Ashmore Reef Research Articles

Remote Underwater Video Confirms the Presence of Dugongs (Dugong dugon) at Ashmore Reef Australian Marine Park in the Eastern Indian Ocean

Remote Underwater Video Confirms the Presence of Dugongs (Dugong dugon) at Ashmore Reef Australian Marine Park in the Eastern Indian Ocean

The assembly and ecological roles of biofilms attached to plastic debris of Ashmore reef

Plastic pollution in the ocean is a global environmental hazard aggravated by poor management of plastic waste and growth of annual plastic consumption. Microbial communities colonizing the plastic's surface, the plastisphere, has gained global interest resulting in numerous efforts to characterize the plastisphere. However, there are insufficient studies deciphering the underlying metabolic processes governing the function of the plastisphere and the plastic they reside upon. Here, we collected plastic and seawater samples from Ashmore Reef in Australia to examine the planktonic microbes and plastic associated biofilm (PAB) to investigate the ecological impact, pathogenic potential, and plastic degradation capabilities of PAB in Ashmore Reef, as well as the role and impact of bacteriophages on PAB. Using high-throughput metagenomic sequencing, we demonstrated distinct microbial communities between seawater and PAB. Similar numbers of pathogenic bacteria were found in both sample types, yet plastic and seawater select for different pathogen populations. Virulence Factor analysis further illustrated stronger pathogenic potential in PAB, highlighting the pathogenicity of environmental PAB. Furthermore, functional analysis of Kyoto Encyclopedia of Genes and Genomes (KEGG) metabolic pathways revealed xenobiotic degradation and fatty acid degradation to be enriched in PABs. In addition, construction of metagenome-assembled genomes (MAG) and functional analysis further demonstrated the presence of a complete Polyethylene (PE) degradation pathway in multiple Proteobacteria MAGs, especially in Rhodobacteriaceae sp. Additionally, we identified viral population presence in PAB, revealing the key role of bacteriophages in shaping these communities within the PAB. Our result provides a comprehensive overview of the various ecological processes shaping microbial community on marine plastic debris.

Dinamika Sengketa Internasional Wilayah Ashmore Reef Antara Indonesia Dengan Australia

The Ashmore Reef territorial dispute between Indonesia and Australia has attracted international attention over the past few decades. This journal aims to investigate the dynamics of this dispute. This research uses an international legal analysis approach to explore the legal basis and latest developments in dispute resolution. In addition, through careful analysis, this Journal also reviews the possible political, economic and environmental impacts that may arise as a result of this dispute.

Between the traditional and modern: Ashmore Reef in the collective memories of Rotenese fishermen in Papela

ABSTRACT In 2021, the Australian government apprehended several Indonesian fishing boats for carrying out their fishing activities on the sea border between Rote Island and Ashmore Reef. This issue was further exacerbated by the growing demand from the traditional leader of the Rotenese community to reassess the status of Ashmore Reef, known as Pulau Pasir, by the Rotenese. The claim could be traced back to the previous attempt in the 2000s, in which they demanded the Australian government restore Ashmore Reef to Pulau Pasir. Collective memory played a significant role in directing the thoughts and decisions made by Rotenese fishermen, as the passing down of the narrative of origin led them to continue their journeys and activities in the islet. In a struggle to preserve their tradition, however, the fishermen had reached an inevitable encounter with modern-day policy, as the 1974 Memorandum of Understanding closed the dispute. This article shall elaborate on the encounter between two ways of life that shaped the perception of the Rotenese fishermen within the critical approach from studies on collective memory as their basis of survival.

