Gran Canaria Research Articles

Stranding of Mesopelagic Fishes in the Canary Islands.

Most mesopelagic fishes perform large diel vertical migrations from the deep-sea zone to the surface. Although there is a trade-off between a higher food availability at the upper layers and an energy cost and predation risk, incursion towards the surface also implies a transport by currents, where the fish are exposed to a stranding risk on the coast. Here, we reported the first documented stranding of mesopelagic fishes along the southeast shore of Gran Canaria Island. Our study hypothesized that (1) the influence of the Canary Current, (2) the dominant incidence of the Trade Winds during summer, and (3) the presence of an upwelling filament coupled with an anticyclonic eddy south of Gran Canaria Island were the causative mechanisms of the strandings. Diaphus dumerilii (Myctophidae family) was the main species found as observed from an external morphological analysis using traditional taxonomy. The otolith contour analysis suggested the presence of other Diaphus spp. and Lobianchia dofleini. Nevertheless, the otolith morphological features described in the literature suggested that all the specimens were actually D. dumerelii. Errors in the identification were mainly due to the high intraspecific variability found in the otolith morphology. Even so, two patterns of oval and elliptic shapes were described with significant differences in its morphometry.

Microplastics ingestion and chemical pollutants in seabirds of Gran Canaria (Canary Islands, Spain)

Plastic pollution constitutes an environmental problem in the Canary Islands nowadays. Nevertheless, studies evaluating the impact of plastics on its avifauna are still scarce. Gastrointestinal tracts of 88 birds belonging to 14 species were studied for the presence of plastics. Moreover, their livers were analyzed for the determination of bromodiphenyl ethers (BDEs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs). Among Cory's shearwaters (n = 45), the frequency of occurrence of plastic ingestion was considerably high (88.89 %). This species had the highest mean value of items (7.22 ± 5.66) and most of them were compatible with lines derived from fishing gear. PCBs and PAHs were detected in all of the samples and OCPs in the great majority of them (98.86 %). Our results highlight the problems that plastic debris (mainly for seabirds) and organic pollutants pose to these species.

Valorization of Seaweed Wracks: Inclusion as Additive in Diets for Grass Carp (Ctenopharyngodon idella).

Macroalgae have been recently described as a potential ingredient for aquafeeds, exerting several physiological benefits. Grass carp (Ctenopharyngodon idella) is a freshwater species, which has been the major fish species produced in the world in the last years. In order to determine the potential use of macroalgal wracks in fish feeding, C. idella juveniles were fed with an extruded commercial diet (CD) or the CD supplemented with 7% of a wind dried-powder (1 mm) from either a multispecific macroalgal wrack (CD + MU7) or a monospecific macroalgal wrack (CD + MO7) obtained from Gran Canaria island (Spain) coasts. After 100 days of feeding, survival, fish weight, and body indexes were determined, and muscle, liver, and digestive tract samples were collected. The total antioxidant capacity of macroalgal wracks was analyzed by assesing the antioxidant defense response and digestive enzymes activity in fish. Finally, muscle proximate composition, lipid classes (LC), and fatty acid (FA) profiles were also studied. Our results suggest that dietary inclusion of macroalgal wracks does not have negative effects on growth, proximate, and lipid composition, antioxidative status, or digestive capacity of C. idella. In fact, both macroalgal wracks caused a general lower fat deposition, and the multispecific wrack enhanced catalase activity in the liver.

