Island Of Mallorca Research Articles

From Roman to Byzantine: The Rural Occupation of Eastern Mallorca (Balearic Islands)

This paper explores the Late Antique occupation of rural territories in the eastern part of the island of Mallorca (Balearic Islands). Data and ceramics from several old field surveys have been re-analysed and different spatial analyses have been carried out in order to understand better the settlement patterns in this area of variable geomorphology, which includes plains, hills and coastlands. Evidence of Late Roman, Vandal and Byzantine occupation is discussed. The study of the ceramic materials enables us to investigate differences between the various historical periods of Late Antiquity on the island. The results show a significant decrease of occupied sites in the Late Roman period as compared to Early Roman times, and a slight recovery through the Vandal and Byzantine periods. The paper also explores the phenomenon of the re-occupation of pre-Roman indigenous sites, the continuity or discontinuity of Roman sites and new foundations in previously unoccupied locations. Overall, the results allow us to produce a first impression of the countryside in this area of Mallorca, in which a remarkable degree of continuity in site location coexists with a range of changes in the nature and appearance of rural settlement.

Molecular evidence of shared hookworm Ancylostoma tubaeforme haplotypes between the critically endangered Iberian lynx and sympatric domestic cats

Hookworms of the genus Ancylostoma are the most pathogenic parasites of young cats, and A. tubaeforme may cause morbidity or mortality in young individuals of the most endangered felid species in the world, the Iberian lynx (Lynx pardinus). Since the transmission of monoxenous parasites is related to host density and remaining lynx populations are currently very small, the presence of reservoir hosts may be necessary for the maintenance of the hookworm life-cycle, the domestic cat being the most likely reservoir of A. tubaeforme. In order to confirm this hypothesis, the mitochondrial cytochrome c oxidase subunit I gene (Cox I) sequences of three A. tubaeforme specimens from a road-killed Iberian lynx from Doñana were compared with 14 specimens retrieved from five sympatric free-roaming cats from the same area, and with six specimens from three free-roaming cats from the Mediterranean island of Mallorca. Gene fragments (300bp) from 23 A. tubaeforme individuals representing 16 different haplotypes were obtained. A statistical parsimony haplotype network analysis showed that the three specimens infecting an Iberian lynx corresponded to two different haplotypes, one of which was identical to a specimen in a cat found only 10km from the lynx. Specimens from the Iberian lynx and those from cats in Doñana were only 1.03% genetically divergent, whereas specimens from Mallorca cats and those from Doñana cats and the lynx diverged by 1.33% and 1.36%, respectively. The existence of shared haplotypes of hookworms between lynx and cat reinforces the hypothesis that the abundant sympatric domestic cat population is acting as a reservoir for A. tubaeforme infection in the endangered Iberian lynx.

Modelling mortality causes in longitudinal data in the presence of tag loss: application to raptor poisoning and electrocution

Summary1. A first step for the effective management of vulnerable populations is to identify population threats and measure their relative impact on population fluctuations. The relative importance of proximate causes of mortality can be calculated from longitudinal data using capture–mark–recapture models. If marks are lost or cease to function, survival is underestimated.2. We provide an analytical framework based on conditional probabilities to obtain a robust estimate of the contribution of multiple sources of mortality while accounting for tag loss and imperfect detection.3. We applied this approach to radiotracking and wing tags‐resighting data of red kites Milvus milvus to estimate the impact of illegal poisoning and the mortality by electrocution on power lines in the island of Mallorca (Spain).4. Illegal poisoning was responsible for 53% of the total mortality and electrocution on power lines for 12%. Results indicated that poisoning‐related mortality was higher in immature birds, probably due to their more wide‐ranging prospective behaviour.5. Assuming the two human‐related mortalities are additive, the survival probability of kites would increase by 17% (from 0·76 to 0·91) if both threats were removed.6. Synthesis and applications. We present a new approach to estimate the contribution of different sources of mortality accounting for tag loss, state uncertainty and detection failures in wildlife populations. Our results will allow the demographic consequences of human‐related mortality in threatened populations to be refined. The approach is suitable for the study of multiplicative latent processes in a vast range of applied conservation studies such as, for example, wildlife epidemiology.

