Mostrando recursos 81 - 100 de 1,708

  1. The Acridian plagues, a new Holocene and Pleistocene palaeoclimatic indicator

    Meco, J.; Petit Maire, Nicole; Ballester Santos, Javier; Betancort-Lozano, Juan Francisco; Ramos, Antonio G.

    [EN] Five palaeosols, intercalated within the Quaternary dune beds of Fuerteventura and Lanzarote (Canary Islands), off the Moroccan coast, mark wetter climatic episodes. In all of them, billions of calcified insect ootheca testify to past occurrences of Acridian plagues, such as those reaching the western Sahara following heavy rainfall events over the Sahel.

  2. Late Pliocene and Quaternary Eurasian locust infestations in the Canary Archipelago

    Meco, J.; Muhs, Daniel R.; Fontugne, M.; Ramos, Antonio G.; Lomoschitz, Alejandro; Patterson, Deanna

    [EN] The Canary Archipelago has long been a sensitive location to record climate changes of the past. Interbedded with its basalt lavas are marine deposits from the principal Pleistocene interglacials, as well as aeolian sands with intercalated palaeosols. The palaeosols contain African dust and innumerable relict egg pods of a temperate-region locust (cf. Dociostaurus maroccanus Thunberg 1815). New ecological and stratigraphical information reveals the geological history of locust plagues (or infestations) and their palaeoclimatic significance.

  3. Uranium-series ages of corals, sea level history, and palaeozoogeography, Canary Islands, Spain: An exploratory study for two Quaternary interglacial periods

    Muhs, Daniel R.; Meco, J.; Simmons, Kathleen R.

    [EN]We present the first U-series ages of corals from emergent marine deposits on the Canary Islands. Deposits at +. 20. m are 481 ± 39 ka, possibly correlative to marine isotope stage (or MIS) 11, while those at +. 12 and +. 8. m are 120.5 ± 0.8. ka and 130.2 ± 0.8. ka, respectively, correlative to MIS 5.5. The age, elevations, and uplift rates derived from MIS 5.5 deposits on the Canary Islands allow calculations of hypothetical palaeo-sea levels during the MIS 11 high sea stand. Estimates indicate that the MIS 11 high sea stand likely was at least...

  4. Extralimital Senegalese species during Marine Isotope Stages 5.5 and 11 in the Canary Islands (29 degrees N): Sea surface temperature estimates

    Montesinos del Valle, Mercedes; Ramos, Antonio G.; Lomoschitz, Alejandro; Coca, Josep; Redondo, Alexandre; Betancort-Lozano, Juan Francisco; Meco, J.

    [EN] The presence of Harpa doris Röding, 1798 in marine deposits of the last interglacial period, ~. 130-120. ka (marine isotope stage or MIS 5.5) in the Canary Islands (Gran Canaria, Lanzarote and Fuerteventura) enabled us to compare this occurrence with its present habitat in the Gulf of Guinea and the Cape Verde Islands, well to the south. This comparison leads to the conclusion that sea surface temperatures (SSTs) in the waters around the Canary Islands during the last interglacial period were at least 3.3. °C higher than today. H. doris is found in association with the large gastropod Persististrombus...

  5. The Canary record of the evolution of the North Atlantic Pliocene: New Ar-40/Ar-39 ages and some notable palaeontological evidence

    Meco, J.; Koppers, Anthony A. P.; Miggins, Daniel P.; Lomoschitz, Alejandro; Betancort-Lozano, Juan Francisco

    [EN] Two new 40Ar/39Ar ages (*) and previously published K/Ar ages of basaltic pillow lava flows are coeval with closely-related fossiliferous marine layers, allowing us to establish the beginning (5.8; 5.0; 4.8Ma at Ajuí, Fuerteventura Island and 4.8±0.03Ma (2?)* at Tamaraceite) and a middle stage (4.20±0.18Ma (2?)* at La Esfinge in Gran Canaria Island) of Early Pliocene marine deposits in the Canary Islands. Here the presence of tropicopolitan fossils (Megaselachus megalodon, Janthina typica) suggests the influence of a possible Central American Circumtropical Current during the Pliocene and in the North Atlantic basin.

