Search Results (771)

Introduction: The Strait of Gibraltar, a narrow gateway between the Atlantic Ocean and the Mediterranean Sea, concentrates intense biotic exchange and functions as a global “ecological gate” for marine species. Despite its ecological relevance, sustained acoustic telemetry monitoring has long been hindered by oceanographic complexity, strong currents, intense maritime traffic, and geopolitical constraints. As its Atlantic approach, the Gulf of Cádiz is a highly productive area supporting diverse habitats, key spawning and nursery grounds, and major migration pathways, while underpinning important commercial fisheries. Objective: to deploy a system to enable continuous monitoring of animal movements across this key biogeographic boundary. Methodology: The EU-funded STRAITS project, a multidisciplinary consortium integrating physical oceanography and marine biotelemetry, has deployed an acoustic telemetry curtain across the Strait of Gibraltar, complemented by a coastal acoustic receiver array in the Gulf of Cádiz. Results: Over the past two years, a consistent pattern of frequent acoustic detections has demonstrated the system’s potential. Data reveal spatio-temporal migration patterns of commercially important species such as Atlantic bluefin tuna (Thunnus thynnus) and meagre (Argyrosomus regius), alongside conservation-relevant species like ocean sunfish (Mola mola). Conclusions: These results highlight the Strait of Gibraltar as a biodiversity hotspot and a strategic location for quantifying connectivity, migration timing, and species fluxes, supporting ecosystem-based management and blue policy frameworks. Full article

The little Neptune grass Cymodocea nodosa (Ucria) Ascherson is common in shallow coastal areas, lagoons and estuaries in the Mediterranean Sea. As a pioneer and habitat-forming macrophyte, it plays an important ecological role and deserves attention for conservation, especially in areas affected by anthropogenic stressors. A C. nodosa meadow located in a marina of the northern Adriatic Sea (Porticciolo di Torrette, Ancona, Italy) was monitored during its seasonal development (May–October 2024). Structural parameters (shoot density, leaf length and width, percentage of leaves with broken apices), plant fertility and composition of the epiphytic community were assessed across five sampling dates. This population exhibited the typical Mediterranean developmental pattern, with a fully developed canopy in summer (July–September). Female flowers were rarely found, whereas male flowers and fruits were not observed, suggesting that the meadow is likely to rely mainly on clonal propagation. Epiphytic communities displayed low diversity; encrusting corallines and filamentous red algae (Ceramium sp.) were the main algal epiphytes, whereas serpulid polychaetes and ascidiaceans were the main animal epiphytes. Overall, structure, phenology and epiphytic assemblages of the studied meadow are similar to those of other Mediterranean Cymodocea meadows, suggesting that this meadow has persisted under long-term urban conditions despite multiple anthropogenic pressures (not directly tested in the present study). Full article

The rare charophyte species Chara corfuensis, which has an almost exclusively Mediterranean distribution, was recorded for the first time in two small waterbodies in southern Serbia, deep inland and far from the coast. Habitat characteristics were described in detail, as was the morphometry of the collected specimens, which corresponded well with literature data. In particular, reproductive structures—oospores and gyrogonites—were analyzed in detail, as the previous data on oospores was scarce and none existed for gyrogonites. The genetic profile of the Serbian specimens was determined based on DNA barcoding of the matK and rbcL plastid genes, confirming their taxonomic identity and showing close evolutionary relationships with most species of the subsection Hartmania. Full article

Coastal lagoons are key wintering habitats for waders, yet long-term changes in their community structure remain poorly understood in Mediterranean systems. We analyzed a 30-year dataset (1993–2022, excluding 2021) of wintering waders in the Venice Lagoon to assess trends in abundance, community structure, thermal composition and spatial patterns. Total abundance increased significantly (+3.5% yr⁻¹), while species richness ranged between 12 and 21 species per winter and increased over time. Community structure changed markedly, but the assemblage remained highly dominated by Dunlin Calidris alpina without evidence of increasing dominance or declining evenness. Instead, richness, Shannon diversity and Pielou’s evenness increased, whereas Berger–Parker dominance declined slightly but significantly. Species-level analyses showed a prevalence of increasing trends: ten of the 19 species analyzed increased significantly, three declined, one was stable, and five showed uncertain trends. Multivariate analyses based on Bray–Curtis dissimilarities showed significant compositional differences among approximately decadal periods, both including and excluding Dunlin, indicating that long-term assemblage reorganization was not solely attributable to the dominant species. The Community Temperature Index (CTI) increased significantly (p = 0.001), but this abundance-weighted signal was weak in biological magnitude and contrasted with a declining presence–absence CTI; moreover, this pattern was not robust to the exclusion of Dunlin, indicating dominance-driven dynamics. Spatial analyses revealed a strong increase in the proportion of counted birds recorded in the open lagoon (p < 0.001) and a decline in fish farms (p < 0.001), but this pattern disappeared after excluding Dunlin, suggesting that the apparent spatial redistribution was largely driven by this species. Overall, the assemblage is increasing and compositionally reorganized, while remaining strongly influenced by Dunlin dominance, highlighting the need to integrate species- and community-level approaches when interpreting ecological indicators. Full article

