Northwestern Iberian Peninsula Research Articles

From the Strait of Gibraltar to northern Europe: Pleistocene refugia and biogeographic history of heather (Calluna vulgaris, Ericaceae)

AbstractCalluna vulgaris (Ericaceae) is the most widespread and prevalent woody species of the European dry heathland, from the African side of the Strait of Gibraltar to northern Europe. However, previous biogeographic analyses of this species have ignored the western Mediterranean region, despite its preponderant role as a major glacial refugium for European biota. Here, we explore the existence of further Pleistocene glacial refugia for C. vulgaris in the Iberian Peninsula and the Strait of Gibraltar area and provide new insights into the post-glacial colonization of Europe by this emblematic heathland species. We carried out phylogeographical analyses of C. vulgaris samples from 44 locations using four plastid markers (matK, trnH-psbA, trnL-F and rpl16). We built palaeodistribution models using MAXENT to identify possible refugia for C. vulgaris during the mid-Pliocene, Last Interglacial (LIG), Last Glacial Maximum (LGM) and mid-Holocene. Our results identified a genetic lineage exclusive to the Strait of Gibraltar area s.l. (south-western Iberian Peninsula and north-western tip of Africa) as the most probable close to the clade of origin of the species. This lineage also had more private haplotypes than more recent, Eurosiberian clades. The obtained data highlighted two main refugia for C. vulgaris during the LGM, one around the Strait of Gibraltar and another in the north-western Iberian Peninsula. The Strait of Gibraltar area is a major centre of origin or glacial refugium for the heather C. vulgaris. However, the north-western Iberian Peninsula seems to have acted as a secondary glacial refugium for the more recent, Eurosiberian lineage of this species. This study stresses the importance of the Strait of Gibraltar area in the biogeographic history and conservation of the heather and, by extension, the European heathland habitat.

Peasants, Market Exchange and Economic Agency in North-Western Iberia, c.850–c.1050

Abstract Our understanding of the economic foundations of rural society in early medieval north-western Iberia remains wedded to explanations that emphasize the structural limitations that framed human activity while seeking to attenuate the economic agency of non-elite groups and individuals. This article argues that the early medieval peasantry of north-western Iberia was not the staid caricature presented by much of the historiography, but a much more economically dynamic section of society. To demonstrate this dynamism, it uses charters to analyse peasant productive strategies that went beyond subsistence. These reveal that peasants not only dabbled in the land market but invested in non-movable capital goods, with the result that some peasants produced surpluses for the express purpose of exchange by the tenth century, fundamentally altering the contours of their communities from within. By examining the evidence concerning peasant ownership of watermills, the article sheds new light on causal explanations for phenomena as diverse as social mobility, the possibilities of commercial integration, and the logic of market exchange. It concludes by contending that narratives focused on uncovering the beginnings of growth must more readily concede that its origins are to be found both beyond as well as within seigneurial contexts.

Progress in Grassland Cover Conservation in Southern European Mountains by 2020: A Transboundary Assessment in the Iberian Peninsula with Satellite Observations (2002–2019)

