Fuerteventura Research Articles

Miocene rifting of Fuerteventura (Canary Islands)

The older geological units of the volcanic island of Fuerteventura (Canary Islands), i.e., the so‐called basal complex and the lower part of the subaerial volcanic rocks, show abundant structures indicative of a long‐lived period of Miocene tectonic activity. These structures include faults, dike swarms, kilometer‐scale folds, tilted sequences, and fissural and central volcanic edifices. A detailed structural study, based on geological mapping and the use of fault slip inversion techniques and statistical analysis of dike orientation, has allowed the identification of three separated Miocene deformation phases: M‐D1, M‐D2, and M‐D3. The average extension directions determined for these phases are NW‐SE, NNE‐SSW, and ENE‐WSW, respectively. A model of oceanic lithosphere rifting is proposed to account for this deformation history. A buoyant, anomalous sublithosphere mantle triggered the extension in the lithosphere beneath Fuerteventura, isolating it during the early and middle Miocene from the plate‐scale collision regime predominant in the NW corner of the African plate.

Population genetics of Matthiola bolleana (Brassicaceae) in the Canary Islands

Genetic variation at 11 isozyme loci was used to explore the levels and apportionment of genetic variation in the eight known populations of Matthiola bolleana, an endemic Brassicaceae to the Eastern Canarian islands of Fuerteventura and Lanzarote. Within islands, ecosystem antiquity and uniformity, lack of evidence for selection or genetic bottlenecks, the high genetic identities between the populations, and the low values of F ST converge to suggest that the high levels of variation detected have been maintained in a context of prolonged environmental stability through an overall predominance of outbreeding and unrestricted gene flow. Despite the geographical closeness between Fuerteventura and Lanzarote and the long range dispersal features of the propagules of M. bolleana, we detected a striking qualitative genetic differentiation between the two islands. We suggest that wind direction has made seed and pollen flow between Fuerteventura and Lanzarote much less likely than expected, and that the lack of inter-island dispersal has far overriden the influence of stochastic forces and of the reproductive attributes of M. bolleana in shaping the patterns of inter-island genetic differentiation. However, genetic similarity in M. bolleana is within the ranges defined by Canarian taxa for which the extent of genetic differentiation has also been assessed using the values of isozyme genetic identity.

Linking the Canary and Cape-Verde Hot-Spots, Northwest Africa

The Canary and Cape-Verde archipelagos are two groups of volcanic islands often cited as case examples of the surface expression of two distinct hot-spot plumes. However, several considerations that␣we enumerate suggest a link between the two archipelagos. Using seismic profiles we describe a continuous morphological basement ridge that exists between the two archipelagos. We then examine the stratigraphic record available from field data on Fuerteventura Island (Canary) and Maio Island (Cape-Verde) and from a few Deep Sea Drilling Project (DSDP) holes. The geological history of these volcanic islands is very similar since the formation of their oceanic basement during the Late Jurassic. They share the same and synchronious sedimentary evolution (subsidence, uplift and emersion) as well as very similar timing of volcanism and deformation. The two distinct hot-spots model does not appear adapted to account for the formation of these structures as it ignores the existence of the ridge, as well as most of the geological coincidences. By describing the coinciding geological incidents, we argue that it is misleading to treat these two regions apart.

A new Canariella species (Gastropoda: Helicoidea: Hygromiidae) of the new subgenus Majorata, both endemic to the Jandía Peninsula (Fuerteventura, Canary Islands)

Canariella jandiaensis sp. nov. and Canariella (Majorata) subgen. nov. are described from the Jandía Peninsula mountains (Fuerteventura Island). The new subgenus, which includes C. jandiaensis and C. eutropis, is characterized mainly by the following synapomorphies: The shell is without hairs and there is a large penial papilla present arising from all the five epiphallar folds. C. jandiaensis differs from C. eutropis in the unkeeled, almost globular shell, which is smaller but taller than that of C. eutropis and has more numerous but smoother radial ribs. Also, C. jandiaensis has a pseudopapilla in the distal penial cavity instead of the thick longitudinal pilaster present in C. eutropis. The range of Majorata is small, declining from 30,000 years ago and the new species should be classified as “Critically Endangered” based on the very small size of its distribution area (smaller than 1 km2) and the very abundant and free-range livestock present. Mainly goats, grazing freely destroy the habitat in the entire Jandía mountains. Protection of their habitat is recommended, mainly by means of strict livestock control.