Levels of autotrophy and heterotrophy in mesophotic corals near the end photic zone

Mesophotic corals live at ~30-150 m depth and can sustain metabolic processes under light-limited conditions by enhancing autotrophy through specialized photoadaptations or increasing heterotrophic nutrient acquisition. These acclimatory processes are often species-specific, however mesophotic ecosystems are largely unexplored and acclimation limits for most species are unknown. This study examined mesophotic coral ecosystems using a remotely operated vehicle (Ashmore Reef, Western Australia at 40–75m depth) to investigate the trophic ecology of five species of scleractinian coral (from genera Leptoseris, Pachyseris, and Craterastrea) using stable isotope analyses (δ13C and δ15N) of host and symbiont tissues and protein concentration. Trophic strategies were analyzed between species and between overall corals sampled above and below the end-photic point, where light is only 1% of surface irradiance. Results showed species-specific differences in resource use. Leptoseris hawaiiensis, L. scabra, and P. speciosa had similar Δ13C values (δ13C host - δ13C symbiont) approaching zero (< 0.5 ‰) which indicated greater dependence on symbiont autotrophy. In contrast, Leptoseris glabra and Craterastrea levis had higher Δ13C values (1.4 to 3.5 ‰) which indicated a greater reliance on external carbon sources. The latter two species also demonstrated tight nitrogen recycling within the holobiont, exhibiting low Δ15N values (host δ15N - symbiont δ15N =< 0.5 ‰), compared to more autotrophic species (Δ15N = >1.2 ‰). Some species demonstrated the ability to maintain metabolic processes despite substantially reduced light availability (0.5 – 2% of surface irradiance). This research challenges our knowledge of acclimation limits for many scleractinian corals and contributes novel information for Ashmore Reef, the Western Australia region and mesophotic ecosystems in general, and critically examines common methods used to interpretate trophic ecology with bulk stable isotopes δ13C and δ15N.

Coral reef development and sea-level changes over the past 50,000 years: new evidence from the north-west shelf of Australia

Understanding of global sea-level changes and coral reef development is poorly constrained during Marine Isotope Stage 3 (MIS 3; ~ 60 to 30 ka). Australia’s North West Shelf (NWS), at depths of ~ 50 to 120 m below present sea-level (mbsl), represents an ideal natural laboratory to address these knowledge gaps. In this study, the authors investigate a unique suite of sea-bed rock drill (PROD) cores recovered as part of a geotechnical survey from the NWS ~ 150 km south-east of Ashmore Reef. Twenty cores, penetrating to 28 m below sea floor, were collected from the top of the now drowned platform complex in similar water depths (74.8 to 81.6 mbsl), forming two transects ~ 17 km apart. High-resolution 3D seismic and multibeam bathymetry data reveal three distinct, multigenerational platforms that are rimmed by smaller reef terraces and bisected by deeper channels, placing the core transects into a robust, regional geomorphic context that includes a succession of linear palaeo-shorelines and tidal-estuarine channel systems on the adjacent shelf between ~ 90 to 110 mbsl. The authors have completed detailed logging, high-spatial resolution hyperspectral scanning, petrologic, mineralogic and sedimentary facies analysis of these cores, including a precise palaeoenvironmental reconstruction based on coral, algal and larger benthic foraminifera assemblages; and extensive radiometric dating. The authors have observed a complex suite of lithologies including in situ coralgal reef frameworks, well-lithified to friable grainstones, packstones and coralline algal floatstone facies separated by at least two major palaeosol horizons. Together with thirty 14C-AMS and closed-system U/Th ages spanning 10.7 to > 50 ka, the authors define a complex but consistent record of four distinct chrono-stratigraphic units (Units 1 to 4), representing a repeated succession of shallow reef to deep reef-slope depositional settings as the platforms experienced repeated sea-level oscillations (interstadial/stadial to glacial/deglacial) over the last 75,000 yr. Two distinct phases of shallow-water, high-energy reef development are defined. The age of the older, diagenetically distinct reef unit (Unit 3) is unknown but interpreted to have developed before the MIS 4 lowstand (~ 65 ka). However, firm chronological constraints on the MIS 3 development of the younger reef unit (Unit 2), place the position of relative sea-level (RSL) between ~ 63 to 75 + 1.8 mbsl by 45.95 to 39.23 + 0.2 ka, consistent with other predictions and observations for the region. Following its exposure and demise due to sea-level fall to the Last Glacial Maximum (LGM), the platform system was unable to re-establish fully as it was reflooded during the subsequent deglacial sea-level rise. Deeper reef slope (Unit 1) facies dominate the core tops between ~ 13.2 to 10.7 ka, representing a major hiatus in shallow-water reef development on the platforms. Deglacial sea-level rise was either too fast and/or other environmental conditions inadequate (i.e. massive riverine sediment flux due to the strengthening Australian summer monsoon and/or reworking of shelf sediments) to allow re-establishment of shallow-water coral reef development on the platforms apart from a few isolated and distal locations (i.e. Ashmore, Cartier, Adele and Scott Reefs).

