15 resultados para small islands

em Deakin Research Online - Australia


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Despite being a relatively common and well-known species locally, the ecology of the Manus Friarbird Philemon albitorques is not well documented in the literature. Here I present information on breeding and range extensions for this species, and for other bird species on small islands in the Admiralties Group, Papua New Guinea.

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Single crystal seeds of the nickel-base superalloy CMSX-4 have been partially melted in a temperature gradient and then quenched. Small islands of random orientation are observed throughout the melted-back semi-solid. These random orientations appear to be pinched-off secondary dendrite arms, but there is no evidence that they are transported ahead of the dendrite tips to nucleate stray grains during directional solidification.

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This paper examines the strategic interaction between firms and governments in two Small Island Tourism Economies (SITEs). In a situation where congestion can threaten the viability of tourism industries in SITEs, we highlight the role of two factors that determine the distribution of tourists across SITEs: whether the tourism market is vertically or horizontally differentiated, and the extent to which tourists care about congestion. Under these circumstances, counterintuitive results are possible: congestion in a SITE may rise in response to tourists caring more about congestion in the SITE. Moreover, maximising tourism tax revenue emerges as a dominant strategy for governments.

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The Komodo dragon (Varanus komodoensis) is the world's largest lizard and endemic to five islands in Eastern Indonesia. The current management of this species is limited by a paucity of demographic information needed to determine key threats to population persistence. Here we conducted a large scale trapping study to estimate demographic parameters including population growth rates, survival and abundance for four Komodo dragon island populations in Komodo National Park. A combined capture mark recapture framework was used to estimate demographic parameters from 925 marked individuals monitored between 2003 and 2012. Island specific estimates of population growth, survival and abundance, were estimated using open population capture-recapture analyses. Large island populations are characterised by near or stable population growth (i.e. λ~. 1), whilst one small island population (Gili Motang) appeared to be in decline (λ= 0.68 ± 0.09). Population differences were evident in apparent survival, with estimates being higher for populations on the two large islands compared to the two small islands. We extrapolated island specific population abundance estimates (considerate of species habitat use) to produce a total population abundance estimate of 2448 (95% CI: 2067-2922) Komodo dragons in Komodo National Park. Our results suggest that park managers must consider island specific population dynamics for managing and recovering current populations. Moreover understanding what demographic, environmental or genetic processes act independently, or in combination, to cause variation in current population dynamics is the next key step necessary to better conserve this iconic species.

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Understanding the mechanisms that afford invasive species their ecological success as important agents of global change is key to addressing their biodiversity impacts. Species invasions that occur on small islands are especially detrimental and suggest that invaders intensify their ecological impacts by exploiting novel ecological functions. However, it remains unknown whether such strong impacts are also a consequence of an invader's indirect effect (e.g. causing physiological stress or reproductive failure) on island species. Therefore, it is valuable to quantify the physiological mechanisms through which invasive species can exert indirect effects on the performance, and ultimately the fitness of island endemics. In this study, we investigated whether the invasive cane toad (Rhinella marina) caused indirect competitive impacts on the endemic Fijian ground frog (Platymantis vitiana) on the small (60 ha) Viwa Island, Fiji. We used large (4 × 10 000 m2), natural and replicated enclosures to monitor ground frog stress hormone levels, reproductive hormone cycle, body condition, breeding and survival in the presence/absence of the cane toad. We conducted monthly sampling to analyse annual patterns in testosterone for males, estradiol and progesterone for females, corticosterone for both sexes and body condition of ground frogs in replicated enclosures or natural habitats with high/low cane toad densities. We also measured survival and reproductive success of ground frogs in enclosures. Results showed that in both enclosures and natural habitats with high cane toad densities, ground frogs had a significant reduction in body condition, increased urinary corticosterone metabolites and suppressed sex steroid metabolites. Most importantly, annual field surveys showed significant reduction in ground frog reproductive success (fewer eggs were laid in enclosures with toads present); however, survival was not severely reduced. Our study clearly demonstrated that on small islands, invasive species may exploit broader ecological roles with strong indirect effects that amplify their impacts beyond those seen on continents. Overall, the effects of cane toad competition had the capacity to strongly reduce ground frog reproductive success. We strongly advocate management actions that either minimize invasion or limit the strength of invasive-native species interactions (e.g. through habitat conservation) to prevent further extinctions on islands.