Conservation and policy agendas, such as the European Biodiversity strategy, Aichi biodiversity (target 5) and Common Agriculture Policy (CAP), are overlooking the progress made in mountain grassland cover conservation by 2020, which has significant socio-ecological implications to Europe. However, because the existing data near 2020 is scarce, the shifting character of mountain grasslands remains poorly characterized, and even less is known about the conservation outcomes because of different governance regimes and map uncertainty. Our study used Landsat satellite imagery over a transboundary mountain region in the northwestern Iberian Peninsula (Peneda-Gerês) to shed light on these aspects. Supervised classifications with a multiple classifier ensemble approach (MCE) were performed, with post classification comparison of maps established and bias-corrected to identify the trajectory in grassland cover, including protected and unprotected governance regimes. By analysing class-allocation (Shannon entropy), creating 95% confidence intervals for the area estimates, and evaluating the class-allocation thematic accuracy relationship, we characterized uncertainty in the findings. The bias-corrected estimates suggest that the positive progress claimed internationally by 2020 was not achieved. Our null hypothesis to declare a positive progress (at least equality in the proportion of grassland cover of 2019 and 2002) was rejected (X2 = 1972.1, df = 1, p < 0.001). The majority of grassland cover remained stable (67.1 ± 10.1 relative to 2002), but loss (−32.8 ± 7.1% relative to 2002 grasslands cover) overcame gain areas (+11.4 ± 6.6%), indicating net loss as the prevailing pattern over the transboundary study area (−21.4%). This feature prevailed at all extents of analysis (lowlands, −22.9%; mountains, −17.9%; mountains protected, −14.4%; mountains unprotected, −19.7%). The results also evidenced that mountain protected governance regimes experienced a lower decline in grassland extent compared to unprotected. Shannon entropy values were also significantly lower in correctly classified validation sites (z = −5.69, p = 0.0001, n = 708) suggesting a relationship between the quality of pixel assignment and thematic accuracy. We therefore encourage a post-2020 conservation and policy action to safeguard mountain grasslands by enhancing the role of protected governance regimes. To reduce uncertainty, grassland gain mapping requires additional remote sensing research to find the most adequate spatial and temporal data resolution to retrieve this process.

The Atlantic connection: coastal habitat favoured long distance dispersal and colonization of Azores and Madeira by Dysdera spiders (Araneae: Dysderidae)

The woodlouse hunter Dysdera spiders have colonized all Macaronesian archipelagos. We report here for the first time an evolutionary connection between the Iberian Peninsula, Madeira, and the remote archipelago of Azores. Based on museum specimens from the 1950s, we describe the first endemic Dysdera species from the Azores. Additionally, we report the recent collection of immature individuals related yet probably not conspecific to the new species, rejecting previous suggestions that the endemic lineage had gone extinct. A multi-locus target phylogeny revealed that an undescribed species from Madeira was the closest relative to the Azores lineage, and that both island taxa were in turn sister to an Iberian endemic species, within a mostly Iberian clade. Interestingly, the Madeiran relative was not closely related to the remaining endemic species reported in the archipelago, suggesting an independent colonization. A divergence time estimation analysis unravelled that Dysdera colonized both archipelagos early after their emergence. The colonization pathway remains ambiguous, but the Iberian Peninsula acted as the ultimate source of the ancestral colonizers. Finally, we describe the new species Dysdera cetophonorum Crespo & Arnedo sp. nov. from Pico and Dysdera citauca Crespo & Arnedo, sp. nov. from Ilhéu de Cima (Porto Santo) and redescribe and illustrate the female genitalia for the first time of their poorly known closest relative, Dysdera flavitarsis Simon, 1882 from the north-western Iberian Peninsula. http://zoobank.org/urn:lsid:zoobank.org:pub:1E75CCEC-1632-4581-93A5-E61721970022

Evolution of the Iberian Massif as deduced from its crustal thickness and geometry of a mid-crustal (Conrad) discontinuity

Abstract. Normal incidence seismic data provide the best images of the crust and lithosphere. When properly designed and continuous, these sections greatly contribute to understanding the geometry of orogens and, along with surface geology, unraveling their evolution. In this paper we present the most complete transect, to date, of the Iberian Massif, the westernmost exposure of the European Variscides. Despite the heterogeneity of the dataset, acquired during the last 30 years, the images resulting from reprocessing the data with a homogeneous workflow allow us to clearly define the crustal thickness and its internal architecture. The Iberian Massif crust, formed by the amalgamation of continental pieces belonging to Gondwana and Laurussia (Avalonian margin), is well structured in the upper and lower crust. A conspicuous mid-crustal discontinuity is clearly defined by the top of the reflective lower crust and by the asymptotic geometry of reflections that merge into it, suggesting that it has often acted as a detachment. The geometry and position of this discontinuity can give us insights into the evolution of the orogen (i.e., of the magnitude of compression and the effects and extent of later-Variscan gravitational collapse). Moreover, the limited thickness of the lower crust below, in central and northwestern Iberia, might have constrained the response of the Iberian microplate to Alpine shortening. Here, this discontinuity, featuring a Vp (P-wave velocity) increase, is observed as an orogen-scale boundary with characteristics compatible with those of the globally debated Conrad discontinuity.

