Australian Great Barrier Reef Research Articles

Can zeolites be used in sugarcane cropping systems to help reduce nitrogen losses into the Australian Great Barrier Reef?

Can zeolites be used in sugarcane cropping systems to help reduce nitrogen losses into the Australian Great Barrier Reef?

Transboundary effects from idealized regional geoengineering

Regional geoengineering, by reflecting sunlight over a very limited spatial domain, might be considered as a means to target specific regional impacts of climate change. One of the obvious concerns raised by such approaches is the extent to which the resulting effects would be detectable well beyond the targeted region (e.g. in neighbouring countries). A few studies have explored this question for targeted regions that are still comparatively large. We consider idealized simulations with increased ocean albedo over relatively small domains; the Gulf of Mexico (0.23% of Earth's surface) and over the Australian Great Barrier Reef (0.07%), both with negligible global radiative forcing. Applied over these very small domains, the only statistically significant non-local changes we find are some limited reduction on summer precipitation in Florida in the Gulf of Mexico case (adjacent to the targeted region). The lack of transboundary effects suggests that governance needs for such targeted interventions are quite distinct from those for more global sunlight reflection.

Valuing ecosystem services in complex coastal settings: An extended ecosystem accounting framework for improved decision-making

What gets measured gets managed is an axiom common to the business world that also applies to the management of environmental assets and processes. But what is the most adequate way to measure ecosystem value to optimise ecosystem management? In this paper, we unpack three valuation frameworks often applied in understanding ecosystem services and their benefits: 1) the Ecosystem Services framework, operationalised by the United Nations System of Environmental Economic Accounting - Ecosystem Accounting (SEEA-EA) framework; 2) value-centric approaches operationalised by the Total Economic Value framework; and 3) First Nations Peoples (FNP) frameworks, which seek to capture values from FNPs’ perspective. By assessing the strengths and weaknesses of these value frameworks for managing the World’s largest reef ecosystem—the Australian Great Barrier Reef—we construct an extended SEEA-EA valuation framework tailored to complex coastal settings. The significance of our approach is the inclusion of the whole range of benefits from all coastal and marine uses and users and therefore the integration of non-market and FNP values into the more traditional market-based valuation approach. Assessments that jointly consider multiple values originating from these three different frameworks are more likely to produce sustainable management outcomes than more restrictive approaches.

Title Corals, Geo-Sociality, and Anthropocene Dwelling

Foreboding reports of the Australian Great Barrier Reef’s peril signal not only a fraught politics but the site’s significance as a potent global environmental imaginary and Anthropocene signifier. In this paper I draw on the site’s ecological emergency and consider what humans could learn from coral life through its evolved fluid-dynamic and planetary relationships. Corals, I argue, offer novel insight into more-than-human ontologies, revealing constitutively solid-fluid ways of being responsive to planetary flux and churn. The research responds to increased interest with multi-disciplinary more-than-human investigation of the ways in which human and nonhuman are inextricably connected, as well as work taking Anthropocene ideas as a generative epistemological and ontological opening. Drawing on fieldwork in Cairns and on the Great Barrier Reef itself, I use embodied methods to trace encounters both above and below the water. The properties of water and fluidity lead me to contemplate further qualities that liquid and ocean phenomena bring to understanding planetary sociality, revealing a dimensionality and relationality beyond surface and fixed readings. Paradoxically, whilst corals and the Great Barrier Reef are commonly framed as needing our protection, they demonstrate enduring structural resilience and tenacity. Such qualities are highly relevant in contemplating strategies responsive to Anthropocene instability and flux.

Assessment of Governance and Ecological Status of Terengganu Marine Park, Malaysia: Toward Marine Spatial Planning

