Seychelles Islands Foundation

Victoria, Seychelles

Seychelles Islands Foundation

Victoria, Seychelles
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Morgan E.J.,ETH Zurich | Kaiser-Bunbury C.N.,TU Darmstadt | Edwards P.J.,Singapore Center | Fleischer-Dogley F.,Seychelles Islands Foundation | Kettle C.J.,ETH Zurich
Conservation Genetics | Year: 2017

The fine-scale spatial genetic structure (FSGS) of plant populations is strongly influenced by patterns of seed dispersal. An extreme case of limited dispersal is found in the charismatic yet endangered palm Lodoicea maldivica, which produces large fruits (up to 20 kg) dispersed only by gravity. To investigate patterns of seed dispersal and FSGS in natural populations we sampled 1252 individual adults and regenerating offspring across the species’ natural range in the Seychelles archipelago, and characterised their genotypes at 12 microsatellite loci. The average dispersal distance was 8.7 ± 0.7 m. Topography had a significant effect on seed dispersal, with plants on steep slopes exhibiting the longest distances. FSGS was intense, especially in younger cohorts. Contrary to what might be expected in a dioecious species, we found high levels of inbreeding, with most neighbouring pairs of male and female trees (≤10 m) being closely related. Nonetheless, levels of genetic diversity were relatively high and similar in the various sampling areas, although these differed in disturbance and habitat fragmentation. We discuss potential trade-offs associated with maternal resource provisioning of progeny, seed dispersal and inbreeding, and consider the implications of our findings for managing this globally significant flagship species. © 2017 Springer Science+Business Media Dordrecht

Edwards P.J.,ETH Zurich | Fleischer-Dogley F.,Seychelles Islands Foundation | Kaiser-Bunbury C.N.,TU Darmstadt
New Phytologist | Year: 2015

The iconic Lodoicea maldivica palm appears to invest heavily in reproduction, with females bearing the world's largest seeds and males producing copious pollen. We asked how these palms, which grow in extremely poor soils, obtain sufficient nutrients to support such high levels of reproductive function. Our study site was the Vallée de Mai UNESCO Site on Praslin, Seychelles. We measured the trees' allocations of dry matter, nitrogen (N) and phosphorus (P) to aboveground growth and reproduction, quantified stemflow and throughfall, and measured availabilities of N and P in the soil. We show that the nutrient costs of reproduction are very high in male and female plants, and for P far exceed those of vegetative growth. We describe how the palm leaves form a huge funnel that intercepts particulate material, especially pollen, which is flushed to the base of the trunk when it rains. In this way, Lodoicea improves its nutrient supply and that of its dispersal-limited offspring. Lodoicea shares many functional characteristics with dominant trees of other monodominant forests in the humid tropics. It also exhibits unique features, including its huge seed, effective funnelling mechanism and diverse community of closely associated animals, suggesting a long evolutionary history under relatively stable conditions. © 2015 New Phytologist Trust.

Noble T.,University of East Anglia | Bunbury N.,Seychelles Islands Foundation | Kaiser-Bunbury C.N.,ETH Zurich | Bell D.J.,University of East Anglia
Journal of Zoology | Year: 2011

In island ecosystems, reptiles play diverse ecological roles as a result of niche broadening, which increases potential niche overlap between species. Ecological niche partitioning is a means of reducing direct competition between coexisting species and differences in habitat use among island gecko species have been suggested as a by-product of specialization to feeding on certain resources. Here, we examine modes and drivers of niche partitioning of two endemic species of Phelsuma gecko (Phelsuma sundbergi and Phelsuma astriata) in relict native palm forest in the Seychelles to further understanding of congeneric reptile co-existence in native habitats. Phelsuma abundance, microhabitat use and habitat composition were quantified in different macrohabitat types. P. sundbergi showed a clear preference for habitat dominated by the coco de mer palm, Lodoicea maldivica and a strong association with male individuals of this dioecious species. P. astriata density increased significantly with arboreal biodiversity but did not display a relationship with a specific tree type. High levels of resource segregation were determined along the microhabitat axis, based on differential tree preference. Our results suggest that P. sundbergi and P. astriata may have evolved to co-exist in this habitat type through partitioning of microhabitat as members of a divergent specialist/generalist assemblage determined by consumption of L. maldivica pollen by P. sundbergi. Our findings concur with the hypothesis that differences in habitat use among island reptiles are a by-product of trophic specialization and support the conservation of native habitat for maintenance of reptile diversity. © 2010 The Authors. Journal of Zoology © 2010 The Zoological Society of London.

