71 resultados para Canaries


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Includes indexes

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Mode of access: Internet.

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Illustrations by Paul Louis Oudart.

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Photocopy. Ann Arbor, Mich., University Microfilms International, 1977.

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Cover-title:: North Atlantic islands and Africa from cape Spartel to cape Palmas.

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Mode of access: Internet.

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The coral reefs around the world may be likened to canaries down the mineshaft of global warming. These sensitive plant-like animals have evolved for life in tropical seas. Their needs are quite specific – not too cold, not too hot. A rise of as little as one degree Celsius is enough to cause some bleaching of these colourful jewels of the sea. Many climate models indicate we can expect sea temperature increases of between two and six degrees Celsius. Research - such as that detailed in a 2004 report by the University of Queensland’s Centre for Marine Studies – indicates that by the year 2050 most of the worlds major reef systems will be dead. Many of us have heard this kind of information, but it remains difficult to comprehend. It’s almost impossible to imagine the death of the Great Barrier Reef. Some six to nine thousand years old and visible from space, it is the world’s largest structure created by living organisms. Yet whilst it is hard to believe, this gentle, sensitive giant is at grave risk because it cannot adapt quickly enough to the changes in the environment. This cluster of fluffy felt brain coral sculptures are connected in real time to temperature data collected by monitoring stations within the Great Barrier Reef, that form part of the Australian Institute of Marine Science’s Great Barrier Reed Ocean Observing System. These corals display illumination patterns showing changes in sea temperature at Heron Reef, one of the 2,900 reefs that comprise the Great Barrier Reef. Their spectrum of colour ranges from cool hues, through warm tones to bright white when temperatures exceed those that tropical corals are able to tolerate over sustained periods. The Flower Animals also blush in colour and make sound when people come within close proximity. In a reef, fishes and other creatures generate significant amounts of sound. These cacophonies are considered an indicator of reef health, and are used by reef fish to determine where they can best live and forage.

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Seagrasses, marine flowering plants, have a long evolutionary history but are now challenged with rapid environmental changes as a result of coastal human population pressures. Seagrasses provide key ecological services, including organic carbon production and export, nutrient cycling, sediment stabilization, enhanced biodiversity, and trophic transfers to adjacent habitats in tropical and temperate regions. They also serve as “coastal canaries,” global biological sentinels of increasing anthropogenic influences in coastal ecosystems, with large-scale losses reported worldwide. Multiple stressors, including sediment and nutrient runoff, physical disturbance, invasive species, disease, commercial fishing practices, aquaculture, overgrazing, algal blooms, and global warming, cause seagrass declines at scales of square meters to hundreds of square kilometers. Reported seagrass losses have led to increased awareness of the need for seagrass protection, monitoring, management, and restoration. However, seagrass science, which has rapidly grown, is disconnected from public awareness of seagrasses, which has lagged behind awareness of other coastal ecosystems. There is a critical need for a targeted global conservation effort that includes a reduction of watershed nutrient and sediment inputs to seagrass habitats and a targeted educational program informing regulators and the public of the value of seagrass meadows.

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Studies on the flora and fauna of the Canary Islands show that this Archipelago is one of the planet’s diversity hot spots. However, an analysis of the differences in the phytogeographic characteristics of each of the islands that make up this Archipelago is lacking. This article focuses on the phytogeographic characterization of the island of Gran Canaria. This island exhibits geological and climatic characteristics resulting in a rich vascular flora, including endemic species and genera that are significantly different from the other islands of the Archipelago. These differences are verified through statistical analysis of the existing similarity between the floras of the members of the Canary Islands. This study also analyses the subdivision of Gran Canaria Island, indicating that there are three well-differentiated areas on the island itself. Finally, this study argues that these areas, themselves, should be considered biogeographic sectors.

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The genus Asparagopsis was studied using 25 Falkenbergia tetrasporophyte strains collected worldwide. Plastid (cp) DNA RFLP revealed three groups of isolates, which differed in their small subunit rRNA gene sequences, temperature responses, and tetrasporophytic morphology (cell sizes). Strains from Australia, Chile, San Diego, and Atlantic and Mediterranean Europe were identifiable as A. armata Harvey, the gametophyte of which has distinctive barbed spines. This species is believed to be endemic to cold-temperate waters of Australia and New Zealand and was introduced into Europe in the 1920s. All isolates showed identical cpDNA RFLPs, consistent with a recent introduction from Australia. Asparagopsis taxiformis (Delile) Trevisan, the type and only other recognized species, which lacks spines, is cosmopolitan in warm-temperate to tropical waters. Two clades differed morphologically and ecophysiologically and in the future could be recognized as sibling species or subspecies. A Pacific/Italian clade had 4-8degrees C lower survival minima and included a genetically distinct apomictic isolate from Western Australia that corresponded to the form of A. taxiformis originally described as A. sanfordiana Harvey. The second clade, from the Caribbean and the Canaries, is stenothermal (subtropical to tropical) with some ecotypic variation. The genus Asparagopsis consists of two or possibly three species, but a definitive taxonomic treatment of the two A. taxiformis clades requires study of field-collected gametophytes.

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The North Atlantic is considered a stronghold for the critically endangered leatherback sea turtle. However, limited information exists regarding the movements of individuals to and from the seas off Europe's northwesterly fringe, an area where featherbacks have been historically sighted for the past 200 yr. Here, we used satellite telemetry to record the movements and behaviour of 2 individuals bycaught in fisheries off the southwest coast of Ireland. The turtle T1 (tagged 1 September 2005; female; tracked 375 d) immediately travelled south via Madeira and the Canaries, before residing in West African waters for 3 mo. In spring, T1 migrated north towards Newfoundland where transmissions ceased. T2 (29 June 2006; male; 233 d) travelled south for a short period before spending 66 d west of the Bay of Biscay, an area previously asserted as a high-use area for leatherbacks. This prolonged high latitude summer residence corresponded with a mesoscale feature evident from satellite imagery, with the implication that this turtle had found a rich feeding site. A marked change in dive behaviour was apparent as the turtle exited this feature and provided useful insights on leatherback diving behaviour. T2 headed south in October 2006, and performed the deepest-ever dive recorded by a reptile (1280 m) southwest of Cape Verde. Unlike T1, T2 swam southwest towards Brazil before approaching the major nesting beaches of French Guiana and Surinam. Importantly, these tracks document the movement of leatherbacks from one of the remotest foraging grounds in the North Atlantic. © Inter-Research 2008.

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Tese de mestrado. Biologia (Ecologia e Gestão Ambiental). Universidade de Lisboa, Faculdade de Ciências, 2014