Video surveys of sea snakes in the mesophotic zone shed light on trends in populations

Declines in abundance of sea snakes have been observed on reefs throughout the Indo-Pacific, although the reasons are unknown. To date, surveys have occurred on shallow reefs, despite sea snakes occurring over a large depth range. It is not known if populations of sea snakes in deep habitats have undergone similar declines. To address this, we analysed deep-water video data from a historical hotspot of sea snake diversity, Ashmore Reef, in 2004, 2016, and 2021. We collected 288 hours of video using baited remote underwater videos and a remotely operated vehicle at depths between 13 and 112 m. We observed 80 individuals of seven species with Aipysurus laevis (n = 30), Hydrophis peronii (n = 8), and H. ocellatus (n = 6) being the most abundant. Five of the species (A. duboisii, A. apraefrontalis, H. ocellatus, H. kingii, and Emydocephalus orarius) had not been reported in shallow waters for a decade prior to our study. We found no evidence of a decline in sea snakes across years in deep-water surveys, although abundances were lower than those in early shallow-water surveys. A comparison of BRUVS data from 2004 and 2016 was consistent with the hypothesis that predation by sharks may have contributed to the loss of sea snakes in shallow habitats. Our study highlights the use of underwater video to collect information on sea snakes in the mesophotic zone and also suggests that future monitoring should include these depths in order to capture a more complete representation of habitats occupied.

Growth, biomass and productivity of the seagrass Thalassia hemprichii at Ashmore Reef, Australia

Ashmore Reef, located approximately 630 km north of Broome, Australia, is notable for its contribution to overall seagrass cover in the Timor Province bioregion, providing valuable ecosystem services including critical habitat for feeding and breeding green turtles (Chelonia mydas) and a small geographically isolated population of dugong (Dugong dugon). Yet, seagrass surveys at Ashmore Reef have not been completed since 2005. Seagrass was surveyed in 2019, with only two (Thalassia hemprichii and Halophila ovalis) of the five previously recorded species observed. Monitoring survey sites were established to determine density, biomass and productivity of the dominant species, T. hemprichii. Overall mean total biomass was 116.9 DW m−2 with an above- and below-ground biomass ratio of 1:2.5. Mean shoot density was 407 shoots m−2 (range 88.9–600 shoots m−2) with a mean canopy height of 42.8 mm (range 10–80 mm), and average blade length of 37.6 mm ( ± 1.1 SE) and blade width of 4.5 mm ( ± 0.2). Mean leaf growth was calculated as 2.2–2.4 mm day−1 and shoot growth 3.2–3.5 mm day−1. Canopy height increased by 5.3–5.7 % day−1 with a turnover rate of 17.5–21.3 days. Mean biomass of emergent leaves was 8 g DW m−2 with a grazing rate of 0.4 g DW m−2 day −1 or 123 kg DW ha−1 month−1. This study suggests that T. hemprichii at Ashmore Reef is productive and may support high turtle grazing rates.

Pinpointing Drivers of Extirpation in Sea Snakes: A Synthesis of Evidence From Ashmore Reef

Over the past decade, vertebrate populations globally have experienced significant declines in distribution and abundance. Understanding the reasons behind these population declines is the first step in implementing appropriate management responses to improve conservation outcomes. Uncovering drivers of extirpation events after the fact, however, requires a careful forensic approach to prevent similar declines elsewhere. The once abundant and species-rich sea snake fauna of Ashmore Reef Marine Park, in the Timor Sea, collapsed dramatically in the early 2000s. No such decline has occurred on surrounding reefs. We synthesise the evidence for this collapse and the subsequent slow recovery and evaluate the plausibility of potential drivers for the declines, as well as provide evidence against certain explanations that have been proposed in the past. Our systematic review shows that of seven possible hypotheses considered, at least three are credible and require additional information: (1) stochastic environmental events may have increased the snakes’ susceptibility to pathogens, (2) a resurgence in the abundance of top predators may have induced a localised change in trophic structure, and (3) an acute increase in local boat traffic may have had negative physical impacts. One or more of these factors, possibly acting in combination with as yet other unidentified factors, is the most plausible explanation for the precipitous decline in sea snake populations observed. Based on this position, we identify future research directions with a focus on addressing critical gaps in knowledge to inform and prioritise future management actions.