Terengganu Marine Parks (TMP) is a 591.37 km2 marine protected area. TMP are popular tourist destinations that significantly generate revenue to the government and local businesses through tourism sector. However, the anthropogenic activities have contributed to TMP’s declining ecosystem health, particularly the coral reefs. Therefore, a sustainable ecosystem-based management is required to maintain the ecosystem. In this study, we identify issues related to the marine park’s governance, development on islands, tourist activities and coral health status in the TMP for assessing potential management strategy for conserving the ecosystem. The findings on management in TMP found that there is an overlapping in managing the marine park between the federal and state government. Unintegrated development to accommodate rising number of tourist and their activities in the marine parks are identified as the factors contributing towards degradation of the ecosystems. Relatively, reef areas close to these local pressures are in ‘poor’ condition, indicating that threats arising from the activities affecting the marine ecosystem. Hence, this study analyses the potentials in adopting Marine Spatial Planning (MSP) in the TMP for managing the conflict between user and the ecosystem. The Australian Great Barrier Reef Marine Park which applied the zoning of marine area is used as a benchmark to examine the best practices of MSP to govern the TMP. At present, we suggest using coral reef health status as an early alternative and best practice to provide different zoning criteria for strategic marine protected area (MPA) management for TMP.

A parameter optimizer based on genetic algorithm for the simulation of carbonate facies

In this work we present a model for the dispersion of rocks in carbonate environments. The parameters used in this model are provided by the user who is simulating. However, defining values for such parameters is a time-consuming task and can generate inaccuracy in the simulation. To get around this, we propose a parameter optimizer based on genetic algorithm, in order to refine physical and categorical parameters used in the presented model. To condition the simulation we use an objective facies model that is considered as the optimal map, and we refine the initial parameters provided by the user through the fitness function that compares the simulated map and the objective. We present two experiments, considering the facies dispersion model applied in the Australian Great Barrier Reef. To analyze the convergence profiles of the genetic algorithm, we present a sensitivity analysis that helps in choosing the input values for the genetic operators. Finally, we briefly discuss the applicability of the optimizer in geological process simulation softwares.

Reef pedagogy: A narrative of vitality, intra-dependence, and haunting

This article is a reexamination of the author’s understanding of pedagogy, aimed at developing an increased awareness of the provinciality, limits and blind spots of the pedagogy and knowledge systems of colonial modernity. It engages with particular Indigenous epistemological theorisations of non-human agency, with Haraway’s notion of multispecies entanglement, and with the Australian Great Barrier Reef in an inquiry aimed at noticing absences and hauntings of pedagogies of modernity, including the absence of ways of knowing and being without separability and determinacy and the damage that has come of this. This opens space for contemplating separability and determinacy as ontological difficulties contributing to socio-ecological crises of our time. The article is intended as a move by the author toward developing greater capacity to stay with the trouble of educating and living on a damaged planet that is fast becoming uninhabitable.

Progressive seawater acidification on the Great Barrier Reef continental shelf

Coral reefs are highly sensitive to ocean acidification due to rising atmospheric CO2 concentrations. We present 10 years of data (2009–2019) on the long-term trends and sources of variation in the carbon chemistry from two fixed stations in the Australian Great Barrier Reef. Data from the subtropical mid-shelf GBRWIS comprised 3-h instrument records, and those from the tropical coastal NRSYON were monthly seawater samples. Both stations recorded significant variation in seawater CO2 fugacity (fCO2), attributable to seasonal, daytime, temperature and salinity fluctuations. Superimposed over this variation, fCO2 progressively increased by > 2.0 ± 0.3 µatm year−1 at both stations. Seawater temperature and salinity also increased throughout the decade, whereas seawater pH and the saturation state of aragonite declined. The decadal upward fCO2 trend remained significant in temperature- and salinity-normalised data. Indeed, annual fCO2 minima are now higher than estimated fCO2 maxima in the early 1960s, with mean fCO2 now ~ 28% higher than 60 years ago. Our data indicate that carbonate dissolution from the seafloor is currently unable to buffer the Great Barrier Reef against ocean acidification. This is of great concern for the thousands of coral reefs and other diverse marine ecosystems located in this vast continental shelf system.

Searching for humpback whales in a historical whaling hotspot of the Coral Sea, South Pacific

