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The age of whole otoliths from barramundi (Lates calcarifer) obtained from the southern Gulf of Carpentaria were estimated using Fourier transform near-infrared (FT-NIR) spectroscopy. Otoliths from 1716 barramundi collected in 2006, 2009 and 2012–2015 were used in this study. Partial least-squares regression models (PLS-R) and multiple linear regression models (MLR) were developed from the diffuse reflectance spectra and the age was obtained from traditional sectioned otoliths. Calibration models were built up over consecutive years (2012–2015) by using a subset of the samples and used to predict the age of the remaining samples and samples from the following year. Results suggest that when seasonal (temporal) variability is incorporated into the calibration model, FT-NIR has the ability to predict barramundi age (validation R2 ranged from 0.73 to 0.78; RMSEP ranged from 6.92 to 7.64 months). The predicted age class was within 1 year of the reference age in over 96% of the samples. These models were also able to predict the age of otoliths from 2006 and 2009, which were retrieved from long-term storage (validation R2 ranged from 0.77 to 0.84; RMSEP ranged from 8.66 to 10.88 months). The results from this study have shown the potential for barramundi from the southern Gulf of Carpentaria to be aged quickly and accurately by using FT-NIR.

Penaeid prawns (shrimp) are short-lived and fecund, with a complicated life cycle that includes offshore spawning followed by a coastal or estuarine postlarval and juvenile phase. Factors affecting survival during the early life-history stages, and during movement between these stages, will affect variability in recruitment to the nursery ground, the offshore subadult and adult population, and, ultimately, catch. The inability to predict recruitment, and ultimately commercial offshore catch, has been complicated by an incomplete understanding of these factors. The reproductive dynamics of Penaeus (Fenneropenaeus) merguiensis were investigated by simultaneous adult and larval sampling on 66 lunar-monthly surveys from March 1986 to March 1992 in Albatross Bay, northeastern Gulf of Carpentaria, Australia. Egg production was seasonal, with the highest production from 6-mo-old newly recruited spawners, and another peak from 12mo-old spawners. Larval abundance (no. m-2) followed the same seasonal pattern as the abundance of eggs. However, interannual variation in egg and larval abundance was large, and there was a weak correlation between monthly egg and larval abundance. Larval abundance appeared to be further influenced by fluctuations in chlorophyll a concentration, a measure of food availability. There was evidence of a match/mismatch relationship between larval abundance and episodic chlorophyll increases. While there was no direct spawner (egg production)-fishery recruit relationship in P. merguiensis over the 6-yr study, there was a strong relationship between total larval abundance in spring and the size of the commercial catch 3 to 6 mo later. Therefore, factors affecting larval survival, including food availability, have significant implications for fishery production.

A combination of elemental analysis, bulk stable isotope analysis (bulk SIA) and compound-specific stable isotope analysis of amino acids (CSIA-AA) was used to assess and monitor carbon (C), nitrogen (N) and sulfur (S) cycling of a mangrove ecosystem that suffered mass dieback of trees in the Gulf of Carpentaria, Australia in 2015–2016, attributed to an extreme drought event. Three field campaigns were conducted 8, 20 and 32 months after the event over a period from 2016 to 2018 to obtain biological time-series data. Invertebrates and associated organic matter including mangroves and sediments from the impacted ecosystem showed enrichment in 13C, 15N and 34S relative to those from an adjacent unimpacted reference ecosystem, likely indicating lower mangrove carbon fixation, lower nitrogen fixation and lower sulfate reduction in the impacted ecosystem. For example, invertebrates representing the feeding types of grazing, leaf feeding and algae feeding were more 13C enriched at the impacted site, by 1.7 ‰–4.1 ‰, and these differences did not change over the period from 2016 to 2018. The CSIA-AA data indicated widespread 13C enrichment across five essential amino acids and all groups sampled (except filter feeders) within the impacted site. The seedling density increased from 0.2 m−2 in 2016 to 7.1 m−2 in 2018 in the impacted forest, suggesting recovery of the vegetation. Recovery of CNS cycling, however, was not evident even after 32 months, suggesting a biogeochemical legacy of the mortality event. Continued monitoring of the post-dieback forest is required to predict the long-term trajectory of ecosystem recovery. This study shows that time-series SIA can track biogeochemical changes over time and evaluate recovery of an impacted ecosystem from an extreme event.

During the strong El Nino event of 2015-2016 large-scale dieback of mangrove forests was observed in the Gulf of Carpentaria region of northern Australia. These and other intertidal communities are also extensive along the 7,400 km coastline of north-eastern Australia. Determination of their floristic composition, potential carbon (C) store and sequestration capacity, and vulnerability to climate extremes is required for their effective conservation management and was the aim of this study. Standardized, state-wide quantitative classification methods identified five mangrove forest and three saltmarsh communities covering 2,604 km(2)along this coastline. Estuarine and oceanic mangrove forests were mapped separately. Carbon storage and sequestration capacity of the intertidal communities and their vulnerability to strong El Nino events were estimated using published data and GIS analyses. An estimated potential 126.2 (+/- 27.3 SEM) Tg C and 8.3 (+/- 0.4 SD) Tg C were stored in the mangrove forests and saltmarshes, respectively. Comparatively, the rainforests of the region stored an estimated equivalent amount of C but covered three times the area, and the most widespread woodlands (Eucalyptus tetrodonta) of the region stored an estimated 1.5 times the C but covered 16 times the area. The C stored in the intertidal communities was estimated as equivalent to 493.47 Tg of CO(2,)valued at AU$6.8 billion on the Australian carbon market in December 2018. Annual C sequestration potential was 0.18-0.34 Tg C/year, valued between AU$8.9 and $17 million. Approximately 360 ha of mangrove forest was estimated as lost because of dieback during the 2015-16 El Nino event. Three types of mangrove forest were identified as potentially vulnerable to dieback from El Nino-driven climate events. This study highlights the national and global significance of these intertidal systems and our findings need to be incorporated in future conservation and development planning of northern Australia.

A new population of eastern short eared rock-wallaby (Petrogale wilkinsi) has been recorded in Queensland. The animals were photographed on a sandstone cliff face in Lawn Hill Gorge, Boodjamulla National Park, ~160 km from the closest record on Wollogorang Station in the Northern Territory. The species was originally thought to occur north of the 600-mm rainfall isohyet, with most of the population found in the monsoonal tropics of the Top End. This record significantly extends the known range of this taxon to the south-east and places P. wilkinsi at the 450-mm rainfall isohyet. Sympatry in rock-wallabies is unusual but P. wilkinsi at Boodjamulla appears to be sympatric with the more common purple necked rock-wallaby (Petrogale purpureicollis). A recent taxonomic revision of the brachyotis group found that there was a significant mitochondrial DNA (mtDNA) divergence between the Wollogorang record and the rest of the P. wilkinsi group further north, but further genetic sampling across the southern Gulf of Carpentaria is required to determine whether these populations represent an additional distinct taxon.

Extreme climatic events can trigger sudden but often long‐lasting impacts in ecosystems by causing near to complete mortality of foundation (habitat‐forming) species. The magnitude and frequency of such events are expected to rise due to anthropogenic climate change, but the impacts that such events have on many foundation species and the ecosystems that they support remains poorly understood. In many cases, manipulative experimentation is extremely challenging and rarely feasible at a large scale. In late 2015 to early 2016, an extensive area of mangrove forest along ∼ 1000 km of coastline in the Gulf of Carpentaria, Australia, experienced severe dieback, an event associated with climatic extremes. To assess the effect this dieback event had on the mangrove ecosystem, we assessed benthic faunal assemblages and food web structure using stable carbon and nitrogen isotopes in a comparative experiment of impacted forest and adjacent unimpacted forest. Eighteen months after the dieback, the forest that suffered dieback contained significantly fewer crabs that rely on mangrove litter food source but more crabs that rely on microphytobenthos food source than the unimpacted forest. However, the infaunal biomass was largely unaffected by the mortality effect. This is most likely because microphytobenthos was largely unaffected and consequently, this buffered the food web responses. However, overall, the habitat value for mangrove ecosystem services most likely decreased due to lower physical habitat complexity following tree mortality. Longer‐term monitoring could lead to better understanding of biological effects of this extreme event and underlying biological mechanisms that drive changes and recovery.