This study investigates the spatial variability of benthic foraminiferal assemblages across the shoreface–inner shelf transition of the Porto Pino coastal system (SW Sardinia, western Mediterranean). Porto Pino is a microtidal, wave-dominated embayment characterized by an environmental gradient extending from siliciclastic shoreface sands to mixed bioclastic sediments associated with the Posidonia oceanica meadow. A total of 33 sediment samples were analyzed for grain size, benthic foraminiferal assemblages, morphotypes and diversity indices. Cluster analysis and Principal Component Analysis (PCA) were used to investigate the spatial variability of the assemblages. Three main benthic foraminiferal assemblages were identified, each corresponding to a distinct benthic habitat: shallow unvegetated shoreface sands, a transitional zone near the upper limit of the P. oceanica meadow, and deeper mixed bioclastic sediments associated with its lower boundary. The distribution of the foraminiferal assemblage reflects the combined influence of hydrodynamic energy, substrate composition, water depth, and proximity to the meadow. Diversity indices indicate generally low-stress environmental conditions, whereas morphotype composition reflects changes in habitat structure and substrate characteristics along the shoreface–inner shelf gradient. These results demonstrate that benthic foraminifera effectively track environmental and sedimentological gradients in Mediterranean embayed systems and highlight their value for environmental reconstructions and biomonitoring applications. Full article

Global change alters forestry habitats and facilitates the entry of new pathogens that do not share a co-evolution history with the forest, leading them into a spiral of decline. As a result, relationships between forest organisms become imbalanced. RNA viruses are of particular concern given their capacity to infect hosts across different kingdoms of life, yet the viromes of Mediterranean forests remain largely unexplored. For this reason, the study of RNA viruses is essential for understanding how viral flow across different hosts might occur, and to prevent possible outbreaks of diseases in the future. In this work, the RNA virus diversity found in trees, arthropods, and fungi from declining Mediterranean forests is described. To this extent, three habitats (Quercus ilex, Castanea sativa and Pinus radiata) were sampled and RNAseq was performed on tree tissues, arthropods, and fungi. In total, 146 viral sequences were detected by searching for matches with conserved motifs of the RNA-dependent RNA polymerase (RdRP) using Palmscan. Up to 15 viral families were identified, with Botourmiaviridae (28.7%) and Partitiviridae (9.6%) being the most abundant. In terms of genome type, ssRNA(+) viruses were the most represented (83.5%), followed by dsRNA (15%) and two ssRNA(−) representatives. Notably, families with documented cross-kingdom capabilities such as Hypoviridae (1), Mitoviridae (6), and Narnaviridae (5) were detected across multiple host types, with one Mitovirus sequence recovered unexpectedly from pine tree tissue. Distribution of viruses across ecosystems included Q. ilex (57.5%), P. radiata (26.7%), and C. sativa (15.8%). Interestingly, two RdRP sequences showed no similarity to any entry in current viral databases, representing potentially novel viruses warranting further characterization. These findings reveal a rich and partially uncharacterized RNA virosphere in declining Mediterranean forests and underscore the importance of multi-host virome surveys for understanding viral flow across kingdoms in threatened ecosystems. Full article