Humpback whalesMegaptera novaeangliaewere severely depleted by commercial whaling. Understanding key factors in their recovery is a crucial step for their conservation worldwide. In Oceania, the Chesterfield-Bellona archipelago was a primary whaling site in the 19thcentury, yet has been left almost unaffected by anthropogenic activities since. We present the results of the first multidisciplinary dedicated surveys in the archipelago assessing humpback whale populations 2 centuries post-whaling. We encountered 57 groups during 24 survey days (2016-2017), among which 35 whales were identified using photographs of natural markings (photo-ID), 38 using genotyping and 22 using both. Humpback whales were sparsely distributed (0.041 whales km-1): most sightings concentrated in shallow inner-reef waters and neighbouring offshore shallow banks. The recently created marine protected area covers most of the areas of high predicted habitat suitability and high residence time from satellite-tracked whales. Surprisingly for a breeding area, sex ratios skewed towards females (1:2.4), and 45% of females were with calf. Connectivity was established with the New Caledonia breeding area to the east (mtDNAFST= 0.001, p > 0.05, 12 photo-ID and 10 genotype matches) and with the Australian Great Barrier Reef breeding area to the west (mtDNAFST= 0.006, p > 0.05). Movement of satellite-tracked whales and photo-ID matches also suggest connections with the east Australian migratory corridor. This study confirms that humpback whales still inhabit the Chesterfield-Bellona archipelago 2 centuries post whaling, and that this pristine area potentially plays a role in facilitating migratory interchange among breeding grounds of the western South Pacific.

A Crown-of-Thorns Seastar recombinant relaxin-like gonad-stimulating peptide triggers oocyte maturation and ovulation

The Acanthaster planci species-complex [Crown-of-Thorns Seastar (COTS)] are highly fecund echinoderms that exhibit population outbreaks on coral reef ecosystems worldwide, including the Australian Great Barrier Reef. A better understanding of the COTS molecular biology is critical towards efforts in controlling outbreaks and assisting reef recovery. In seastars, the heterodimeric relaxin-like gonad stimulating peptide (RGP) is responsible for triggering a neuroendocrine cascade that regulates resumption of oocyte meiosis prior to spawning. Our comparative RNA-seq analysis indicates a general increase in RGP gene expression in the female radial nerve cord during the reproductive season. Also, the sensory tentacles demonstrate a significantly higher expression level than radial nerve cord. A recombinant COTS RGP, generated in a yeast expression system, is highly effective in inducing oocyte germinal vesicle breakdown (GVBD), followed by ovulation from ovarian fragments. The findings of this study provide a foundation for more in-depth molecular analysis of the reproductive neuroendocrine physiology of the COTS and the RGP.

Marine Heat Waves and the Influence of El Niño off Southeast Queensland, Australia

In this paper, we investigate the occurrence and spatial variability of marine heat waves (MHWs) off the southeast coast of Queensland, Australia. The focus is on identifying sea surface temperature (SST) variability in two key ecological hotspots located south of the Australian Great Barrier Reef. This coastal region is bordered in the east by the intensification zone of the East Australian Current (EAC). It includes Hervey Bay, which is part of a UNESCO declared marine biosphere and the Southeast Fraser Island Upwelling System. The analysis of remotely sensed SST for the period 1993 to 2016 identifies the largest number of MHW days for Hervey Bay with a mean length of 12 days. The maximum length of 64 days occurred during the austral summer 2005/2006. The years with the largest number of MHW days was found to occur following the El Nino events in 1998, 2010 and 2016. A cross-correlation and Empirical Orthogonal Function analysis identified a significant correlation with a time lag of seven months between SST anomalies in the Nino 3.4 region and the southeast Queensland coast. 78% of variance in SST anomalies is explained by the first mode of variability. The strength of the relationship with El Nino was spatially variable and the weakest in Hervey Bay. Due to its sheltered location and shallowness, it is argued that local weather patterns and air-sea fluxes influence this area more than the other two regions, where remotely forced changes in oceanic heat advection may have a stronger impact on generating MHWs. Biodiverse coastal shelf ecosystems are already under tremendous pressure due to human activities. This is likely to be compounded by continued climatic change and an increasing number of MHWs. Thus, similar studies are encouraged for other regional shelfs and smaller scale coastal systems.