Southwest Mallorca Island: A cool-water carbonate margin dominated by drift deposition associated with giant mass wasting

By means of new high-resolution Parasound, multi-channel reflection seismic and multibeam swath bathymetry data, we provide new insight into the sedimentation processes at the margin of a cool-water carbonate ramp system off southwestern Mallorca Island, western Mediterranean Sea. Here, we mapped 7 depositional units which we tied to the Messinian unconformity. The oldest units (1–3) are deposited from late Messinian to late Pliocene during phases of extreme sea-level fluctuations. 2.4Ma ago with the global climate cooling, when the estuarine water mass circulation switched into an anti-estuarine pattern in the Mediterranean Sea and sea-level highstands reached the today level, bottom currents started to shape the distal deposits of the cool-water carbonate system off southwestern Mallorca, represented by depositional units 4–7. Although, sediment supply from the carbonate shelf to the slope is low due to the insignificant input of terrigenous clastics and slow reef growth, slope sediments reach thicknesses >140m. Our study displays that the accumulation of sediments at the southwestern insular margin was mainly controlled by long-lived bottom currents and giant submarine landslides. The bottom currents formed elongated mounded drifts that contemporaneously developed in alongslope and upslope direction. They are probably controlled by an isobath-parallel bottom current in a present water depth of 350–550m which we associate with the Levantine Intermediate Water (LIW); and an upslope current acting in 250–600m associated with the Algerian mesoscale gyres that enter the Balearic straits from SE. Several scarps at the present sea-floor indicate the predominance of slope failures in the study area. Additionally, mass transport deposits occur basinwards in almost all depositional units. Accordingly, giant mass wasting events took place from the Pliocene into recent times.Locally, above the alongslope drift a field of sediment waves occurs in a water depth of 170–310m. They are oriented slightly oblique to the contour lines with their steep flank facing upslope, showing wavelengths of 400–800m and heights of 10–15m. We suggest that the waves migrate in upslope direction perpendicular to the main isobath-parallel flow.Furthermore, the results of this study indicate that sea-level fluctuations have only a minor influence on drift deposition; instead submarine landslides caused the creation of new drift units. They significantly altered the relief of the sea-floor and thereby initiate the realignment of the prevailing current pattern. The fault scarps and detachment surfaces left behind were the nucleolus for the development of new drift units.

A new species of extinct little owl from the Pleistocene of Mallorca (Balearic Islands)

Athene vallgornerensis nov.sp. (Aves: Strigiformes: Strigidae) from the Early Pleistocene of the island of Mallorca (Balearic Islands, Western Mediterranean) is described. The material came from a fossil assemblage obtained in a collapsed gallery from Cova des Pas de Vallgornera (Llucmajor, south of Mallorca), the longest karstic system currently known in the Balearics. Associated remains include primitive representatives of the insular endemic fauna of Mallorca (Myotragus, Hypnomys, Nesiotites), as well as fossils of bats, birds (among them, Tyto balearica), lizards and toads. Although only two bones of Athene have been obtained, its highly distinctive tarsometatarsus—short, highly robust and significantly small—differentiates it from the remaining extant and extinct Athene species from the Palaearctic, justifying its description as a new species. At least four insular species of Athene are now known from the Mediterranean area, and two groups can be identified according to the shape of their tarsometatarsi.

Islands beneath islands: phylogeography of a groundwater amphipod crustacean in the Balearic archipelago

BackgroundMetacrangonyctidae (Amphipoda, Crustacea) is an enigmatic continental subterranean water family of marine origin (thalassoid). One of the species in the genus, Metacrangonyx longipes, is endemic to the Balearic islands of Mallorca and Menorca (W Mediterranean). It has been suggested that the origin and distribution of thalassoid crustaceans could be explained by one of two alternative hypotheses: (1) active colonization of inland freshwater aquifers by a marine ancestor, followed by an adaptative shift; or (2) passive colonization by stranding of ancestral marine populations in coastal aquifers during marine regressions. A comparison of phylogenies, phylogeographic patterns and age estimations of clades should discriminate in favour of one of these two proposals.ResultsPhylogenetic relationships within M. longipes based on three mitochondrial DNA (mtDNA) and one nuclear marker revealed five genetically divergent and geographically structured clades. Analyses of cytochrome oxidase subunit 1 (cox1) mtDNA data showed the occurrence of a high geographic population subdivision in both islands, with current gene flow occurring exclusively between sites located in close proximity. Molecular-clock estimations dated the origin of M. longipes previous to about 6 Ma, whereas major cladogenetic events within the species took place between 4.2 and 2.0 Ma.ConclusionsM. longipes displayed a surprisingly old and highly fragmented population structure, with major episodes of cladogenesis within the species roughly correlating with some of the major marine transgression-regression episodes that affected the region during the last 6 Ma. Eustatic changes (vicariant events) -not active range expansion of marine littoral ancestors colonizing desalinated habitats-explain the phylogeographic pattern observed in M. longipes.

