Javier Xavier Leon

• PhD
• Lecturer at University of the Sunshine Coast

Background Nest selection is widely regarded as a key process determining the fitness of individuals and viability of animal populations. For marine turtles that nest on beaches, this is particularly pivotal as the nesting environment can significantly control reproductive success. The aim of this study was to identify the environmental attributes...

Low-lying reef islands in the Solomon Islands provide a valuable window into the future impacts of global sea-level rise. Sea-level rise has been predicted to cause widespread erosion and inundation of low-lying atolls in the central Pacific. However, the limited research on reef islands in the western Pacific indicates the majority of shoreline ch...

Among the biggest global challenges for policymakers is the development of land use policies robust to climate change impacts. While diverse fields can inform adaptation, integrated social-ecological assessment of the multiple adaptation options are rare and cannot be easily applied. Here, we build on past studies by undertaking an integrated fine...

Sea-level rise will change environmental conditions on coral reef flats, which comprise extensive habitats in shallow tropical seas and support a wealth of ecosystem services. Rapid relative sea-level rise of 0.6 m over a relatively pristine coral reef in Solomon Islands, caused by a subduction earthquake in April 2007, generated a unique opportuni...

Coastal communities in the Coral Triangle are increasingly threatened by climate change. Sea-level rise (SLR) will result in biophysical and socioeconomic impacts that could increase the loss of livelihoods, cultural heritage and infrastructure. Effective adaptation requires a holistic approach that incorporates scientific knowledge together with l...

Context Urban landscapes present a diverse matrix of structures and habitats containing significant physical and behavioural barriers to terrestrial wildlife dispersal. Yet, our understanding of these barriers for large mammals in the context of genetic connectivity within urbanising landscapes is limited. Objective We investigated the effects of...

The island of Guam in the west Pacific has seen a significant decrease in coral cover since 2013. Lafac Bay, a marine protected area in northeast Guam, served as a reference site for benthic communities typical of forereefs on the windward side of the island. The staghorn coral Acropora abrotanoides is a dominant and characteristic ecosystem engine...

Restoration projects are increasingly widespread and many promote habitat succession and the diversity and abundance of faunal communities. These positive effects on biodiversity and abundance may extend to enhancing the ecological functioning and resilience of previously degraded ecosystems, but this is rarely quantified. This study surveyed a 200...

Context Urban landscapes present a diverse matrix of structures and habitats containing significant physical and behavioural barriers to terrestrial wildlife dispersal. As a result, large mammals, with large home ranges, may be negatively impacted as behavioural and physical barriers are created. However, our understanding of these barriers in the...

Connectivity and landscape context are common considerations in the spatial prioritisation of conservation actions. Similar spatial principles can also be used to inform the selection, prioritisation and monitoring of sites for restoration, but it is not clear whether these variables consistently shape the delivery of benefits from restoration. Thi...

Technological innovations that improve the speed, scale, reproducibility, and accuracy of monitoring surveys will allow for a better understanding of the global decline in tropical reef health. The DiveRay, a diver-operated hyperspectral imager, and a complementary machine learning pipeline to automate the analysis of hyperspectral imagery were dev...

The complexity of tropical reef habitats affects the occurrence and diversity of the organisms residing in these ecosystems. Quantifying this complexity is important to better understand and monitor reef community assemblages and their roles in providing ecological services. This study employed structure-from-motion photogrammetry to produce accura...

Early indicators of restoration success can inform adaptive management strategies and maintain community interest and financial investment. Coastal wetland restoration projects prioritize monitoring the succession of habitat forming communities. However, these communities often expand slowly. In contrast, fish and crustaceans can quickly occupy new...

The Sunshine Coast area of South-East Queensland (SEQ) is an area of high biodiversity, yet effective landscape-level conservation of terrestrial mammal species is lacking, including those listed as least concerned, like the Eastern Grey Kangaroos (Macropus giganteus). Recent spatial genetic studies have identified kangaroo mobs within this region...