Coastal Garbage Patches: Fronts Accumulate Plastic Films at Ashmore Reef Marine Park (Pulau Pasir), Australia

Millions of tons of buoyant plastic materials enter oceans annually, the majority originating from terrestrial sources and transported to oceans where oceanographic processes disperse or accumulate them. Some of these materials beach while others accumulate in convergent zones in coastal seas and the open ocean. Although accumulations associated with subtropical gyres, for example, the “Great Pacific Garbage Patch” (GPGP) are well-known, coastal accumulation zones have received less attention. Here we report quantities and characteristics of plastics accumulated in fronts encountered within the Ashmore Reef marine park (Pulau Pasir), northern Australia. These areas, as well as surrounding waters, were sampled using Manta trawls, drone, and snorkel surveys conducted in October 2018. With mean plastic concentrations of 523,146 pieces km−2 for plastics > 500 micron these hotpots contained plastic concentrations an order of magnitude higher than surrounding waters (16,561 pieces km−2) and comparable to the largest known accumulation zone: the GPGP. Furthermore, the mean mass within hotspots was 5,161 g km–2 vs. 9 g km–2 in surrounding waters. Therefore, we classify the features described in this study as types of “Coastal Garbage Patches” (CGPs). Importantly, the coastal fronts accumulating plastics in CGPs are key habitats for many marine species. Biomass outnumbered plastics by weight, with a ratio of 0.521 in CGPs and 0.016 in surrounding waters vs. 287.7 recorded in the GPGP. Polymer types found between the CGPs and GPGP were similar, but plastic films vastly dominated in the CGPs, whilst they were amongst the rarest types found in the GPGP. This study demonstrates the existence of CGPs coinciding with high priority conservation zones in coastal waters and highlights a need for further research into these environments.

A review of extantTudivasumRosenberg & Petit, 1987 (Neogastropoda: Turbinellidae) and description of three new species from Western Australia

ABSTRACTTudivasum Rosenberg & Petit, 1987 is a morphologically distinct gastropod genus of low diversity. All but one species are known from Australia and they occur from the intertidal zone down to hundreds of metres on the continental shelf. These carnivorous gastropods are thought to have intracapsular development. The six currently recognized extant species are reviewed here and their geographical ranges clarified. Two new species, Tudivasum chaneyi n. sp. and T. ashmorense n. sp., are described from Ashmore Reef, Western Australia, and are characterized by differences in protoconch colour and shell sculpture. The third new species, T. westrale n. sp., is described from the mid-west coast of Western Australia, where it has long been misidentified as T. spinosum (H. Adams & A. Adams, 1864). We generated a molecular phylogeny based on mitochondrial DNA sequence data to test morphological species concepts and reconstruct relationships among four of the described species. High levels of divergence within one of the new species could indicate an additional cryptic species.

Forensic genetic case study: Species identification and traceability of sea turtle caught in illegal trade in Bali, Indonesia