  6. Güímar and la Orotava mega-landslides (Tenerife) and Tsunamis deposits in Canary Islands

    Ferrer, Mercedes; González de Vallejo, Luis I.; Coello, Juan Jesús; García, Joshua Carlos; Hernández Gutiérrez, Luis E; Casillas, Ramón; Martín, Candelaria; Rodríguez, José A; Madeira, J; Andrade, C; Freitas, Maria Conceição; Lomoschitz, Alejandro; Yepes Temiño, Jorge; Meco, J.; Betancort-Lozano, Juan Francisco

    [EN] More than 20 mega-landslides have been described in the Canary Islands affecting the flanks of the volcanic edifices. Güímar and La Orotava landslides, in Tenerife, are two exceptional cases due to their huge dimensions and outstanding geomorphological features. The estimated volume of these landslides exceed tens of cubic km. Tsunami deposits have been also identified in some of the islands of the archipelago probably associated to the large landslides of the islands flanks. An investigation has been carried out to explain the causes of these large instability processes and their failure mechanisms.

  7. Cambios del clima, durante los últimos cinco millones de años, observados en el África Atlántica (Islas Canarias)

    Meco, J.; Guillou, Hervé; Carracedo, J.C.; Petit Maire, Nicole; Lomoschitz, Alejandro; González Ramos, Antonio J; Ballester Santos, Javier

    [ES] En las Canarias orientales, testimonios geológicos del inicio del Plioceno hasta la actualidad han permitido constatar la evolución paleoclimática desde una importante posición en el margen sahariano atlántico. Esta evolución revela la existencia de oscilaciones climáticas caracterizadas por la sucesión de climas que pasan de húmedos y cálidos a cálidos y áridos y que coinciden, respectivamente, con el inicio y el final de períodos interglaciales durante los que el mar fue transgresivo.

  8. Uranium-series ages of fossil corals from Mallorca, Spain: The Neotyrrhenian high stand of the Mediterranean Sea revisited

    Muhs, Daniel R.; Simmons, Kathleen R.; Meco, J.; Porat, Naomi

    [EN] The emergent marine deposits of the Mediterranean basin have been recognized as an important record of Quaternary sea level history for more than a century. Previous workers identified what have been interpreted to be two separate high stands of sea in the late Quaternary, namely the "Eutyrrhenian" (thought to be ~ 120 ka) and the "Neotyrrhenian" (thought to be either ~ 100 ka or ~ 80 ka). On Mallorca, Spain, both of these named deposits lie close to present sea level, implying paleo-sea levels slightly above present during both marine isotope stages (MIS) 5.5/5e and either 5.3/5c or 5.1/5a....

  9. Snakes on an island: independent introductions have different potentials for invasion

    Monzón Argüello, Catalina; Patiño-Martínez, Clara; Christiansen, Fredrik; Gallo Barneto, Ramón; Cabrera-Pérez, Miguel Ángel; Peña-Estévez, Miguel Ángel; López-Jurado, Luis Felipe; Lee, Patricia

    [EN] Snakes introduced to islands can be devastating to naïve native fauna. However, introduced populations must establish before range expansion (invasion) can occur. The factors that can determine successful invasion are those associated with the introduction event (e.g., characteristics of the founding population), the location (e.g., suitable environment and prey availability) and the species (e.g. life history characteristics). Here, we collected morphometric, ecological and genetic data on the recently introduced California Kingsnake (Lampropeltis californiae) in Gran Canaria.

  10. Satellite tracking derived insights into migration and foraging strategies of male loggerhead turtles in the eastern Atlantic 

    Varo-Cruz, Nuria; Hawkes, Lucy A.; Cejudo, Daniel; López, Pedro; Coyne, Michael S.; Godley, B. J; López-Jurado, Luis Felipe

    [EN] In recent years, information about the movements and timing of migration by male sea turtles has begun to be unraveled. Here, we present the first satellite tracking of male loggerhead sea turtles (Caretta caretta) in the eastern Atlantic. Satellite linked transmitters were attached to five adult males, captured in the near shore waters off Boavista, Republic of Cape Verde. This archipelago hosts the single most important breeding site of loggerhead turtles in the eastern Atlantic.