Reproduction in an endemic bird of a semiarid island: a food‐mediated process

We analyse the effects of rainfall, temperature, food availability and nest predation on the between‐year variation in reproduction of the Canary Islands stonechat Saxicola dacotiae, a bird species endemic of the semiarid island of Fuerteventura (Canary Islands, Spain). We monitored the reproductive performance and output of the species across its whole distribution area during three consecutive breeding periods, also measuring rainfall, temperature and food (arthropod) availability on the ground monthly. Rainfall varied from 27.3 mm in 2000–2001 (dry year) to 124.5 mm and 125.1 mm (average years), respectively, in the 2001–2002 and 2002–2003 breeding seasons. The onset of breeding closely matched variation in the onset of the autumn‐winter rains among years. Arthropod availability was strongly and positively related to rainfall one month before. Reproductive investment (number of clutches and clutch size) was correlated to arthropod availability both among years and among sites within years. Stonechat pairs bred once or did not breed at all in the dry year whereas they bred twice in the other two years. Clutch size was smaller in the dry year and larger in the second as compared with the first in the other two years. Reproductive investment largely determined reproductive output (number of fledglings) as there were no significant spatial or temporal variation in hatching success (90% on average) or nest predation (29% on average, mostly due to feral cats Felis catus). Within‐ and among years variability in temperature or predation did not match variability in the onset, length or reproductive investment and output recorded throughout the study years. These results suggest that variability in annual fecundity in the Canary Islands Stonechat was mainly driven by rainfall through a food‐mediated process.

The submarine volcanic succession of the basal complex of Fuerteventura, Canary Islands: A model of submarine growth and emergence of tectonic volcanic islands

Three lithostratigraphic units have been distinguished in the volcanic succession of the basal complex of Fuerteventura Island. These units are, from bottom to top: the submarine volcanic group, the transitional volcanic group, and the subaerial volcanic group. These three groups record the submarine growth and emergence of the island. The volcanism is represented by ultra-alkaline and strongly alkaline igneous series. The igneous activity was due to the presence of an anomalous zone in the sublithospheric mantle, the low density of which also caused uplift of the Mesozoic oceanic crust. Two extensional phases and an intervening contractional phase developed coeval to the generation of the volcanic succession. The submarine volcanic group was deposited in the hanging wall basin of a large listric extensional detachment directed toward the SSW. The transitional volcanic group was syntectonic with respect to a late inversion of the listric detachment. Finally, the subaerial volcanic group resulted from a second episode of WNW extension. This study of the evolution of the basal complex of Fuerteventura serves as the basis for a tectonic model of submarine growth and emergence of volcanic islands.

Isotope geochemistry and FOZO mantle component of the alkaline–carbonatitic association of Fuerteventura, Canary Islands, Spain

Carbonatites are very rare in oceanic environments, where they have been reported only at the Canary and Cape Verde islands in the Atlantic Ocean. In the Canary archipelago, calciocarbonatites occur only on the island of Fuerteventura, in clear spatial and temporal association to alkaline silicate rocks, ranging from ultramafic to salic, and comprising alkaline clinopyroxenites, melteigites–ijolites–urtites, nepheline-bearing gabbros and nepheline–syenites, together with their volcanic equivalents. Selected isotopic (Sr, Nd and Pb) data from representative samples of this alkaline–carbonatitic association show a very restricted range of isotopic compositions, with those of the calciocarbonatites overlapping those of the alkaline silicate rocks. Despite the fact that all these rocks display cumulate textures and cover a wide range of SiO 2 and Sr, Nd, Pb contents, initial isotopic compositions are approximately constant and mantle-like, indicating that evolution of the alkaline–carbonatitic association of Fuerteventura must have taken place in the absence of crustal contamination processes. Regarding the mantle source for the alkaline–carbonatitic association, its depleted initial Sr ( 87Sr/ 86Sr = 0.7032–0.7036) and Nd ( 143Nd/ 144Nd = 0.5128–0.5129) compositions, fall on the same trend as the East African young (< 40 Ma) carbonatites. In 143Nd/ 144Nd and 87Sr/ 86Sr vs. 206Pb/ 204Pb diagrams, the alkaline–carbonatitic association of Fuerteventura shows FOZO compositions for Sr and Nd, and slightly higher (towards HIMU) Pb compositions. Furthermore, these data fit the projection of the mantle plane defined by Sr, Nd and Pb isotopic compositions of the DMM, HIMU and EMI components, this fit not being found in sources containing crustal components. In view of this, we propose that the alkaline–carbonatitic association of Fuerteventura was derived mainly from a heterogeneous mantle plume with a deep-seated (FOZO) signature, mixed with HIMU component.