The explosive-effusive transition within the Miocene Fataga suite, Gran Canaria

Many volcanoes show transitions between explosive and effusive eruptive styles both through the history of the volcano as a whole and occasionally within the course of a single eruption. These differing eruptive styles have vastly different implications for hazard assessments in surrounding regions and so understanding such changes is important. Here, we investigate the intercalated lavas and ignimbrites of the Miocene Fataga Group on the island of Gran Canaria, Spain. Ignimbrites reflect the products of explosive events from the Tejeda caldera, while lavas found within the pyroclastic succession were erupted from extra-caldera sources some 5–10 km from the caldera margin. The ignimbrites exhibit textural complexity containing both crystal-poor juvenile pyroclasts and late-erupted crystal-rich juvenile clasts interpreted to reflect interaction between cumulates and recharge magmas. The lavas meanwhile are almost phenocryst-free, with the exception of few large (cm-scale), unzoned sanidine crystals. Despite their textural differences, the lavas are geochemically similar (in terms of bulk rock and feldspar compositions) to the crystal-poor juveniles in the ignimbrites. Oxygen and lead isotopic compositions of the lavas and surrounding ignimbrites reveal that the magmas shared a deeper source and that petrographic variability is imprinted upon the magmas at shallow levels. We interpret the lavas as originating from peripheral magmatic pockets, on the edges of the main caldera-feeding reservoir. These peripheral magma chambers felt the effects of recharge only as slight thermal fluctuations that fostered the production of the large sanidine crystals. Our findings highlight the potential for storage of magmas aside from the main magmatic system that may represent an underappreciated hazard at volcanoes worldwide.

Water table dynamics of dune slacks in an arid zone

In this study, a characterisation is undertaken of the humid dune slacks water table situated in the arid transgressive coastal dune field of the Maspalomas Special Area of Conservation, ES701007 (Gran Canaria, Canary Islands, Spain). Humid dune slacks are listed as a European Union Habitat (EU Habitat 2190 humid dune slacks) in Annex I of the EU Habitats Directive. This water table is relatively stable throughout the year, with a 41 cm maximum oscillation. The annual dynamics of the flow pattern and water table level depend on the climate conditions. At the end of the hydrological dry season the mean water table drops (ca. 11 cm) and water flows to the lagoon. After rains, the mean water table level rises (ca. 4 cm) and flows towards the Maspalomas beach. The distribution of plant communities (associated to EU Habitat 2190) in the Maspalomas humid dune slacks depends on water table depth, pH and salinity. The knowledge acquired in this study of the water table dynamics has enabled a better understanding of the spatial distribution patterns of the vegetation of these slacks, in particular with respect to the relationship between the water table flux toward the coast during the dry season and the distribution of plant communities in the slacks closest to the coast. The study of the dynamics of the water table of the slacks and the associated vegetation has allowed us to better understand the characteristics of the Maspalomas humid dune slacks and potentially improve their management as EU Habitat. This is especially significant considering that the only European arid climate dune field where this habitat can be found is in Maspalomas.

Accurate assessment of walking energy expenditure in the main seafront walking route of Las Palmas de Gran Canaria to promote health-related tourism

Accurate assessment of walking energy expenditure in the main seafront walking route of Las Palmas de Gran Canaria to promote health-related tourism

Ambient noise tomography of Gran Canaria island (Canary Islands) for geothermal exploration

Ambient noise tomography (ANT) has proved to be efficient in resolving crustal structures for different purposes. Despite the numerous studies carried out in Gran Canaria in the past for purposes of geothermal exploration, ANT had never been used before on this island. We applied this technique to understand Gran Canaria island’s shallow structure, determining the 3-D S-wave velocity model of the island and focusing on its implications for geothermal exploration. We used data from 30 seismic stations installed between October 2019 and February 2020. Our findings revealed five relevant velocity anomalies helpful in understanding the island’s geology and its geothermal potential. In particular, we identified two high-velocity anomalies in the central part of the island aligned with the primary northwest–southeast structural trends of Gran Canaria. We interpret them as evidence of intrusive volcanic bodies emplaced during the early stages of the island’s geological history. We also identified three low-velocity zones located in different parts of the island. We maintain that these anomalies could be associated with porous and highly fractured materials produced during the more recent volcanic episodes. In addition, we observed a spatial correlation of anomalies in the electric conductivity identified in previous studies and strong lateral gradients in our S-wave velocity model. We interpret them as evidence of hydrothermal circulation and thermal anomalies in correspondence of lateral contacts between different geological units and/or faults.