Hotel water consumption at a seasonal mass tourist destination. The case of the island of Mallorca

While it is true that tourism is one of the main driving forces behind economic growth in several world regions, it is also true that tourism can have serious negative environmental impacts, especially with regard to water resources. The tourist water demand can generate big problems of sustainability, mainly in those regions where water is scarce, as occurs in most coastal and small island destinations where a large part of world tourism is concentrated. Given the shortage of literature on the subject, further research into the tourist water demand is required, with particular attention to the hotel sector, since hotels are the most popular option for tourists, displaying higher levels of water consumption. The main purpose of this study is to develop a model to analyse hotel water consumption at a mature sun and sand destination with a strong seasonal pattern and scarcity of water; characteristics shared by some of the world’s main tourist destinations. Our model includes a set of different hotel variables associated with physical, seasonal and management-related factors and it improves on the capacity to explain water consumption at such destinations. Following a hierarchical regression methodology, the model is empirically tested through a survey distributed to managers of a representative sample of hotels on the island of Mallorca. From the obtained results, interesting recommendations can be made for both hotel managers and policy makers. Among these, it should be highlighted that the strategic move contemplated by many mature destinations towards a higher quality, low-season model could have significant negative effects in terms of the sustainability of water resources. Our results also conclude that managerial decisions, like the system of accommodation that is offered (i.e. the proliferation of the “all-inclusive” formula, both at mature and new destinations), could give rise to the same negative effect. Development of water saving initiatives (usually introduced in response to demand-based factors), also reveals significant effects over water consumption. Finally, other key factor in explaining hotel water consumption is the management system under which the hotel is run.

Pitiüsa–Ibicenca goat conservation program: Current status

The Ibicenca or Pitiüsa goat is the most endangered goat breed of Spain. This breed occurs only on the Pitiüse islands (Ibiza and Formentera), with fewer than 147 animals on 17 different farms, indicating a clear risk of extinction. In response to this condition, a program to rescue the breed was initiated, involving: (1) the characterization of morphological variables of the breed, (2) the genetic characterization of the breed and (3) the initiation of an ex situ preservation program securing the participation of farmers, linked to the germplasm bank network of Spain. This paper describes the genetic characterization and ex situ plans that have been thus far developed. Genetic characterization, based on neutral allelic variation (using 27 microsatellite markers), was conducted along with 12 other goat breeds from Spain, all with known characterization, to serve as referential breeds for assessing the status of the Ibicenca or Pitiüsa goat in the current context of goat genetic resources of Spain. The ex situ program was initiated by selecting unrelated bucks and training them to produce semen for conservation purposes. Results from the genetic characterization showed that the Ibicenca or Pitiüsa goat is a single genetic entity, and is more related to Continental breeds of Spain than to breeds from the other Balearic islands. This finding justifies its conservation by means of cryopreservation of semen. The ex situ plan obtained 384 semen doses from 3 sires collected in the Pitiüse islands, which are to be used in AI programs in the future. These samples were stored in two replicates: one at the Regional Germplasm Bank of Mallorca Island for Mallorca breeds and the second, as a backup, at the Spanish National Germplasm Bank located in Madrid. The implementation of this plan, in particular the establishment of an ex situ conservation condition, prevents the potential risk of extinction faced by this breed. The plan well accepted by farmers will be linked to research on the production and adaptive traits of the breed to identify attributes that could potentially enhance its economic value and allow its population expansion in situ.

