Tanna Island Research Articles

Slab steepening and rapid mantle wedge replacement during back-arc rifting in the New Hebrides

The effects of the composition and angle of the subducting slab and mantle wedge flow on tectonic and magmatic processes in island arcs and associated back-arcs are poorly understood. Here we analyse the ages and compositions of submarine lavas from the flanks and the floor of the back-arc Futuna Trough some 50 km east of Tanna Island in the New Hebrides arc front. Whereas >2.5 Ma-old back-arc lavas formed from an enriched mantle source strongly metasomatized by a slab component, the younger lavas show less slab input into a depleted mantle wedge. The input of the slab component decreased over the past 2.5 million years while the enriched mantle was replaced by depleted peridotite. The change of Futuna Trough lava compositions indicates rapid (10 s of km/million years) replacement of the mantle wedge by corner flow and slab steepening due to rollback, causing extensional stress and back-arc rifting in the past 2.5 million years.

Tracing the origins of Plasmodium vivax resurgence after malaria elimination on Aneityum Island in Vanuatu

BackgroundFive years after successful malaria elimination, Aneityum Island in Vanuatu experienced an outbreak of Plasmodium vivax of unknown origin in 2002. Epidemiological investigations revealed several potential sources of P. vivax. We aimed to identify the genetic origin of P. vivax responsible for the resurgence.MethodsFive P. vivax microsatellite markers were genotyped using DNA extracted from archived blood samples. A total of 69 samples from four P. vivax populations was included: 29 from the outbreak in 2002, seven from Aneityum in 1999 and 2000, 18 from visitors to Aneityum in 2000, and 15 from nearby Tanna Island in 2002. A neighbour-joining phylogenetic tree was constructed to elucidate the relationships among P. vivax isolates. STRUCTURE and principal component analysis were used to assess patterns of genetic structure.ResultsHere we show distinct genetic origins of P. vivax during the outbreak on Aneityum. While the origin of most P. vivax lineages found during the outbreak remains unidentified, limited genetic diversity among these lineages is consistent with a rapid expansion from a recent common ancestor. Contemporaneous P. vivax from neighboring Tanna and potential relapse of P. vivax acquired from other islands in 1999 and 2000 are also identified as minor contributors to the outbreak.ConclusionsMultiple reintroductions of P. vivax after elimination highlight the high receptivity and vulnerability to malaria resurgence in island settings of Vanuatu, despite robust surveillance and high community compliance to control measures.

Long range infrasound monitoring of Yasur volcano

The atmospheric injection of gas and material produced by an explosive volcanic eruption determines a rapid compression of the atmosphere, which subsequently propagates as longitudinal elastic waves (sound). The size of the source, generally greater than tens of meters, and its duration, longer than a few seconds, result into an emitted signal that is particularly rich in low frequencies (f < 20 Hz), thus determining an efficient infrasound radiation. Thanks to the low spectral content and the reduced attenuation in the atmosphere, infrasound is capable of propagating for very large distances.In this study we show how the infrasonic monitoring at regional distances (> 100 km) is efficient in recording and characterizing volcanic events. For the purpose of our study, infrasound signal radiated from Yasur volcano (Tanna Island, Vanuatu) was studied for a period of twelve years (January 2008 – December 2019). Signals from Yasur were registered at a source-to-receiver distance of 400 km by the IS22 infrasound array, located in New Caledonia, part of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) International Monitoring System (IMS). The predominantly explosive Strombolian activity of this volcano makes it a perfect subject to be studied by infrasound technology. Detections of volcanic infrasound are modulated according to the seasonal variation of stratospheric winds and corrected for attenuation accounting for real atmospheric specification between the source and the receiver to retrieve the pressure at the source. Next, they are used to evaluate long-term (yearly) and short term (hourly) variations of activity over the period of analysis. Results are compared with thermal anomalies recorded by the MODerate resolution Imaging Spectroradiometer (MODIS) installed on NASA's Terra and Aqua satellites.We show that even at regional distances (400 km) it is possible to follow the long term (yearly) fluctuations of ordinary explosive activity during periods of optimal propagation of infrasonic waves in the atmosphere. In addition, we show that the time resolution retrieved from the signal analysis allows to follow variations of volcanic activity at hourly time scale, thus representing a valuable source of information, in particular in areas where local geophysical observations are missing.