Assessment of the Retrofit Strategies on Thermal Insulation Applied in Buildings Located on the Southern Border of the EU: The Case of the Canary Islands

Nowadays, a large amount of the total primary energy is consumed by buildings, accounting for about 40% of the total energy demand. Aligned with the EU objectives and the strategies to reduce the demand, cooling and heating are stated as the most energy consuming processes and the building envelope plays an important role to reduce the energy consumption. In this work, the energy demand related to heating and cooling in a typical building has been evaluated, which has been simulated in 35 cities located in different climatic zones, using the DesignBuilder v.6.1.7.007 software. Although the increase in insulation and the replacement of windows lead to a reduction in energy demand, in the case of the cities of Santa Cruz de Tenerife and Las Palmas de Gran Canaria without insulation, the demands are lower than 1.7 kWh/m2/year and 5 kWh/m2/year, respectively, and these results indicate that energy saving strategies, driven by policies and economic support, based on the renovation and improvement of the thermal insulation of the building envelope, are not the most appropriate due to the need for an additional energy load for cooling and to maintain comfort within the regulatory limits.

Long-Term Performance of a Hybrid-Flow Constructed Wetlands System for Urban Wastewater Treatment in Caldera de Tirajana (Santa Lucía, Gran Canaria, Spain).

This paper describes the results that have been obtained in a real case study of a hybrid constructed wetlands system, which has been in continuous operation for over 11 years. The main aim of the study was to understand the long-term operation and efficiency of the system (which is situated in the municipality of Santa Lucía, Gran Canaria, Spain), which comprises two vertical-flow and one horizontal-flow constructed wetlands for the treatment of urban wastewater. The system, which was originally designed to treat a flow rate of 12.5 m3/day, with a load of 100 equivalent inhabitants, has been operating since its inauguration (July 2008), with a flow rate of almost 35 m3/day and a load of 400 equivalent inhabitants. Despite this, the mean total removal efficiencies during the study period (2014-2019) are optimal for a system of these characteristics, as follows: 92% for 5-day biochemical oxygen demand (BOD5), 89% for the chemical oxygen demand (COD), and 97% for the total suspended solids (TSS). The system efficiency, with respect to nutrient removal, was somewhat lower, resulting in 48% for total N and 35% for NH4. It has been confirmed with this study that this type of system is an appropriate, robust, resilient nature-based solution for the treatment of the wastewater that is generated in small communities, especially in zones with a warm climate, stable mean temperatures, and mild winters.

Rural tourism activities in mass tourism destinations: residents vs non-residents perspectives

Actividades de turismo rural en destinos de turismo de masas: Perspectivas de residentes vs no residentesResumenObjetivo Este trabajo examina las preferencias del turismo rural como nicho de mercado alternativo a los destinos turísticos de masas. El análisis discute las diferencias en las percepciones y la disposición a pagar por varios paquetes de actividades de turismo rural en la isla de Gran Canaria entre residentes y no residentes.Diseño/metodología/enfoque El análisis se basa en una muestra de conveniencia de potenciales clientes jóvenes que están familiarizados con las actividades recreativas al aire libre en la naturaleza. El estudio considera un experimento de elección discreta que incluye el tipo de alojamiento, así como cuatro tipos de actividades de turismo rural: activo, pasivo, cultural y acuático. El grado de preferencia por los atributos considerados se obtiene a partir de la estimación de diferentes modelos de elección discreta.Resultados Los resultados revelan que la inclusión de los atributos investigados en los paquetes vacacionales aumenta la utilidad de los turistas, lo que motiva la promoción del turismo rural para jóvenes residentes y no residentes. Las diferencias más significativas en las percepciones de los atributos entre residentes y no residentes se encontraron en las actividades de buceo/snorkel y observación de estrellas, así como en el tipo de alojamiento y el precio del paquete.Originalidad Hasta donde los autores saben, este es el primer estudio que evalúa la disposición a pagar por paquetes de turismo rural como una alternativa más sostenible en destinos de turismo masivo y que tiene en cuenta las percepciones de los residentes frente a los no residentes.Implicaciones prácticas El estudio contribuirá a una mejor comprensión de un mercado turístico alternativo que ayudará a los principales agentes del sector turístico a atender mejor este importante segmento de la industria y a fomentar un turismo más sostenible en el futuro.