Climate-driven changes in oceanographic conditions are increasingly affecting the distribution of marine species, particularly vulnerable elasmobranchs. The undulate ray, Raja undulata, is a Near Threatened batoid species distributed throughout the northeastern Atlantic Ocean and parts of the Mediterranean Sea, yet its potential response to future climate change remains poorly understood. This study assessed current and future habitat suitability using species distribution modelling approaches and CMIP6 climate projections under the SSP245 scenario. Species occurrence records were compiled from biodiversity databases and published sources, and environmental predictors were selected following multicollinearity screening. Among twelve evaluated modelling algorithms, MaxEnt showed the highest predictive performance (AUC = 0.99; TSS = 0.95) and was selected for subsequent analyses. Current habitat suitability was concentrated along the Iberian Peninsula, the Bay of Biscay, the English Channel, and parts of the western Mediterranean Sea. Future projections indicated substantial habitat contraction, with habitat loss (57.3%) greatly exceeding habitat gain (2.2%), resulting in a southward redistribution of suitable habitats. Minimum phytoplankton concentration, sea surface temperature, and silicate concentration were identified as the most influential environmental predictors. Areas predicted to remain suitable under both current and future conditions may represent important climate refugia for the species. Overall, the results indicate that R. undulata is highly vulnerable to future environmental change and highlight the need to incorporate climate-driven habitat shifts into conservation planning, fisheries management, and long-term monitoring strategies. Full article

Coastal zones are facing rising exposure to climate-related hazards alongside intensifying human pressures, which highlights the need for robust tools to assess vulnerability. This study uses a GIS-based Coastal Vulnerability Index (CVI) to quantify and map relative vulnerability along ~13 km of shoreline in Al Hoceima Bay (northern Morocco). The proposed CVI integrates eight geological and physical indicators, including geomorphology, shoreline erosion and accretion rates, coastal slope, elevation, natural habitats, relative sea-level rise, significant wave height, and tidal range. Spatial analyses were performed using remote sensing data, historical records, field measurements, and Geographic Information Systems (GIS). The analysis reveals that 37% of the shoreline is categorized as high vulnerability, 44% is moderate, and 19% is low. Highly vulnerable sectors are primarily associated with low elevations, gentle coastal slopes, sandy beach systems, limited natural habitat protection, and proximity to river mouths. These findings demonstrate that the applied CVI provides a rapid and cost-effective framework for identifying priority areas for coastal management and climate adaptation. The proposed approach offers valuable decision-support insights for sustainable coastal planning in Al Hoceima Bay and other Mediterranean coastal environments characterized by limited data availability. Full article

Ecosystem restoration on Mediterranean islands is often hindered by the residual effects of past land use and invasive species. Decades of holm oak forest exploitation, the establishment of secondary pine plantations, and the introduction of invasive mammals have altered habitat configurations. Consequently, converting these conifer stands to promote the recovery of native Quercus ilex L. communities has become a conservation priority. This study investigates the regeneration constraints of Q. ilex in Mediterranean insular environments, focusing on the inhibitory role of conifer-derived litter and seed predation by invasive rodents and lagomorphs. We integrated an ex situ experiment (384 acorns) testing germination under varying local pine-forest soil and commercial substrate conditions, with an in situ field experiment (300 acorns) across five areas, comparing three treatments: closed cages (exclusion of all mammals), open cages (exclusion of lagomorphs), and unfenced controls. Results indicate that, while ex situ, local pine-forest soil significantly favoured germination over the commercial mixture, predation represents the main obstacle in situ, outweighing any soil-mediated effects. Seedling emergence was substantially reduced by early predation and, to a lesser extent, by litter presence. These findings highlight the necessity of integrated management strategies in insular ecosystems. Full article

The understorey vegetation of mature Quercus robur L. mixed forests (MF) was compared for richness and composition with that of natural forest gaps (FG) and of 30-year-old artificial Q. robur plantations (AF) in Mediterranean Italy. Richness was similar in AF and MF and was almost double in FG, due to the arrival of species from non-forest habitats, among which 14% were aliens. In these specific conditions, natural gap dynamics did not support forest recruitment, while AF hosted typical nemoral species, demonstrating that afforestation may be successful for nature restoration, provided that connectivity with natural systems is maintained for the supply of forest species propagules. Full article