A revised Holocene sea-level history for the southern Gulf of Carpentaria is presented based on new data from the South Wellesley Archipelago and age recalibration of previous research. Results confirm that rising sea levels during the most recent post-glacial marine transgression breached the Arafura Sill ca. 11,700 cal. yr BP. Sea levels continued to rise to ca. –30 m by 10,000 cal. yr BP, leading to full marine conditions. By 7700 cal. yr BP, sea-level reached present mean sea-level (PMSL) and continued to rise to an elevation of between 1.5 m and 2 m above PMSL. Sea level remained ca. + 1.5 between 7000 and 4000 cal. yr BP, followed by rapid regression to within ± 0.5 m of PMSL by ca. 3500 cal. yr BP. When placed into a wider regional context results from this study show that coastal landscape evolution in the tropical north of Australia was not only dependent on sea-level change but also show a direct correlation with Holocene climate variability. Specifically, the formation and preservation of beach-rock deposits, intertidal successions, beach and chenier ridge systems hold valuable sea-level and Holocene climate proxies that can contribute to the growing research into lower latitude Holocene sea-level and climate histories.

Northern Australia has been identified as the last stronghold for the dwarf sawfish Pristis clavata, green sawfish P. zijsron, and largetooth sawfish P. pristis, making these populations key in global conservation efforts for each species. This research assesses the levels of genetic diversity in these 3 sawfishes in Australian waters, testing for the presence of population bottlenecks using data at microsatellite loci. Levels of observed heterozygosity in each species from the west coast of Australia and the north-eastern Gulf of Carpentaria were generally high. M ratio tests suggest that assemblages of P. zijsron and P. pristis on the west coast and P. clavata and P. zijsron in the Gulf of Carpentaria may have experienced population bottlenecks. The bottlenecks are especially pronounced in P. zijsron populations and in P. clavata from the Gulf of Carpentaria. Demographic analyses, based on mtDNA data, indicate relatively recent (evolutionarily) range expansions in Pristis sawfishes in northern Australian waters, which could account for the population bottlenecks. A more recent range expansion in each of P. clavata and P. zijsron, as evidenced by more recent population divergence and more recent/higher rates of historic maternal gene flow, could account for the more pronounced bottlenecks in these species when compared to P. pristis. Given that Pristis sawfishes in Australian waters have experienced population bottlenecks, whether they be historic, contemporary or both, the preservation of remaining genetic diversity should be a high conservation priority.

We examined the influence of past and present landscape structure across five regions of northern and eastern Australia on phylogeographic structure in the freshwater fish Glossamia aprion. We predicted the geological isolation of North West Australia would promote the strongest phylogeographic structure, including highest endemism of candidate species and deepest divergences within species, and past low sea level riverine connections in the Carpentaria Region would greatly reduce phylogeographic structure. The allozyme data indicated five candidate species within Australian Glossamia, although the mtDNA data revealed only four of these taxa. Diversity and endemism of the candidate species was highest in North West Australia, but Carpentaria was not the only region to have low species diversity or an absence of endemic species. Three of the five candidate species were narrow range endemics and occurred in regions with known endemism of candidate species in other freshwater fauna. The reported subspecies Glossamia aprion gillii was clearly distinct based on the genetic data, while the fifth species, G. a. aprion, was widely distributed across four of the five regions. The intra-specific analyses for G. a. aprion showed highest phylogeographic structure in North West Australia and lowest phylogeographic structure in Carpentaria. Overall, the results demonstrate the long-term legacy of variable landscape structure on phylogeographic patterns and allopatric speciation.

Growing evidence indicates that tree-stem methane (CH4 ) emissions may be an important and unaccounted-for component of local, regional and global carbon (C) budgets. Studies to date have focused on upland and freshwater swamp-forests; however, no data on tree-stem fluxes from estuarine species currently exist. Here we provide the first-ever mangrove tree-stem CH4 flux measurements from >50 trees (n = 230 measurements), in both standing dead and living forest, from a region suffering a recent large-scale climate-driven dieback event (Gulf of Carpentaria, Australia). Average CH4 emissions from standing dead mangrove tree-stems was 249.2 ± 41.0 μmol m-2 d-1 and was eight-fold higher than from living mangrove tree-stems (37.5 ± 5.8 μmol m-2 d-1 ). The average CH4 flux from tree-stem bases (c. 10 cm aboveground) was 1071.1 ± 210.4 and 96.8 ± 27.7 μmol m-2 d-1 from dead and living stands respectively. Sediment CH4 fluxes and redox potentials did not differ significantly between living and dead stands. Our results suggest both dead and living tree-stems act as CH4 conduits to the atmosphere, bypassing potential sedimentary oxidation processes. Although large uncertainties exist when upscaling data from small-scale temporal measurements, we estimated that dead mangrove tree-stem emissions may account for c. 26% of the net ecosystem CH4 flux.

Few freshwater aquatic species have ecological traits that deal with the vagaries of flow in ephemeral tropical rivers. In northern Australia, the tropical freshwater crab, Austrothelphusa transversa (von Martens, 1868) is a conspicuous species that occupies seasonal rivers, where it is thought to estivate in underground burrows while waiting for summer rain. During a survey in seasonal river catchments the first photographic evidence was obtained of an estivating female crab containing 42 crablets under the abdomen plate. Uncovering this female with crablets suggests that egg development progressing to crablets occurs during the dry season estivation when crabs are underground and no water exists in river channels; if this is the case then this female crab may have been waiting for rain, to emerge and successfully continue the life cycle in water. Since 2012 the southern Gulf of Carpentaria has experienced below average rainfall, contributing to no or short flow periods over most of the landscape. In lig...

The South Wellesley Islands in the Gulf of Carpentaria, northern Australia, were the recent focus of a palynological investigation which found vegetation change during the Holocene was driven by coastal progradation and regional climate. Here, we present new elemental data from x-ray fluorescence core scanning which provides non-destructive, continuous and high resolution analysis from three wetlands across Bentinck Island, the largest of the South Wellesley Islands. Elemental data and grain size analyses are combined with lead-210 (210Pb) and accelerator mass spectrometry (AMS) carbon-14 (14C) dates. An open coastal environment was present 1250 cal. a BP on the south east coast of Bentinck Island, with sediment supply incorporating fluvial deposition and detrital input of titanium and iron from eroding lateritic bedrock. Prograding shorelines, dune development and river diversion formed a series of swales parallel to the coast by ~800 cal. a BP, forming the Marralda wetlands. Wetlands developed at sites on the north and west coasts ~500 and ~450 cal. a BP, respectively. Geochemical and grain size analyses indicate that wetlands formed as accreting tidal mudflats or within inter-dune swales that intercepted groundwater draining to the coastal margins. The timing of wetland initiation indicates localised late-Holocene sea level regression, stabilisation and coastal plain development in the Gulf of Carpentaria. Elemental data provide new records of wetland development across Bentinck Island, highlighting the value of a multi-proxy approach to understanding environmental change during the Holocene in tropical northern Australia.

Across their range, mangroves are responding to coastal environmental change. However, separating the influence of human activities from natural events and processes (including that associated with climatic fluctuation) is often difficult. In the Gulf of Carpentaria, northern Australia (Leichhardt, Nicholson, Mornington Inlet, and Flinders River catchments), changes in mangroves are assumed to be the result of natural drivers as human impacts are minimal. By comparing classifications from time series of Landsat sensor data for the period 1987–2014, mangroves were observed to have extended seawards by up to 1.9 km (perpendicular to the coastline), with inland intrusion occurring along many of the rivers and rivulets in the tidal reaches. Seaward expansion was particularly evident near the mouth of the Leichhardt River, and was associated with peaks in river discharge with LiDAR data indicating distinct structural zones developing following each large rainfall and discharge event. However, along the Gulf coast, and particularly within the Mornington Inlet catchment, the expansion was more gradual and linked to inundation and regular sediment supply through freshwater input. Landward expansion along the Mornington Inlet catchment was attributed to the combined effects of sea level rise and prolonged periods of tidal and freshwater inundation on coastal lowlands. The study concluded that increased amounts of rainfall and associated flooding and sea level rise were responsible for recent seaward and landward extension of mangroves in this region.