Response of sulfate‐reducing bacteria to an artificial oil‐spill in a coastal marine sediment

In situ mesocosm experiments using a calcareous sand flat from a coastal area of the island of Mallorca in the Mediterranean Sea were performed in order to study the response of sulfate-reducing bacteria (SRB) to controlled crude oil contamination, or heavy contamination with naphthalene. Changes in the microbial community caused by the contamination were monitored by a combination of comparative sequence analysis of 16S rRNA genes, fluorescence in situ hybridization, cultivation approaches and metabolic activity rates. Our results showed that crude oil and naphthalene negatively influenced the total microbial community as the natural increase in cell numbers due to the seasonal dynamics was attenuated. However, both contaminants enhanced the sulfate reduction rates, as well as the culturability of SRB. Our results suggested the presence of autochthonous deltaproteobacterial SRBs that were able to degrade crude oil or polycyclic aromatic hydrocarbons such as naphthalene in anaerobic sediment layers.

Late Pleistocene and Holocene cool‐water carbonates of the Western Mediterranean Sea

AbstractPost‐glacial, neritic cool‐water carbonates of the Western Mediterranean Sea were examined by means of hydroacoustic data, sediment surface sampling and vibrocoring to unravel geometries and to reconstruct sedimentary evolution in response to the last sea‐level rise. The analysed areas, located on the Alboran Ridge, in the Bay of Oran, and at the southern shelf of the island of Mallorca, are microtidal and bathed by oligotrophic to weakly mesotrophic waters. Seasonal water temperature varies between 13 °C and 27 °C. Echosounder profiles show that the Bay of Oran and the southern shelf of Mallorca are distally steepened ramps, while the Alboran Ridge forms a steep‐flanked rugged plateau around the Alboran Island. In the three areas, an up to 10 m thick post‐glacial sediment cover overlies an unconformity. In Oran and Mallorca, stacked lowstand wedges occur in water depths of 120 to 130 m. On the Alboran Ridge and in the Bay of Oran, highstand wedges occur at 35 to 40 m. Up to 5 m long cores of upper Pleistocene to Holocene successions were recovered in water depths between 40 and 81 m. Deposits contain more than 80% carbonate, with mixed carbonate‐volcaniclastics in the lower part of some cores in Alboran. The carbonates consist of up to 53% of aragonite and up to 83% of high magnesium calcite. Radiocarbon dating of bivalve shells, coralline algae and serpulid tubes indicates that deposits are as old as 12 400 cal yr bp. The carbonate factories in the three areas are dominated mostly by red algae, but some intervals in the cores are richer in bivalves. A facies rich in the gastropod Turritella, reflecting elevated surface productivity, is restricted to the Mallorca Shelf. Rhodoliths occur at the sediment surface in most areas at water depths shallower than 70 m; they form a 10 to 20 cm thick veneer overlying rhodolith‐poor bioclastic sediments which, nonetheless, contain abundant red algal debris. This rhodolith layer has been developing for the past 800 to 1000 years. Similar layers at different positions in the cores are interpreted as reflecting in situ growth of rhodoliths at times of reduced net sedimentation. Sedimentary successions in the cores record the post‐glacial sea‐level rise and the degree of sediment exposure to bottom currents. Deepening‐upward trends in the successions are either reflected by shallow to deep facies transitions or by a corresponding change of depth‐indicative red algae. There are only weak downcore variations of carbonate mineralogy, which indicate that no dissolution or high magnesium to low magnesium calcite neomorphism occurs in the shallow subsurface. These new data support the approach of using the Recent facies distribution for interpretation of past cool‐water, low‐energy, microtidal carbonate depositional systems. Hydroacoustic data show that previous Pleistocene transgressive and highstand inner ramp deposits and wedges were removed during sea‐level lowstands and accumulated downslope as stacked lowstand wedges; this suggests that, under conditions of high‐amplitude sea‐level fluctuations, the stratigraphic record of similar cool‐water carbonates may be biased.