Analysis of the genetic structure of the canary goat populations using microsatellites

A total of 393 individuals belonging to the Canary Goat Group were typed with 27 microsatellites. A mean of 5.91 alleles per population per marker was typed, the gene diversity varied between 0.29 and 0.84 and FIS values between 0.45 and − 0.48. The fixation index FST was only 0.04 demonstrating a poor level of interbreed differentiation. The unrooted neighbour-joining tree was built from Reynolds distances, the individual tree from Das distances and the correspondence analysis detected admixtures between the populations. Microsatellite analysis is one of the best tools to characterize and define a breed and to support the traditional methods for goat breed differentiation based exclusively on morphological criteria. In this way, the existence of four populations in the Canary Goat Group was recognized although poorly differentiated. The Palmera, South Tenerife and North Tenerife have enough genetic evidences to be considered as breeds. Remaining populations from Fuerteventura Island, known as the Majorera breed, and Gran Canaria, Gomera and Lanzarote Islands, known as crossbreed, constitute a homogeneous genetic group, for this reason, all of them should be considered as the same breed. Furthermore it is the most numerous and widespread goat population over the Canary Archipelago.

Divorce in the Canary Islands Stonechat (Saxicola dacotiae)

I report the first case of divorce for the Canary Islands Stonechat (Saxicola dacotiae), an endemic bird species of the semiarid island of Fuerteventura (Canary Islands, Spain). I studied 72 pairs during three breeding seasons (2000–2001, 2001– 2002, and 2002–2003). In 2001–2002, a female divorced after a successful first nesting. This female settled in a neighboring territory where the owner was unpaired, built a new nest, and laid four eggs. The low rate of divorce (1.4%) suggests that unforced mate changes by Canary Islands Stonechats are rare.

Using a genetic algorithm for 3-D inversion of gravity data in Fuerteventura (Canary Islands)

The use of genetic algorithms in geophysical inverse problems is a relatively recent development and offers many advantages in dealing with the non-linearity inherent in such applications. We have implemented a genetic algorithm to efficiently invert a set of gravity data. Employing several fixed density contrasts, this algorithm determines the geometry of the sources of the anomaly gravity field in a 3-D context. The genetic algorithms, based on Darwin’s theory of evolution, seek the optimum solution from an initial population of models, working with a set of parameters by means of modifications in successive iterations or generations. This searching method traditionally consists of three operators (selection, crossover and mutation) acting on each generation, but we have added a further one, which smoothes the obtained models. In this way, we have designed an efficient inversion gravity method, confirmed by both a synthetic example and a real data set from the island of Fuerteventura. In the latter case, we identify crustal structures related to the origin and evolution of the island. The results show a clear correlation between the sources of gravity field in the model and the three volcanic complexes recognized in Fuerteventura by other geological studies.

Geologic evolution of the Canarian Islands of Lanzarote, Fuerteventura, Gran Canaria and La Gomera and comparison of landslides at these islands with those at Tenerife, La Palma and El Hierro

In this paper we discuss the results of a swath bathymetric investigation of the Canary archipelago offshore area. These new data indicate that volcanism is pervasive throughout the seafloor in the region, much more that would be suggested by the islands. We have mapped tens of volcanic edifices between Fuerteventura and Gran Canaria and offshore Tenerife, La Gomera, El Hierro and La Palma. Volcanic flows are present between Tenerife and La Gomera and salic necks dominate the eastern insular slope of La Gomera. This bathymetry also supports land geologic studies that indicate that the oceanic archipelago has acquired its present morphology in part by mass wasting, a consequence of the collapse of the volcanic edifices. In the younger islands, Tenerife, La Palma and El Hierro, the Quaternary (1.2 to 0.15 Ma) debris avalanches are readily recognizable and can be traced offshore for distances measured in tens of km. Off the older islands, Lanzarote, Fuerteventura, Gran Canaria and La Gomera (<20 to 3.5 Ma), the avalanches have been obscured by subsequent turbidity current deposition and erosion as well as hemipelagic processes. The failure offshore western Lanzarote is in the form of a ramp at the base of the insular slope bound on the seaward side by a scarp. Its size and the lack of evidence of rotation along its landwards side precludes the possibility that it is a slump. It probably represents a slide whose outer scarp is caused by break-up of the slide. Mounds on the ramp’s surface may represent post-displacement volcanic structures or exotic blocks transported to their present locations by the slide. The failures offshore Fuerteventura are so large that, although they occurred in the Miocene-Pliocene, exotic blocks displaced from upslope are still recognizable in the insular margin morphology. The Canary Island insular margin appears to be a creation of Miocene-Pliocene mass wasting and more recent turbidity current deposition and erosion, and hemilepagic deposition. Failures offshore La Gomera are due to debris flows and/or turbidity currents. These events have obscured earlier mass wasting events.