Satellite tracking was used to identify the foraging areas of post-nesting flatback turtles ( n = 66) from four rookeries (Barrow Island, Thevenard Island, Mundabullangana and Port Hedland) within the South East Indian Ocean Regional Management Unit. Foraging areas were in water shallower than 130 m and within 315 km of the shore, with many areas located in 50 m water depth and 66 km from shore. Thirty-one turtles departed their first foraging area prior to the tracking unit transmissions ceasing, with 15 identified as utilising more than one separate foraging area. The furthest foraging area was situated 2511 km from the original nesting site within the Gulf of Carpentaria in Queensland state waters. Identified overlaps of individual's foraging home range areas were used to delineate five important foraging areas, with each area utilised by flatback turtles tracked from more than one rookery. Four of these areas were situated within the Kimberley region and one area within the Pilbara region of Western Australia. There was a large overlap of foraging home range areas and foraging locations with existing protected areas in the region, with 48.5% of the combined overall home range area overlapping with a protected marine reserve. There was minimal interaction between foraging home range areas and the three identified regional fisheries, with the highest overlap occurring with the Northern Prawn Fishery (12.5% of combined overall home range area). There was a high overlap between petroleum title areas (areas that currently host, or have the potential to host, resource sector activities) with foraging areas (67.1% of combined overall home range area). Characteristics of their foraging behaviour were considered to reduce their susceptibility to potential anthropogenic and natural threats within the region i.e. they foraged in areas that were broadly dispersed across the entire region, they utilised inter-connecting pathways between several foraging areas and the same foraging areas were used by multiple turtles. Foraging behaviour by some flatback turtles appeared flexible, with this strategy further reducing their susceptibility by facilitating a capability to adapt to anthropogenic or natural threats within the region.

The largetooth sawfish Pristis pristis (Linnaeus, 1758) is a highly threatened euryha- line elasmobranch that in recent times has undergone a significant range contraction. It now only remains in a few areas, with northern Australia being the main stronghold. Previous work using a single mitochondrial gene approach suggested the existence of regional barriers to gene flow in northern Australia. In this study, whole mitochondrial sequences of 92 P. pristis from 7 river drainages across northern Australia were used to refine the population structure. This approach revealed barriers to gene flow at a scale as fine as between adjacent river drainages. Except for those flowing into the Gulf of Carpentaria, all river drainages appeared to host a genetically dis- tinct population. The apparent genetic homogeneity in the Gulf is probably due to freshwater con- nectivity between river drainages, either during the last glaciation event when the Gulf was a freshwater lake or through contemporary wet season flooding. These results suggest that each river drainage across the species' range should be considered a discrete management unit unless there is evidence of freshwater connectivity. More broadly, the improved resolution of population structure obtained with whole mitogenome analysis compared to single mitochondrial gene approaches suggests that female reproductive philopatry may have been overlooked in previous studies of some elasmobranch species.

A major decline in the catch of the banana prawn [shrimp], Penaeus (Fenneropenaeus) merguiensis, occurred over a six-year period in the Weipa region of the northeastern Gulf of Carpentaria, Australia. Three main hypotheses have been developed to explain this decline: (1) prawn recruitment collapsed due to overfishing; (2) recruitment collapsed due to a change in the prawn's environment; and (3) adult banana prawns were still present, but fishers could no longer effectively find or catch them. Qualitative mathematical models were used to link population biology, environmental factors, and fishery dynamics to evaluate the alternative hypotheses. This modeling approach provides the means to rapidly integrate knowledge across disciplines and consider alternative hypotheses about how the structure and function of an ecosystem affects its dynamics. Alternative models were constructed to address the different hypotheses and also to encompass a diversity of opinion about the underlying dynamics of the system. Key findings from these analyses are that: instability in the system can arise when discarded fishery bycatch supports relatively high predation pressure; system stability can be enhanced by management of fishing effort or stock catchability; catch per unit effort is not necessarily a reliable indicator of stock abundance; a change in early-season rainfall should affect all stages in the banana prawn's life cycle; and a reduced catch in the Weipa region can create and reinforce a shift in fishing effort away from Weipa. Results from the models informed an approach to test the hypotheses (i.e., an experimental fishing program), and promoted understanding of the system among researchers, management agencies, and industry. The analytical tools developed in this work to address stages of a prawn life cycle and fishery dynamics are generally applicable to any exploited natural. resource.

Recent evidence indicates that climate change and intensification of the El Niño Southern Oscillation (ENSO) has increased variation in sea level. Although widespread impacts on intertidal ecosystems are anticipated to arise from the sea level seesaw associated with climate change, none have yet been demonstrated. Intertidal ecosystems, including mangrove forests are among those ecosystems that are highly vulnerable to sea level rise, but they may also be vulnerable to sea level variability and extreme low sea level events. During 16 years of monitoring of a mangrove forest in Mangrove Bay in north Western Australia, we documented two forest dieback events, the most recent one being coincident with the large-scale dieback of mangroves in the Gulf of Carpentaria in northern Australia. Diebacks in Mangrove Bay were coincident with periods of very low sea level, which were associated with increased soil salinization of 20–30% above pre-event levels, leading to canopy loss, reduced Normalized Difference Vegetation Index (NDVI) and reduced recruitment. Our study indicates that an intensification of ENSO will have negative effects on some mangrove forests in parts of the Indo-Pacific that will exacerbate other pressures.

The female of Delias aestiva smithersi Daniels, 2012 comb. nov. from northern Australia is illustrated and described for the first time. The subspecies is diagnosed and its taxonomic status clarified. Several unique character states concerning wing colour pattern elements of D. aestiva smithersi, together with evidence of the male genitalia, support the hypothesis that the subspecies belongs to D. aestiva Butler, 1897 and not to D. mysis (Fabricius, 1775). The taxon appears to have a restricted geographical range, being limited to the eastern Gulf of Carpentaria on the western side of Cape York Peninsula, Queensland (from Weipa to Karumba), where it occurs in mangrove habitats in coastal lowland areas. Delias aestiva smithersi and the nominate subspecies, D. aestiva aestiva Butler, 1897 from the "Top End", Northern Territory, are allopatric and geographically separated by the Gulf of Carpentaria, suggesting that this biogeographical barrier (the Carpentarian Gap) has facilitated differentiation within the species, either though vicariance or dispersal.

Biodiversity assessments by research scientists are often logistically difficult and expensive to implement in remote areas. Locally-based approaches have the potential to overcome some of these challenges by capitalising on the knowledge and capacity of local people. Many Indigenous people in northern Australia are custodians of coastal areas that support globally significant populations of tropical marine mammals, including coastal dolphins and dugongs. The objective of our study was to design and implement a locally-based approach in a cross-cultural environment to assess the distribution of marine mammals in the remote waters of the Gulf of Carpentaria, Northern Territory. The study was conducted as a partnership between Yanyuwa Aboriginal families, research scientists, government officers and the li-Anthawirriyarra Sea Rangers. We conducted a series of participatory mapping workshops to share and record local observations of dolphins and dugongs. These observations provided the longitudinal information required to inform the design of the first dedicated marine mammal vessel survey in the Gulf of Carpentaria. The vessel surveys found three species of dolphins present in the area (Australian snubfin, humpback and bottlenose dolphins), even though sightings were low; dugongs being much more common. We found that the integrative and locally-based approach built the capacity of both the li-Anthawirriyarra Sea Rangers and research scientists to assess the distribution of marine mammals. If replicated over longer time-frames and coordinated over broader spatial scales, information on distribution and abundance derived from locally-based approaches has the potential to inform the status of marine mammals.

Dramatic changes in shellfishing behaviors occur across northern Australia during the late Holocene, marked most conspicuously by the cessation of large shell mound construction in some areas, and the reorganization of shellfishing behaviors towards more intensive production in the last 1,000 years. Excavations reveal rapid and widespread changes within coastal sites, an increasing diversification in overall subsistence resources, and patterns of increase in site establishment and use. Some of these changes have been argued to be associated with increasing climate variability and a trend towards increasing aridity during the late Holocene, thought to have transformed coastal ecosystems and mollusc availability. However, when these hypotheses are tested at the local level, more nuanced patterns of human-environment interaction emerge, which call into question interpretations based on broad-scale climate records. We suggest that disjunctions in the timing of the cessation of shell mound construction...