Characterization of the particle emission from a ship operating at sea using an unmanned aerial vehicle

Abstract. This research demonstrates the use of an unmanned aerial vehicle (UAV) to characterize the gaseous (CO2) and particle (10–500 nm) emissions of a ship at sea. The field study was part of the research voyage “The Great Barrier Reef as a significant source of climatically relevant aerosol particles” on board the RV Investigator around the Australian Great Barrier Reef. Measurements of the RV Investigator exhaust plume were carried out while the ship was operating at sea, at a steady engine load of 30 %. The UAV system was flown autonomously using several different programmed paths. These incorporated different altitudes and distances behind the ship in order to investigate the optimal position to capture the ship plume. Five flights were performed, providing a total of 27 horizontal transects perpendicular to the ship exhaust plume. Results show that the most appropriate altitude and distance to effectively capture the plume was 25 m a.s.l. and 20 m downwind. Particle number emission factors (EFPNs) were calculated in terms of number of particles emitted (no.) per weight of fuel consumed (kgfuel). Fuel consumption was calculated using the simultaneous measurements of plume CO2 concentration. The calculated EFPN was 7.6±1.4×1015no. kgfuel-1 which is in line with those reported in the literature for ship emissions ranging from 0.2 to 6.2×1016 no. kgfuel-1. This UAV system successfully assessed ship emissions to derive EFPN under real world conditions. This is significant as it provides a novel, relatively inexpensive and accessible way to assess ship EFPN at sea.

Dwarf minke whales from the South Pacific share a matrilineal lineage distinct from Balaenoptera acutorostrata acutorostrata and B. a. scammoni

Dwarf minke whales are regarded as an undescribed subspecies of common minke whales (Balaenoptera acutorostrata), but appropriate conservation action requires taxonomic confirmation. The relationship of the Australian Great Barrier Reef (GBR) dwarf minke whale aggregation to other minke whales is unknown. This study aims to clarify the phylogenetic relationship of GBR dwarf minke whales, using partial mitochondrial DNA sequence data from 23 GBR dwarf minke whales, compared with other available minke whale sequences. GBR dwarf minke whales share haplotypes with other West South Pacific (WSP) dwarf minke whales. Satellite tagging studies corroborate these findings, indicating that GBR dwarf minke whales migrate south along the east Australian coast towards the Southern Ocean. Despite nuclear data not being available, GBR and WSP dwarf minke whales share a distinctive mitochondrial lineage compared with other common minke whales and should be managed independently of North Pacific and Atlantic Ocean common minke whale populations.

Late Pleistocene evolution of the mixed siliciclastic and carbonate southwestern New Caledonia continental shelf/lagoon

The main island of New Caledonia (NC) is surrounded by the second largest barrier reef in the world after the Australian Great Barrier Reef. The Upper Pleistocene evolution of this barrier reef–lagoon complex offers the opportunity to examine the response of a modern mixed tropical siliciclastic/carbonate system to relative sea-level changes and to better constrain the relative role of lagoon backfilling and paleo-drainage system in sediment transfer across the shelf. This paper mainly focuses on the results of chronostratigraphic and sedimentological interpretations of new seismic, bathymetric and coring data collected in the SW NC lagoon. Several significant points are highlighted from this study and allow the construction of a refined model which includes the evolution of both the SW NC mixed shelf and lagoon. New results show that the NC lagoon has not recorded a reciprocal sedimentation during glacial-interglacial sea-level cycles but a unique mixed regime. Strong contrasts are observed and these depend above all on the two lagoon domains: the outer coral plateau and the inner lagoon depression corresponding to a semi-closed proximal basin which is separated from the plateau by a basement ridge. In the depression, clastic sediments remain dominant from early flooding to highstand stages while carbonate sedimentation continued through time across the coral plateau. This spatial contrast between terrigenous and carbonate deposits was maintained throughout various sea level cycles. Thus, even if spatial segregation is also observed for other examples of mixed shelf environments, the SW NC shelf appears quite unique in comparison to the other mixed systems when considering conceptual models of reciprocal sedimentation. Moreover, the presence of a semi-enclosed lagoon depression allows the preservation of larger volume of terrigenous deposits. This semi-filled geometry of the lagoon is assumed to be the result of several factors: a significant subsidence that offers accommodation for aggrading deposits, evacuation through channels of sediments mobilized during storm events, the tidal currents, and fairweather wave dynamics. Lastly, the inherited morphologic and structures may explain the geomorphic evolution of the “escarpment margin” type of the SW NC rimmed shelf and its differentiation with the opposite SE NC ramp type shelf.