Introduction: Elasmobranchs play a crucial role in ecosystem regulation, but they are highly vulnerable to rapid environmental changes, particularly those driven by anthropogenic activities. Therefore, elasmobranchs are among the most threatened vertebrate groups worldwide, with overfishing and habitat degradation representing the primary threats to their survival. To address these challenges, in situ and ex situ conservation programs are complementary approaches. Objective: The implementation of assisted reproductive technologies, still poorly developed for elasmobranchs, represents a critical component of these ex situ strategies. Focused on that aspect, the main goal of this work was to get a better understanding of the sperm cells morphologies of different Mediterranean elasmobranch species. Results: The Elasmobranchii spermatozoa possesses a long and he-lical head, an elongated midpiece, and a flagellum supplemented with additional ultrastructural components to its axoneme. The comparative analysis of sperm head morphology revealed substantial interspecific variation among the studied elasmobranchs. Head length was relatively conserved, ranging from 48.5 to 62.0 μm, whereas helical parameters showed much greater variability. S. canicula and M. mobular exhibited the most compact head morphology, characterized by short helical wavelengths, low amplitudes, and the highest numbers of helices. In contrast, the batoids R. rhinobatos, R. radula, and R. clavata displayed broader, more widely spaced helices and fewer turns. Phylogenetic patterns were partially evident, as the closely related rajids shared very similar sperm morphology, while R. rhinobatos showed a comparable batoid morphotype. However, similarities between the distantly related M. mobular and S. canicula, and differences between the scyliorhinids S. canicula and G. melastomus, suggest that ecological and reproductive factors, in addition to phylogeny, have influenced the evolution of sperm head morphology in elasmobranchs. Conclusion: Elasmobranchii species possess big spermatozoa (compared to bony fishes) with an elongated helical head and tail similar to one currently existing (but later diverged) in birds, reptiles, and amphibians, which can be considered an evolutionary ancient. Sperm head morphology varies markedly among elasmobranchs, mainly regarding helical traits rather than head length. While phylogeny explains similarities among rajids, convergent patterns in distantly related species suggest that additional ecological and reproductive factors influence sperm evolution and structural design. Full article

Fish Aggregating Devices (FADs), traditionally used to attract and concentrate fish, can also serve as effective environmental enrichment tools in reservoirs, particularly in those with homogeneous characteristics and scarce refuge habitat, enhancing structural complexity and promoting recreational fishing opportunities. This study aimed to evaluate patterns in the use of prototype fish aggregation devices (FADs) in small size reservoirs. It was conducted at the Nascentes Reservoir (Crato), a small Mediterranean reservoir (ca. 10 ha) located in southern Portugal. These FADs were installed to enhance refuge habitat for fish species of interest to recreational fisheries, particularly largemouth bass (Micropterus salmoides Lacepède, 1802), thereby promoting the occurrence of trophy specimens. Two types of FADs were deployed and tested: (1) bank FADs (TREES), used in shallow waters near the margins; and (2) pelagic FADs (DAPs), suspended in the water column in deeper areas at the center of the reservoir. To monitor movement patterns and habitat use, an acoustic telemetry receiver array was deployed with a design to secure a three-dimensional fine-scale positioning with high accuracy. A total of 20 largemouth bass were tagged with acoustic transmitters equipped with pressure (i.e., depth) sensors. A before–after approach was used with 10 fish tracked before FAD deployment and 10 after. Results of fish behavior analysis provide strong evidence of fish using DAPs, but not TREES. In the presence of FADs, fish reduced their home ranges and movement amplitudes, becoming closely associated with these artificial habitats. Several environmental predictors explained fish behavior in the presence of artificial refuges, namely, diel period, moonlight intensity, and fish depth. The findings of this study are expected to contribute to the development of guidelines for refuge habitat enhancement in small- to medium-sized Mediterranean reservoirs, thereby increasing their recreational fishing attractiveness. Full article

Introduction: The circum-Mediterranean region is a global biodiversity hotspot, hosting a highly distinctive freshwater fauna with a high degree of endemism and conservation concern. However, these ecosystems are increasingly threatened by biological invasions, particularly by non-native fish species, which represent a major driver of biodiversity loss. Objective: This study aims to compile a comprehensive and updated inventory of non-native inland fish species across the circum-Mediterranean region and to identify the main taxonomic, biogeographical, and socio-environmental drivers shaping their distribution. Methodology: We conducted an extensive review of the scientific literature, online databases (including EASIN, GISD, and CABI), and technical reports to compile records of non-native fish species across inland and transitional waters of Mediterranean-climate basins. Analyses focused on species composition, taxonomic representativeness, introduction pathways, native regions, and the relationship between species richness and selected environmental and socio-economic variables. Results: A total of 151 non-native fish species were recorded across the study area. Italy, Spain, Bosnia and Herzegovina, France, and Croatia exhibited the highest numbers of established species. Taxonomic representation was uneven, with Salmoniformes and Esociformes overrepresented among established non-native species, while Siluriformes and Characiformes were underrepresented. Most introductions originated from Europe, Asia, and North America, primarily through intentional releases and escape events. Non-native species richness was positively correlated with gross domestic product, precipitation, and the number of dams, highlighting the role of economic development and habitat modification in facilitating invasions. Conclusions: Biological invasions by non-native fishes are widespread across the Mediterranean basin and are strongly driven by human activities and environmental conditions. The high invasion levels observed in this biodiversity hotspot pose a significant threat to endemic freshwater faunas. These findings underscore the need for coordinated transnational management strategies, stricter regulation of introduction pathways, and prioritization of high-risk species to mitigate further impacts. Full article