Abstract. Pertiwi NPD, Suhendro MD, Yusmalinda NLA, Putra ING, Putri IGRM, Artinigsih EY, Al Malik MD, Cahyani NKD, Sembiring A. 2020. Forensic genetic case study: Species identification and traceability of sea turtle caught in illegal trade in Bali, Indonesia. Biodiversitas 21: 4276-4283. Although known as protected endangered species, sea turtle trade is still occurring, especially in Indonesia. Understanding the species and population origin of sea turtle being sold in the illegal market is crucial for its conservation, where it will reveal the traceability of sea turtle trade to its population origin in the management unit areas. Thus, genetic forensic has been used as a key investigating tool to help with this problem. In this research, we aim to identify the species and population origin of the sea turtle caught and traded in the illegal market in Bali. Of the 20 samples collected from confiscated sea turtle during illegal trade, by-catch, and a traditional restaurant serving sea turtle meat, 17 samples were successfully analyzed and identified using PCR (polymerase chain reaction) methods. The result identified 15 samples as a green sea turtle (Chelonia mydas), while two samples were olive ridley sea turtle (Lepidochelys olivacea). Mixed Stock Analysis (MSA) with Bayesian indicated that the green sea turtle caught in illegal trade in Bali is originated mostly from the rookeries populations in Berau (29.98%), Terengganu (17.84%), Sarawak (14.84%), and Ashmore Reef (11.85%). Meanwhile, 18 other locations only showed the MSA value below 2%, including the locations of Penang and Perak, Vietnam, Perhentian, Redang, Pahang, Mersing, Sabah Turtle Island Park (TIP), Sipadan, Coral Sea, western New Caledonia, Commonwealth of the Northern Mariana Island and Guam, northern New Guinea, Gulf of Carpenteria, Scott Reef, West Java, North West Self, Cobourg Peninsula, Cocos Keeling Island. Therefore, the exploitation of sea turtle in Bali will impact the decline in the genetic diversity of sea turtles population Indonesia and adjacent locations. Monitoring and protection of sea turtle species in Bali have to be a high priority because Bali is known as the hub for sea turtle illegal trade, and the exploitation of sea turtle in Bali will have an impact on the sea turtle population in other locations.

Historical context, current status and management priorities for introduced Asian house geckos at Ashmore Reef, north-western Australia

Historical context, current status and management priorities for introduced Asian house geckos at Ashmore Reef, north-western Australia

A Cenozoic Great Barrier Reef on Australia's North West shelf

Abstract The Great Barrier Reef of Australia is the largest modern coral reef system on Earth. However, a similar-sized barrier reef (~2000 km long) existed on Australia's north-western margin in the middle Miocene and to some extent, still exists today. Seismic profiles reveal that this reef system was first initiated in the late Paleogene (~34–28 Ma) and reached its zenith as a prograding barrier reef during the middle Miocene (16–15 Ma). This giant reef system backstepped in the late Miocene (~10 Ma), forming a series of isolated atolls and pinnacle reefs. These remaining reefs were gradually extinguished, leaving only a few surviving isolated atolls today (Rowley Shoals, Scott Reef, Seringapatam Reef and Ashmore Reef). The distribution of these extant reefs therefore outlines the former presence of the mid-Miocene Great Barrier Reef of the Australian North West Shelf. This middle Miocene shallow-water rimmed-reefal shelf grew contemporaneously on a deeper-water heterozoan ramp, producing an unusual mixed heterozoan/photozoan carbonate system for most of its length. The initiation of reef growth appears related to Australia's northward drift into lower latitudes, combined with warm mid-Miocene climatic optimum conditions. However, the sudden and simultaneous initiation of reef growth in the mid-Miocene across the North West Shelf was probably also related to changes in paleoceanography (increased aragonite saturation and/or nutrient-depletion) perhaps influenced by changing climatic conditions (increased aridity). From the late Miocene (~10 Ma) to Holocene, high rates of subsidence across the North West Shelf probably set the scene for ultimate demise of this giant barrier reef system and led to widespread backstepping with the development of a series of isolated atolls and pinnacle reefs. It is likely that other paleoceanographic and climatic events (like nutrient supply, carbonate saturation, eustasy etc) combined with continued high subsidence rates acted to gradually extinguish the reef system in a series of steps over a period of 10 million years. The onset (~1 Ma) of a strong Leeuwin Current (with the delivery of warm and nutrient depleted water from the north) and its effect on the Quaternary reefs of the Western Australian coast is a good example of a paleoceanographic process that would be difficult to recognize in an ancient setting. It is likely that similar paleoceanographic events have controlled the rich and complex history of reef growth and drowning since the mid-Miocene on the North West Shelf.

Protection from illegal fishing and shark recovery restructures mesopredatory fish communities on a coral reef.