An Investigation into Alternative Reservoirs of Canine Leishmaniasis on the Endemic Island of Mallorca (Spain)

The role of wild and free-roaming domestic carnivores as a reservoir of Leishmania infantum was investigated on the Mediterranean island of Mallorca (Balearic Islands, Spain), an endemic area for this disease. Serum, blood and/or spleen samples from 169 animals [48 dogs from a kennel, 86 wild-caught feral cats, 23 pine martens (Martes martes), 10 common genets (Genetta genetta) and two weasels (Mustela nivalis)] were analysed. Seroprevalence determined by Western blotting was 38% in dogs and 16% in feral cats, while the prevalence of infection determined by PCR was 44% in dogs, 26% in cats, 39% in pine martens and 10% in genets. This is the first report of infection by L.infantum in the pine marten or any other member of the Mustelidae family. Restriction fragment length polymorphism (RFLP) analysis found 33 different patterns in 23 dogs, 14 cats and three martens. Two patterns were shared by dogs and cats, two by different cats, and one by different dogs. Patterns were different to those previously reported in carnivores from peninsular Spain. No external lesions compatible with leishmaniasis were observed in any species other than the dogs. Although the dog is probably the primary reservoir of leishmaniasis in endemic areas, the prevalence and the absence of apparent signs of this disease within the island's abundant feral cat and pine marten populations could make these species potential primary or secondary hosts of L.infantum in Mallorca.

Solutional features and cave deposits related to hypogene speleogenetic processes in a littoral cave of Mallorca Island (western Mediterranean)

The Cova des Pas de Vallgornera, located in the southern part of Mallorca Island (western Mediterranean) and developed in Upper Miocene reefal carbonate limestones, is an exceptional coastal cave because of its particular morphological features and the presence of deposits with uncommon mineralogies. Littoral mixing dissolution processes represent the most important speleogenetic mechanism to be considered in the eogenetic karst platform, where it develops; nevertheless, part of the cave consists of an extensive network of galleries that show morpho-sedimentary features pointing up to a possible participation of hypogene speleogenesis. The morphological assemblage of the cave illustrates besides the typical coastal karstification, a noticeable meteoric water recharge along with a possible deep recharge of hypogenic character. Features consisting in upwards solutional channels are abundant, including a complete morphologic suite of rising flow supporting the involvement of hypogene speleogenetic processes. Furthermore, the presence of vents and some related speleothems, such as crusts and cave rims, together with Mn and Fe-rich deposits hosting several minerals not observed until present in other caves of the region must be highlighted. Given the monotonous surface geology around the cave, it is suspected that ascending Sr, Ba, Mn, and Al-rich hypogene solutions may have reacted with the host rock to form this unique mineral assemblage. These deep-seated speleogenetic and mineralogical phenomena could be associated with the feeble geothermal anomalies existing currently in the Llucmajor platform, related to SW–NE faults which delimitate the subsidence basin existing in the southern end of Mallorca Island.

Urban and tourist land use patterns and water consumption: Evidence from Mallorca, Balearic Islands

The island of Mallorca is the main Balearic resort and sustainable water management is a key challenge for the economic and ecological sustainability of tourism as the main economic activity. The critical water supply situation on the island is being exacerbated by the extension of the tourist base to so-called “quality tourism”. Since the mid 1990s, low-density residential tourist land uses associated with second homes and more affluent urban dwellers have spread around existing mass tourist urban centres. Increasing water consumption for outdoor uses (gardens, swimming pools) is a direct consequence of this development. Available water consumption data mask the impact of residential tourism on water consumption levels. The objective of the present paper is to compare per capita water consumption in quality tourist, mass tourist and residential urban areas, and to provide quantitative information on the magnitude of water consumption by gardens and swimming pools as water-related leisure structures. The analysis combines water consumption data with a land use geodatabase at the sub-parcel scale, a detailed population inventory, and an estimate of pool water use. The results show that quality tourism produces higher water consumption levels per capita than mass tourism. Garden irrigation is the single main cause of the high water consumption in quality tourist areas and accounts for more than 70% of these areas’ total consumption in summer. But even in mass tourist and residential areas, garden irrigation accounts for up to 30% and 20%, respectively, of total water consumption in summer. Individually owned swimming pools cause an additional average water consumption of 22 litres/person/day. The proliferation of swimming pools and lavish ‘Atlantic’ gardens may turn out as one of the biggest threats to sustainable water management on the island of Mallorca and in other tourist destinations adapting the quality tourist model.