Between art and ritual

This article analyses the short performances of Drag Sethlas at the yearly Gran Canaria Drag Queen Contest in Spain (2017–20) from the perspective of religious studies and gender studies, following on from an earlier article in which this case was explored in light of the severe blasphemy accusations (by local and national bishops and lay organisations) against the 2017 show. These short performances consist of remarkable representations of Roman Catholic texts, saints, symbols and rituals acted out as prize-winning drag-queen shows that were aired on national television. At the same time, these acts are situated, by reference to famous earlier controversial acts by the pop artists Madonna, Lady Gaga and Ariana Grande, in a genealogy of provocations and blasphemy accusations that are currently made in North American and Western European countries. In exploring the forms of ritualisation (cf. Bell 1989) in the provocation that this type of popular artistic performance with strong religious connotations evokes, I show the presence of a double theatricality in Sethlas’s first and most controversial performance: on the one hand a ‘holy drama’ centred around a religious pattern of penance, repentance and redemption, and on the other hand a specific drag theatricality, with its parodies, mockery and daring erotic scenes. It is precisely the connection between both forms of theatricality, especially the representation of the Virgin Mary and Jesus, who play a large and special role in both forms of theatricality, that contributes most to the provocativeness of this scene.

New molecular evidence for Canarian endemicRuta(Rutaceae: Ruteae) reveals a complex evolutionary history and overlooked diversification processes

AbstractWe studied four currently recognized endemics of Ruta (Rutaceae) from the Canary Islands, an oceanic biodiversity hotspot, to identify genetic variation, reconstruct evolutionary relationships and clarify the taxonomic delimitation of several recently discovered populations. We analysed four plastid DNA regions for a thorough population sampling of Ruta oreojasme on Gran Canaria, R. pinnata on Tenerife and La Palma and R. microcarpa and the only known population of the recently described R. nanocarpa on La Gomera. Bayesian clock dating analysis, haplotype network and ancestral area reconstructions were carried out. Our results reveal a complex, extremely dynamic and largely overlooked pattern of colonization and evolutionary history of Ruta in the archipelago. Thirty haplotypes were found, but only one of them was shared across more than one island. Species divergence and all colonization events in the Canary Islands were dated from the late Pliocene to the Pleistocene, and R. oreojasme has an earlier origin than its Canarian congeners. Multiple secondary colonization events between and within islands account for the diversification of R. pinnata and R. microcarpa. Our data cannot discard a possible independent origin of R. oreojasme and do not support the currently accepted circumscription of R. pinnata and R. microcarpa. Rather, the high levels of genetic differentiation detected suggest the existence of ongoing diversification processes and of new taxa. Urgent population-level conservation efforts should be undertaken, especially focused on the single population on La Gomera that can be attributed to R. microcarpa, R. nanocarpa and genetically distinct populations from La Palma and the palaeo-islands of Tenerife.

Small Ultrasound-Based Corrosion Sensor for Intraday Corrosion Rate Estimation

The conventional way of studying corrosion in marine environments is by installing corrosion coupons. Instead, this paper presents an experimental field study using an unattended corrosion sensor developed on the basis of ultrasound (US) technology to assess the thickness loss caused by general atmospheric corrosion on land close to the sea (coastal region). The system described here uses FPGA, low-power microcontroller, analog front-end devices in the sensor node, and a Beaglebone black wireless board for posting data to a server. The overall system is small, operates at low power, and was deployed at Gran Canaria to detect the thickness loss of an S355 steel sample and consequently estimate the corrosion rate. This experiment aims to demonstrate the system's viability in marine environments and its potential to monitor corrosion in offshore wind turbines. In a day, the system takes four sets of measurements in 6 hour intervals, and each set consists of 5 consecutive measurements. Over the course of 5 months, the proposed experiment allowed for us to continuously monitor the corrosion rate in an equivalent corrosion process to an average thickness loss rate of 0.134 mm/year.

Boundary element model for the analysis of the dynamic response of the Soria arch dam and experimental validation from ambient vibration tests

This paper presents a 3D boundary element time–harmonic model for the analysis of the dynamic behavior, under low-level vibrations, of the Soria arch dam (Gran Canaria, Spain). The model takes into account dynamic Soil–Structure Interaction (DSSI), Fluid–Structure Interaction (FSI) and the actual geometry of dam wall and reservoir. The rock and the dam wall are considered as viscoelastic regions, and the water in the reservoir is modeled as an inviscid fluid. The influence of DSSI, FSI, height of the water in the reservoir, accuracy of the geometric modeling of the canyon, and type of transmitting boundary conditions at the truncated end of the reservoir, are evaluated. DSSI and FSI have a significant influence on the dynamic response of the dam, and the accurate representation of the geometry of the canyon is relevant for the correct estimation of the modal shapes. Ambient vibrations tests were also performed, from which the first and third modes could be clearly identified. The comparison between the experimental and numerical natural frequencies and mode shapes suggests that the proposed complete numerical model is able to capture the dynamic response and can be used for the structural health monitoring of the wall of this dam.