  11. Potential adverse health effects of persistent organic pollutants on sea turtles: Evidences from a cross-sectional study on Cape Verde loggerhead sea turtles

    Camacho, María; Luzardo, Octavio P.; Boada, Luis D.; López-Jurado, Luis Felipe; Medina Suárez, María E.; Zumbado, Manuel; Orós, Jorge

    [EN] The Cape Verde nesting population of loggerhead sea turtles (Caretta caretta) is the third largest population of this species in the world. For conservation purposes, it is essential to determine how these reptiles respond to different types of anthropogenic contaminants. We evaluated the presence of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) in the plasma of adult nesting loggerheads from Boa Vista Island, Cape Verde, and studied the effects of the contaminants on the health status of the turtles using hematological and biochemical parameters. All turtles had detectable levels of non-dioxin like PCBs, whereas dioxin-like...

  12. Phenotypically linked dichotomy in sea turtle foraging requires multiple conservation approaches

    Hawkes, Lucy A.; Broderick, Annette C.; Coyne, Michael S.; Godfrey, Matthew H.; López-Jurado, Luis Felipe; López, Pedro; Merino, Sonia Elsy; Varo-Cruz, Nuria; Godley, B. J

    [EN] Marine turtles undergo dramatic ontogenic changes in body size and behavior, with the loggerhead sea turtle, Caretta caretta, typically switching from an initial oceanic juvenile stage to one in the neritic, where maturation is reached and breeding migrations are subsequently undertaken every 2-3 years [1-3]. Using satellite tracking, we investigated the migratory movements of adult females from one of the world's largest nesting aggregations at Cape Verde, West Africa. In direct contrast with the accepted life-history model for this species [4], results reveal two distinct adult foraging strategies that appear to be linked to body size. The larger turtles...

  13. Origin and dispersal routes of foreign green and Kemp's ridley turtles in Spanish Atlantic and Mediterranean waters

    Carreras, Carlos; Monzón Argüello, Catalina; López-Jurado, Luis Felipe; Calabuig, P.; Bellido, Juan Jesús; Castillo, Juan José; Sánchez-Jerez, Pablo; Medina, Pas; Tomás, Jesús M.; Gozalbes, Patricia; Fernández, Gloria; Marco, Adolfo; Cardona, Luis

    [EN] The presence of the green and Kemp's ridley turtles is rare at Atlantic and Mediterranean Spanish waters, but the records have increased during the last decades. We reported a new set of records and reviewed all the historical observations of these species. The analysis of a mitochondrial DNA fragment of the newest records provided insights about the origin of the individuals. The Kemp's ridley turtles arrived from the western Atlantic nesting beaches, although the discovering of a new haplotype suggested the existence of an unknown or low sampled nesting area of origin.

  14. Morphological and molecular characterization of a new species of Atlantic stalked barnacle (Scalpelliformes: Pollicipedidae) from the Cape Verde Islands

    Quinteiro, Javier; Rodríguez-Castro, Jorge; López, Pedro; López-Jurado, Luis Felipe; González-Henríquez, Nieves; Rey Méndez, Manuel

    [EN] The taxonomy of pedunculate cirripedes belonging to the genus Pollicipes has essentially remained unchanged since Charles Darwin described them in his exhaustive work on the Cirripedia. This genus includes three species of stalked barnacles: Pollicipes pollicipes in the north-eastern Atlantic, P. polymerus in the north-eastern Pacific and P. elegans in the central-eastern Pacific. However, a population genetics analysis of P. pollicipes suggested the presence of a putative cryptic species collected from the Cape Verde Islands in the central-eastern Atlantic. This study examines the morphology of these genetically divergent specimens and compares them with that of representative Atlantic samples of...

  15. Modelling the niche for a marine vertebrate: A case study incorporating behavioural plasticity, proximate threats and climate change

    Pikesley, Stephen K.; Broderick, Annette C.; Cejudo, Daniel; Coyne, Michael S.; Godfrey, Matthew H.; Godley, B. J; López, Pedro; López?Jurado, Luis Felipe; Elsy Merino, Sonia; Varo Cruz, Nuria; Witt, Matthew J.; Hawkes, Lucy A.