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The goal of this paper is to examine the relationship between real GDP and oil prices using time series data for the period 1970–2005. Our main finding is that an increase in oil has a positive, albeit inelastic, impact on real GDP, inconsistent with the bulk of the literature. We argue that this is not a surprising result for the Fiji Islands. Our central argument focuses on two aspects of the Fijian economy: (1) the fact that actual output in Fiji has been around 50 per cent less than potential output; thus, Fiji's actual output has not reached a threshold level at which oil prices can negatively impact output; and (2) a rise in oil prices filters through to value added, which in turn is reflected in a larger actual output.

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Fiji is a small open island economy dependent on energy for its growth and development; hence, the relationship between energy consumption and economic growth is crucial for Fiji's development. In this paper, we investigate the nexus between electricity consumption and economic growth for Fiji within a multivariate framework through including the labour force variable. We use the bounds testing approach to cointegration and find that electricity consumption, GDP and labour force are only cointegrated when GDP is the endogenous variable. We use the Granger causality F-test and find that in the long-run causality runs from electricity consumption and labour force to GDP, implying that Fiji is an energy dependent country and thus energy conservation policies will have an adverse effect on Fiji's economic growth.

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This research identified the causes of poor water quality and algal blooms in Lagoon of Islands, a small shallow lake in Tasmania. The findings of this research identified options for rehabilitation and remediation of the lake.

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The Small Island Developing States (SIDS)1 in the Pacific, spread out over an area of 30 million square kilometres of ocean, and home to over 9 million people, face a complex and unique set of development challenges. As small, highly open economies they are particularly susceptible to external shocks, including fluctuations in import prices and export earnings in particular. Remoteness from major ports and export markets, low levels of connectivity with the outside world and susceptibility to natural hazards further complicate matters and have resulted in the Pacific islands being amongst the most vulnerable economies in the world. In spite of their increasing integration into global markets, most face further challenges owing to very limited absorptive capacities, limited resources, inadequate technology, lack of infrastructure and poor economic management and institutional capabilities. As a consequence, economic growth and related outcomes in most remain heavily reliant on external resources, typically including at least one of aid, migrant remittances, and foreign direct investment (FDI) (AusAID 2008 and McGillivray et al. 2008). The particular constraints and growth challenges of Pacific SIDS are too often overlooked in the development research literature. Moreover, the policy debate on how to promote and achieve growth in the Pacific islands can benefit from a deeper understanding of the nature and consequences of these often unique, combination of constraints. This Focus is devoted to development challenges facing these islands, specifically relating to the achievement of economic growth, and draws on five papers that were presented or tabled at the World Institute for Development Economics Research (WIDER) ‘Fragility and Development’ research project meeting held in Fiji in December 2006.

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Islands-in-the-sea nanofibres are a very interesting system: one polymer (islands) is distributed in fibrillar domains within a second polymer (sea). This fibre geometry is often used in microfiber technologies to obtain very fine fibers, by removing the “sea” polymer. This geometry also allows to combine two polymers with very different properties. In this work this geometry is introduced applied to electrospun hydrogel nanofibers, in a novel fashion, and as a way to improve and stabilize the hydrogel nanofibers. Thermo-responsive islands-in-the-sea nanofibers are here produced by electrospinning solutions of a hydrogel-forming thermo-responsive polymer (crosslinked poly(N-isopropylacrylamide), PNIPAM) and a reinforcing polymer (polyetherketone cardo, PEK-c). The two polymers are thermodynamically incompatible in solution and phase separation takes place, which allows the instant formation of islands-in-the-sea nanofibers upon electrospinning. PNIPAM was then crosslinked post-spinning using an oligomeric silsesquioxane. The formed nanocomposite nanofibers showed intrinsic nanostructure, where the fibril-like PNIPAM domains are intimately adjacent to the strong PEK-c domains. Upon contacting with water, the hydrogel domains became instantly highly swollen, while the PEK-c domains did not. As a result, very wrinkly, swollen fibers were obtained, with increased capillary action, as demonstrated through confocal microscopy. The composite nanofibers in water showed excellent swelling ratios and very fast responses to temperature variations (of the order of 1 second) with morphological and optical effects: variations in fiber-diameter were accompanied by optical transitions: transparent-opaque. The produced hydrogel nanofibers also presented improved mechanical properties (even with small amounts of PEK-c), when compared to their crosslinked-PNIPAM-only nanofibers. It will be also shown how these materials can be used as optical actuators and smart hydrogel platforms with tuneable contact angle and morphology. In brief, this work aims to demonstrate a new platform technology which can be applied to several hydrogel systems, to achieve hydrogel-based composites with new and improved properties, while retaining (and improving) the main properties of the hydrogel. Here this was demonstrated by showing that the composite materials showed thermo-responsiveness, and enhanced transition kinetics.