Imaging the Volcanic Structures Beneath Gran Canaria Island Using New Gravity Data

AbstractFrom a new gravity data set that covers homogeneously the whole surface of Gran Canaria (Canary Islands, Spain) and marine gravity data in the nearest offshore, we have obtained a Bouguer anomaly gravity map of the island which improves the previous ones. Using these gravity anomalies, we have applied a gravity inversion approach to investigate the structures beneath the surface of Gran Canaria Island and derive a 3D gravity sources model. The geometry of structures with anomalous density values is constrained up to a depth of approximately 20,000 m below the sea level. The interpretation of the density model identified structures related to the different volcanic stages of Gran Canaria. Several deep‐rooted high‐density structures represent the intrusive bodies emplaced in the early formation of Gran Canaria and the magma plumbing system of the Miocene volcanic edifices. A low‐density body in the center of the island may be associated with the syenitic core of the felsic central volcanic edifice (Tejeda Caldera). Shallow low‐density structures identified fractures which acted as feeder dikes of monogenetic volcanoes during the rejuvenated stage. Finally, the NW‐SE rift, which is the most important volcano‐tectonic structure of Gran Canaria, has a characteristic gravimetric signature and represents a long‐lived extensional fracture zone that has controlled the volcanic activity at least since the Miocene.

Coupling phenotypic changes to extinction and survival in an endemic prey community threatened by an invasive snake

When facing novel invasive predators, native prey can either go extinct or survive through exaptation or phenotypic shifts (either plastic or adaptive). Native prey can also reflect stress-mediated responses against invasive predators, affecting their body condition. Although multiple native prey are likely to present both types of responses against a single invader, community-level studies are infrequent. The invasive California kingsnake (Lampropeltis californiae) a good example to explore invasive predators’ effects on morphology and body condition at a community level, as this invader is known to locally extinct the Gran Canaria giant lizard (Gallotia stehlini) and to notably reduce the numbers of the Gran Canaria skink (Chalcides sexlineatus) and the Boettger’s gecko (Tarentola boettgeri). By comparing a set of morphological traits and body condition (i.e. body index and ectoparasite load) between invaded and uninvaded areas for the three squamates, we found clear evidence of a link between a lack of phenotypic change and extinction, as G. stehlini was the single native prey that did not show morphological shifts. On the other side, surviving C. sexlineatus and T. boettgeri exhibited phenotypic differences in several morphological traits that could reflect plastic responses that contribute to their capacity to cope with the snake. Body condition responses varied among species, indicating the potential existence of simultaneous consumptive and non-consumptive effects at a community level. Our study further highlights the importance addressing the impact of invasive predators from a community perspective in order to gain a deeper understanding of their effect in native ecosystems.

Ex vivo evaluation of adhesive strength and barrier effect of a novel treatment for esophagitis

AimTo investigate the mucoadhesive strength and barrier effect of Esophacare® (Atika Pharma SL, Las Palmas de Gran Canaria) in an ex vivo model of gastro-oesophageal reflux. MethodsAn ex vivo evaluation through the Falling Liquide Film Technique with porcine esophagi was performed, compared to a positive control (Ziverel®; Norgine, Amsterdam), after different washing periods with saline, acidified saline (pH 1.2) and acidified saline with pepsin (2000U/mL). ResultsThe adhesive mean strength on the oesophageal mucosa of Esophacare was 94.7 (6.0)%, compared to 27.6 (19.1)% of the positive control (p<0.05). These results were homogeneous across the different washes and throughout the tissue. The area covered by 1mL of Esophacare, and its respective persistence after washing was also assessed, yielding a mean global persistence of 74.29 (19.7)% vs. 18.9 (12.3)% for the control (p<0.05). In addition, after 30min exposure to acidified saline with pepsin, Esophacare shows a protective effect on the oesophageal mucosa, detectable histologically: preserved integrity and structure of the apical layers was observed, as well as reduced permeability to the washing solution. ConclusionsEsophacare shows an adhesive strength close to 100%, irrespective of the washing solution applied or the oesophageal region studied. Histologically, it reduces the abrasive effects of the acidic solution on the oesophageal epithelium, reducing permeability to the washing solution. The results in this ex vivo model of gastro-oesophageal reflux disease (GERD) support its therapeutic potential.

