Flores, Indonesia
Flores, Indonesia

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Short F.T.,SeagrassNet | Short F.T.,University of New Hampshire | Coles R.,James Cook University | Fortes M.D.,University of the Philippines | And 4 more authors.
Marine Pollution Bulletin | Year: 2014

Seagrass systems of the Western Pacific region are biodiverse habitats, providing vital services to ecosystems and humans over a vast geographic range. SeagrassNet is a worldwide monitoring program that collects data on seagrass habitats, including the ten locations across the Western Pacific reported here where change at various scales was rapidly detected. Three sites remote from human influence were stable. Seagrasses declined largely due to increased nutrient loading (4 sites) and increased sedimentation (3 sites), the two most common stressors of seagrass worldwide. Two sites experienced near-total loss from of excess sedimentation, followed by partial recovery once sedimentation was reduced. Species shifts were observed at every site with recovering sites colonized by pioneer species. Regulation of watersheds is essential if marine protected areas are to preserve seagrass meadows. Seagrasses in the Western Pacific experience stress due to human impacts despite the vastness of the ocean area and low development pressures. © 2014 Elsevier Ltd. All rights reserved.


Purwandana D.,Denpasar | Ariefiandy A.,Denpasar | Imansyah M.J.,Denpasar | Ciofi C.,University of Florence | And 7 more authors.
Ecography | Year: 2015

The population dynamics of island species are considered particularly sensitive to variation in environmental, demographic and/or genetic processes. However, few studies have attempted to evaluate the relative importance of these processes for key vital rates in island endemics. We integrated the results of long-term capture-mark-recapture analysis, prey surveys, habitat quality assessments and molecular analysis to determine the causes of variation in the survival rates of Komodo dragons Varanus komodoensis at 10 sites on four islands in Komodo National Park, Indonesia. Using open population capture-mark-recapture methods, we ranked competing models that considered environmental, ecological, genetic and demographic effects on site-specific Komodo dragon survival rates. Site-specific survival rates ranged from 0.49 (95% CI: 0.33-0.68) to 0.92 (0.79-0.97) in the 10 study sites. The three highest-ranked models (i.e. ΔQAICc < 2) explained ∼70% of variation in Komodo dragon survival rates and identified interactions between inbreeding coefficients, prey biomass density and habitat quality as important explanatory variables. There was evidence of additive effects from ecological and genetic (e.g. inbreeding) processes affecting Komodo dragon survival rates. Our results indicate that maintaining high ungulate prey biomass and habitat quality would enhance the persistence of Komodo dragon populations. Assisted gene flow may also increase the genetic and demographic viability of the smaller Komodo dragon populations. © 2015 Nordic Society Oikos.


Purwandana D.,Komodo Survival Program | Ariefiandy A.,Komodo Survival Program | Imansyah M.J.,Komodo Survival Program | Rudiharto H.,Komodo National Park | And 4 more authors.
Biological Conservation | Year: 2014

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. © 2014 Elsevier Ltd.


PubMed | The Nature Conservancy, James Cook University, Palau International Coral Reef Center, Komodo National Park and 3 more.
Type: Journal Article | Journal: Marine pollution bulletin | Year: 2014

Seagrass systems of the Western Pacific region are biodiverse habitats, providing vital services to ecosystems and humans over a vast geographic range. SeagrassNet is a worldwide monitoring program that collects data on seagrass habitats, including the ten locations across the Western Pacific reported here where change at various scales was rapidly detected. Three sites remote from human influence were stable. Seagrasses declined largely due to increased nutrient loading (4 sites) and increased sedimentation (3 sites), the two most common stressors of seagrass worldwide. Two sites experienced near-total loss from of excess sedimentation, followed by partial recovery once sedimentation was reduced. Species shifts were observed at every site with recovering sites colonized by pioneer species. Regulation of watersheds is essential if marine protected areas are to preserve seagrass meadows. Seagrasses in the Western Pacific experience stress due to human impacts despite the vastness of the ocean area and low development pressures.


Jessop T.S.,Center for Conservation and Research of Endangered Species | Sumner J.,Museum Victoria | Imansyah J.,Komodo Dragon Species Survival Program Indonesia | Purwandana D.,Komodo Dragon Species Survival Program Indonesia | And 3 more authors.
Australian Zoologist | Year: 2010

In this study we assessed interactions among Komodo dragon Varanus komodoensis populations, individual Komodo dragons and two tick parasites Amblyomma robinsoni and Aponomma komodoense to assess variation in host-parasite aggregations. Prevalence of ticks was uniformly high (> 98%) but median tick abundance varied 3.52 fold among 9 host lizard populations.There was no evidence to suggest that average tick abundances were correlated with genetic similarities (Rm = 0.133, P = 0.446) or geographic proximities (Rm = 0.175 P=0.303) among host populations. Temporal concordance in tick abundance was measured for host populations between two different years but not for the individual hosts within these populations. General linearized modelling indicated that ≈ 23% of host variation in tick abundance was positively correlated to a multivariate function incorporating lizard body size, body condition, their interactions, and habitat differences.The covariates of host population density and Inbreeding coefficients, which are often associated with significant variation in parasite abundance, were not associated with variation in tick abundance on Komodo dragons. However, despite larger lizards generally harbouring more ticks, relative levels of ticks (controlling for host body mass differences) indicated that smaller individuals carried significantly higher tick abundances compared to larger lizards. There was no significant interaction between tick abundance and an individual host's growth rate.The major implications of our results indicated considerable variation in tick abundance across their host's range and that host body size is likely to be a significant determinant to what degree ticks impact the fitness of their hosts.