Species identity matters: Functional responses to warming in congeneric turfs differ from those of a canopy algae but are species-specific

The decline of kelps and algal canopies and the expansion of algal turfs because of global change is a recurrent pattern reported in temperate coasts worldwide. This pattern has also been identified in recent years in the northwestern Iberian Peninsula where Fucus serratus, a cold-water species that used to form extensive canopies in the intertidal, is reducing its abundance while the warm-water turf-forming Vertebrata hypnoides and V. reptabunda are becoming more abundant in the same tidal level. As ecophysiological performance in seaweeds is strongly influenced by temperature, understanding their response to increasing thermal gradients may assist us to predict their vulnerability to future warming scenarios. In this study, we compared the effects of warming on the photosynthetic and respiratory performance of F. serratus and two species of Vertebrata using a highly resolved temperature gradient (from 7 to 31 °C) under controlled laboratory conditions. Only productivity at the optimum temperature showed a consistent difference between the canopy F. serratus and the two turfs, being significantly higher in the latter. Photosynthesis responsiveness to temperature was significantly higher in one of the Vertebrata than in F. serratus while net photosynthesis was significantly higher in V. hypnoides than in V. reptabunda. Altogether, our results show that photosynthesis in algal turfs responded in a species-specific manner to warming, indicating that species composition should be taken into consideration in future ecophysiological studies.

Development of a PCR-based method for the screening of potential predators of the African citrus psyllid Trioza erytreae (Del Guercio)

Trioza erytreae is one of the vectors of Huanglongbing (HLB), the main global citrus groves threat. Since its recent detection in the north-western Iberian Peninsula (Spain and Portugal), its contention and eradication have been a priority to prevent its spread. For the biological control of T. erytreae, it is important to understand the role that each potential natural enemy could have. With the aim to determine which predators have incorporated T. erytreae into their diet, a PCR-based method has been developed for the specific detection of T. erytreae in their gut contents. For this, a pair of specific primers was designed from the mitochondrial cytochrome c oxidase subunit I (COI) region. Specificity of this pair of primers was studied and feeding trials with two predator species were conducted to determine the decay rates of T. erytreae within their gut. None of the non-target species was amplified, showing the high specificity of these T. erytreae primers. Feeding trials showed 4.8 h and 4.5 h half-life time detections of T. erytreae ingested by Chrysoperla carnea and Cryptolaemus montrouzieri, respectively. Finally, field-collected generalist predators of T. erytreae-infested citrus trees from the Canary Islands and Galicia (Spain), were analysed by conventional PCR for the presence of T. erytreae in their guts. Results showed that a wide range of predator taxa ingested the target prey, like the families Coccinellidae, Anthocoridae, Chrysopidae, Hemerobiidae, Forficulidae, Miridae, Syrphidae, Formicidae, Erythraeidae and the order Araneae, with detection percentages ranging from 20 to 100%. These results confirm that most of the analysed generalist predators found in citrus trees could be potential candidates for the biological control of T. erytreae in future biological control programs of this HLB vector.