Monkeypox and HIV in the Canary Islands: A Different Pattern in a Mobile Population.

Background. The clinical and epidemiological data of the recent outbreak of monkeypox (MPX) differ from previous reports. One difference is the epidemiological profile; the disease mainly affects a subgroup of MSM (men who have sex with men) with high-risk sexual behaviors, frequently persons living with human immunodeficiency virus (PLHIV). Methods. In this observational analysis, all patients with PCR (polymerase chain reaction)-confirmed MPX attending an Infectious Diseases and Tropical Medicine Unit in Gran Canaria (Spain) between May and July 2022 were considered. Results. In total, 42 men were included; 88% were identified as MSM, with a median age of 40 years. Only 43% were born in Spain. All the patients had systemic symptoms and skin lesions. The distribution of lesions was more frequent in the genital/anal region, and the involvement of hands and feet was less common. Fever and lymphadenopathies were less frequent than in other series. Other unusual manifestations were proctitis, pharyngitis and penile–scrotal edema. Half of the patients had other associated infections (mainly STIs, sexually transmitted infections), and 60% of the monkeypox patients had PLHIV (People Living with HIV). When comparing the clinical characteristics between HIV-positive and -negative patients, we found three main differences: (i) a higher frequency of perioral lesions, (ii) a higher frequency of pharyngitis and (iii) a higher number of sexually transmitted infections in HIV-positive patients. Conclusions. The clinical findings in this outbreak of MPX had great variability in presentation. Several clinical differences were found in PLHIV-coinfected patients.

It’s worth it! High performance work systems for employee job satisfaction: The mediational role of burnout

This study aims to analyse the mechanisms through which high performance work systems (HPWSs) affect employee job satisfaction in hospitality firms. A sample of 202 hotel employees working on Gran Canaria (Spain) was surveyed, and partial least squares structural equation modelling was applied to analyse the data. The results confirmed both the direct positive effect of HPWSs on job satisfaction and the indirect effect through a reduction in burnout. This study provides the first evidence of burnout as a mediating mechanism in the so-called black box that relates HPWSs to employee outcomes in the context of tourism and hospitality, and it contributes to the field with important theoretical contributions, as well as managerial recommendations.

A distributive environmental justice index to support green space planning in cities

Environmental justice (EJ) raises concerns about just allocating environmental harms and goods. It has been mainly analysed from a distributive lens through indicators and screening tools that have underlined communities' proximity to pollution and risk sources. However, for urban areas, existing gaps relate to the need for more comprehensive assessments of green space benefits distribution (e.g., flood mitigation, air pollution control and recreation, etc.) as well as aligning EJ indicators to local planning and policy efforts for simultaneously addressing planning issues and reinforce the evaluation of existing unjust realities.To address these issues, we developed a composite distributive environmental justice index (DEJI) structured into three sub-indices that reflect locally relevant patterns of environmental risks, disadvantaged communities, and the provision of green space benefits. The construction of this index also relies on a qualitative content analysis of planning and policy documents to contextualise EJ priorities relevant to the planning administration, and a detailed methodological rationale for composite indicator building. Applying the DEJI in Las Palmas de Gran Canaria (Spain) at the census tract level, we identified a complex city-wide pattern of distributive injustices driven by the historical segregation patterns of insular contexts. Based on our results, we discuss how using the DEJI could help planning and policymakers reach specific goals, including those related to enhancing greening interventions in urban areas. Moreover, we argue that EJ composite indicators are needed to support environmentally just trajectories in cities with realities and planning patterns different from those found in mainland territories.