Microbialites in Last Glacial Maximum and deglacial reefs of the Great Barrier Reef (IODP Expedition 325, NE Australia)

Microbialites are volumetrically abundant components in Last Glacial Maximum and deglacial reefs in the Australian Great Barrier Reef sampled by IODP Expedition 325 in 34 holes from 17 sites (M0030–M0058), along four transects on the shelf edge. Detailed radiometric datings show that four distinct reef phases developed between 28and 10 ka, displaying offlapping and then backstepping patterns. The reef boundstone facies include coralgal, coralgal-microbialite and microbialite boundstone. The microbialite consists of combinations of micrite/microspar, bioclasts, siliciclastic grains (up to 14.5%), fenestrae and encrusting epibionts. The micrite/microspar is high-magnesian calcite commonly irregularly clotted, fenestral and peloidal. Mesoscale microbialite fabrics include laminated, structureless, digitate, intraskeletal and boring-filling, and coatings on debris. Intraskeletal and boring-filling is the first fabric to develop in skeletal voids and borings. It is usually followed by structureless and laminated microbialite, locally overlain by digitate fabric. Microbialite-coated debris can occur at any stage in this succession, including in bioclastic accumulations where the scarce in situ framework builders are mainly encrusting corals. Lipid biomarkers of intermediate to high specificity for sulfate-reducing bacteria, together with δ13C values of these lipids, indicate that microbialite formation was favored by sulfate-reducing bacteria in anoxic microenvironments, probably under high nutrient levels. The microbialite in fore-reef deposits accumulated in the photic zone in water depths of a few to several tens of meters, within small spaces generated by large bioclasts and encrusting corals in the topmost centimeters of the sediment. These crusts that formed on the illuminated surface constitute a previously unrecognized style of microbialite formation in Quaternary reefs. As with the cryptic crusts described from other reef locations, its greatest development occurred during the Last Glacial Maximum and early deglaciation. Microbial carbonate formation during this interval may reflect elevated seawater carbonate saturation corresponding with relatively low levels of atmospheric CO2.

Ephemeral and Localized Outbreaks of the Coral Predator Acanthaster cf. solaris in the Southwestern Lagoon of New Caledonia.

Mehdi Adjeroud, Mohsen Kayal, Christophe Peignon, Matthieu Juncker, Suzanne C. Mills, Ricardo Beldade, and Pascal Dumas (2018) Outbreaks of the coral predator Acanthaster spp., the crown-of-thorns seastar (COTS), cause major coral declines across the Indo-Pacific. However, the processes surrounding the initiation and propagation of COTS outbreaks are still unclear. We observed COTS outbreak abundances on several mid-shelf and inner-barrier reefs in the southern section of the New Caledonian lagoon, a multi-location initiation event that we expected to precede a broader region-wide disturbance. However, reef monitoring over 3 years revealed the highly localized and ephemeral character of these outbreaks. Outbreaks that were observed at four reef locations at the beginning of the survey simply faded away, without any specific management actions such as culling efforts. We also found no distinct reef biotope on which COTS outbreaks originated, although mid-shelf and inner-shelf barrier reefs seem to be favoured. New Caledonia has been exempted from to widespread regional COTS outbreaks, which is surprising given its proximity to the Australian Great Barrier Reef - a reef complex particularly vulnerable to COTS - and Vanuatu - where large-scale outbreaks were recorded during the same period. The availability of coral prey is probably not a limiting factor for the propagation of COTS outbreaks on New Caledonian reefs, given the high abundance and diversity of coral assemblages. Our findings reveal that localized and ephemeral COTS outbreaks can be naturally contained and do not necessarily result in widespread disturbances.

Effect-based approach for screening of chemical mixtures in whole blood of green turtles from the Great Barrier Reef