An Epizootic of Avian Pox in Endemic Short-toed Larks (Calandrella rufescens) and Berthelot's Pipits (Anthus berthelotti) in the Canary Islands, Spain

Between January 2002 and November 2003, 50% (n = 395) of short-toed larks (Calandrella rufescens) and 28% (n = 139) of Berthelot's pipits (Anthus berthelotti) examined on the islands of Fuerteventura and Lanzarote, Canary Islands, had gross lesions compatible with avian pox. However, Spanish sparrows (Passer hispaniolensis, n = 128) and trumpeter finches (Bucanetes githagineus, n = 228), which inhabit the same steppe habitats associated with goat husbandry, did not have poxlike lesions. Histopathology and electron microscopy confirmed poxvirus in the lesions, whereas serology using standard, fowl poxvirus-and pigeon poxvirus-based diagnostic agar gel immunodiffusion techniques was negative, likely because of the limited (74.6% pipit; 74.9% lark) similarity between the viruses in our species and fowlpox virus on which the serologic tests rely. On the basis of polymerase chain reaction analyses, the virus isolated from dried lesions of C. rufescens has 80.5% similarity with the virus isolated from A. berthelotti and 91.3% similarity with canarypox, whereas A. berthelotti poxvirus has only 80% similarity with canarypox. We have two distinct and possibly new avian poxviruses. Both poultry and the wild birds on the farms were heavily infested by fleas, which may have acted as vectors in transmission of poxvirus. Disease prevalence in these Canary Island passerines is higher than that described in song birds in Hawaii that are now threatened, endangered, or extinct. Environmental and biological factors contributing to increased disease susceptibility of these isolated populations must be investigated.

Análisis del riesgo volcánico asociado al flujo de lavas en Tenerife (Islas Canarias): escenarios previsibles para una futura erupción en la isla

The spatial and temporal distribution of volcanic eruptions in the Canarian Archipelago are a consequence of their origin and evolution, in response to hotspot activity. Therefore, the probability that eruptive phenomena will occur is greater in the western islands (Tenerife, La Palma and El Hierro), the closest to the hotspot vertex, where hundreds of eruptions have been localized in the last 20.000 years. By contrast, in La Gomera (presently in the volcanic repose stage) and in the easterly islands of Gran Canaria, Fuerteventura and Lanzarote (the most distant and oldest, in the post-erosive stage of development), few eruptions, if any, have taken place during this period. Rift structures known as «dorsals» have been defined in the more active westerly islands, where the greater part of the recent volcanic activity has been concentrated. Objective data therefore exist that permit the assessment and zonification of eruptive hazards in the archipelago. In this work the assessment of volcanic hazards in the island of Tenerife is presented, whichare concentrated in the volcanic system formed by the central edifice of Mt. Teide and the Northwest Rift. Numerous radiometric datings (14C and K/Ar) and the preparation of detailed digitalized and georeferenced geological mapping (GIS) have permitted an initia1 analysis and assessment of the volcanic hazards in this island, which presents the greatest risk of eruptions because of the number of recent eruptions and their complexity, in addition to demographic density.

Extraction of PCDDs from Marine Sediments Using Polyoxyethylene 10 Lauryl Ether and Oligoethylene Glycol Monoalkyl Ether Surfactants

In this study, the microwave assisted micellar extraction (MAME) methodology has been optimised to extract and determine a mixture of nine polychlorinated dibenzo‐p‐dioxins (PCDD) from marine sediments. This is a very efficient extraction procedure which considerably reduces the volume of extractant to be used and the analysis time. The PCDDs under study have been extracted using the non‐ionic surfactants polyoxyethylene 10 lauryl ether (POLE) and oligoethylene glycol monoalkyl ether (Genapol X‐080), which are biodegradable, meaning that the toxical effects of the method have been avoided. The optimal extraction variables, such as surfactant and salt concentration, together with the radiation time and microwave power, were determined for each surfactant and then compared. To get the benefit of the properties that non‐ionic surfactants possess, in order to obtain a better signal of the analytes under study, the Genapol X‐080 extracts were then preconcentrated using the cloud‐point methodology, and analysed by liquid chromatography with UV detection system under the optimised conditions. The proposed method was applied to marine sediment samples from Gran Canaria and Fuerteventura islands (Canary Islands, Spain). The results were then compared with those obtained using the traditional Soxhlet extraction methodology.