Understanding connectivity between groups of a species is fundamental to effective management and conservation practices, yet is poorly understood for tropical estuarine fishes. Here, age-related trends in otolith elemental chemistry were examined to assess the degree of connectivity of Polydactylus macrochir, a large, non-diadromous, tropical estuarine teleost, across the species' Australian distribution. Elemental signatures (7Li, 43Ca, 55Mn, 88Sr and 138Ba) of transverse sections of otoliths of 3+ yr fish from the 2005 year class collected from 17 locations were sampled using laser ablation inductively coupled plasma mass spectrometry, providing elemental profiles from the otolith core through the first 3 yr of a fish's life. Univariate and cluster analyses revealed differences in elemental signatures of the otolith core among most locations, although similarities were evident among locations in the Gulf of Carpentaria and among 2 neighbouring locations in both Western Australia and the east coast of Queensland. Fewer differences were observed for post-settlement life history stages, although some differences were observed among neighbouring locations separated by as little as 50 km. SIMPROF analyses revealed that 138Ba generally provided the greatest discrimination among locations. Positive correlations were observed between otolith 138Ba concentration of individual fish and river flow indices for material laid down in all age groups, suggesting differences in flow was a significant driver of the observed patterns in 138Ba. Examined in conjunction with complementary studies into the connectivity of the study species, the spatial structuring suggests that P. macrochir populations are susceptible to localised depletion, with limited opportunity for replenishment from neighbouring populations. The results highlight the importance of using multiple, complementary methods for assessing connectivity of aquatic organisms.

The Australian Monsoonal Tropics (AMT) is a unique location for the study of phylogeography and intraspecific genetic variation in freshwater fish. We assessed the phylogeographic structure of 5 species from 2 genera across the region. The species included 3 neosilurids (Plotosidae, Neosilurus hyrtlii, Neosilurus ater, and Neosilurus pseudospinosus) and 2 members of the genus Oxyeleotris (Eleotridae, O. selheimi and O. lineolata). We used mitochondrial deoxyribonucleic acid (mtDNA) and phylogenetic analyses to explore the phylogeographic histories of these species. Overall, phylogeographic patterns were inconsistent. Some species were highly structured, and phylogeographic breaks were detected (e.g., N. hyrtlii, N. pseudospinosus, and O. selheimi), but other species showed no obvious divergences across the AMT (N. ater and O. lineolata). All species sampled in the Gulf of Carpentaria had shallow phylogenies, consistent with the expectation that historically, Lake Carpentaria would have provided co...

A wealth of palaeoecological studies from the Australasian region identify periods of significant environmental change during the Holocene. However, relatively few studies have focused on the coastal lowlands of tropical northern Australia, limiting our ability to accurately reconstruct this vast bioregion’s history. This study addresses the gap in spatially distributed paleoenvironmental research in northern Australia by producing the first reconstructions from the South Wellesley Islands in the Southern Gulf of Carpentaria. Radioisotope analysis of lead (210Pb), plutonium (239/240Pu) and radiocarbon (14C) provide robust geochronologies. Chronologies are combined with loss on ignition, particle size and micro X-ray fluorescence analyses to identify site formation and development through time. Pollen and macroscopic and microscopic charcoal records were used to examine vegetation change and fire regimes throughout the late Holocene. This research shows coastal wetlands developed during the late Holocene in the South Wellesley Islands. Combined multi-proxy results indicate environmental change initially drove vegetation succession, but that human occupation and abandonment of the islands significantly affected vegetation composition and fire regimes. Radioisotope and geochemical analyses were conducted in collaboration with the Australian Nuclear Science and Technology Organisation. 210Pb alpha spectrometry analysis of 18 samples provide sedimentation rates and a chronology of the last 150 years across three key sites. This period is significant as traditional owners were removed in 1948, leaving the South Wellesley Islands unoccupied for the first time in 2,000 years. This research attempted to calibrate 210Pb results using the anthropogenic radioisotope plutonium by analysing 10 samples using accelerator mass spectrometry (AMS). Results of 239/240Pu isotope analysis found the site’s stratigraphy was insufficiently laminated to accurately pick peaks in fallout. However, levels of 239/240Pu indicate fallout occurred across far northern Australia and the technique has the potential to validate 210Pb results in appropriate sedimentary settings. Geochronologies combined 210Pb dates and bulk sediment 14C AMS dates. This research examined seven sediment profiles using micro X-ray fluorescence geochemical data and particle size analysis. 210Pb and 14C dates provide age-depth chronologies, identifying local and island-wide trends. Elemental analysis of coastal wetlands through time identified key phases of development including open coastal environments, mangrove establishment, hypersaline mudflat expansion and brackish/freshwater wetland development. An open coastal environment was present 1,250 cal. yr BP on the southeast coast of Bentinck Island, with fluvial deposition of detrital elements from the eroding lateritic bedrock. A prograding shoreline, dune development and tributary diversion created a series of swales parallel to the coast by 800 cal. yr BP, forming the extensive Marralda Wetlands. Saline mudflats developed at sites on the north and west coast at 500 and 450 cal. yr BP, respectively. Geochemical and grain size analyses provide evidence that wetlands formed as accreting supratidal environments or coastal swales intercepting groundwater. The timing of coastal environments transitioning to saline mudflats and eventual wetland development indicates localised late Holocene sea-level regression, stabilisation and coastal plain development in the southern Gulf of Carpentaria. Elemental data identified phases of wetland development across Bentinck Island, highlighting the value of geochemical analysis as a proxy of past environments in tropical northern Australia. Palynological and charcoal analysis of four key wetlands across Bentinck Island were used to reconstruct vegetation succession and fire regimes in the late Holocene. This thesis conducted the first comprehensive floristic surveys and modern pollen profiles of the islands, supporting the interpretation of fossil pollen assemblages. An initial study of the Marralda Swamp wetlands found a protected coastal setting from 2,400-500 cal. yr BP, transitioning to a supratidal environment dominated by a mixed mangrove community. Mangroves declined and transitioned to freshwater swamp taxa only in the last 60 years. Analysis of a site 1km inland of the preliminary study found a diverse mangrove community was present between 1,250 and 850 cal. yr BP, with particle size analysis indicating a high-energy environment associated with a tributary. These results are further supported by the geochemical data. Palynological results suggest that mangrove species declined, woodland and savanna species increased and freshwater aquatic taxa increased by 800 cal. yr BP indicating a brackish/freshwater wetland developed. Further freshwater expansion occurred on the southeast coast by 400 cal. yr BP, reaching its maximum extent in the last 200 years. Palynological investigations from the north and west coast of Bentinck Island span the last 550 cal. yr. On the west coast an open savanna landscape was replaced by a mixed woodland and aquatic taxa significantly increased suggesting wetland expansion in the last 200 years. On the north coast the salt-tolerant Chenopodiaceae dominated, suggesting a hypersaline mudflat developed at 450 cal. yr BP. The increasing presence of Pandanus and the appearance of aquatic taxa suggest this site remained an ephemeral source of freshwater during the monsoon season, with the water table below the surface for the majority of the year. This research reconstructed vegetation and fire regimes during periods of human occupation and abandonment, separating anthropogenic and natural drivers of change during the Holocene. Macroscopic charcoal results analysed using CharAnalysis show that interpolated charcoal accumulation increased between 350-200 cal. yr BP on the southeast and west coast of Bentinck Island. Charcoal results correlated well with archaeological evidence of population increase on Bentinck Island in the late Holocene. Peak charcoal and magnitude significantly increased across all sites after AD 1950. Results indicate that the removal of Kaiadilt people in AD 1948 interrupted traditional burning practices and caused the area burned and severity of fire events to increase.