The recovery of communities of predatory fishes within a no‐take marine reserve after the eradication of illegal fishing provides an opportunity to examine the role of sharks and other large‐bodied mesopredatory fishes in structuring reef fish communities. We used baited remote underwater video stations to investigate whether an increase in sharks was associated with a change in structure of the mesopredatory fish community at Ashmore Reef, Western Australia. We found an almost fourfold increase in shark abundance in reef habitat from 0.64 hr−1 ± 0.15 SE in 2004, when Ashmore Reef was being fished illegally, to 2.45 hr−1 ± 0.37 in 2016, after eight years of full‐time enforcement of the reserve. Shark recovery in reef habitat was accompanied by a two and a half‐fold decline in the abundance of small mesopredatory fishes (≤50 cm TL) (14.00 hr−1 ± 3.79 to 5.6 hr−1 ± 1.20) and a concomitant increase in large mesopredatory fishes (≥100 cm TL) from 1.82 hr−1 ± 0.48 to 4.27 hr−1 ± 0.93. In contrast, near‐reef habitats showed an increase in abundance of large mesopredatory fishes between years (2.00 hr−1 ± 0.65 to 4.56 hr−1 ± 1.11), although only smaller increases in sharks (0.67 hr−1 ± 0.25 to 1.22 hr−1 ± 0.34) and smaller mesopredatory fishes. Although the abundance of most mesopredatory groups increased with recovery from fishing, we suggest that the large decline of small mesopredatory fish in reef habitat was mostly due to higher predation pressure following the increase in sharks and large mesopredatory fishes. At the regional scale, the structure of fished communities at Ashmore Reef in 2004 resembled those of present day Scott Reefs, where fishing still continues today. In 2016, Ashmore fish communities resembled those of the Rowley Shoals, which have been protected from fishing for decades.

Population declines, genetic bottlenecks and potential hybridization in sea snakes on Australia's Timor Sea reefs

Population bottlenecks can result in loss of genetic variation, increased extinction risk, and hybridization with related sympatric species. Many challenges are associated with empirical detection of population declines, thus conservation biologists often use molecular approaches as surrogates. This study explored whether declines in abundances of viviparous sea snakes on Australia's Timor Sea reefs could have been foreshadowed using genetic surveys. Ashmore Reef (the largest Timor Sea reef) once hosted large breeding populations of sea snakes. Abundances have declined precipitously since 1994 and Ashmore Reef has been devoid of snakes since 2012. Moreover, high rates of hybridization between two sympatric species have been documented on Timor Sea reefs, possibly associated with sea snake declines. I analysed mitochondrial DNA and 11 nuclear microsatellites for >250 sea snakes from three species, Aipysurus laevis, Aipysurus fuscus and Emdocephalus annulatus, sampled on four Timor Sea reefs in 2002 and 2010. While there was strong spatial genetic structure among reefs, there was little temporal genetic divergence for A. laevis at Ashmore Reef, despite the massive declines in abundance during that temporal window. Positive Tajima's D and Fu's FS values at Ashmore Reef indicated demographic contraction for: A. laevis in 2002 and 2010; E. annulatus (2002); but not A. fuscus (2002). Microsatellites showed inbreeding depression (positive Fis values) and non-random mating (heterozygote deficit) for all three species at Ashmore Reef, consistent with population declines. Bottleneck tests were equivocal, with significant heterozygous excesses at Ashmore Reef, but non-significant M-ratios or mode-shifts in allele frequencies, with the significance of tests differing markedly with microsatellite mutation models. Thus genetic analyses alone would not have been sufficient to provide managers with unequivocal evidence of population declines. There was little evidence for hybridization between A. laevis and A. fuscus, despite previous research suggesting that the Endangered A. fuscus was at risk of reverse speciation secondary to the highly porous reproductive barriers between these species.