Plant succession and soil degradation in desertified areas (Fuerteventura, Canary Islands, Spain)

The eastern Canary Islands constitute a region that is vulnerable to desertification processes, mainly due to its intensely arid climate and the action of man. Vegetation in the island of Fuerteventura has been profoundly transformed over the last few hundred years, and the greater part of the insular territory is presently covered by substitution brush. In this work, a study of soil degradation processes relating to plant cover transformation is presented. To this end, soils that characterize the present-day countryside of the island and those associated with enclaves of original vegetation are studied, and the sequential variation of soil properties along the plant succession is established by means of multivariant analysis of environmental gradients. The results indicate that the original vegetation was established on soils with a low natural quality, severely limited by natural aridity, salinity and sodicity as well as the water and wind erosion processes dominant in the island. These same ecological factors condition the quality of the island's present soils, although the degradation of the plant cover has increased the severity of several soil degradation processes, particularly those of a physical and biological nature.

The impact of water harvesting on soil properties in the island of Fuerteventura, Spain

The impact of water harvesting on soil properties in the island of Fuerteventura, Spain

The impact of water harvesting on soil properties in the island of Fuerteventura, Spain

Abstract. In the extremely arid island of Fuerteventura (Canary Islands, Spain), a traditional water harvesting practice has evolved in slightly sloping areas, which receive runoff water from time to time. The system is particularly effective in the rehabilitation of saline–sodic soils where the improved fertility allows certain crops to be grown, which would not be possible without water harvesting. The influence of the water harvesting on soil fertility was investigated by comparing the properties of the cultivated soils receiving periodic runoff with those of natural control soils that did not receive runoff. The saline–sodic characteristics of the four uncultivated soils were absent from the four cultivated soils which, on average, contained only one quarter of the exchangeable sodium and more than twice the exchangeable calcium content. The clay and silt content of all four of the cultivated soils had been substantially enhanced relative to the control soils, by sediment contained in the runoff.

Sexual Dimorphism of Gallotia atlantica atlantica and Gallotia atlantica mahoratae (Lacertidae) from the Eastern Canary Islands

I examined sexual dimorphism in the lacertids Gallotia atlantica atlantica and Gallotia atlantica mahoratae from Lanzarote and Fuerteventura Islands, respectively. Mean body size was smaller in G. a. mahoratae than in G. a. atlantica. Sexual size dimorphism was greater in G. a. atlantica than in G. a. mahoratae, but relative size of several morphological traits was not different between the two populations. In both subspecies, head and body traits scaled to SVL, with head size of males having a positive allometry, indicating a disproportionate increase of this trait with the increase in body size. Relative size in hind-limb length was greater in males than in females in G. a. atlantica but not in G. a. mahoratae.

Geologic evolution of the Canarian Islands of Lanzarote, Fuerteventura, Gran Canaria and La Gomera and comparison of landslides at these islands with those at Tenerife, La Palma and El Hierro

Geologic evolution of the Canarian Islands of Lanzarote, Fuerteventura, Gran Canaria and La Gomera and comparison of landslides at these islands with those at Tenerife, La Palma and El Hierro

Operating results of a wind–diesel system which supplies the full energy needs of an isolated village community in the Canary Islands

Following is a discussion of the operational strategies of a wind–diesel system which has been installed in an isolated fishing village community on the island of Fuerteventura in the Canarian Archipelago. The project was implemented with the aim of meeting the complete energy requirements of the community: street lighting and domestic consumption, desalination plant, freezer plant, sewage water purifier, hydrocompressor for the supply of potable water and a winch for small vessels. An analysis is also made of the results which were obtained with respect to the quality of the service supplied, the percentage of wind penetration in the system, fuel savings and the decrease of CO 2 emissions into the atmosphere. A comparison of these results has also been made with the corresponding estimated figures for the performance of the system when originally designed. The conclusion is drawn that, from a technical point of view, the system that has been developed supplies all the service needs of the community on a regular basis with an acceptable level in the quality of the energy and a substantial improvement in the quality of the environment. This is a contributing factor to providing a satisfactory level in the quality of life for the inhabitants of the community.