Knowledge of coral larval precompetency periods and maximum competency windows is fundamental to understanding coral population dynamics, informing biogeography and connectivity patterns, and predicting reef recovery following disturbances. Yet for many species, estimates of these early-life history metrics are scarce and vary widely. Furthermore, settlement cues for many taxa are not known despite consequences to habitat selection.
View Article and Find Full Text PDFSpecies abundance, diversity and community assemblage structure are determined by multiple physical, habitat and management drivers that operate across multiple spatial scales. Here we used a multi-scale coral reef monitoring dataset to examine regional and local differences in the abundance, species richness and composition of fish assemblages in no-take marine reserve (NTMR) and fished zones at four island groups in the Great Barrier Reef Marine Park, Australia. We applied boosted regression trees to quantify the influence of 20 potential drivers on the coral reef fish assemblages.
View Article and Find Full Text PDFOutbreaks of the corallivorous Crown-of-Thorns Seastar (CoTS) Acanthaster cf. solaris contribute significantly to coral reef loss. Control of outbreaks is hampered because standard monitoring techniques do not detect outbreaks at early (low density) stages, thus preventing early intervention.
View Article and Find Full Text PDFMercury distribution and bioaccumulation in aquatic ecosystems of tropical Australia is poorly characterised. Barramundi (Lates calcarifer), a widespread high-order predator in both fresh and coastal marine waters of the region, fulfils requirements for a bio-indicator of mercury contamination. In a study of the Mary River system of the Northern Territory, total mercury in the muscle tissue of 300 specimens gathered over four years (2013-2017, across both wet and dry seasons) was determined by direct combustion-atomic absorption spectrometry.
View Article and Find Full Text PDFGood water quality is essential to the health of marine ecosystems, yet current metrics used to track water quality in the Great Barrier Reef are not strongly tied to ecological outcomes. There is a need for a better water quality index (WQI). Benthic irradiance, the amount of light reaching the seafloor, is critical for coral and seagrass health and is strongly affected by water quality.
View Article and Find Full Text PDFCoral reef management is increasingly focused on supporting the resilience of coral communities to increasing and cumulative pressures. The coral index provides a concise summary of coral community resilience that can be efficiently communicated to a range of management and policy stakeholders. We detail the development of the index both as a technical reference for users but also as an example of an approach that could be more generally applied to the reporting of ecosystem resilience.
View Article and Find Full Text PDFQuantifying the role of biophysical and anthropogenic drivers of coral reef ecosystem processes can inform management strategies that aim to maintain or restore ecosystem structure and productivity. However, few studies have examined the combined effects of multiple drivers, partitioned their impacts, or established threshold values that may trigger shifts in benthic cover. Inshore fringing reefs of the Great Barrier Reef Marine Park (GBRMP) occur in high-sediment, high-nutrient environments and are under increasing pressure from multiple acute and chronic stressors.
View Article and Find Full Text PDFKnowledge of the time of HIV-1 infection and the multiplicity of viruses that establish HIV-1 infection is crucial for the in-depth analysis of clinical prevention efficacy trial outcomes. Better estimation methods would improve the ability to characterize immunological and genetic sequence correlates of efficacy within preventive efficacy trials of HIV-1 vaccines and monoclonal antibodies. We developed new methods for infection timing and multiplicity estimation using maximum likelihood estimators that shift and scale (calibrate) estimates by fitting true infection times and founder virus multiplicities to a linear regression model with independent variables defined by data on HIV-1 sequences, viral load, diagnostics, and sequence alignment statistics.
View Article and Find Full Text PDFRecovery of coral reefs after disturbance relies heavily on replenishment through successful larval settlement and their subsequent survival. As part of an integrated study to determine the potential effects of water quality changes on the resilience of inshore coral communities, scleractinian coral settlement was monitored between 2006 and 2012 at 12 reefs within the inshore Great Barrier Reef. Settlement patterns were only analysed for the family Acroporidae, which represented the majority (84%) of settled larvae.
View Article and Find Full Text PDFClimate change threatens coral reefs across the world. Intense bleaching has caused dramatic coral mortality in many tropical regions in recent decades, but less obvious chronic effects of temperature and other stressors can be equally threatening to the long-term persistence of diverse coral-dominated reef systems. Coral reefs persist if coral recovery rates equal or exceed average rates of mortality.
View Article and Find Full Text PDFSensitive molecular analyses show that most corals host a complement of Symbiodinium genotypes that includes thermo-tolerant types in low abundance. While tolerant symbiont types are hypothesized to facilitate tolerance to temperature and recovery from bleaching, empirical data on their distribution and relative abundance in corals under ambient and stress conditions are still rare. We quantified visual bleaching and mortality of coral hosts, along with relative abundance of C- and D-type Symbiodinium cells in 82 Acropora millepora colonies from three locations on the Great Barrier Reef transplanted to a central inshore site over a 13 month period.
View Article and Find Full Text PDFKnowledge of the relationships between environmental forcing and demographic parameters is important for predicting responses from climatic changes and to manage populations effectively. We explore the relationships between the proportion of sea cows (Dugong dugon) classified as calves and four climatic drivers (rainfall anomaly, Southern Oscillation El Niño Index [SOI], NINO 3.4 sea surface temperature index, and number of tropical cyclones) at a range of spatially distinct locations in Queensland, Australia, a region with relatively high dugong density.
View Article and Find Full Text PDFObesity is a global epidemic that results in significant morbidity and mortality. Mutations in the melanocortin 4 receptor (MC4R) gene, which codes for a G-protein-coupled receptor responsible for postprandial satiety signaling, have been associated with monogenic obesity. The prevalence of obesity is on the increase in South Africa, and it is hypothesized that mutations in MC4R are a contributing factor.
View Article and Find Full Text PDFThe specific activity of aminoacyl-tRNA synthetases (spAARS), an index of growth rate, and of the electron transport system (spETS), an index of respiration, was measured in three size fractions (73-150 μm, >150 μm and >350 μm) of zooplankton during five cruises to tropical coastal waters of the Kimberley coast (North West Australia) and four cruises to waters of the Great Barrier Reef (GBR; North East Australia). The N-specific biomass of plankton was 3-4-fold higher in the Kimberley than on the GBR in all 3 size classes: Kimberley 1.27, 3.
View Article and Find Full Text PDFNetworks of no-take marine reserves (NTMRs) are widely advocated for preserving exploited fish stocks and for conserving biodiversity. We used underwater visual surveys of coral reef fish and benthic communities to quantify the short- to medium-term (5 to 30 years) ecological effects of the establishment of NTMRs within the Great Barrier Reef Marine Park (GBRMP). The density, mean length, and biomass of principal fishery species, coral trout (Plectropomus spp.
View Article and Find Full Text PDFNetworks of no-take marine reserves (NTMRs) are widely used for managing marine resources. Because they restrict fishing, managers need to monitor reserves to reassure stakeholders that they are achieving the intended results. In 2004, the Great Barrier Reef (GBR) Marine Park was rezoned and the area of NTMRs was greatly increased.
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