Evidence for rapid recovery of shark populations within a coral reef marine protected area

There is limited evidence on the rate at which the shark populations of coral reefs can rebound from over-exploitation, the baselines that might signify when recovery has occurred and the role of no-take Marine Protected Areas (MPA) in aiding this process. We surveyed shark assemblages at Ashmore Reef in Western Australia using baited remote underwater video stations in 2004 prior to enforcement of MPA status and then again in 2016 after eight years of strict enforcement. We found an increase in the relative mean abundance of Carcharhinus amblyrhynchos from 0.16 ± 0.06 individuals h−1 in 2004 to 0.74 ± 0.11 individuals h−1 in 2016, a change that was also accompanied by a shift in the assemblage of sharks to greater proportions of apex species (from 7.1% to 11.9%) and reef sharks (from 28.6% to 57.6%), and a decrease in the proportional abundance of lower trophic level species (from 64.3% to 30.5%). Abundances and trophic assemblage of sharks at Ashmore Reef in 2004 resembled those of the Scott Reefs, where targeted fishing for sharks still occurs, whereas in 2016, abundances and trophic structures had recovered to resemble those of the Rowley Shoals, a reef system that has been a strictly enforced MPA for over 25 years. The shift in abundance and community structure coincident with strict enforcement of the MPA at Ashmore Reef has occurred at a rate greater than predicted by demographic models, implying the action of compensatory processes in recovery. Our study shows that shark communities can recover rapidly after exploitation in a well-managed no-take MPA.

Modelling tropical fire ant (Solenopsis geminata) dynamics and detection to inform an eradication project

Invasive species threaten endangered species worldwide and substantial effort is focused on their control. Eradication projects require critical resource allocation decisions, as they affect both the likelihood of success and the overall cost. However, these complex decisions must often be made within data-poor environments. Here we develop a mathematical framework to assist in resource allocation for invasive species control projects and we apply it to the proposed eradication of the tropical fire ant (Solenopsis geminata) from the islands of Ashmore Reef in the Timor Sea. Our framework contains two models: a population model and a detection model. Our stochastic population model is used to predict ant abundance through time and allows us to estimate the probability of eradication. Using abundance predictions from the population model, we use the detection model to predict the probability of ant detection through time. These models inform key decisions throughout the project, which include deciding how many baiting events should take place, deciding whether to invest in detector dogs and setting surveillance effort to confirm eradication following control. We find that using a combination of insect growth regulator and toxins are required to achieve a high probability of eradication over 2 years, and we find that using two detector dogs may be more cost-effective than the use of lure deployment, provided that they are used across the life of the project. Our analysis lays a foundation for making decisions about control and detection throughout the project and provides specific advice about resource allocation.

A record of the Siberian Blue Robin Larvivora cyane at Ashmore Reef off north-western Australia, April 2012

An immature male Siberian Blue Robin Larvivora cyane was recorded on West Island, Ashmore Reef, off northwestern Australia, on 23–25 April 2012. This is the first record of this species anywhere in Australia or its territories.

New range and habitat records for threatened Australian sea snakes raise challenges for conservation

Hydrophiine (true) sea snakes are large predatory live-bearing marine reptiles. Australia is a biodiversity hotspot for true sea snakes with almost half of the ~70 extant species (including 11 endemics). Two Australian endemics, Aipysurus foliosquama and Aipysurus apraefrontalis, were listed as Critically Endangered (CR) under IUCN Red List (2010) criteria and Australia's Threatened Species Legislation (2011) due to their restricted geographic ranges being <10km2 (i.e. Ashmore and Hibernia Reefs, Timor Sea), from where they disappeared between 1998 and 2002. However, museum and anecdotal records suggested that these species might also occur in coastal locations of Western Australia (WA). We used intensive field surveys, habitat data, and molecular genetics to document the first unequivocal records of living A. foliosquama (n=16) and A. apraefrontalis (n=7) since they were listed as Critically Endangered, in coastal WA. Our data significantly increases the known geographic range and habitats of A. foliosquama, to include seagrass meadows in subtropical Shark Bay (latitudes 24.5°S to 26.6°S), which is 500km further south than any previous sighting. Most sea snakes were collected from demersal prawn trawl by-catch surveys, indicating that these species are vulnerable to demersal trawl gear. Nonetheless, the disappearance of these two species from Ashmore Reef (which coincided with extirpations of at least three other sea snake species) could not be attributed to trawling and remain unexplained. Key threatening processes will need to be identified if effective conservation strategies are to be implemented to protect these newly discovered coastal populations of two Critically Endangered species.