The spectacular threat display of the savannah specialist Australo-Papuan frilled lizards has made them one of the world's most iconic reptiles. They are increasingly used as a model system for research in evolutionary biology and ecology but little is known of their population structure. Their distribution across northern Australia and southern New Guinea also provides an opportunity to examine biogeographic patterns as they relate to the large-scale movement of savannah habitat during the Plio/Pleistocene and the associated increase in aridity. We generated sequence data for one mitochondrial and four nuclear DNA loci (5052 base pairs) for 83 frilled lizards sampled throughout their range. We also quantified body proportion variation for 279 individuals. Phylogenetic analyses based on maximum likelihood and Bayesian species-tree methods revealed three shallow clades that replace each other across the monsoon tropics. We found the expected pattern of male biased sexual size dimorphism in both maximum body size and head size but there was no sexual dimorphism in overall body shape or in frill size, relative to head size, supporting the hypothesis that the frill is used primarily as a threat display rather than a sexual display. The genetic clades are broadly consistent with known clinal variation in frill color that gradually shifts from west to east (red, orange, yellow/white) but otherwise show little morphological differentiation in body proportion measures. The biogeographic breaks between clades occur at the Carpentaria Gap and the lowlands surrounding the Ord River, and our ecological niche modeling predicts lower habitat suitability for C. kingii in these regions. While this biogeographic pattern is consistent with numerous other taxonomic groups in northern Australia, the overall low genetic diversity in frilled lizards across the entire monsoon tropics and southern New Guinea contrasts starkly to patterns seen in other terrestrial vertebrates. Extremely low intra-clade genetic diversity over vast geographic areas is indicative of recent gene flow that would likely have been facilitated by widespread savannah during interglacials, or alternatively may reflect population bottlenecks induced by extreme aridity during Pleistocene glacials. The shallow divergence between Australian and New Guinean samples is consistent with recent connectivity between Australia and New Guinea that would have been possible via a savannah corridor across the Torres Strait. Based on our molecular and morphological data, we do not support taxonomic recognition of any of the frilled lizard clades and instead consider C. kingii a single species with shallow phylogeographic structure and clinal variation in frill color.

Understanding the life history of exploited fish species is not only critical in developing stock assessments and productivity models, but has a dual function in the delineation of connectivity and geographical population structure. In this study, patterns in growth and length and age at sex change of Polydactylus macrochir, an ecologically and economically important protandrous estuarine teleost, were examined to provide preliminary information on the species' connectivity and geographic structure across northern Australia. Considerable variation in life history parameters was observed among the 18 locations sampled. Both unconstrained and constrained (t(0) = 0) estimates of von Bertalanffy growth function parameters differed significantly among all neighbouring locations with the exception of two locations in Queensland's east coast and two in Queensland's Gulf of Carpentaria waters, respectively. Comparisons of back-calculated length-at-age 2 provided additional evidence for growth differences among some locations, but were not significantly different among locations in the south-eastern Gulf of Carpentaria or on Queensland's east coast. The length and age at sex change differed markedly among locations, with fish from the east coast of Australia changing sex from males to females at significantly greater lengths and ages than elsewhere. Sex change occurred earliest at locations within Queensland's Gulf of Carpentaria, where a large proportion of small, young females were recorded. The observed differences suggest that P. macrochir likely form a number of geographically and/or reproductively distinct groups in Australian waters and suggest that future studies examining connectivity and geographic population structure of estuarine fishes will likely benefit from the inclusion of comparisons of life history parameters. (C) 2012 Elsevier B.V. All rights reserved.

Long-term vital rate and life-history data essential for sustainable harvest management are rare in tropical fisheries. Two commercially important shark species, Australian blacktip ( Carcharhinus tilstoni ) and spot-tail ( C. sorrah ) sharks in northern Australia have changed in size and population status over the last 25 years. These populations were exploited heavily from the early 1970s to the mid-1980s by foreign fishers, and since then have been harvested by a relatively small domestic fishery. We examined the differences in fork length of these species caught in 1983–1985 and 2002–2006 using Bayesian forms of generalised linear and mixed-effects models. We found clear regional differences and changes in size over time. For blacktips, sharks from the Gulf of Carpentaria have become smaller, and those from the western Northern Territory, larger over time. For spot-tail sharks, average size increased from the 1980s in the Gulf of Carpentaria, but not in the western Northern Territory. On average, sharks from the Gulf of Carpentaria were larger than those on the west coast of the Northern Territory, and females were larger than males. We suggest that changes over time and between regions in the size of spot-tail sharks are most likely due to over-exploitation in the past and subsequent recovery of populations. We discuss the uncertainty in trends for blacktip sharks in relation to fishing effort, availability of resources and species identification errors.

Aim Within Australia the Carpentaria Barrier has been identified as an important biogeographical barrier. Here we test this long‐standing hypothesis using a medically important mosquito, Aedes (Ochlerotatus) vigilax. Location We obtained samples of Ae. vigilax from throughout its Australian distribution and from New Caledonia. Methods We constructed a distributional database from 602,417 specimens and obtained sequence data from 66 female specimens from 16 localities. The distributional database of Ae. vigilax comprised historical data from 13 organizations and was used to develop our molecular sampling strategy. Genetic structure within Ae. vigilax was examined via haplotype networks, FST values, analysis of molecular variance and neutrality test statistics based on one mitochondrial (cytochrome c oxidase subunit I, COI) and two nuclear (alpha amalyse and zinc finger) loci. The historical demography of Ae. vigilax was investigated using extended Bayesian skyline plot (EBSP) methods, with past migration rates estimated using migrate. Results We identified three distinct lineages within Ae. vigilax; however, two of the three lineages show a large distributional overlap across the Carpentaria Barrier. The mitochondrial locus suggested a pattern of significant genetic differentiation, with high FST values, significant genetic differentiation within the COI locus, and significantly more variation between the lineages than within. A higher number of migrants per generation were estimated for the overlapping lineages and both the neutrality test statistics and EBSP suggested the occurrence of post‐population expansion in these lineages. Main conclusions Significant deviation from genetic neutrality, in combination with estimates of migration and the demographic history of Ae. vigilax lineages, suggests that the incongruence of the Ae. vigilax phylogeny with the hypothesized Carpentaria Barrier could be attributed to the separation of eastern and western populations of Ae. vigilax around 770 ka and subsequent secondary contact within the last 100 kyr. Sea‐level and precipitation fluctuations within the Carpentaria area during the late Quaternary could have facilitated the current biogeographical patterns of Ae. vigilax. Mosquitoes represent one of the most medically important insect groups; however, understanding the factors that influence past and present distributions of mosquitoes is critical in the face of a range of emerging arboviruses.

Po ore, G.C.B. 2012. Four new valviferan isopods from diverse tropical Australian habitats (Crustacea: Isopoda: Holognathidae and Idoteidae). Memoirs of Museum Victoria 69: 327–340. Two new isopods of the family Holognathidae are described from tropical Australia: Cleantioides carpentaria sp. nov. from shallow seagrass sediments in the Gulf of Carpentaria and an eastern Queensland port; and Zenobianopsis cidaris sp. nov. from 500 m depth in the Coral Sea. The latter is the third in its genus. Two new species of Synidotea (Idoteidae), S. innatans sp. nov. and S. karumba sp. nov. are described. Both are distinguished from others of the S. hirtipes-group of species, on the basis of subtle differences in colour and proportions of the body and limbs. The material of S. innatans was taken from flotsam in the Timor Sea and is potentially an obligate rafting species. Synidotea karumba is from shallow sedimentary environments in the Gulf of Carpentaria.

The genetic structure of the freshwater fish Ambassis macleayi Castelnau 1878 was explored across the tropical catchments of the Gulf of Carpentaria Basin, northern Australia. The Gulf of Carpentaria provides a unique opportunity to explore simultaneously contemporary and historical gene flow resulting from unique climatic patterns and historical connectivity among catchments via a freshwater lake that existed during lower sea levels. The control region of the mtDNA genome and 4 microsatellite loci were used to detect significant genetic structure among and within catchments. Within catchments, genetic structure suggested that dispersal of A. macleayi is restricted, despite high levels of connectivity during summer monsoonal events. Among catchments, divergence appeared to be deeper than what would be predicted based on the last opportunity for connectivity via the lake of Carpentaria (∼10,000 years before present [ybp]). Overall, these results have important implications for A. macleayi and other...