Forecasting Daily Air Arrivals in Mallorca Island Using Nearest Neighbour Methods

This paper investigates the feasibility of using different generalizations of the nearest neighbour method in a tourism forecasting problem. The method is widely employed in different fields of research but, inexplicably, it is practically unknown in tourism forecasting. The analysis is centred not only in knowing the exact value of arrivals (point prediction), but also in anticipating the direction of the sign movement (sign prediction). Furthermore, this study also offers further evidence on a subject scarcely treated in tourism economics: the searching of predictable non-linear dynamics. The results encourage the use of this technique and reveal the existence of a non-linear seasonal effect in the analysed tourism time series.

Methodology for applying the Limits of Acceptable Change process to the management of recreational boating in the Balearic Islands, Spain (Western Mediterranean)

The objective of this study is to propose a simple methodological approach, based on the Limits of Acceptable Change process, to support the formulation of management measures for recreational boating in bays. Management measures have been determined using statistical and geospatial analyses of data of biophysical characteristics, use, and user perceptions in a bay on the island of Mallorca. The results suggest that the optimal use level of the study site is being surpassed and a range of potential management options is provided. This methodology is applicable to additional management scenarios where balancing social and environmental needs is necessary and should be implemented as part of a broader Integrated Coastal Zone Management framework.

Spatial analysis of recreational boating as a first key step for marine spatial planning in Mallorca (Balearic Islands, Spain)

Recreational boating is an important, growing leisure activity on the island of Mallorca, Balearic Islands, Spain. This spatial analysis of anchoring of recreational boating along the coast of Mallorca is intended to generate new data to contribute to the achievement of a comprehensive marine and coastal spatial planning on the island in addition to providing important information related to the pressure of increasing demand for anchoring space that, if not properly managed, could jeopardize the coastal and marine environments. The study combines data from the natural (habitats, geology), physical (wave patterns), and social sciences (survey interviews), using Geographic Information Systems (GIS) as the main analytical tool. The final result is an estimate of the average amount of seabed available for anchoring during the highest levels of boating activity in Mallorca (i.e. summer high season) based on a number of different sustainability scenarios (i.e. average distance between boats, weather conditions). In addition to being applicable to any location wishing to manage recreational boating activity, the methodology presented in this study represents an integrated, multidisciplinary approach which could be applied to a number of management scenarios with a spatial dimension in marine environments.

How frequent is varicella-associated pneumonia in children?

Varicella is a frequent though mild infection in children, but it can cause important morbidity in adults. The most frequent complication in adults is varicella pneumonia. However, lower airway complications associated to varicella have been scarcely studied in children. We retrospectively reviewed the clinical records of the children hospitalized for varicella-associated pneumonia in the three public hospitals on the Island of Mallorca. We discovered that 17/213 (8%) children hospitalized for varicella were diagnosed of pneumonia. The rate of hospitalization for varicella complication due to pneumonia was 4.3 cases per 10,000 varicella infections. Only one patient was diagnosed of varicella pneumonia, which accounts for 0.3 cases per 10,000 varicella infections. Nine of 17 (53%) cases were classified as bacterial pneumonia. Statistical differences (p < 0.05) in the median time from rash (5.9 vs. 2.4days) and fever (4.1 vs. 2.2 days) to admission were observed between bacterial and viral pneumonia. However, outcome differences measured by the median length of stay, need for oxygen, and admission to the intensive care unit were not observed. Varicella pneumonia is a very rare complication of varicella in children. Most of the lower airway infections in the course of varicella are associated to other co-infections.