Teaching strategies are shaped by experience with formal education: Experimental evidence from caregiver-child dyads in two Tannese communities.

Humans are extraordinary in the extent to which we rely on cumulative culture to act upon and make sense of our environment. Teaching is one social learning process thought to be fundamental to the evolution of cumulative culture as a means of adaptation in our species. However, the frequency of teaching and how we teach are known to vary across human sociocultural contexts. Understanding this variation adds to our understanding of the complex interplay between cognition and culture in shaping learning behavior but also contributes to theory around the costs and benefits of different social learning processes. Here, we examined how prior experience with formal education is related to the frequency and diversity of teaching behaviors in an experimental paradigm where caregivers were motivated (but not instructed) to teach a simple skill to a child (7-10 years old). We identified and coded a suite of subtle nonverbal behaviors that could be construed as facilitating learning. Dyads (n = 64) were recruited from two communities on Tanna Island that differ in their experience with formal schooling and their acceptance of Western institutions. We found evidence for parallel teaching strategies in both communities. However, the rate and diversity of teaching behaviors were positively associated with caregiver's experience with formal schooling and independently and negatively associated with being from a village that rejects Western-derived institutions. These results further our understanding of how multiple cultural processes influence social learning and highlights the powerful influence of formal schooling on the cultural evolution of teaching in humans.

Moralistic and local god beliefs and the extent of prosocial preferences on Tanna Island, Vanuatu

ABSTRACT The co-existence of Christian and indigenous “Kastom” belief systems on Tanna Island, Vanuatu provides a rare opportunity to explore the relationship between cooperation and religion. Here, we use data on religious beliefs and practices, religious priming, and four versions of a dictator game at two sites—one predominantly Christian and one predominantly Kastom—to test a suite of hypotheses linking prosocial behavior to beliefs about and commitment to both a powerful moralistic god and a less morally concerned local supernatural force. We found belief that the moralistic god was more punitive did not predict increased giving towards co-religionists but did predict giving more to a religious outgroup member over a co-religionist. Belief that the moralistic god was more rewarding predicted less giving towards a distant coreligionist or outgroup member. Religious commitment predicted giving to a distant coreligionist over someone from one's own village. We did not find any effect of beliefs about and commitment to less morally-concerned local supernatural forces on giving. We also did not find the predicted effects of religious priming on giving. These findings suggest a more complex relationship between religious beliefs and prosocial behavior than current theory can accommodate.

Volcanic disaster risk reduction in indigenous communities on Tanna Island, Vanuatu

This research addresses how an Indigenous disaster risk reduction framework, which calls for the integration of cultural aspects in order to assess the risk of people and communities and their abilities to cope with the impact of a disaster, can apply to volcano hazards in the context of rural communities where villagers strongly maintain a spiritual connection to an active volcano. In the area called Sulphur Bay, Tanna Island, Vanuatu, although deemed vulnerable to Mt Yasur eruptions, no evacuation or any sort of science-based volcano risk reduction plans have ever been implemented. This is because the villages are governed according to traditional belief systems, which see Mt Yasur as their ancestor and have rejected the introduction of external ontologies. Our interviews with the chiefs, custom leaders and general villagers find that for the majority of the villagers, the risk is to internalize any external ontologies, not the volcano, and they understand a volcano eruption as the expression of anger by their ancestor because of a wrong action of community members. Although their ontology has been constantly influenced by external agents and a few see such an ontology becoming out-of-date, under the hierarchal chiefly governing system, they are still certain to perform rituals to calm down Mt Yasur's angry spirit if it erupts. While existing research on volcano risk reduction has called the combination of indigenous belief systems and science-based approaches to improve volcano risk reduction, this research spots challenges to do so in some particular contexts.