Valerius of Bierzo as an interpreter of the seventh-century ecclesiastical environment of northwestern Iberia

ABSTRACT Valerius of Bierzo, a hermit who lived in northern Iberia in the last years of the Visigothic Kingdom of Toledo (568–711), is considered an eccentric character by many scholars. Valerius left a rich, although not long, literary production that is surprising for its originality, equal only to its relative obscurity outside of the Iberian world. Among other things, he wrote a treatise about the “degenerate” monasticism practiced in his region and three short pieces known as his autobiographical works in which he describes his vicissitudes on the path towards an ascetic way of life. Incidentally addressing numerous topics of society, culture, power, and of course, religion, Valerius offers a precious source of information regarding early medieval society in Galicia. This article analyses his comments and impressions based on his personal opinion about the clergy and monastic life in his region. In doing so, it unveils his character and situates his behaviour – and apparent eccentricity – as reflections of his personal life choices and the religious and political impositions to which he was subjected.

Habitat differentiation and geographic separation of Isoetes velata populations in central Iberian Peninsula

Populations of Isoetes velata were studied in order to provide more information on their habitat and distribution in the Western and Northwestern Iberian Peninsula. Habitat together with morphology of megaspores were used as diagnostic features. The form I. velata subsp. velata f. lereschii is considered here as a synonym of I. velata subsp. asturicense and therefore only two taxa remain within the species: I. velata subsp. velata and I. velata subsp. asturicense. Intermediate individuals have been found in the Western Central System. The differentiation within the I. velata group appears to be the result of gradual genetic divergence after isolation. Palaeobotanical data confirm the presence of I. velata subsp. asturicense in Late Glacial lake sediments in northwestern Spain. Cluster classification of the soft-water vegetation with Isoetes velata subsp. asturicense revealed two main groups in the Spanish Central System. A single association, the Sparganio angustifolii-Callitrichetum fontqueri which includes Iberian Atlantic stands of Sparganium angustifolium and Isoetes velata subsp. asturicense, is here recognized. Besides, a variant of the association with Eleocharis acicularis is identified in shallow temporary waters in the Western Sierra de Gredos.

A tectonic carpet of Variscan flysch at the base of a rootless accretionary prism in northwestern Iberia: U–Pb zircon age constrains from sediments and volcanic olistoliths

Abstract. The allochthonous complexes of Galicia–Trás-os-Montes Zone (NW Iberia) are part of a rootless tectonic stack which preserves part of a Variscan accretionary prism. They are formed by individual tectonic slices marked by specific tectonometamorphic evolutions, which were piled up in a piggy-back mode onto its relative autochthon, the Central Iberian Zone (CIZ). Allochthony decreases from the structurally upper thrust sheets towards the lower ones. The lowermost unit of the stack is known as the Parautochthon or Schistose Domain. It is characterized by a low metamorphic grade in contrast with higher temperatures and/or pressures estimated for the overlying allochthonous units and shares the stratigraphic sequence with the underlying autochthon. The Parautochthon is divided in two structural and stratigraphic sub-units: (i) the Lower Parautochthon (LPa) is made of synorogenic flysch-type sediments with varied turbiditic units and olistostrome bodies, showing Upper Devonian–lower Carboniferous age according to the youngest zircon populations and fossiliferous content; (ii) the Upper Parautochthon (UPa) is composed of highly deformed preorogenic upper Cambrian–Silurian volcano-sedimentary sequence comparable with the nearby autochthon and to some extent, also with the high-P and low-T Lower Allochthon laying structurally above. The UPa was emplaced onto the LPa along the Main-Trás-os-Montes Thrust, and the LPa became detached from the CIZ relative autochthon by a regional-scale structure, the Basal Lower Parautochthon Detachment, which follows a weak horizon of Silurian carbonaceous slates. A review on the detrital zircon studies on the synorogenic LPa complemented by zircon dating of 17 new samples is presented here. The results support the extension of the LPa underneath the NW Iberian allochthonous complexes, from Cabo Ortegal, to Bragança and Morais massifs. Its current exposure follows the lowermost tectonic boundary between the Galicia–Trás-os-Montes (allochthon) and Central Iberian (autochthon) zones. The youngest zircon age populations point to a maximum sedimentation age for the LPa formations ranging from Famennian to Serpukhovian and supports the piggy-back mode of emplacement of the Galicia–Trás-os-Montes Zone, of which it represents the latest imbricate. The zircon age populations in the LPa allow the sedimentary provenance areas to be constrained, showing the intervention of nearby sources (mostly the UPa) and/or multiply recycled and long-transport sediments with a typically north-central Gondwana age fingerprint, also found in the Lower Allochthon, UPa and Autochthon. Complementary geochronology of volcanic olistoliths trapped in the LPa sediments and of late Cambrian to Upper Ordovician rhyolites from the UPa is also presented. It shows a direct relationship between the major blocks source area (UPa) and the setting place (LPa). Old zircon age patterns show that the LPa sedimentary rocks were recycled from detrital rocks of the allochthon (advancing wedge) and the nearby autochthon (peripheral bulge).

