34 resultados para Chiloé Archipelago


Relevância:

10.00% 10.00%

Publicador:

Resumo:

Reef fishes may associate with marine turtles and graze on their shells, or clean their head, neck and flippers. on a reef flat at Fernando de Noronha Archipelago, SW Atlantic, we recorded green turtles (Chelonia mydas) grazed, cleaned and followed by reef fishes. The green turtle seeks specific sites on the reef and pose there for the grazers and/or cleaners. Fishes recorded associated to green turtles included omnivorous and herbivorous reef species such as the dam-selfish Abudefduf saxatilis and the surgeonfishes Acanthurus chirurgus and A. coeruleus. The turtle is followed by the wrasse Thalassoma noronhanum only while engaged in foraging bouts on benthic algae. Following behaviour is a previously unrecorded feeding association between turtles and fishes.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

At Fernando de Noronha Archipelago, southwest Atlantic, reef fishes associated with spinner dolphins (Stenella longirostris) were recorded when the cetaceans congregated in a shallow inlet. In the reef waters the dolphins engaged in several behaviors such as resting, aerial displays and other social interactions, as well as eliminative behaviors such as defecating and vomiting. Twelve fish species in seven families were recorded feeding on dolphin offal. The black durgon (Melichthys niger) was the most ubiquitous waste-eater, and its group size was positively and significantly correlated with dolphin group size. The durgons recognized the postures a dolphin adopts prior to defecating or vomiting, and began to converge to an individual shortly before it actually voided. Offal was quickly fed upon, and the fishes concentrated in the area occupied by the dolphins until the latter left the shallows. Since all the recorded offal-feeding species feed on plankton or drifting algae, feeding on cetacean droppings may be regarded as a switch from foraging on drifting organisms to foraging on drifting offal, a predictable food source in the inlet. Further instances of this cetacean-fish association are predicted to occur at sites where these mammals congregate over reefs with clear water and plankton-eating fishes.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The South Orkney Islands are the exposed part of a continental fragment on the southern limb of the Scotia are. The islands are to a large extent composed of metapelites and metagreywackes of probable Triassic sedimentary age. Deformation related to an accretionary wedge setting, with associated metamorphism from anchizone to the greenschist facies, are of Jurassic age (176-200 Ma). on Powell Island, in the centre of the archipelago, five phases of deformation are recognized. The first three, associated with the main metamorphism, are tentatively correlated with early Jurassic subduction along the Pacific margin of Gondwana. D-4 is a phase of middle to late Jurassic crustal extension associated with uplift. This extension phase may be related to opening of the Rocas Verdes basin in southern Chile, associated with the breakup of Gondwanaland. Upper Jurassic conglomerates cover the metamorphic rocks unconformably. D-5 is a phase of brittle extensional faulting probably associated with Cenozoic opening of the Powell basin west of the archipelago, and with development of the Scotia are.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The most significant studies about the spinner dolphin (Stenella longirostris) in the Southwestern Atlantic Ocean were conducted in Fernando de Noronha Archipelago, off Northeastern Brazil. The continuity of these studies depends upon the development of non-invasive methods. In this work, we present results from the skin swabbing sampling procedure for this species. We tested the performance of this method for nuclear and mitochondrial DNA analysis, unknown for this population. A total of skin 161 samples were collected during two expeditions. After the contacts the most of the dolphins remained close to the boat. Microsatellites markers and cytochrome b region primers were evaluated and the respective fragments were successfully amplified. Thus, skin swabbing may be considered an efficient strategy to obtain tissue samples for spinner dolphin genetic analysis in Fernando de Noronha Archipelago.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Biogeographical systems can be analyzed as networks of species and geographical units. Within such a biogeographical network, individual species may differ fundamentally in their linkage pattern, and therefore hold different topological roles. To advance our understanding of the relationship between species traits and large-scale species distribution patterns in archipelagos, we use a network approach to classify birds as one of four biogeographical species roles: peripherals, connectors, module hubs, and network hubs. These roles are based upon the position of species within the modular network of islands and species in Wallacea and the West Indies. We test whether species traits - including habitat requirements, altitudinal range-span, feeding guild, trophic level, and body length - correlate with species roles. In both archipelagos, habitat requirements, altitudinal range-span and body length show strong relations to species roles. In particular, species that occupy coastal- and open habitats, as well as habitat generalists, show higher proportions of connectors and network hubs and thus tend to span several biogeographical modules (i.e. subregions). Likewise, large body size and a wide altitudinal range-span are related to a wide distribution on many islands and across several biogeographical modules. On the other hand, species restricted to interior forest are mainly characterized as peripherals and, thus, have narrow and localized distributions within biogeographical modules rather than across the archipelago-wide network. These results suggest that the ecological amplitude of a species is highly related to its geographical distribution within and across bio geographical subregions and furthermore supports the idea that large-scale species distributions relate to distributions at the local community level. We finally discuss how our biogeographical species roles may correspond to the stages of the taxon cycle and other prominent theories of species assembly. © 2013 The Authors.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Pós-graduação em Biologia Geral e Aplicada - IBB

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Pós-graduação em Geociências e Meio Ambiente - IGCE

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Pós-graduação em Engenharia Elétrica - FEIS

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)