Effective coastal adaptation needs accurate hazard assessment: a case study in Port Resolution, Tanna Island Vanuatu

Developing countries face risks from coastal hazards that are being amplified by climate change. The selection of effective adaptation interventions to manage these risks requires a sufficiently accurate assessment of the coastal hazard at a given location. Yet challenges remain in terms of understanding local coastal risks given the coarseness of global wave models and the paucity of locally scaled data in most developing countries, including Small Island Developing States (SIDS) like Vanuatu. This paper aims to examine the differences in hazard assessment and adaptation option selections arising from analyses using globally versus locally scaled data on coastal processes. As a case study, we focused on an eroding cliff face in Port Resolution on Tanna Island, Vanuatu, which is of concern to the local community and government authorities. The coastal process modeling revealed that the global wave data generated unrealistically high predictions of wave height within Port Resolution Bay. Expensive engineering adaptations designed to provide coastal protection were therefore likely to fail in preventing ongoing cliff erosion. In this case, the best adaptation solution involves changing land use to revegetate and help stabilize the cliff top. Our case study highlights the importance of accurate hazard assessment, especially in data-poor regions where the extrapolation of global datasets and models in the absence of local data can result in poor adaptation decision-making. Furthermore, the multidisciplinary approach applied here can be applied in other data-poor regions to strengthen analyses exploring the benefits of local adaptation interventions.

Variability of naturally occurring fluoride in diverse community drinking-water sources, Tanna Island, Vanuatu

Abstract Large variations in fluoride concentrations exist in natural waters, many of which are the source of community drinking-water supplies. Determining fluoride concentrations in community drinking waters can be challenging in developing Pacific countries such as Vanuatu that have limited laboratory capacity. Knowledge of naturally elevated fluoride concentrations that cause irreversible, adverse health outcomes may allow communities the opportunity to treat and manage their drinking-water supplies. Community drinking-water samples (n = 69), sourced from groundwaters, roof catchment rainwaters, surface waters and springs, were sampled on Tanna Island, Vanuatu between 2017 and 2020. In an 18 km2 area of Western Tanna, a set of 30 groundwater-based drinking-water samples had a median fluoride concentration of 3.3 mg/L, with 20 samples &amp;gt;1.5 mg/L and seven samples &amp;gt;4.0 mg/L. These concentrations increase the risk of dental and skeletal fluorosis, respectively. Repeat resampling at five sites showed little variation over the sampling period. Rainwater-fed drinking-water supplies were lower overall and highly variable in fluoride concentrations (&amp;lt;0.05–4.0 mg/L, median of 0.53 mg/L), with variable inputs from volcanic emissions from Yasur volcano. We recommend a comprehensive oral health and bone health study for the whole island to determine adverse health effects of excess fluoride in this vulnerable population.

Evaluating coral reef ecosystem services outcomes from climate change adaptation strategies using integrative system dynamics

Coral reef ecosystems provide a broad spectrum of essential ecological, economic and cultural services for Small Island Developing State (SIDS) communities. However, coral reef communities are increasingly threatened by the adverse impacts of human activities at both global and local scales. This study aims to develop an integrated dynamic assessment framework to evaluate coral reef conditions under different adaptation and climate change scenarios, and their consequential economic impacts in the small island community of Port Resolution on Tanna Island in Vanuatu. Our assessment framework follows a sequential multilayered modelling approach that uses System Dynamics (SD) coupled with Bayesian Network (BN) modelling to deal with the complexity and dynamicity of socioeconomic and environmental systems, and impacts from trans-discipline variables. The BN incorporated existing data and expert knowledge to project the future conditions of coral reefs under different scenario settings, and to parametrise and quantify the SD model where the existing data and information was insufficient. The SD was then used to simulate the dynamic relationship between coral reef condition and the economic benefits derived from its ecosystem services under different climate change (i.e. RCPs) and management scenarios through to 2070. Our findings show that sustainable community-based conservation management strategies are key to preserving the flow of coral reef ecosystem services under RCP 2.6 and 6.0. Importantly, we demonstrate that the implementation of an integrated portfolio of management strategies better protects ecosystem services provided by coral reefs and maximises the total economic benefits achieved over the long-term despite a temporary and short-term economic loss due to high initial capital investments and income reduction due to fishing and tourism restrictions.