The use of a spatial model of economic efficiency to predict the most likely outcomes under different fishing strategy scenarios

The current European Union has been progressively implementing since January 2014 a discard ban which includes the obligation to land unwanted catch for certain regulated species and sizes. Although a full enforcement of the landing obligation has a direct impact on discard reduction through more responsible and selective fishing, fishers argue that it will prompt both a decrease in incomes and an increase in working time onboard. Thus, the measure is in a hold in south-western waters due to the difficulties to implement the ban in mixed fisheries This paper analyzes some possible scenarios which fishers could face under the landing obligation. It is shown the construction of a spatial bio-economic model to infer average costs, incomes and gross profits by fishing ground. We illustrate its use using a coastal trawling fleet based in the northwestern Iberian Peninsula as case study. Results show how fishing ground selection will remain the key factor affecting gross profits, well above the selection of closer fishing grounds, the improvement of fuel efficiency, or extending the length of the fishing trip. Increasing the number of crew members to overcome the expected excess of work time onboard would also be a cost-benefit balanced measure. According to our scenario simulations, to maintain business-as-usual (status quo situation) is the most probable fishing strategy without any regulation change. Fishing strategies are tight and maximized to current economic outcomes. Fishers will be reluctant to change their own fishing unless they are forced to for economic and/or regulatory reasons.

Plano-convex ingots and precious metalwork in northwestern Iberia during the Late Iron Age and early Roman period: an analytical approach

The archaeological study of ingots has gained in importance in recent years due to their links with metallurgical production, pre-monetary exchange and the emergence of weighing systems. However, in the northwestern Iberian Peninsula, which has one of the most outstanding protohistoric precious metalworking traditions in Western Europe, little attention has been paid to this method of accumulating raw material. This article provides the first systematic approach to the chemical composition of the precious metal ingots from this geographical area, based on the elemental analyses of 40 examples datable to the Late Iron Age and the early Roman presence. Two types of ingot composition have been identified: gold-silver-copper alloy and silver. In general, the former do not coincide with those documented in the jewellery from the hillforts (c. fourth–first centuries BC). This means that they could belong to the latest period of this metalworking tradition (c. first century BC–first century AD), when there was frequent use of cores of less valuable metals. In addition to their metallurgical function, silver ingots appear to have played an important role in the proto-monetary economy that characterised the early Roman presence. We propose that the different geographical distribution of these types of ingot was related to the diverse interactional dynamics generated between the local communities and the Romans during the long process of their conquest of this territory (138–19 BC).

A prehistoric jade axe from Galicia (Northwestern Iberia): Researching its origin