Coastal wetlands are restored to regenerate lost ecosystem services. Accurate and frequent representations of the distribution and area of coastal wetland communities are critical for evaluating restoration success. Typically, such data are acquired through laborious, intensive and expensive field surveys or traditional remote sensing methods that...

Preliminary results indicate that different tree species were impacted differently by fire. This included both the direct impact of the fire, and their response rate post fire. Initial observations indicated that higher ridge communities, mainly consisting of iron-bark, were the worst affected, but now are showing more notable recovery. In contrast...

Biophysical impacts tend to dominate environmental impact assessments (EIA), yet social values of the environment have an important role to play in decision-making. To foster the inclusion of social values in EIA we developed and applied public participation geographic information system (PPGIS) methods to map Fijian social values of the Sigatoka R...

Headland sediment bypassing is a critical component in understanding the sediment budgets of headland protected beaches, yet the bypassing is often sporadic and complex. In this study we have completed shoreline change analysis from aerial imagery spanning more than 60 years for all the beaches within the Noosa Headland (Queensland, Australia) regi...

The structure of seafloor terrain affects the distribution and diversity of animals in all seascapes. Effects of terrain on fish assemblages have been reported from most ecosystems, but it is unclear whether bathymetric effects vary among seascapes or change in response to seafloor modification by humans. We reviewed the global literature linking s...

Increasing sea surface temperature and extreme heat events pose the greatest threat to coral reefs globally, with trends exceeding previous norms. The resultant mass bleaching events, such as those evidenced on the Great Barrier Reef in 2016, 2017, and 2020 have substantial ecological costs in addition to economic and social costs. Advancing remote...

Seagrass meadows store globally significant organic carbon (Corg) stocks which, if disturbed, can lead to CO2 emissions, contributing to climate change. Eutrophication and thermal stress continue to be a major cause of seagrass decline worldwide, but the associated CO2 emissions remain poorly understood. This study presents comprehensive estimates...

Advances in drone technology have given rise to much interest in the use of drone-mounted thermal imagery in wildlife monitoring. This research tested the feasibility of monitoring large mammals in an urban environment and investigated the influence of drone flight parameters and environmental conditions on their successful detection using thermal...

The response of headland protected beaches to storm events is complex and strongly site dependent. In this study, we investigated the response of several headland protected beaches in Noosa, Australia to a tropical cyclone event. Pre and post topographical surveys of all beaches were completed using both pole-mounted RTK-GNSS and structure-from-mot...

A 50–70 cm sea-level fall around A.D. 1300 may have led to a prolonged food crisis which caused conflict among coastal dwellers on high Pacific islands. The conflict may have necessitated abandoning difficult to defend coastal settlements and establishing ones in fortifiable locations inland. To test this idea, abandoned hillforts (koronivalu)on20k...

Forests and coral reefs are structurally complex ecosystems threatened by climate change. In situ 3D imaging measurements provide unprecedented, quantitative and detailed structural information that allows testing of hypotheses relating form to function. This affords new insights into both individual organisms and their relationship to their surrou...

Drones are often considered an unobtrusive method of monitoring terrestrial wildlife; however research into whether drones disturb wildlife is in its early stages. This research investigated the potential impacts of drone monitoring on a large terrestrial mammal, the eastern grey kangaroo (Macropus giganteus), in urban and peri-urban environments....

Mangroves provide a variety of ecosystem services, which can be related to their structuralcomplexity and ability to store carbon in the above ground biomass (AGB). Quantifying AGB inmangroves has traditionally been conducted using destructive, time-consuming, and costlymethods, however, Structure-from-Motion Multi-View Stereo (SfM-MVS) combined wi...

Whilst future air temperature thresholds have become the centrepiece of international climate negotiations, even the most ambitious target of 1.5 °C will result in significant sea-level rise and associated impacts on human populations globally. Of additional concern in Arctic regions is declining sea ice and warming permafrost which can increasingl...

With almost limitless applications across marine and freshwater environments, the number of people using, and wanting to use, remotely piloted aircraft systems (or drones) is increasing exponentially. However, successfully using drones for data collection and mapping is often preceded by hours of researching drone capabilities and functionality fol...