    [EN] The integration of satellite telemetry, remotely sensed environmental data, and habitat/environmental modelling has provided for a growing understanding of spatial and temporal ecology of species of conservation concern. The Republic of Cape Verde comprises the only substantial rookery for the loggerhead turtle Caretta caretta in the eastern Atlantic. A size related dichotomy in adult foraging patterns has previously been revealed for adult sea turtles from this population with a proportion of adults foraging neritically, whilst the majority forage oceanically. Here we describe observed habitat use and employ ecological niche modelling to identify suitable foraging habitats for animals utilising these...

  16. Density, nest site characteristics and breeding rates of the osprey (Pandion haliaetus) in the southern limit of its range in the Western Palearctic (Boa Vista, Cape Verde Islands).

    Siverio, Manuel; López, Pedro; Siverio, Felipe; Rodríguez, Beneharo; Varo Cruz, Nuria; López-Jurado, Luis Felipe

    [EN] Between 2004 and 2007, we studied density, habitat features and breeding parameters of the osprey (Pandion haliaetus) population in Boa Vista Island (Cape Verde). A total of 79 nest structures were identified, 37 of which were occupied for at least 1 year during the study period. The osprey population ranged between 14 and 18 pairs, and the mean density and distance between neighbouring occupied nests were 2.58 pairs per 100 km2 and 3089 m, respectively. Occupied nests were found to be significantly further from the coastline and roads than unoccupied nests, but the distances from villages were similar.

  17. Taxonomic status and origin of the shrews (soricidae) from the canary islands inferred from a mtdna comparison with the european crocidura species

    Vogel, Peter; Cosson, Jean-François; López-Jurado, Luis Felipe

    [EN] European island shrews are either relicts of the endemic Pleistocene fauna, e.g., Crocidura zimmermanni, or were introduced from continental source populations. In order to clarify the taxonomic status and the origin of the two shrew species from the Canary Islands, a 981 bp fragment of cytochrome b gene was investigated in all European Crocidura species and compared with the Canary shrew (Crocidura canariensis) and the Osorio shrew (Crocidura osorio). The first shares its karyotype with the Sicilian shrew Crocidura sicula (2N = 36), the second with the Greater white-toothed shrew Crocidura russula (2N = 42), suggesting possible sister species...

  18. Comparative study of hematologic and plasma biochemical variables in Eastern Atlantic juvenile and adult nesting loggerhead sea turtles (Caretta caretta).

    Casal, Ana B; Camacho, María; López-Jurado, Luis Felipe; Juste, Candelaria; Orós, Jorge

    [EN] Background: Plasma biochemical and hematologic variables are important in the management of endangered sea turtles, such as loggerheads. However, studies on blood biochemistry and hematology of loggerheads are limited, and different concentrations according to variable criteria have been reported. Objective: The purpose of this study was to establish and compare baseline plasma chemistry and hematology values in Eastern Atlantic juvenile and adult nesting loggerhead sea turtles (Caretta caretta).

  19. La génesis de los cuerpos: de la turba al turbo

    Moreno Velásquez, Juan Gonzalo
    Asistimos al quiebre de la rigidez ética, vital y epistémica que se amparaba en una condición marcial y en una imagen del universo fundamentada en el orden tal como se ve en la física moderna. Hoy por el contrario, y por el efecto de bucle, hemos recuperado una imagen distinta, fundada en las consideraciones de Lucrecio sobre la Naturaleza, su carácter erótico, su consideración de que es en la turbulencia en donde se engendran múltiples formas de orden. En este sentido, el retorno de lo trágico, es también el retorno de una afirmación de la vida, y en términos de...

  20. As representações dos alunos relativamente às acções que têm lugar nas aulas da disciplina de ciências da terra e da vida no 10º ano de escolaridade

    Farinheira, Ana Margarida Gonçalves
    Dissertação de mest. em Observação e Análise da Relação Educativa, Faculdade de Ciências Humanas e Sociais, Univ. do Algarve, 2003

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