Introduction: The Iberian killifish (Apricaphanius iberus), an endemic cyprinodontid of the Spanish Mediterranean coast, is a key conservation species due to its restricted distribution, high sensitivity to habitat alteration and invasive fish, and ecological role in saline wetlands. Classified as Endangered by national administration and listed in Annex II of the EU Habitats Directive, its populations have undergone severe declines across its native range. Coastal salt pans have become critical refuges for the persistence of this species, often supporting some of the highest population densities recorded. However, the conservation value of these anthropogenic systems strongly depends on hydrological management, which directly influences habitat stability and suitability. Objectives: This study aims to assess the long-term population responses of A. iberus under contrasting hydrological management regimes in coastal salt pans. Methodology: We analysed ten years of monitoring data across five salt pan circuits in the perimeter area of the Mar Menor coastal lagoon (SE Spain), covering a salinity gradient and three management regimes: economic exploitation (EE), preventive management (PM), and non-management (NM). Population metrics (occurrence, abundance and breeder proportion) were evaluated. Results: Population performance differed markedly among management regimes. EE circuits showed consistently high occurrence and abundance, including in hypersaline ponds, high breeder proportions, low interannual variability, and weak dependence on meteorological conditions and ephemeral prey. PM circuits displayed intermediate patterns. In contrast, NM circuits exhibited low occurrence and abundance, low breeder proportions, high temporal fluctuations, and strong dependence on meteorological variability. Conclusions: Hydrological management is a key determinant of A. iberus population stability in coastal salt pans. Maintaining or restoring traditional management practices enhances habitat suitability, buffers environmental variability, and supports conservation actions such as reintroduction. These findings highlight the critical role of managed anthropogenic wetlands as refuges for endangered fishes and provide a transferable framework for conservation under global change. Full article

Introduction: Freshwater fish communities in Mediterranean basins have undergone profound changes over recent decades due to biological invasions, habitat alteration, and hydrological regulation. The Segura River basin (SE Spain), particularly in the Region of Murcia, represents a paradigmatic case of these transformations, with increasing pressures on native ichthyofauna and growing relevance for recreational fisheries. Objective: This study aims to provide an updated inventory of fish communities in the rivers and reservoirs of the Region of Murcia, assessing current composition, relative abundance, and conservation status. Methodology: Fish assemblages were surveyed during sampling campaigns conducted in autumn 2023, 2024 and 2025. Sampling sites included representative reservoirs and river reaches within the middle sector of the Segura River basin, focusing on areas of interest for recreational fishing. Passive fishing gears were used in reservoirs, while electrofishing was conducted in riverine habitats. Presence and relative abundance data were recorded for all detected taxa. Results: A total of 15 taxa were identified (8 in reservoirs and 15 in river reaches). Reservoir communities were almost entirely dominated by non-native invasive species, including Cyprinus carpio, Alburnus alburnus, Sander lucioperca, Micropterus salmoides, Lepomis gibbosus, and Gambusia holbrooki, with Luciobarbus sclateri as the only native species. Riverine sections of the main channel also showed a strong dominance of exotic taxa, with additional species such as Esox lucius, Oncorhynchus mykiss, Gobio lozanoi, and Pseudochondrostoma polylepis. Native species detected included L. sclateri (dominant), Anguilla anguilla, and Salariopsis fluviatilis, the latter showing a recent expansion likely linked to human-mediated introduction. Isolated tributaries hosted the most valuable assemblages, including populations of L. sclateri, Squalius tartessicus, and the endangered Valencia hispanica (recently unauthorized translocations into the Segura river basin). Conclusions: Current fish communities in the Region of Murcia reflect a marked ecological degradation compared to historical conditions, driven by the proliferation of non-native species and habitat alteration. Changes over the last 30 years have been particularly pronounced in reservoirs and regulated sections of the main river channel, where local extinction of the native S. tartessicus has also been detected. Only the headwaters of certain tributaries retain fish assemblages of notable conservation interest, highlighting their priority for management and protection. Full article