Mangrove forests support a variety of ecosystem functions and services imperative for ecosystem health. Despite the importance of mangroves, however, mangrove forests worldwide are under threat from human development and climate change. To date, most research on mangrove change in Australia has drawn on approximately 40 years of remotely sensed ima...

Island societies are being disproportionately affected by climate change, a situation likely to continue for some decades. Using an example of an island affected by multiple climate-linked stressors, a situation likely to become more common in the future, this paper examines the nature of these, the ways they are perceived and responded to by local...

Structure from Motion with Multi-View Stereo photogrammetry (SfM-MVS) is increasingly used in geoscience investigations, but has not been thoroughly tested in gullied savanna systems. The aim of this study was to test the accuracy of topographic models derived from aerial (via Unmanned Aerial Vehicle, ‘UAV’) and ground-based (via handheld digital c...

A 2007 earthquake in the western Solomon Islands resulted in a localised subsidence event in which sea level (relative to the previous coastal settings) rose approximately 30–70 cm, providing insight into impacts of future rapid changes to sea level on coastal ecosystems. Here, we show that increasing sea level by 30–70 cm can have contrasting impa...

Structure from Motion with Multi-View Stereo photogrammetry (SfM) is increasingly utilised in geoscience investigations as a cost-effective method of acquiring high resolution (sub-meter) topographic data, but has not been thoroughly tested in gullied savanna systems. The aim of this study was to test the accuracy of topographic models derived from...

Rock seawalls and groynes are common coastal structures, but these flexible type structures can be damaged. Monitoring of these structures, particularly after severe events, can enable repairs to be implemented economically before a major and costly failure occurs. The conventional method, until recently, has been topographic surveys based on total...

Spatial distribution of nest sites for the 2010–2011 nesting season Spatial distribution of nest sites for the 2010–2011 nesting season (Map data ©NearMap Pty. Ltd. 2015).

Spatial distribution of nest sites for 2008–2009 nesting season Spatial distribution of nest sites for 2008–2009 nesting season (Map data ©NearMap Pty. Ltd. 2015).

Spatial distribution of nest sites for the 2013–2014 nesting season Spatial distribution of nest sites for the 2015–2016 nesting season (Map data ©NearMap Pty. Ltd. 2015).

Dataset of the nest and reference site environmental attributes

Spatial distribution of nest sites for the 2012–2013 nesting season Spatial distribution of nest sites for the 2012–2013 nesting season (Map data ©NearMap Pty. Ltd. 2015).

Spatial distribution of nest sites for the 2013–2014 nesting season Spatial distribution of nest sites for the 2013–2014 nesting season (Map data ©NearMap Pty. Ltd. 2015).

Spatial distribution of nest sites for the 2009–2010 nesting season Spatial distribution of nest sites for the 2009–2010 nesting season (Map data ©NearMap Pty. Ltd. 2015).

Spatial distribution of nest sites for the 2011–2012 nesting season Spatial distribution of nest sites for the 2011–2012 nesting season (Map data ©NearMap Pty. Ltd. 2015).

Seagrass habitat is globally threatened from the cumulative impact of human activities on coastal ecosystems. Successful conservation and restoration of seagrass requires knowledge of the environmental factors that limit seagrass presence; however, quantifying the relative importance of these environmental factors is a significant challenge. To res...

Evidence on the impacts of climate change is rapidly increasing but there is little change to the speed of climate adaptation by governments and individuals. There are multiple barriers to climate adaptation, including among others: the lack of the public understanding of risks, lack of leadership and availability of resources to adapt. In this stu...

Our understanding of Earth surface processes is rapidly advancing as new remote sensing technologies such as LiDAR and close-range digital photogrammetry become more accessible and affordable. A very-high spatial resolution digital terrain model (DTM) and orthophoto mosaic (mm scale) were produced using close-range digital photogrammetry based on ‘...

Increasing threats to natural ecosystems from local and global stressors are reinforcing the need for baseline data on the distribution and abundance of organisms. We quantified spatial and/or temporal patterns of seagrass distribution, shoot density, leaf area index, biomass, productivity, and sediment carbon content in shallow water (0–5 m) at Li...