Fleischer-Dogley F.,Seychelles Islands Foundation | Kettle C.J.,ETH Zurich | Edwards P.J.,ETH Zurich | Ghazoul J.,ETH Zurich | And 2 more authors.
Diversity and Distributions | Year: 2011

Aims Developing plant conservation strategies requires knowledge of ecological and genetic processes underlying population dynamics. We aimed to quantify morphological and genetic differentiation among remnant populations of the iconic coco-de-mer palm Lodoicea maldivica. We hypothesized that limited gene flow among widely spaced populations would result in high genetic variation and large phenotypic differences among populations. Location Islands of Praslin and Curieuse (CU), Seychelles, Indian Ocean. Methods We conducted an extensive population survey and recorded morphological parameters for 447 Lodoicea in the main populations at Vallée de Mai (VM) and Fond Ferdinand (FF) on Praslin, and on CU. We collected leaf material from 180 trees in these populations for DNA genotyping using amplified fragment length polymorphisms. Results A total of 16,766 Lodoicea trees were recorded in the three populations (72.6% of Lodoicea on both islands). Lodoicea trees at VM and FF showed similar morphology, but differed in most parameters from those at CU, which were shorter, grew more slowly and produced fewer seeds. Mean overall genetic diversity was 0.337, and percentage of polymorphic loci was 91.1. Genetic diversity of the CU population was lower than that at VM and FF. There was weak genetic differentiation between CU and Praslin populations, but 99% of all genetic diversity was within populations. Main conclusions Trees on CU differed in growth and morphology from those of the two Praslin populations. These phenotypic differences, however, were not mirrored in the genetic structure of the populations. All populations were relatively genetically diverse with remarkably little differentiation among populations. This suggests that the capacity of Lodoicea to dominate across a range of habitats may be because of high phenotypic plasticity. High genetic connectivity may be maintained through long-distance wind pollination. Given the uncertainty about the extent of underlying adaptive variation, we recommend that restoration projects avoid transferring seeds between island populations. © 2010 Blackwell Publishing Ltd.

Loewenthal D.,University of Cape Town | Paijmans D.M.,University of Cape Town | Haupt P.W.,Seychelles Islands Foundation | Hockey P.A.R.,University of Cape Town
Ostrich | Year: 2015

The African Black Oystercatcher Haematopus moquini is classified as Near Threatened because the population size is small (<10 000) and numbers have decreased or were previously recorded as decreasing. Although human activity has increased in many parts of the species’ breeding range, oystercatchers may be benefiting from an increase in the extent of Marine Protected Areas as well as an improved food supply provided by an alien invasive mussel, Mytilus galloprovincialis. The study reassesses the global population (last assessed in the early 1980s) and, where changes have occurred, to provide an explanation for these changes. Between the early 1980s and early 2000s the global population increased by c. 45% from about 4 600 to about 6 670 birds. On rocky and mixed shores, the presence of Mytilus and protection status explained most of the increase in oystercatchers. At 41 of the 129 study sites numbers of oystercatchers decreased, most probably on account of movement of birds out of areas that experienced human-induced habitat degradation, rather than unsustainable reproductive rates. Overall, there was undoubtedly an improvement in the species’ conservation status; given its current status and trends it may soon be possible to change the status to Least Concern on the IUCN Red List. © 2015, Copyright © NISC (Pty) Ltd.

Harper G.A.,Biodiversity Restoration Specialists | Harper G.A.,Seychelles Islands Foundation | van Dinther M.,Seychelles Islands Foundation | Russell J.C.,University of Auckland | Bunbury N.,Seychelles Islands Foundation
Biological Conservation | Year: 2015

Rat eradications on tropical islands have been less successful than operations in temperate climates. This is likely due to poor understanding of the factors unique to tropical regions that rat populations respond to, such as high numbers of land crabs, aseasonal climates and habitats not found at higher latitudes. On Aldabra Atoll, southern Seychelles, black rats were monitored for one year in three habitats over three climatic seasons to investigate changes in density and breeding to inform planning for a possible rat eradication. Rats bred all year in mangrove forest and in two of three seasons, including the dry season, in Pemphis forest, probably resulting from the saline tolerance of these habitats: lush vegetation and seeds were available there during the dry season. In contrast, rats from the adjacent mixed-scrub habitat only bred in the wet season due to desiccation of vegetation and lack of fresh water during other times of the year. Bait consumption trials showed that all rats ingested dyed bait when applied at 15. kg/ha, despite high rat densities and substantial bait interference by non-target species, but not at an application rate of 10. kg/ha. A novel 'bola' technique was tested for distributing bait into mangrove forest, where aerially applied rat bait would normally be lost due to tidal inundation. The method is likely to improve rat exposure to bait in mangrove forest and other habitats on tropical islands, and warrants further development. © 2014 Elsevier Ltd.