Cultural Components of Sex Differences in Color Preference.

Preferences for pink and blue were tested in children aged 4–11 years in three small‐scale societies: Shipibo villages in the Peruvian Amazon, kastom villages in the highlands of Tanna Island, Vanuatu, and BaYaka foragers in the northern Republic of Congo; and compared to children from an Australian global city (total N = 232). No sex differences were found in preference for pink in any of the three societies not influenced by global culture (ds − 0.31–0.23), in contrast to a female preference for pink in the global city (d = 1.24). Results suggest that the pairing of female and pink is a cultural phenomenon and is not driven by an essential preference for pink in girls.

Disaster resilience of traditional societies from Small Island Developing States: The 2015 tropical cyclone Pam in Vanuatu

This paper investigates the resilience of traditional societies from Small Island Developing States in the face of disaster. It focuses on tropical cyclone Pam that impacted Vanuatu in 2015. Drawing upon focus group discussions using participatory tools in disaster-affected villages between 2015 and 2017, it examines both the recovery challenges faced and mechanisms developed by traditional societies from Tanna Island post-disaster. The study emphasizes that traditional societies’ resilience goes beyond absorbing and recovering from a large event but also relates to recurrent small-scale hazards. The paper further highlights traditional societies’ capacities in the face of disaster and stresses the need to strengthen or reintroduce traditional practices while supporting newly adopted mechanisms such as transnational kinship networks and remittances. It also points out the role of external aid intervention post-disaster that, if top-down and delivered disproportionally can compete with local initiatives and have negative effects on traditional societies’ resilience. The paper concludes that traditional societies should themselves define and assess their own resilience and ways to strengthen it.

Development of pacific exposure dataset for use in catastrophe risk assessment

An exposure dataset is one of the critical components of catastrophe risk modelling. It can also be one of the most difficult to create. When small numbers of buildings are involved, less than a thousand or so, it may be practicable to view each building and to acquire all the necessary attributes with a reasonable level of confidence. For regional or national-scale projects, however, the task is next to impossible. Ideally, for each building within the modelling areas we would know the location and value, and have enough structural information to underpin the assignment of vulnerability functions for each of several hazards. Such a dataset does not exist in the Pacific region, though various exposure databases have been developed in the past couple of decades. Instead, we have developed a systematic approach to populate and maintain a somewhat less rigorous, but practicable, exposure dataset for use in catastrophe risk modelling. In this paper, a brief review of previous development of exposure databases in the Pacific region is presented, followed by an overview of each class of available data that is used to develop the exposure dataset. Next, the methodologies adopted are illustrated, and application to a test case in Tanna Island, Vanuatu is described. Finally, the proposed exposure dataset development is discussed.

Exploring the Multiple Benefits of Ecosystem-Based Adaptation in Tourism for Climate Risks and Destination Well-Being

Tourism is strongly interlinked with the natural and social environment, in particular in destinations around the Pacific. These environments are vulnerable to climate change which impacts on the social–ecological system of destinations. Ecosystem-based Adaptation (EbA) uses ecosystems to manage the risks of climate change. However, a gap remains in understanding how the tourism sector can use EbA to create destination-wide benefits. The destination EbA framework presented here aims to address this gap by focusing on well-being and climate risk reduction. The framework is applied to a Pacific case study site, Tanna Island in Vanuatu, by drawing on primary qualitative data. Results highlight that EbA offers an approach for the tourism sector to create holistic benefits to destinations. Several constraints to successful implementation, and how these may be overcome, are identified. The article contributes by providing a framework for other destinations which aim to create benefits through tourism.

Mapping long-term coral reef ecosystems regime shifts: A small island developing state case study.