The Australian coast can be subdivided into three broad sedimentary provinces occupying the east, south, west, and northwest coasts. The 11,978-km long eastern province extends from the western Gulf of Carpentaria along the entire east coast to eastern Tasmania. It is characterized by tropical to temperate humid climates, quartz sediments, and overall northerly sediment transport, with significant onshore transport where shoreline orientation and wave and wind energy combine to produce massive coastal dune systems, including the world's largest sand islands. The 9587-km long south and west coast province has an arid to semiarid climate with little terrigenous sediment. Much of the coast faces into the prevailing southerly winds and the high year-round Southern Ocean swell, resulting in massive transfer of shelf and nearshore carbonate-rich sediments to the shore and into extensive coastal barrier-dunes systems, the largest dunes extending 110 km inland. The 9106-km long northwest province has a t...

As part of a study of the reasons for declining commercial banana prawn catches in the Weipa area of the Gulf of Carpentaria, and in order to assess whether changes in predator numbers may be a factor influencing prawn numbers, the species composition, numbers and biomasses of fishes in the Embley estuary were re-examined in February 2005 for comparison with the results of a study between 1986 and 1990. The new study duplicated previous methods and used the same sampling sites and the same gear employed during February sampling periods from 1986 to 1990. Overall, the species diversity and catch rates, as well as the numbers of penaeid prawn predators had changed little over 20 years. The overall catch rate for 2005 was 37.4 g m −1 h −1 , not significantly different from the overall catch rate of 32.8 g m −1 h −1 (SE 6.6) for the period from 1987 to 1989. The results are discussed in relation to environmental factors and climate change, as well as the substantial declines in prawn catches, which had fallen from over 800 tonnes per annum prior to 1998, to about 70 tonnes per annum.

Mangroves are a major ecosystem within Kakadu National Park in Australia’s Northern Territory, providing coastal protection, high biodiversity and an important resource for Aboriginal people. In the late Holocene (from c. 6000 before present), mangroves occupied much of the estuarine and coastal plains, but their range has subsequently contracted to the main river systems (the West Alligator, South Alligator and East Alligator Rivers, and the Wildman River), tributary creeks and offshore islands (Field and Barrow Islands). On the basis of maps of mangrove extent generated from aerial photography (1950, 1975, 1984 and 1991), compact airborne spectrographic imagery (CASI; 2002), light detection and ranging (LIDAR; 2011) and RapidEye data (2014 onward), changes in net area have been minor but significant redistribution has occurred, with this being attributed to both inland intrusion and seaward colonisation of mangroves. The greatest area changes have been associated with lower-stature mangroves dominated by Avicennia marina and Sonneratia alba, as determined from these datasets. Aerial surveys, conducted using a remote piloted aircraft (RPA) and fixed wing aircraft in September 2016, showed dieback of mangroves, with spaceborne RapidEye observations suggesting this occurred between late 2015 and 2016 and at the same time as the extensive mangrove losses reported in the Gulf of Carpentaria. Given the recent dieback and the associated need to better monitor and protect mangroves and proximal ecosystems in the World Heritage- and Ramsar-listed Kakadu National Park, the study recommends the development and implementation of a robust and long-term monitoring system that better utilises existing and ongoing earth observation and ground data, and is supported by a national approach.

'Hemidactylus frenatus' is an invasive gecko with an expanding distribution in Australia. We collated all available locality records and investigated the habitats associated with the species in the Northern Territory. 'H. frenatus' is more widespread in the Top End, Gulf of Carpentaria and Victoria River regions than previously documented. The species remains primarily associated with artificial anthropogenic structures and surrounding vegetation (particularly denser tropical forests), but there are also a small number of records of it living in natural vegetation further than 1 km from such structures. We speculate that H. frenatus will continue to spread through suitable habitats in northern Australia.

Aim: This study investigated the use of stable δ13C and δ18O isotopes in the sagittal otolith carbonate of narrow-barred Spanish mackerel, Scomberomorus commerson, as indicators of population structure across Australia. Location: Samples were collected from 25 locations extending from the lower west coast of Western Australia (30°), across northern Australian waters, and to the east coast of Australia (18°) covering a coastline length of approximately 9500 km, including samples from Indonesia. Methods: The stable δ13C and δ18O isotopes in the sagittal otolith carbonate of S. commerson were analysed using standard mass spectrometric techniques. The isotope ratios across northern Australian subregions were subjected to an agglomerative hierarchical cluster analysis to define subregions. Isotope ratios within each of the subregions were compared to assess population structure across Australia. Results: Cluster analysis separated samples into four subregions: central Western Australia, north Western Australia, northern Australia and the Gulf of Carpentaria and eastern Australia. Isotope signatures for fish from a number of sampling sites from across Australia and Indonesia were significantly different, indicating population separation. No significant differences were found in otolith isotope ratios between sampling times (no temporal variation). Main conclusions: Significant differences in the isotopic signatures of S. commerson demonstrate that there is unlikely to be any substantial movement of fish among these spatially discrete adult assemblages. The lack of temporal variation among otolith isotope ratios indicates that S. commerson populations do not undergo longshore spatial shifts in distribution during their life history. The temporal persistence of spatially explicit stable isotopic signatures indicates that, at these spatial scales, the population units sampled comprise functionally distinct management units or separate ‘stocks’ for many of the purposes of fisheries management. The spatial subdivision evident among populations of S. commerson across northern and western Australia indicates that it may be advantageous to consider S. commerson population dynamics and fisheries management from a metapopulation perspective (at least at the regional level).

This study identifies to species or species units 572 lots (>1000 specimens) of pilargids from six localities in the Arafura Sea and Gulf of Carpentaria (including the ports at Gove and McArthur River). We analyze the taxonomic data against geomorphic unit, depth, and sediment type. Preliminary results show that pilargid fauna of northern Australia comprises 13 species in seven genera (Ancistrosyllis, Cabira, Litocorsa, Loandalia, Pilargis, Sigambra, and Synelmis). Although all four localities have a similar diversity of species (six or seven species each), the species composition differs between each region: Litocorsa annamita and Synelmis rigida were found in all sediment types in the Arafura Sea and Gulf of Carpentaria; Ancistrosyllis cf. hartmanae (mud and sand dominated sediments only) and Sigambra pettiboneae (all sediment types) were restricted to the inshore localities of Gove and McArthur River; Loandalia gladstonensis and Sigambra sp. 2 were found on the shelf and in the inshore habitats of the Gulf of Carpentaria only; Litocorsa sp. ‘arafura’, Sigambra sp. ‘arafura’ and Synelmis gibbsi were found only in the Arafura Sea, with sediments dominated by sand and gravel; and Cabira sp. 1 and Sigambra cf. tentaculata were found at all locations, in all sediment types. Based on these distribution patterns and the Recent Quaternary geological history of the area, hypotheses of post-glacial colonization of the Gulf of Carpentaria are presented. The pilargid species composition in northern Australia is also compared to neighboring Indo-west Pacific regions.

The majority of rivers in the Australian tropics possess near-natural flow regimes and are an ecological asset of global significance. We examined flow variability in large floodplain rivers in the Gulf of Carpentaria, northern Australia, and the potential ecological impacts of future water resource development (WRD). Flow metrics based on long-term records were used to classify flow regimes and predict hydrological drivers of ecological function. Flow regimes of selected rivers were then compared with those simulated for pre- and post-WRD flows in the Darling River, a highly modified river in Australia's south-east. Generally, rivers were classified as typically 'tropical' (more permanent, regular flows) or 'dryland' (more ephemeral, with greater flow variability). In addition, all rivers displayed wet-dry seasonality associated with changes in flow magnitude or number of zero-flow days. We propose that these features (flow permanence and regularity; flow variability and absence; wet-dry seasonality) are the key hydrological drivers of biodiversity and ecological function in the floodplain rivers of Australia's north. In terms of WRD, inter-annual flow variability was predicted to increase or decrease depending on rivers' natural flow regimes, specifically their tendency toward lower or higher flow magnitudes. Either outcome is expected to have adverse effects on the biodiversity and ecological function of these relatively pristine rivers and floodplain habitats. In particular, reduced and homogenized habitat, loss of life-history cues, inhibited dispersal and shifts in community composition, as a result of WRD, threaten the ecological integrity of rivers adapted to the three hydrological drivers above. These findings serve as a caution for careful consideration of WRD options for rivers in the Australian tropics and for those with similar flow regimes the world over.