The distribution, abundance, behaviour, and morphology of marine species is affected by spatial variability in the wave environment. Maps of wave metrics (e.g. significant wave height Hs, peak energy wave period Tp, and benthic wave orbital velocity URMS) are therefore useful for predictive ecological models of marine species and ecosystems. A numb...

The distribution, abundance, behaviour, and morphology of marine species is affected by spatial variability in the wave environment. Maps of wave metrics (e.g. significant wave height Hs, peak energy wave period Tp, and benthic wave orbital velocity URMS) are therefore useful for predictive ecological models of marine species and ecosystems. A numb...

Rapid sea level rise over the 21st century threatens coastal settlements and populations worldwide. Significant land-use policy reform will be needed to mitigate exposure to hazards in the coastal zone. Sea-level rise maps that indicate areas that are potentially prone to future inundation are a valuable tool for policymakers and decision makers. H...

Sea-level rise will result in changes in water depth over coral reefs, which will influence reef platform growth as a result of carbonate production and accretion. This study simulates the pattern of reef response on the reefs around Lizard Island in the northern Great Barrier Reef. Two sea-level rise scenarios are considered to capture the range o...

Coastal managers require reliable spatial data on the extent and timing of potential coastal inundation, particularly in a changing climate. Most sea level rise (SLR) vulnerability assessments are undertaken using the easily implemented bathtub approach, where areas adjacent to the sea and below a given elevation are mapped using a deterministic li...

Ecosystems are linked within landscapes by the physical and biological processes they mediate. In such connected landscapes, the response of one ecosystem to climate change could have profound consequences for neighbouring systems. Here, we report the first quantitative predictions of interdependencies between ecosystems in response to climate chan...

Coral reefs represent major accumulations of calcium carbonate (CaCO3). The particularly labyrinthine network of reefs in Torres Strait, north of the Great Barrier Reef (GBR), has been examined in order to estimate their gross CaCO3 productivity. The approach involved a two-step procedure, first characterising and classifying the morphology of reef...

Coastal managers require reliable spatial data on the extent and timing of potential coastal inundation, particularly in a changing climate. Most sea level rise (SLR) vulnerability assessments are undertaken using the easily implemented bathtub approach, where areas adjacent to the sea and below a given elevation are mapped using a deterministic li...

An object based image analysis approach (OBIA) was used to create a habitat map of the Lizard Reef.Briefly, georeferenced dive and snorkel photo-transect surveys were conducted at different locations surrounding Lizard Island, Australia. For the surveys, a snorkeler or diver swam over the bottom at a depth of 1-2m in the lagoon, One Tree Beach and...

The ability of benthic communities inhabiting coral reefs to produce calcium carbonate underpins the development of reef platforms and associated sedimentary landforms, as well as the fixation of inorganic carbon and buffering of diurnal pH fluctuations in ocean surface waters. Quantification of the relationship between reef flat community calcium...

Hydrographers have traditionally referred to the nearshore area as the ‘white ribbon’ area due to the challenges associated with the collection of elevation data elevation hereafter refers to both topography and bathymetry in this highly dynamic transitional zone between terrestrial and marine environments. Accordingly, available information in thi...

The distribution and abundance of seagrass ecosystems could change significantly over the coming century due to sea level rise (SLR). Coastal managers require mechanistic understanding of the processes affecting seagrass response to SLR to maximize their conservation and associated provision of ecosystem services. In Moreton Bay, Queensland, Austra...

Coral reefs represent major accumulations of calcium carbonate (CaCO3). The particularly labyrinthine network of reefs in Torres Strait, north of the Great Barrier Reef (GBR), has been examined in order to estimate their gross CaCO3 productivity. The approach involved a two-step procedure, first characterising and classifying the morphology of reef...

Underwater georeferenced photo-transect surveys were conducted on December 10-15, 2011 at various sections of the reef at Lizard Island, Great Barrier Reef. For this survey a snorkeler or diver swam over the bottom while taking photos of the benthos at a set height using a standard digital camera and towing a GPS in a surface float which logged the...