Purwandana D.,Komodo Survival Program | Ariefiandy A.,Komodo Survival Program | Imansyah M.J.,Komodo Survival Program | Seno A.,Komodo National Park | And 3 more authors.
Die Naturwissenschaften | Year: 2016

Ontogenetic allometries in ecological habits and niche use are key responses by which individuals maximize lifetime fitness. Moreover, such allometries have significant implications for how individuals influence population and community dynamics. Here, we examined how body size variation in Komodo dragons (Varanus komodoensis) influenced ecological allometries in their: (1) prey size preference, (2) daily movement rates, (3) home range area, and (4) subsequent niche use across ontogeny. With increased body mass, Komodo dragons increased prey size with a dramatic switch from small (≤10 kg) to large prey (≥50 kg) in lizards heavier than 20 kg. Rates of foraging movement were described by a non-linear concave down response with lizard increasing hourly movement rates up until ∼20 kg body mass before decreasing daily movement suggesting reduced foraging effort in larger lizards. In contrast, home range area exhibited a sigmoid response with increased body mass. Intrapopulation ecological niche use and overlap were also strongly structured by body size. Thus, ontogenetic allometries suggest Komodo dragon's transition from a highly active foraging mode exploiting small prey through to a less active sit and wait feeding strategy focused on killing large ungulates. Further, our results suggest that as body size increases across ontogeny, the Komodo dragon exhibited marked ontogenetic niche shifts that enabled it to function as an entire vertebrate predator guild by exploiting prey across multiple trophic levels.


Ariefiandy A.,The Komodo Survival Program | Purwandana D.,The Komodo Survival Program | Seno A.,Komodo National Park | Ciofi C.,University of Florence | Jessop T.S.,University of Melbourne
PLoS ONE | Year: 2013

Camera trapping has greatly enhanced population monitoring of often cryptic and low abundance apex carnivores. Effectiveness of passive infrared camera trapping, and ultimately population monitoring, relies on temperature mediated differences between the animal and its ambient environment to ensure good camera detection. In ectothermic predators such as large varanid lizards, this criterion is presumed less certain. Here we evaluated the effectiveness of camera trapping to potentially monitor the population status of the Komodo dragon (Varanus komodoensis), an apex predator, using site occupancy approaches. We compared site-specific estimates of site occupancy and detection derived using camera traps and cage traps at 181 trapping locations established across six sites on four islands within Komodo National Park, Eastern Indonesia. Detection and site occupancy at each site were estimated using eight competing models that considered site-specific variation in occupancy (ψ)and varied detection probabilities (p) according to detection method, site and survey number using a single season site occupancy modelling approach. The most parsimonious model [ψ (site), p (site*survey); ω = 0.74] suggested that site occupancy estimates differed among sites. Detection probability varied as an interaction between site and survey number. Our results indicate that overall camera traps produced similar estimates of detection and site occupancy to cage traps, irrespective of being paired, or unpaired, with cage traps. Whilst one site showed some evidence detection was affected by trapping method detection was too low to produce an accurate occupancy estimate. Overall, as camera trapping is logistically more feasible it may provide, with further validation, an alternative method for evaluating long-term site occupancy patterns in Komodo dragons, and potentially other large reptiles, aiding conservation of this species. © 2013 Ariefiandy et al.


Ariefiandy A.,Komodo Survival Program | Purwandana D.,Komodo Survival Program | Seno A.,Komodo National Park | Chrismiawati M.,Balai Besar Konservasi Sumber Daya Alam | And 2 more authors.
Biodiversity and Conservation | Year: 2014

Finding practical ways to robustly estimate abundance or density trends in threatened species is a key facet for effective conservation management. Further identifying less expensive monitoring methods that provide adequate data for robust population density estimates can facilitate increased investment into other conservation initiatives needed for species recovery. Here we evaluated and compared inference-and cost-effectiveness criteria for three field monitoring-density estimation protocols to improve conservation activities for the threatened Komodo dragon (Varanus komodoensis). We undertook line-transect counts, cage trapping and camera monitoring surveys for Komodo dragons at 11 sites within protected areas in Eastern Indonesia to collect data to estimate density using distance sampling methods or the Royle-Nichols abundance induced heterogeneity model. Distance sampling estimates were considered poor due to large confidence intervals, a high coefficient of variation and that false absences were obtained in 45 % of sites where other monitoring methods detected lizards present. The Royle-Nichols model using presence/absence data obtained from cage trapping and camera monitoring produced highly correlated density estimates, obtained similar measures of precision and recorded no false absences in data collation. However because costs associated with camera monitoring were considerably less than cage trapping methods, albeit marginally more expensive than distance sampling, better inference from this method is advocated for ongoing population monitoring of Komodo dragons. Further the cost-savings achieved by adopting this field monitoring method could facilitate increased expenditure on alternative management strategies that could help address current declines in two Komodo dragon populations. © 2014 Springer Science+Business Media Dordrecht.

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