Summary 1. Flow regime and riverine architecture are two important landscape characteristics that influence genetic diversity and gene flow in riverine species. 2. Using population genetic markers (mtDNA, microsatellites and allozymes), this study aimed to investigate genetic diversity and gene flow in the freshwater fish, Neosilurus hyrtlii, across two major drainage divisions in northern and central Australia (the Gulf of Carpentaria and Lake Eyre basins). These basins lie adjacent to each other and differ in their hydrological inputs and riverine structure, providing an ideal opportunity to identify the impact of landscape processes upon population dynamics of freshwater fish. 3. Populations were strongly structured among basins, among catchments within basins and were weakly structured within catchments in the Lake Eyre Basin, providing support for the Stream Hierarchy Model. 4. Interestingly, mtDNA and microsatellite diversity was much higher in the Gulf of Carpentaria Basin compared to the Lake Eyre Basin. It was concluded that this difference was due to the extreme hydrological variability in this basin and boom-bust population cycles resulting in smaller effective population sizes in the Lake Eyre Basin.

We used miniature light-level/immersion loggers (geolocators) to study the movements and behavior of two Streaked Shearwaters (Calonectris leucomelas) during their travel away from Japan, after the breeding season. During the period from late October until late December, the tracked shearwaters moved south over subtropical pelagic waters with low productivity. The birds traveled to the seas off northern New Guinea and the Gulf of Carpentaria, Australia, 3400–5200 km distant from Mikura Island, their breeding colony in Japan. During the wintering period (December–February), the birds were on the sea surface for 77–85% of their time on average. The migratory and wintering behavior of Streaked Shearwaters are discussed in relation to the physical and biological marine environment of the north-western Pacific.

Many commercially important fish species use coastal marine environments such as mangroves, tidal flats and seagrass beds as nurseries or breeding grounds. The ecological importance of spatially connected habitats to conservation is well established for terrestrial environments. However, few studies have applied spatial metrics, including measures of structural connectivity to marine environments. We examined the relationship between catch-per-unit-effort for commercially caught species and the spatial patterning of mapped benthic habitat types along the coast of Queensland, Australia in their dominant fisheries (trawl, line, net or pot fisheries). We quantified the composition and spatial configuration of seascapes and calculated coastline length, number of estuaries, river length and geographical latitude using 12 metrics within ninety 30-nautical-mile grid cells, which supported inshore fish catch data from 21 species groups. Multiple regression analysis and non-metric multidimensional scaling plots indicated that ecological linkages may exist between geomorphic coastal features and nearshore fisheries production for a number of species groups. Connectivity indices for mangroves, salt marsh and channels explained the largest proportion (30–70%), suggesting the importance of connected tidal wetlands for fisheries. Barramundi (Lates calcarifer) catch-per-unit-effort was best explained by the number of wetland patches, mangrove connectivity and wetland connectivity (r2 = 0.38, n = 28). Catch-per-unit-effort for the Gulf of Carpentaria was highly correlated with wetland connectivity, the number of estuaries and seagrass patch density (r = 0.57, n = 29). The findings could guide the spatial design of marine protected area networks to maintain ecosystem services and avoid potential disruption to connectivity caused by habitat removal or modification. Application of the same approach to analyses of finer spatial scales would enable catch information to be related to particular estuarine habitats and provide better understanding of the importance of habitat connectivity for fisheries.

Pleistocene sea-level fluctuations profoundly changed landmass configurations around northern Australia. The cyclic emergence of the Torres Strait land bridge and concomitant shifts in the distribution of shallow-water marine habitats repeatedly sundered east and west coast populations. These biogeographical perturbations invoke three possible scenarios regarding the directions of interglacial range expansion: west to east, east to west, or bidirectional. We evaluated these scenarios for the olive sea snake, Aipysurus laevis, by exploring its genetic structure around northern Australia based on 354 individuals from 14 locations in three regions (Western Australia, WA; Gulf of Carpentaria, GoC; Great Barrier Reef, GBR). A 726-bp fragment of the mitochondrial DNA ND4 region revealed 41 variable sites and 38 haplotypes, with no shared haplotypes among the three regions. Population genetic structure was strong overall, φST = 0.78, P < 0.001, and coalescent analyses revealed no migration between regions. Genetic diversity was low in the GBR and GoC and the genetic signatures of these regions indicated range or population expansions consistent with their recent marine transgressions around 7000 years ago. By contrast, genetic diversity on most WA reefs was higher and there were no signals of recent expansion events on these reefs. Phylogenetic analyses indicated that GBR and GoC haplotypes were derived from WA haplotypes; however, statistical parsimony suggested that recent range expansion in the GBR-GoC probably occurred from east coast populations, possibly in the Coral Sea. Levels of contemporary female-mediated gene flow varied within regions and reflected potential connectivity among populations afforded by the different regional habitat types.

We surveyed herbaceous biomass across the range of Eucalyptus tetrodonta savannas in north-western Australia. Sample sites (n = 211) were stratified within four broad geographical regions characterized by different mixes of land management regimes. Grasses dominated (87% mean) the herbaceous biomass. After controlling for climatic and edaphic gradients, herbaceous biomass was highest in the Greater Darwin region (2.2 t ha -1 ) which is managed predominantly by Europeans, and least under semi-traditional Aboriginal management in Arnhem Land region (1.1 t ha -1 ). In the drier Gulf of Carpentaria and Kimberley regions, where a mix of Aboriginal, conservation and pastoral land uses occurs, fuel loads were higher than in Arnhem Land region but still considerably lower than around Darwin. Sarga was recorded in all regions except the Gulf of Carpentaria and had the highest biomass in Darwin (0.88 t ha -1 ) and lowest biomass in the Kimberley (0.54 t ha -1 ). The proportion of herbaceous biomass made up of perennial grasses was least in Darwin (17%) and greatest in the Gulf (77%) regions. We suggest that climate, soils and land management account for differences between the drier pastoral regions of the Gulf of Carpentaria and the Kimberley and the wet Greater Darwin region relative to the Arnhem Land region. The high frequency, and larger spatial scale, of fires in the Greater Darwin region relative to the Arnhem Land region underpins the contrasting trends in total herbaceous biomass and abundance of flammable annual grasses.

Three cases of severe necrotising fasciitis due to Vibrio vulnificus (two cases) and Vibrio parahaemolyticus (one case, fatal), have occurred in Caucasian tourists while fishing at a remote tropical northern Australian estuarine area. Infections were acquired over a 4-year period during the tourist fishing season (April to July 2000-2003), when water temperatures range from 23 to 30 degrees C. They are notable for their geographical clustering in the remote western aspect of the Gulf of Carpentaria, an area characterised by sedimentary stratiform zinc-lead-silver deposits and a major mining operation. Patients presented with classical bullous cellulitis with necrotising fasciitis, accompanied by severe sepsis. Underlying risk factors were identified in each patient; in one instance, previously unrecognised haemochromatosis was diagnosed. Likely reasons for Vibrio occurrence in this particular ecological niche are discussed.

It is becoming increasingly apparent that the development of management initiatives for sea turtles depends on the collection of biological data at all life stages. Substantial gaps include a lack of data on both the population's demographic structure and reference values for biochemical parameters that can be used to assess the health and condition of sea turtle populations. Here we pre- sent comparative data on population demographics and biochemical blood parameters for green sea turtles Chelonia mydas in their foraging grounds of the Sir Edward Pellew (SEP) Islands in the Gulf of Carpentaria, Australia. Turtles within the adult size range for Australian green turtles comprised 54% of turtles caught. Of the turtles with curved carapace lengths (CCL) greater than 85 cm, 41 were adult males, one was an adult female, and 15 could not be confidently sexed. Continued surveys are needed to distinguish between the potential causes underlying this male-biased sex ratio and the dif- ference between the sex ratio we found and those previously published for the population. Based on biochemical analysis of blood, green turtles in the SEP foraging grounds appeared to be healthy. However, mean levels of glucose and magnesium were generally lower than the ranges observed in other studies of clinically healthy green turtles. Additionally, glucose levels were lower in turtles with CCLs of over 85 cm.