The Vilapedre axe (Lugo, Northwest Iberia) has been traditionally considered by archaeologists as evidence of prehistoric long-distance contacts along the Atlantic Coast of France and Spain. This artefact - as other “Tumiac type” axes (long polished blades, generally butt-perforated) - would have been produced in Brittany during the Neolithic (5th millennium BCE) using jadeitite as raw material, a green-coloured rock for which there are sources in the western Italian Alps. In this paper, we have traced the possible archaeological origin of this artefact back by examining the personal files of one of its first owners, Santiago de la Iglesia. Furthermore, we have conducted a mineralogical (X-Ray Diffraction, XRD) and an elemental analysis (Scanning Electron Microscopy with Energy Dispersive X-ray Detection, SEM-EDX) of both the Vilapedre axe and geological samples from several places at the Alps where prehistoric quarrying of greenstones has been reported. The aims were physicochemically characterizing the axe to provide information about its possible geological source. During our analyses, we have found significant compositional similarities between the Vilapedre axe and one of the geological samples coming from the Alps (Alp06). The results are therefore consistent with the alleged Alpine origin of this artefact. The presence of this axe in Northwest Spain, together with other evidence, such as the presence of objects of Iberian origin in Breton monuments, strongly suggests the existence of contacts between both regions of the Atlantic façade during the Neolithic onwards in which seafaring would undoubtedly have played an important role.

Multiple Endmember Spectral Mixture Analysis (MESMA) Applied to the Study of Habitat Diversity in the Fine-Grained Landscapes of the Cantabrian Mountains

Heterogeneous and patchy landscapes where vegetation and abiotic factors vary at small spatial scale (fine-grained landscapes) represent a challenge for habitat diversity mapping using remote sensing imagery. In this context, techniques of spectral mixture analysis may have an advantage over traditional methods of land cover classification because they allow to decompose the spectral signature of a mixed pixel into several endmembers and their respective abundances. In this work, we present the application of Multiple Endmember Spectral Mixture Analysis (MESMA) to quantify habitat diversity and assess the compositional turnover at different spatial scales in the fine-grained landscapes of the Cantabrian Mountains (northwestern Iberian Peninsula). A Landsat-8 OLI scene and high-resolution orthophotographs (25 cm) were used to build a region-specific spectral library of the main types of habitats in this region (arboreal vegetation; shrubby vegetation; herbaceous vegetation; rocks–soil and water bodies). We optimized the spectral library with the Iterative Endmember Selection (IES) method and we applied MESMA to unmix the Landsat scene into five fraction images representing the five defined habitats (root mean square error, RMSE ≤ 0.025 in 99.45% of the pixels). The fraction images were validated by linear regressions using 250 reference plots from the orthophotographs and then used to calculate habitat diversity at the pixel (α-diversity: 30 × 30 m), landscape (γ-diversity: 1 × 1 km) and regional (ε-diversity: 110 × 33 km) scales and the compositional turnover (β- and δ-diversity) according to Simpson’s diversity index. Richness and evenness were also computed. Results showed that fraction images were highly related to reference data (R2 ≥ 0.73 and RMSE ≤ 0.18). In general, our findings indicated that habitat diversity was highly dependent on the spatial scale, with values for the Simpson index ranging from 0.20 ± 0.22 for α-diversity to 0.60 ± 0.09 for γ-diversity and 0.72 ± 0.11 for ε-diversity. Accordingly, we found β-diversity to be higher than δ-diversity. This work contributes to advance in the estimation of ecological diversity in complex landscapes, showing the potential of MESMA to quantify habitat diversity in a comprehensive way using Landsat imagery.

Habitat use and space preferences of Eurasian Bullfinches (Pyrrhula pyrrhula) in northwestern Iberia throughout the year