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A hairless adult male southern sea lion (Otaria flavescens) was sighted at Sea Lion Island, Falkland Islands, on the 14th of August 2009. The sea lion was observed on several further occasions and was defending a small harem consisting of four females. To our knowledge, this is the first report of an apparently healthy sea lion being entirely hairless with the exception of vibrissae on the muzzle.

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Large populations of marine turtles breeding in the Cayman Islands were drastically reduced in the early 1800s. However, marine turtle nesting still occurs in the islands. The present-day status of this nesting population provides insight into the conservation of marine turtles, a long-lived species. In 1998 and 1999, the first systematic survey of marine turtle nesting in the Cayman Islands found 38 nests on 22 beaches scattered through the three islands. Three species were found: the green Chelonia mydas, hawksbill Eretmochelys imbricata and loggerhead Caretta caretta turtles. Comparison with other rookeries suggests that the small number of sexually mature adults surviving Cayman’s huge perturbations may be impeding population recovery. This shows the need to implement conservation measures prior to massive reductions in population size.

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Erik Martin explored the implementation of an international tobacco control policy in the Pacific Island nations of the Cook Islands, Nauru, Palau and Vanuatu. This qualitative study explored how tobacco control policies are influenced and provided recommendations on how to advance tobacco control policy to benefit population health.

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Whilst there is good evidence for negative impacts of introduced rat species on island ecosystems, the effects of house mice (Mus musculus) are generally less well documented. In some situations, introduced house mice can exert severe impacts, particularly where this is the only introduced mammal. Here, we examine the distribution, relative abundance and breeding success of small burrowing seabirds on Steeple Jason Island, Falklands, in relation to habitat types and the distribution of house mice which is the sole introduced mammal species, and we make comparisons with seabird distribution and densities on the neighbouring island of Grand Jason where mice are absent. Grey-backed storm-petrel (Garrodia nereis) and Wilson's storm-petrel (Oceanites oceanicus), which due to their extremely small size are likely to be the most vulnerable to mouse predation, were considerably more abundant on mouse-free Grand Jason than on Steeple Jason. Grey-backed storm-petrel, which are typically associated with tussac grass, avoided this habitat on Steeple Jason where it is associated with high levels of house mouse activity (assessed from the proportion of wax baits gnawed overnight), whereas on mouse-free Grand Jason, there was no such avoidance. Wilson's storm-petrel nesting on Steeple Jason suffered high rates of egg and chick loss. Whilst we found evidence for detrimental impacts of house mice on the two small storm-petrel species, there was no relationship between relative mouse activity levels and the distribution or abundance of the larger thin-billed Prion (Pachyptila belcheri). © 2014 Springer-Verlag Berlin Heidelberg.

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BACKGROUND: Mountain landscapes are topographically complex, creating discontinuous 'islands' of alpine and sub-alpine habitat with a dynamic history. Changing climatic conditions drive their expansion and contraction, leaving signatures on the genetic structure of their flora and fauna. Australia's high country covers a small, highly fragmented area. Although the area is thought to have experienced periods of relative continuity during Pleistocene glacial periods, small-scale studies suggest deep lineage divergence across low-elevation gaps. Using both DNA sequence data and microsatellite markers, we tested the hypothesis that genetic partitioning reflects observable geographic structuring across Australia's mainland high country, in the widespread alpine grasshopper Kosciuscola tristis (Sjösted). RESULTS: We found broadly congruent patterns of regional structure between the DNA sequence and microsatellite datasets, corresponding to strong divergence among isolated mountain regions. Small and isolated mountains in the south of the range were particularly distinct, with well-supported divergence corresponding to climate cycles during the late Pliocene and Pleistocene. We found mixed support, however, for divergence among other mountain regions. Interestingly, within areas of largely contiguous alpine and sub-alpine habitat around Mt Kosciuszko, microsatellite data suggested significant population structure, accompanied by a strong signature of isolation-by-distance. CONCLUSIONS: Consistent patterns of strong lineage divergence among different molecular datasets indicate genetic breaks between populations inhabiting geographically distinct mountain regions. Three primary phylogeographic groups were evident in the highly fragmented Victorian high country, while within-region structure detected with microsatellites may reflect more recent population isolation. Despite the small area of Australia's alpine and sub-alpine habitats, their low topographic relief and lack of extensive glaciation, divergence among populations was on the same scale as that detected in much more extensive Northern hemisphere mountain systems. The processes driving divergence in the Australian mountains might therefore differ from their Northern hemisphere counterparts.