Coral reefs are among the most fragile ecosystems that provide essential services to local Small Island Developing States (SIDS) communities. As such, exploring the characteristics and interactions shaping regime shifts of coral reefs is of paramount importance in managing system pressures; enhancing resilience; aiding their regeneration and recovery process; and restoring habitat complexity. However, understanding the dynamics of coral reef ecosystems regime shift requires employing an approach capable of dealing with systems being affected by multiple climatic and socio-economic non-climatic pressures as well as an effective treatment of systemic embedded uncertainties. This study applies Fuzzy Cognitive Mapping (FCM) in a participatory stepwise and systematic procedure to reflect dynamic casualties and temporal changes of coral reef ecosystem regime change over a long-time perspective. This mapping technique allows conceptualising dynamic models to represent causalities and modelling input values to simulate fluctuations within a complex temporal system. Port Resolution on Tanna Island in Vanuatu was selected as the case study region representative of Pacific-SIDS geography and human communities. As an initial outcome and an indicator of multidisciplinary of this study, twenty-seven principal influential factors and their corresponding causal relationships were identified. Subsequently, the coral reef regime shift was analysed under four main plausible scenarios representing major climatic and non-climatic trajectories. The results indicate that climate change factors play pivotal roles in the regime shift of the coral reef ecosystem globally. At the focal scale of this study, the tourism industry and coral fisheries are the most vulnerable services provided by coral reefs. As such, coupled local management interventions and global efforts in mitigating the adverse impacts of climate change is likely to yield better coral reef ecosystem services at a local community level.

Adaptation strategies for coral reef ecosystems in Small Island Developing States: Integrated modelling of local pressures and long-term climate changes

Planning and decision-making vastly benefit from a holistic and systematic understanding of the long-term impacts of climate change and other non-climatic stressors on the health and resilience of coral reef ecosystems, and the efficacy of adaptation strategies and management interventions on mitigating these impacts and maintaining ecosystem condition and associated ecosystem service. This study reports on an approach to modelling coral reef stressors and possible adaptation interventions using the coral reef ecosystem of Port Resolution on Tanna Island, Vanuatu as the case study serving as a microcosm of endangered Pacific Small Island Developing States (SIDS). A novel participatory modelling framework was developed and followed in a stepwise manner to integrate local and long-term climate change pressures by coupling structural analysis and the Bayesian Network (BN) techniques. The BN model was quantified through an advanced consolidated data-induced, evidence-based, and expert-driven approach that incorporated: (1) projections of future climate conditions and changing human activities; (2) the influences of multiple stressors including physical environmental and sociological factors; and (3) spatial variability in the key processes and variables. The first and second phases conceptualised the whole system by providing a graphical presentation of system variables within the Driver-Pressure-State-Impact (DPSI) framework using the structural analysis technique. In the third phase, the BN technique was used to integrate the outcomes of multidisciplinary assessments and analysis with experts’ opinion. The BN modelling phase was completed based on evidence extracted from literature which reported the results of regional and downscaled climate models, GIS-based analysis, parametrised data obtained from the region, and tacit knowledge elicited from experts. The validated model was employed to anticipate the future health and resilience condition of coral reefs under different sets of climatic trajectories and adaptive responses scenarios. The results predict the risks to the health and resilience of the Port Resolution coral reef system from the adverse impacts of climate change and harmful human activities and the possible success of adaptations strategies. A sobering conclusion was that despite the current satisfactory condition of coral reefs in the case study zone, their health and resilience would be severely threatened by 2070 in the absence of implementing adaptation strategies and associated sustainable management interventions.

The dawn of social jetlag: sleep in indigenous villages with and without electric lighting on Tanna Island, Vanuatu

The dawn of social jetlag: sleep in indigenous villages with and without electric lighting on Tanna Island, Vanuatu

Sleep timing and duration in indigenous villages with and without electric lighting on Tanna Island, Vanuatu

It has been hypothesized that sleep in the industrialized world is in chronic deficit, due in part to evening light exposure, which delays sleep onset and truncates sleep depending on morning work or school schedules. If so, societies without electricity may sleep longer. However, recent studies of hunter-gatherers and pastoralists living traditional lifestyles without electricity report short sleep compared to industrialized population norms. To further explore the impact of lifestyles and electrification on sleep, we measured sleep by actigraphy in indigenous Melanesians on Tanna Island, Vanuatu, who live traditional subsistence horticultural lifestyles, in villages either with or without access to electricity. Sleep duration was long and efficiency low in both groups, compared to averages from actigraphy studies of industrialized populations. In villages with electricity, light exposure after sunset was increased, sleep onset was delayed, and nocturnal sleep duration was reduced. These effects were driven primarily by breastfeeding mothers living with electric lighting. Relatively long sleep on Tanna may reflect advantages of an environment in which food access is reliable, climate benign, and predators and significant social conflict absent. Despite exposure to outdoor light throughout the day, an effect of artificial evening light was nonetheless detectable on sleep timing and duration.