Eight polymorphic microsatellite loci were analysed in six population samples from four locations of the Australian endemic brown tiger prawn, Penaeus esculentus. Tests of Hardy-Weinberg equilibrium were generally in accord with expectations, with only one locus, in two samples, showing significant deviations. Three samples were taken in different years from the Exmouth Gulf. These showed no significant heterogeneity, and it was concluded that they were from a single panmictic population. A sample from Shark Bay, also on the west coast of Australia, showed barely detectable differentiation from Exmouth Gulf (F (ST) = 0 to 0.0014). A northeast sample from the Gulf of Carpentaria showed low (F (ST) = 0.008) but significant differentiation from Moreton Bay, on the east coast. However, Exmouth Gulf/Shark Bay samples were well differentiated from the Gulf of Carpentaria/Moreton Bay (F (ST) = 0.047-0.063). The data do not fit a simple isolation by distance model. It is postulated that the east-west differentiation largely reflects the isolation of east and west coast populations that occurred at the last glacial maximum when there was a land bridge between north-eastern Australia and New Guinea.

Pristis microdon, P. zijsron, P. clavata and Anoxypristis cuspidata are distributed throughout the Queensland section of the Gulf of Carpentaria, Australia. In a survey of the four species, Anoxypristis cuspidata was the most abundant and was recorded in both the inshore and offshore set net fisheries. The size distribution and catch locations of A. cuspidata suggest that the inshore area to a depth of 10 m may be the preferred habitat for juveniles of this species, while adults primarily occur offshore. Pristis microdon, P. zijsron and P. clavata were recorded only in the inshore fishery with catches dominated by immature animals. Pristis microdon was caught in the inshore fishery late in the monsoonal wet season (February to April) and inhabited both freshwater and estuarine environments. Pristis zijsron occurred only on the sand and mud flats outside river mouths whilst P. clavata inhabited both the sand and mud flats and upstream estuarine habitats. Observations on reproductive staging and the capture of neonate specimens suggest that in all four pristids, pupping occurred through the wet season until the beginning of the dry season in May. A seasonal set net closure for the barramundi, Lates calcarifer and shark fisheries, which has been in place since 1980 in Queensland Gulf waters, therefore offers a measure of protection to breeding female sawfish and their offspring.

There is convincing geological evidence for the historical existence of an ancient lake on the Australian–New Guinea continental shelf during the late Pleistocene. Lake Carpentaria was a vast fresh- to brackishwater lake that would presumably have provided habitat for, and facilitated gene flow among, aquatic taxa that tolerate low to moderate salinities in this region. Moreover, it has been argued that the outflow of Papua New Guinea's Fly River was diverted westward into Lake Carpentaria during this period, although this hypothesis is controversial. We predicted that these events, if a true history, would have promoted gene flow and population growth via range-expansion events in the giant freshwater prawn (Macrobrachium rosenbergii) and restricted gene flow subsequently by way of a vicariant event as sea levels rose during the late Pleistocene, and a marine environment replaced Lake Carpentaria. We tested these hypotheses using phylogeographical and phylogenetic analyses of mitochondrial DNA variation in M. rosenbergii populations sampled from the Lake Carpentaria region. Our results support the hypothesis that Lake Carpentaria facilitated gene flow among populations of M. rosenbergii that are today isolated, but contest claims of a westward diversion of the Fly River. We inferred the timing of initial expansion in the ‘Lake Carpentaria lineage’ and found the timing of this event to be broadly concordant with geological dating of the formation of Lake Carpentaria. Reconciling geological and molecular data, as presented here, provides a powerful framework for investigating the influence of historical earth history events on the distribution of biological (i.e. molecular) diversity.

Two new species of aploactinids are described from coastal waters of subtropical eastern Australia. Pseudopataecus taenianotus, new genus and species, is described from seven specimens trawled inside the Capricorn-Bunker Group, Queensland. It is readily distinguished from other aploactinids by the markedly compressed head and body, large number of dorsal and anal-fin ray elements, frontal bone with laterally-bowed ridges forming a shallow fleshy depression, and distinctly anterior insertion of the first dorsal spine. Cocotropus microps, new species, is described from three specimens collected from inshore waters of southern Queensland and northern New South Wales. It has the lowest dorsal- and anal-fin ray counts of the genus, dorsal fin forming three elevated sections, and coloration including at least several small pale irregular spots or larger blotches. Two aploactinid species are recorded in Australian waters for the first time. Acanthosphex leurynnis Jordan & Seale, 1905, previously known from Hong Kong, Gulf of Thailand, southeast India, Indonesia and eastern Papua New Guinea, is reported from the Cumberland Group in tropical eastern Australia, Arafura Sea, Northern Territory, and near Perth, Western Australia. Xenaploactis cautes Poss & Eschmeyer, 1980, previously known only from the Andaman Sea and Gulf of Thailand, is reported from off Dampier, northwestern Australia and Gulf of Carpentaria, Queensland.

Growth and survival of Penaeus semisulcatus larvae were measured in factorial combinations of temperature (20°, 23°, 26°, 29°, and 32°C) and salinity (28‰, 29‰, 32‰, 34‰, and 37‰). Three experiments were maintained for 5 to 6 d, between late nauplius and first mysis stages. Salinity did not have a significant effect on growth or survival above 28‰. At 28‰, both growth rate and survival decreased (although the reduced survival occurred only at the lowest temperatures). While temperature had a substantial and regular influence on growth rate (larvae growing more rapidly at warmer temperatures), the effect on survival was not clear. In one experiment, there was significantly lower survival at the higher temperatures (32° and 29°C); however, temperature did not affect larval survival at all in the other two experiments. The results were compared with six years of published data on temperatures and salinities in Albatross Bay, Gulf of Carpentaria, Australia, and indicate that naturally occurring salin...

Nucleotide sequence polymorphism in the left domain of the control region of the mitochondrial genome of over 700 goldband snapper (Pristipomoides multidens) was surveyed using both direct sequencing and innovative restriction enzyme cleavage analysis techniques. Southeast Asian populations were sampled adjacent to western Irian Jaya, northern Papua New Guinea and western Timor. Six Australian populations were sampled from adjacent to Exmouth in western Australia to Weipa in the northern Gulf of Carpentaria. The results show that significant genetic structure occurs among Indonesian and Australian waters along national boundaries; 14% of the total molecular variance among restriction site haplotypes was due to genetic distinction between Indonesian and Australian samples. Several lines of evidence suggest that gene flow does not occur freely along the northern and western Australian coastline, particularly on the northwestern Kimberley coast. Australian fisheries managers need to be alerted to the possibility of at least one genetically distinct population of this important commercial species which should be protected from over-harvesting that may otherwise lead to localised extinction and the erosion of genetic diversity. There is no convincing biological argument for the observed genetic disjunction in the Kimberley area. It may be due to the combined effect of past sea-level changes, sampling error or patterns of exploitation. # 2002 Elsevier Science B.V. All rights reserved.

The Carpentarian rock-rat (Zyzomys palatalis) is a critically endangered endemic rodent known from only four sandstone gorges in the southeast Gulf of Carpentaria, Northern Territory, Australia. These gorges harbour thickets of monsoon rainforest and broadleaf woodland, surrounded by a Eucalypt savanna matrix. The long-term persistence of Z. palatalis is threatened by altered fire regimes, grazing by feral animals and stock, weed intrusion, and the stochastic hazards associated with small, fragmented populations. To assess the relative importance of these threats and develop practical management options, a population and habitat simulation model was developed, based on the best existing data. Population viability was predicted to be highly sensitive to the frequency of hot, late dry-season fires. Progressive habitat degradation (due predominantly to intense late dry-season fires) is likely to substantially reduce population size and lead to the probable extinction of the species within the next 100 years. The most effective management strategy to counteract this threat would be regular, controlled, fuel reduction burns in the vegetation around the gorge entrances during the early dry season. Establishing a new population (through translocation of captive-bred individuals) would not appreciably reduce extinction risk, but could provide valuable additional data on the impact of threats, if conducted as an adaptive management experiment.