their temperature with that of the ground. The exchange of temperature modifies the groundwater temperature around LEGE installations, which may contribute to enhancing the capacity of aquifers to degrade organic contaminants of emerging concern (OCECs), whose presence is significantly increasing in urban aquifers. Here, we investigate the impact of LEGE on OCECs and their bioremediation potential through numerical modelling of synthetic and real-based cases. Simulation results demonstrate that: (i) LEGE facilities have the potential to noticeably modify the concentrations of OCECs; and (ii) the final impact depends on the design of the facility. This study suggests that optimized LEGE facility designs could contribute to the degradation of OCECs present in urban aquifers, thus improving groundwater quality and increasing its availability in urban areas.

Isotopic composition modelling is a key aspect in many environmental studies. This work presents Isocompy, an open source Python library that estimates isotopic compositions through machine learning algorithms with user-defined variables. Isocompy includes dataset preprocessing, outlier detection, statistical analysis, feature selection, model validation and calibration and postprocessing. This tool has the flexibility to operate with discontinuous inputs in time and space. The automatic decision-making procedures are knitted in different stages of the algorithm, although it is possible to manually complete each step. The extensive output reports, figures and maps generated by Isocompy facilitate the comprehension of stable water isotope studies. The functionality of Isocompy is demonstrated with an application example involving the meteorological features and isotopic composition of precipitation in N Chile, which are compared with the results produced in previous studies. In essence, Isocompy offers an open source foundation for isotopic studies that ensures reproducible research in environmental fields.

In the current context of population growth and climate change, it is essential to effectively manage groundwater resources, to improve their quality, and to determine the behaviour of certain contaminants. Groundwater quality can be worsened most often by anthropogenic factors but can also be altered by natural factors depending on the chemical signatures of water sources (i.e., hydrochemical reactions) as a result of mixing processes. In these cases, the use of mixing calculations and multivariate statistical analysis (MSA) methods is crucial for determining the reactions that occur, the origin and fate of the detected compounds, ions or parameters, and the behaviour of the system. Thus, these methods ascertain processes that affect the chemical composition (i.e., quality) of groundwater bodies, and this information is needed for designing groundwater management strategies that exploit aquifers in a sustainable way. However, these methods are rarely employed, as few investigations that consider them focus on urban aquifers. Here, mixing calculations and other MSA methods that consider major ions and environmental isotopes are utilized in an aquifer located in a rural area associated with the Niebla-Posadas aquifer, Spain, where groundwater quality has deteriorated due to geogenic factors. This study proves the usefulness of these methods for deriving essential information that is needed (1) to properly manage the exploitation of aquifers, (2) to avoid the deterioration of groundwater bodies, and (3) to identify the reasons behind poor groundwater quality.