Initiation of a severe thunderstorm over the Mediterranean Sea

The Mediterranean basin is regularly affected by severe weather associated with deep convection. Although convective systems are usually linked to coastal orography, some severe thunderstorms develop and mature over the sea. A recent example is the severe thunderstorm that affected the island of Mallorca in the afternoon of 4 October 2007. The storm formed early in the morning offshore of Murcia, and steadily became organized into a squall line. Arriving in Palma city, this squall line produced severe gusts, heavy rain and several tornadoes. The initiation and evolution of convection in these kinds of maritime events depend on both synoptic and mesoscale features. Representing such interactions is a challenge for numerical weather prediction. The aim of this study is to determine the prominent factors involved in the initiation and evolution of the damaging squall line, by means of high resolution numerical experiments. We also focus on squall line mesovortices to explain the potential for tornado development and the role of Mallorcan orography on their evolution. Simulations performed with the mesoscale model Méso-NH allowed relevant mechanisms for initiation and development of the strong squall line to be identified. The squall line initiates in an area with conditional instability, characterized by a cut-off and a southerly jet aloft and by moist, warm air at low-levels along a front. In addition, the area of low-level convergence offshore of Murcia, associated with the front and enhanced by a low downstream of the Atlas range, was shown to be crucial during the early stage of the convective system. The dry layer in the mid-troposphere and the strong sheared environment provide elements for understanding the development of such a damaging squall line. Moreover, a very high resolution experiment (600 m mesh) gave a very realistic representation of the squall line, including mesovortices ahead of the gust front, which confirmed the potential of this strong convective system for the genesis of small-scale vortices that may precede tornado development. A sensitivity experiment pointed out the prominent role of Mallorcan orography in straightening mesovortices approaching Palma city, and provided interesting elements for the understanding of the localization of tornadoes that occurred on 4 October 2007.

Chemical properties and biological activity in soils of Mallorca following twenty years of treated wastewater irrigation

On the Mediterranean island of Mallorca, the use of secondary-treated municipal wastewater in irrigation was introduced with the construction of the first wastewater treatment plants in the 1970s. In this study, the chemical properties and biological activity of 21 arable soils, irrigated for more than 20 years with secondary-treated wastewater, were tested in order to assess their quality. Soil quality was evaluated by measuring cation exchange capacity, pH, calcium carbonate equivalent, soil organic matter, total nitrogen, available phosphorus, water-soluble organic carbon, soil microbial biomass, soil basal respiration, and the activities of the enzymes dehydrogenase, β-glucosidase and alkaline phosphatase. No negative effects of the irrigation treatment were observed on the measured soil parameters. Indeed, soil water-soluble organic carbon, soil microbial biomass and β-glucosidase and alkaline phosphatase activities increased under treated wastewater irrigation. Biological activity of soils irrigated with treated wastewater was affected mainly by soil organic matter content. Although the typical crop management of alfalfa, and other forage crops associated with treated wastewater irrigation, may have contributed to the increase of these parameters, the results suggest that irrigation with treated wastewater is a strategy with many benefits to agricultural land management.

Erosion of continental margins in the Western Mediterranean due to sea-level stagnancy during the Messinian Salinity Crisis

High-resolution multi-channel seismic data from continental slopes with minor sediment input off southwest Mallorca Island, the Bay of Oran (Algeria) and the Alboran Ridge reveal evidence that the Messinian erosional surface is terraced at an almost constant depth interval between 320 and 380 m below present-day sea level. It is proposed that these several hundred- to 2,000-m-wide terraces were eroded contemporaneously and essentially at the same depth. Present-day differences in these depths result from subsidence or uplift in the individual realms. The terraces are thought to have evolved during one or multiple periods of sea-level stagnancy in the Western Mediterranean Basin. According to several published scenarios, a single or multiple periods of relative sea-level stillstand occurred during the Messinian desiccation event, generally known as the Messinian Salinity Crisis. Some authors suggest that the stagnancy started during the refilling phase of the Mediterranean basins. When the rising sea level reached the height of the Sicily Sill, the water spilled over this swell into the eastern basin. The stagnancy persisted until sea level in the eastern basin caught up with the western Mediterranean water level. Other authors assigned periods of sea-level stagnancy to drawdown phases, when inflowing waters from the Atlantic kept the western sea level constant at the depth of the Sicily Sill. Our findings corroborate all those Messinian sea-level reconstructions, forwarding that a single or multiple sea-level stagnancies at the depth of the Sicily Sill lasted long enough to significantly erode the upper slope. Our data also have implications for the ongoing debate of the palaeo-depth of the Sicily Sill. Since the Mallorcan plateau experienced the least vertical movement, the observed terrace depth of 380 m there is inferred to be close to the Messinian depth of this swell.