Organisms are exposed to mixtures of both known and unknown chemicals which are diverse and variable, and thus difficult and costly to characterise and monitor using traditional target analyses. The objective of this study was to validate and apply in vitro effect-based methods by which whole blood can be used to screen internal exposure to such complex chemical mixtures. For this study, we used whole blood of green sea turtles (Chelonia mydas). To ensure the chemical mixture in blood is transferred with minimal losses or bias, we tested a modified QuEChERS extraction method specifically developed for multi- and non-target instrument analysis. The extracts were dosed to a battery of in vitro bioassays (AhR-CAFLUX, AREc32, NFκB-bla, VM7Luc4E2, Microtox), each with a different mode of action (e.g., AhR receptor mediated xenobiotics, NrF2-mediated oxidative stress, NFκB mediated response to inflammation, estrogen activity and baseline toxicity oxidative stress, respectively) in order to cover a wide spectrum of chemicals. Results confirmed the absence of interferences of the blood extract with the responses of the different assays, thus indicating the methods' compatibility with effect-based screening approaches. To apply this approach, whole blood samples were collected from green turtles foraging in agricultural, urban and remote areas of the Australian Great Barrier Reef. The effect-based screening revealed significant differences in exposure, with higher induction of AhR-CAFLUX, AREc32 and Microtox assays in turtles from the agricultural foraging ground. Overall, these results corroborated with concurrent health, target and non-target analyses in the same animals performed as part of a larger program. This study provides evidence that the proposed effect-based approach is suitable for screening and evaluating internal exposure of organisms to chemical mixtures. The approach could be valuable for advancing understanding on multiple levels ranging from identification of priority chemicals in effect-directed investigations to exploring relationships between exposure and disease, not only in sea turtles, but in any organism.

The neuropeptidome of the Crown-of-Thorns Starfish, Acanthaster planci

Outbreaks of Crown-of-Thorns Starfish (COTS; Acanthaster planci) are a major cause of destruction of coral communities on the Australian Great Barrier Reef. While factors relating to population explosions and the social interactions of COTS have been well studied, little is known about the neural mechanisms underlying COTS physiology and behaviour. One of the major classes of chemical messengers that regulate physiological and behavioural processes in animals is the neuropeptides. Here, we have analysed COTS genome and transcriptome sequence data to identify neuropeptide precursor proteins in this species. A total of 48 neuropeptide precursors were identified, including homologs of neuropeptides that are evolutionarily conserved throughout the Bilateria, and others that are novel. Proteomic mass spectrometry was employed to confirm the presence of neuropeptides in extracts of radial nerve cords. These transcriptomic and proteomic resources provide a foundation for functional studies that will enable a better understanding of COTS physiology and behaviour, and may facilitate development of novel population biocontrol methods. SignificanceThe Crown-of-Thorns Starfish (COTS) is one of the primary factors leading to coral loss on the Great Barrier Reef, Australia. Our combined gene and proteomic findings of this study reveal the COTS neuropeptidome, including both echinoderm-like neuropeptides and novel putative neuropeptides. This represents the most comprehensive neuropeptidome for an echinoderm, contributing to the evolving knowledge of the COTS molecular neurobiology that may assist towards the development of biocontrol methods.

Benthic Foraminifera from the Capricorn Group, Great Barrier Reef, Australia.

Effective reef management and monitoring has become increasingly important as anthropogenic processes impact upon natural ecosystems. One locality that is under direct threat due to human activities is the Australian Great Barrier Reef (GBR). Marine foraminifera represent an abundant and readily applicable tool that can be used in reef studies to investigate a variety of ecological parameters and assist in understanding reef dynamics and influence management protocols. The first step is to establish a baseline knowledge of taxonomic composition within the region to facilitate comparative studies and monitor how assemblages change in order to maximise effective management. A detailed taxonomic assessment is provided of 133 species of benthic foraminifera in 76 genera from Heron Island, One Tree Island, Wistari and Sykes Reefs, which form the core of the Capricorn Group (CG) at the southern end of the GBR. Of these 133 species, 46% belong to the order Miliolida, 34% to Rotaliida, 7% to Textulariida, 5% to Lagenida, 3% to Lituolida, 3% to Spirillinida, 1% to Loftusiida and 1% to Robertinida. Samples were collected from a variety of shallow shelf reef environments including reef flat, lagoonal and channel environments. Seventy species, representing the most abundant forms, are formally described with detailed distribution data for the remaining 63 species supplied.

Strengths that are now weaknesses

Coral Reefs Acroporids have been the dominant reef-building corals over the past few million years. Unfortunately, they are also the most vulnerable species to human impacts. Renema et al. show that acroporids originated more than 50 million years ago but did not dominate reef communities until the intensification of fluctuations in sea level associated with the ice ages. This geologically recent success is attributable to their exceptionally rapid growth and their ability to spread across reefs by clonal fragmentation. These very features, however, have also made them vulnerable to heat stress and disease, as exemplified by the tragic mass bleaching and mortality of corals along the Australian Great Barrier Reef. Sci. Adv. 10.1126.sciadv.1500850 (2016).