Reuleaux A.,Seychelles Islands Foundation | Reuleaux A.,University of Gottingen | Bunbury N.,Seychelles Islands Foundation | Villard P.,Seychelles Islands Foundation | Waltert M.,University of Gottingen
ORYX | Year: 2013

The Seychelles black parrot Coracopsis (nigra) barklyi, endemic to the Seychelles islands, is the only surviving parrot on the archipelago. Although originally classified as a subspecies of the lesser vasa parrot Coracopsis nigra evidence now indicates that the Seychelles population may be a distinct species, in which case its conservation status also requires reassessment. Here, we address the status of the C. (n.) barklyi population on the islands of its current and likely historical range, Praslin and Curieuse, assess the effect of habitat type on relative abundance, and identify the most appropriate point count duration for monitoring the population. We conducted point count distance sampling at 268 locations using habitat type as a covariate in the modelling of the detection function. Density on Praslin was estimated to be 0.14-0.24 individuals per ha, resulting in an estimate of a total of 520-900 individuals (95% confidence interval). The highest densities occurred in endemic palm and mixed forests. Habitats with a high proportion of palms were more likely to support parrots than habitats without palms. As no parrots were detected on Curieuse the number estimated on Praslin is the global wild population. The small size of this population necessitates its categorization as Vulnerable on the IUCN Red List. Our main recommendation for the conservation of C. (n.) barklyi, in addition to continued monitoring, is the preservation and expansion of the parrot's endemic palm forest habitat. © 2013 Fauna & Flora International.

Sur M.,Seychelles Islands Foundation | Bunbury N.,Seychelles Islands Foundation | Van De Crommenacker J.,Seychelles Islands Foundation
Bird Conservation International | Year: 2013

We report the results of a survey of breeding Greater Frigatebird Fregata minor and Lesser Frigatebird F. ariel on Aldabra Atoll, a UNESCO World Heritage site in the Seychelles archipelago, which hosts the largest breeding population of frigatebirds in the Indian Ocean. All four colonies across the atoll were surveyed in 2011 and 2012 by counting adults on nests and chicks, and calculating the number of fledged birds. The breeding population in 2011 consisted of approximately 4,400 pairs of Greater Frigatebird and 6,600 pairs of Lesser Frigatebird. This is a potential increase of at least 10% since the last comparable surveys in 1976/77 and 2000. However, 2012 populations were considerably less than in 2011, highlighting significant annual variation and the need for more data. We also report a new breeding colony on the island of Picard, which was last reported to host breeding frigatebirds a century ago. We outline recommendations for future frigatebird monitoring on Aldabra and elsewhere and revisions to tourist regulations resulting from the census. Copyright © BirdLife International 2013 Â.

Bunbury N.,Seychelles Islands Foundation
Journal of Wildlife Diseases | Year: 2011

Island endemic avifaunas face many threats, including the now well-documented impacts of pathogens. The impacts of pathogens on the endemic Seychelles avifauna, however, have been little studied. The protozoan parasite Trichomonas gallinae has been shown to reduce survival and reproductive success of the endemic Pink Pigeon Columba mayeri on the nearby island of Mauritius. I investigated trichomonad infection prevalence and pathogenicity in endemic Seychelles Blue Pigeons, Alectroenas pulcherrima, and two introduced species of columbid, the Madagascar Turtle-dove, Streptopelia picturata, and the Barred Ground Dove, Geopelia striata, on the Seychelles island of Mahe ́ during September- October 2007. I asked whether: 1) trichomonad infections occur in these species; 2) prevalence varies among species; and 3) birds show any signs of pathogenicity consistent with trichomonosis. I use the results to assess the potential threat of this pathogen to A. pulcherrima. All three species were infected with trichomonads, and the overall prevalence was 27.5%. Alectroenas pulcherrima had higher prevalence (47.1%) than the two introduced species combined (24.3%). No infected individuals showed any signs of disease. These findings suggest that trichomonad parasites should be considered as a potential disease threat to the A. pulcherrima population.© Wildlife Disease Association 2011.

Hamylton S.M.,University of Cambridge | Hagan A.B.,University of Cambridge | Doak N.,Seychelles Islands Foundation
International Journal of Geographical Information Science | Year: 2012

Until recently, it was thought that dugongs (Dugong dugon) were extinct in the Seychelles. However, a collection of sightings at Aldabra Atoll, a World Heritage Site in the Seychelles, has renewed interest in dugong distribution in the western Indian Ocean. This article consolidates the records of dugong sightings held in the Aldabra Research Station library and explores their spatial patterning. The locations of sightings (2001-2009) are plotted onto a high-resolution benthic habitat map of the Aldabra lagoon created by classifying a QuickBird satellite remote-sensing image in January 2009. A spatial cluster detection procedure is applied to point records of sightings to reveal a statistically significant cluster of sightings in the north-west of the lagoon, at Bras Monsieur Clairemont, suggesting a mutual co-existence of dugongs and seagrass beds. A habitat suitability model combines the point data set of dugong sightings within the continuous benthic habitat map and identifies the central western area as containing the most suitable habitat for dugong inside the Aldabra lagoon. © 2012 Copyright Taylor and Francis Group, LLC.

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