Social benefit cost analysis of ecosystem-based climate change adaptations: a community-level case study in Tanna Island, Vanuatu

ABSTRACT Small island developing states are vulnerable to the impacts of climate change, including more intense and frequent extreme weather, warming temperatures, coastal erosion, inundation, and coral bleaching. Locally-specific natural resource threats, associated with population growth and tourism, exacerbate these systemic risks, which are particularly acute where community well-being is subsistence-based and directly reliant on ecosystem services. Garden productivity is falling as the cropping/fallow cycle intensifies and culturally and there is loss of observance of traditional resource taboos, eroding the effectiveness of customary management. Ecosystem based adaptations (EbA) provide a fruitful range of interventions and are beginning to attract development funding. We undertook a social benefit cost analysis for a suite of interconnecting EbAs for Tanna in Vanuatu. We found that funds targeted at increasing the productivity of the gardens returns significant social benefit. This also reduces pressure on natural resource threats and can potentially be adopted by all households on Tanna. In addition, increasing the community’s capacity to balance formal forest and reef conservation with customary management can provide small, but nevertheless important complimentary benefits. Our programme design included interlinking activities, including a series of demonstration garden plots, extension officers, community radio, a community ranger programme and a tree nursery.

Community-based adaptation to climate change: lessons from Tanna Island, Vanuatu

Community-based adaptation has gained significant international attention as a way for communities to respond to the increasing threats and complex pressures posed by climate change. This bottom-up strategy represents an alternative to the prolonged reliance on, and widespread ineffectiveness of, mitigation methods to halt climate change, in addition to the exacerbation of vulnerability resulting from top-down adaptation approaches. Yet despite the promises of this alternative approach, the efficacy of community-based adaptation remains unknown. Its potential to reduce vulnerability within communities remains a significant gap in knowledge, largely due to limited participatory evaluations with those directly affected by these initiatives, to determine the success and failure of project design, implementation, outcomes and long-term impact. This paper seeks to close this gap by undertaking an in-depth evaluation of multiple community-based adaptation projects in Tanna Island, Vanuatu and exploring community attitudes and behavioural changes. This study found that future community-based adaptation should integrate contextual specificities and gender equality frameworks into community-based adaptation design and implementation, as well as recognise and complement characteristics of local resilience and innovation. In doing this, the critical importance of looking beyond assumptions of Small Island Developing States (SIDS) as homogenous, primarily vulnerable to climate change and lacking resilience, was also recognised.

Spatial Bayesian Network for predicting sea level rise induced coastal erosion in a small Pacific Island

An integrated approach combining Bayesian Network with GIS was developed for making a probabilistic prediction of sea level rise induced coastal erosion and assessing the implications of adaptation measures. The Bayesian Network integrates extensive qualitative and quantitative information into a single probabilistic model while GIS explicitly deals with spatial data for inputting, storing, analysing and mapping. The integration of the Bayesian Network with GIS using a cell-by-cell comparison technique (aka map algebra) provides a new tool to perform the probabilistic spatial analysis. The spatial Bayesian Network was utilised for predicting coastal erosion scenarios at the case study location of Tanna Island, Vanuatu in the South Pacific. Based on the Bayesian Network model, a rate of the island shoreline change was predicted probabilistically for each shoreline segment, which was transferred into GIS for visualisation purposes. The spatial distribution of shoreline change prediction results for various sea level rise scenarios was mapped. The outcomes of this work support risk-based adaptation planning and will be further developed to enable the incorporation of high resolution coastal process models, thereby supporting localised land use planning decisions.