Deathly Drool: Evolutionary and Ecological Basis of Septic Bacteria in Komodo Dragon Mouths

Komodo dragons, the world's largest lizard, dispatch their large ungulate prey by biting and tearing flesh. If a prey escapes, oral bacteria inoculated into the wound reputedly induce a sepsis that augments later prey capture by the same or other lizards. However, the ecological and evolutionary basis of sepsis in Komodo prey acquisition is controversial. Two models have been proposed. The “bacteria as venom” model postulates that the oral flora directly benefits the lizard in prey capture irrespective of any benefit to the bacteria. The “passive acquisition” model is that the oral flora of lizards reflects the bacteria found in carrion and sick prey, with no relevance to the ability to induce sepsis in subsequent prey. A third model is proposed and analyzed here, the “lizard-lizard epidemic” model. In this model, bacteria are spread indirectly from one lizard mouth to another. Prey escaping an initial attack act as vectors in infecting new lizards. This model requires specific life history characteristics and ways to refute the model based on these characteristics are proposed and tested. Dragon life histories (some details of which are reported here) prove remarkably consistent with the model, especially that multiple, unrelated lizards feed communally on large carcasses and that escaping, wounded prey are ultimately fed on by other lizards. The identities and evolutionary histories of bacteria in the oral flora may yield the most useful additional insights for further testing the epidemic model and can now be obtained with new technologies

Conservation of komodo dragons varanus komodoensis in the Wae Wuul nature reserve, Flores, Indonesia: a multidisciplinary approach

Multidisciplinary conservation initiatives are increasingly advocated as best practice for recovering endangered species. The Komodo dragon Varanus komodoensis is the world\u27s largest lizard, of prominent conservation value as an umbrella species for protection of south-east Indonesian ecosystems. Komodo dragons have faced multiple human-related threat processes in the past 30 years and are listed on Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora, and considered Vulnerable according to the International Union for Conservation of Nature Red List. We report on a protection programme conducted from 2005 to 2012 in the Wae Wuul nature reserve, on the island of Flores, Indonesia. The Wae Wuul ranger post was completely rebuilt, and community awareness and involvement of local people in habitat-protection schemes were regularly and successfully implemented. Local rangers were trained in wildlife-monitoring techniques. Monitoring results indicated that Komodo dragon densities were lower in Wae Wuul than in the adjacent Komodo National Park; however, a relatively high level of genetic diversity was recorded for this population. Ungulate prey showed a relatively stable prey population density. Community-based initiatives and regular wildlife monitoring are crucial to ensure the persistence of Komodo dragons on Flores. The Wae Wuul protection programme is providing several sustainability indicators by which informed management plans can be designed for long-term conservation of Komodo dragons

Fate of internal solitary wave and enhanced mixing in Manado Bay, North Sulawesi, Indonesia

International audienceThe Sulawesi Sea is one of the most active regions where internal solitary waves (ISWs) are frequently observed through satellite images. These waves that result from the nonlinear evolution of internal tides are generated over the Sibutu Sills and propagate over a long distance, up to 700 km before shoaling in coastal areas. To date there is yet no specific in-situ observation or numerical studies dedicated to characterize their dynamics. We present results from the combination of two simulations and in-situ observations which allow to describe the full life cycle from generation to breaking of ISWs in the Sulawesi Sea. A first set of 2D non-hydrostatic numerical simulations reproduces the generation of ISW from the non-linear steepening of the internal tides. The tidal energy flux emanated from the generation site is of about 15 kW m-1 with progressive decrease in the along flux direction resulting the growth of ISWs. The ISW energy flux increases up to large fraction of 32% of the total energy flux at 700 km from the generation point while the M2 internal tide contributes to 64% of the total energy flux. A second simulation at higher resolution focusing on the shallow coastal area of the Manado Bay reproduces the breaking of the ISWs at the shelf slope and was compared with in-situ observations. About 3.5% of the energy contained in an ISWs packet is dissipated over a 3 km wide cross shelf region of the Manado Bay in the simulation. Both simulations and observations revealed the presence of energetic boluses identified as a sequence of high-frequency waves of elevations in the stratified bottom layer. A high level of turbulence was diagnosed in the observations and simulations from the Thorpe Method. The mean eddy kinetic energy dissipation rate and vertical diffusivity in the observation reaches as 10-6 W kg-1 and 10-3 m2 s-1, respectively; while the dissipation rate is one order of magnitude higher and the vertical diffusivity is one order lower in the model. This discrepancy likely reflects the sparse sampling in the observations as well as differences in the stratification and the absence of surface forcing in the model

Hydrography and turbulent mixing in the Banda Sea inferred from Argo profiles

Two Argo floats circulating in the Banda Sea from July 2017 until April 2019 were analysed to inspect the hydrography and vertical mixing properties. The maximum intrusion of Pacific thermocline and intermediate layers in the Banda Sea were identified during the Southeast Monsoon period with high temporal variability in the mixed layer ([removed]10-8 m2 s-3 and [10-5-10-4] m2 s-1, respectively, were observed in the mixed layer and thermocline layer, with the decreasing trend deeper. The dissipation rate and diffusivity are comparable to previous direct estimates and models, suggesting the potential use of Argo float datasets to quantify vertical mixing in the future

Turning ghosts into dragons: Improving camera monitoring outcomes for a cryptic low-density Komodo dragon population in eastern Indonesia

Detection probability is a key attribute influencing population-level wildlife estimates necessary for conservation inference. Increasingly, camera traps are used to monitor threatened reptile populations and communities. Komodo dragon (Varanus komodoensis) populations have been previously monitored using camera traps; however, considerations for improving detection probability estimates for very low-density populations have not been well investigated