BackgroundFor all vertebrates in general, a concerted effort to move beyond single season research is vital to improve our understanding of species ecology. Knowledge of habitat use and selection by Eurasian Bullfinches (Pyrrhula pyrrhula) is limited with regard to the non-breeding season. To date, research on the habitat of the Iberian subspecies iberiae consists of very general descriptions. In relation to space use, only broad features are available for the entire distribution range of Eurasian Bullfinches, including Iberia.MethodsIn this study, seasonal preferences regarding habitat and space in a population of Eurasian Bullfinches are examined for the first time in the Iberian Peninsula, through direct observation during a six-year period. The essential habitat components, substrate selection and perch height were assessed.ResultsHedgerows were the key essential habitat component for bullfinches during all seasons. Nevertheless, small poplar plantations became increasingly important from winter to summer-autumn. Bullfinches perched mostly in shrubs/trees throughout the year, but there were significant seasonal changes in substrate use, ground and herbs being of considerable importance during spring-summer. Throughout the year, over half of the records corresponded to feeding, reaching almost 90% in winter. Generally, bullfinches perched noticeably lower while feeding. Male bullfinches perched markedly higher than females, notably singing males in spring-summer. Juveniles perched at a height not much lower than that of males. In all seasons, males tended to feed at greater heights than females. Bullfinches of different ages and sexes were seen bathing in all seasons except winter.ConclusionsHedgerow habitat in general appeared to be valuable for bullfinches throughout the year. In summer and autumn, they selected sites with an abundance of food and shade, as well as shelter, a much-needed requirement for fledglings and moulting individuals. There was usually a close link between the most used and most consumed plant species in each season. Males appeared to assume a more important role in vigilance, and often they accompanied dependent young in June and July. Bullfinch conservation strategies should consider seasonal demand for habitat and space.

Spotting intruders: Species distribution models for managing invasive intertidal macroalgae

Invasive macroalgae represent one of the major threats to marine biodiversity, ecosystem functioning and structure, as well as being important drivers of ecosystem services depletion. Many such species have become well established along the west coast of the Iberian Peninsula. However, the lack of information about the distribution of the invaders and the factors determining their occurrence make bioinvasions a difficult issue to manage. Such information is key to enabling the design and implementation of effective management plans. The present study aimed to map the current probability of presence of six invasive macroalgae: Grateloupia turuturu, Asparagopsis armata, Colpomenia peregrina, Sargassum muticum, Undaria pinnatifida, and Codium fragile ssp. fragile. For this purpose, an extensive field survey was carried out along the coast of the north-western Iberian Peninsula. Species distribution models (SDMs) were then used to map the presence probability of these invasive species throughout the study region on the basis of environmental and anthropogenic predictor variables. The southern Galician rias were identified as the main hotspots of macroalgal invasion, with a high probability of occurrence for most of the species considered. Conversely, the probability of presence on the Portuguese coast was generally low. Physico-chemical variables were the most important factors for predicting the distribution of invasive macroalgae contributing between 57.27 and 85.24% to the ensemble models. However, anthropogenic factors (including size of vessels, number of shipping lines, distance from ports, population density, etc.) considerably improved the estimates of the probability of occurrence for most of the target species. This study is one of the few to include anthropogenic factors in SDMs for invasive macroalgae. The findings suggest that management actions aimed at controlling these species should strengthen control and surveillance at ports, particularly in southern Galician rias. Early detection should be of main concern for risk assessment plans on the Portuguese coast.

Impacts of the invasive plant Carpobrotus edulis on herbivore communities on the Iberian Peninsula

Human activities have facilitated the introduction of invasive plants worldwide, altering habitat structure and leading to substantial effects on biodiversity. However, the effects of plant invasions on herbivore communities are understudied. Here, we examine factors influencing the occurrence of herbivores in ten coastal sites invaded by Carpobrotus edulis in the northwestern Iberian Peninsula. The aims were to evaluate the distribution and abundance of herbivorous invertebrates in different communities (invaded vs. non-invaded), explore the structure of plant–herbivore interaction networks, and assess whether the presence of herbivores affects the performance and fitness of C. edulis. Our results show that herbivore species composition was altered by the presence of C. edulis. Non-invaded plots had a higher number of plant–herbivore interactions and more specialized herbivore species, resulting in a greater degree of specialization. We also found an increase in the number of damaged flowers (florivory) of C. edulis by the native snails Theba pisana and Cornu aspersum. We conclude that C. edulis alters herbivore communities compared with non-invaded plots by changing plant–herbivore interactions and increasing the abundance of herbivores in invaded coastal sites. Snails might reduce seed production of C. edulis, acting as a natural biological control agent. Understanding the impacts of introduced species over invertebrate species at different community levels is crucial for implementing long-term management strategies that are key to reducing the impact of C. edulis on biodiversity.