Underwater georeferenced photo-transect surveys were conducted on October 3-7, 2012 at various sections of the reef and lagoon at Lizard Island, Great Barrier Reef. For this survey a snorkeler swam while taking photos of the benthos at a set distance from the benthos using a standard digital camera and towing a GPS in a surface float which logged t...

Here we demonstrate the applicability of using altimetry data and Landsat imagery to provide the most accurate digital elevation model (DEM) of Australia's largest playa lake — Lake Eyre. We demonstrate through the use of geospatial techniques a robust assessment of lake area and volume of recent lake-filling episodes whilst also providing the most...

A fishing pier in Cabo Blanco bay (northern Peru) degraded the surfing quality of Cabo Blanco, one of the best waves in South America. As the pier collapsed under the force of breaking waves, the National Fishing Development Fund (FONDEPES) has proposed to relocate the pier to a new site 500 m to the SW, an area that would compromise the surfing qu...

Mapping the geomorphology of coral reefs provides key information to scientists and managers about the distribution, extent and structure of reef landforms. Geomorphological zones within a reef system are underpinned by geological and environmental gradients in physical and biological processes, usually resulting in well-defined and clearly recogni...

Here we demonstrate the applicability of using altimetry data and Landsat imagery to provide the most accurate digital elevation model (DEM) of Australia's largest playa lake - Lake Eyre. We demonstrate through the use of geospatial techniques a robust assessment of lake area and volume of recent lake-filling episodes whilst also providing the most...

Monitoring coral reefs is of great importance for environmental management of these ecosystems. The use of remote sensing and geographical information systems enables rapid and effective mapping of the geomorphology of reefs that can be used as a basis for biodiversity and habitat assessments. However, pixel-based approaches have not been appropria...

The coastal zone comprises a series of landforms and ecosystems that extend either side of the shoreline, the intersection of land and sea. Coastal systems are highly dynamic, their morphology evolving at a range of time scales in response to the processes acting upon them. Whereas cliffs are generally resistant and change only over long time scale...

Coral reefs are particularly valuable marine ecosystems in terms of biodiversity and socio-economic factors. They are also some of the most vulnerable and threatened of global ecosystems, particularly in view of unprecedented anthropogenic-driven disturbances. Understanding coral reef evolution is not straightforward, as these are complex systems w...

A flood exceeding the 100 year average recurrence interval in November 2005 led to the failure of an upland peat bog in Waterfall Gully. The area is prone to severe bushfire and flood events and the control dam at the base of First Falls was filled with sediment sourced from Wilson Bog. A resistant quartzite bar at Fourth Falls has formed a natural...

A bathymetric grid of the Antarctic region bounded by the coordinates: 60˚ E – 90˚ E and 55˚ S – 70˚ S was generated from the latest available multibeam swath bathymetry, fisheries’ surveys and satellite altimetry data. Datasets were checked for inconsistencies and cleaned prior to interpolation. The final grid was masked to the southern boundary o...

Low-elevation coastal areas like islands sitting on reef platforms have been identified as one of the most sensitive environments to global warming and related impacts like accelerated sea-level rise. High-quality datasets were used to construct a DTM for Warraber Reef, Torres Strait, Australia. The difficulty in mapping intertidal areas limited th...

A set of groynes and breakwaters were constructed in 1956 around the Salaverry Maritime Terminal in the northern coast of Peru to facilitate port operations. As a result, part of the longshore transport was blocked, producing undesirable impacts along the coastline. Apart from local bathymetric monitoring, a thorough shoreline change assessment has...

This thesis uses a novel composite approach to investigate the long-term dynamics of sediment transport on Shelly Beach, Otago Harbour, New Zealand. This approach combines qualitative and quantitative methods including field measurements of coastal processes and morphological change, numerical modelling, analysis of bathymetric charts, comparison o...

A set of groynes and breakwaters were constructed in 1956 around the Salaverry Maritime Terminal in the northern coast of Peru to facilitate port operations. As a result, part of the longshore transport was blocked, producing undesirable impacts along the coastline. Apart from local bathymetric monitoring, a thorough shoreline change assessment has...