Cemeteries and State Formation in the Early-Medieval Northwestern Iberian Peninsula

BASED ON A SIGNIFICANT REVIEW of the literature on early-medieval burials in the Northwestern Iberian Peninsula, this paper aims to offer, for the first time, a comprehensive interpretation of funerary practices and their transformations between the 8th and 10th centuries ad, and to discuss their role as useful indicators of the non-linear processes of state formation in this area. Despite some important regional differences, a general trend toward uniformity and centralised control of funerary behaviours can be detected during this period. However, cemeteries also inform us about the complexity and diversity of social agency at local levels behind the wider trend towards uniformity. It is argued here that both local and regional elites in the Kingdom of Asturias promoted this important change in funerary practices, as they did with the network of churches, given the importance of cemeteries as places of power, and the implications that lay behind the creation and control of a common place of inhumation for local communities.

Following the Roman Army between the Southern Foothills of the Cantabrian Mountains and the Northern Plains of Castile and León (North of Spain): Archaeological Applications of Remote Sensing and Geospatial Tools

Sixty-six new archaeological sites have been discovered thanks to the combined use of different remote sensing techniques and open access geospatial datasets (mainly aerial photography, satellite imagery, and airborne LiDAR). These sites enhance the footprint of the Roman military presence in the northern fringe of the River Duero basin (León, Palencia, Burgos and Cantabria provinces, Spain). This paper provides a detailed morphological description of 66 Roman military camps in northwestern Iberia that date to the late Republic or early Imperial eras. We discuss the different spatial datasets and GIS tools used for different geographic contexts of varied terrain and vegetation. Finally, it stresses out the relevance of these novel data to delve into the rationale behind the Roman army movements between the northern Duero valley and the southern foothills of the Cantabrian Mountains. We conclude that methodological approaches stimulated by open-access geospatial datasets and enriched by geoscientific techniques are fundamental to understand the expansion of the Roman state in northwestern Iberia during the 1st c. BC properly. This renewed context set up a challenging scenario to overcome traditional archaeological perspectives still influenced by the cultural-historical paradigm and the pre-eminence of classical written sources.

ARIOS: a database for ocean acidification assessment in the Iberian upwelling system (1976–2018)

Abstract. A data product of 17 653 discrete samples from 3343 oceanographic stations combining measurements of pH, alkalinity and other biogeochemical parameters off the northwestern Iberian Peninsula from June 1976 to September 2018 is presented in this study. The oceanography cruises funded by 24 projects were primarily carried out in the Ría de Vigo coastal inlet but also in an area ranging from the Bay of Biscay to the Portuguese coast. The robust seasonal cycles and long-term trends were only calculated along a longitudinal section, gathering data from the coastal and oceanic zone of the Iberian upwelling system. The pH in the surface waters of these separated regions, which were highly variable due to intense photosynthesis and the remineralization of organic matter, showed an interannual acidification ranging from −0.0012 to −0.0039 yr−1 that grew towards the coastline. This result is obtained despite the buffering capacity increasing in the coastal waters further inland as shown by the increase in alkalinity by 1.1±0.7 and 2.6±1.0 µmol kg−1 yr−1 in the inner and outer Ría de Vigo respectively, driven by interannual changes in the surface salinity of 0.0193±0.0056 and 0.0426±0.016 psu yr−1 respectively. The loss of the vertical salinity gradient in the long-term trend in the inner ria was consistent with other significant biogeochemical changes such as a lower oxygen concentration and fertilization of the surface waters. These findings seem to be related to a growing footprint of sediment remineralization of organic matter in the surface layer of a more homogeneous water column. Data are available at https://doi.org/10.20350/digitalCSIC/12498 (Pérez et al., 2020).