We present a high-resolution seawater radiocarbon (Δ14C) record from a Porites coral collected from Masthead Island in the southern Great Barrier Reef (GBR) covering the years 1945–2017. The Δ14C values from 1945–1953 (pre-bomb era) averaged –49‰. As a result of bomb-produced 14C in the atmosphere, Δ14C values started to rise rapidly from 1959, levelled off at ∼131‰ in the late 1970s and gradually decreased to ∼40.3‰ by 2017 due to the decrease in the air-sea 14C gradient and the overturning of the 14C ocean reservoir (i.e., surface ocean to subsurface ocean; atmosphere to surface ocean). The Masthead Island record is in agreement with previous 14C coral records from the southern GBR. A comparison between surface ocean and atmospheric Δ14C suggests that, since 2010, the main reservoir of bomb-derived 14C has shifted from the atmosphere to the surface ocean, potentially resulting in reversed 14C flux in regions where the CO2 gradient is favorable. The high-resolution Masthead coral Δ14C sheds light on long-term variability in air-sea exchange and GBR regional ocean dynamics associated with climate change and in conjunction with the previous records provides a robust seawater 14C reference series to date other carbonate samples.

Many parts of the world rely on nutrients like nitrogen and phosphorus to improve farming production and increase yields. There are significant food security as well as socio-economic issues at stake. However, it is also clear that fertilizer loads are particularly damaging to aquatic environments, including lakes, rivers, coral reefs, and wetlands. This article explores governance approaches to fertilizer practices that impact on aquatic environments (eutrophication) by examining a case study of the Great Barrier Reef. Governance involves any and all forms of state and non-state control over a given set of issues. It can include, but is not limited to, rule-based approaches like regulation, although it can also involve market-driven measures like nutrient trading schemes, government grants and other financial incentives. So, which approach to governance works best to combat this particular policy question? What other insights into the design of effective regulation and governance can be gathered? In this article, the authors make three broad arguments for change: firstly, it is crucial that regulation features within government strategies; secondly, there must be a rigorous systematic evaluation of the strategies to ensure that the desired behavioural change is achieved along with the desired outcomes; thirdly, and most importantly, the strategies and the evaluation methods must be appropriate for the culture of the industry they are designed to regulate.

“Envelope crystals” collected during The Great Barrier Reef Expedition in May 1929 have been studied using low-temperature synchrotron single-crystal X-ray diffraction. The crystals are shown to be weddellite, with the largest content of zeolitic water reported to date. A new H2O site has been located within the crystal structure. Study of the crystals show that the end-member formula for weddellite should be reported as CaC2O4·(2.5 – x)H2O, where 0≤x≤ 0.25, instead of CaC2O4·(2H2O or CaC2O4·(2 + x )H2O. This is also the first report of weddellite occurring in a coral reef.

Potential yield is one of the criteria used as an input to nitrogen (N) fertilizer management decisions when using SIX EASY STEPS (6ES), the fertilizer recommendation tool used in the Australian sugar industry. Most commonly, 6ES is implemented using a district yield potential (DYP). In this study, we use analysis of sugar mill and yield monitor data from the Herbert River cane growing district to demonstrate that yield is markedly spatially variable, with this variability following the same patterns from year to year. There would therefore be value in a more location specific consideration of potential yield and application of 6ES. Similar analyses could be readily conducted in other sugar producing regions with potentially important implications for fertilizer use efficiency and the minimization of nutrient accessions to the Great Barrier Reef.

The response of platform reefs to sea-level stabilization over the past 6 ka is well established for the Great Barrier Reef (GBR), with reefs typically accreting laterally from windward to leeward. However, these observations are based on few cores spread across reef zones and may not accurately reflect a reef's true accretional response to the Holocene stillstand. We present a new record of reef accretion based on 49 U/Th ages from Heron and One Tree reefs in conjunction with re-analyzed data from 14 reefs across the GBR. We demonstrate that hydrodynamic energy is the main driver of accretional direction; exposed reefs accreted primarily lagoon-ward while protected reefs accreted seawards, contrary to the traditional growth model in the GBR. Lateral accretion rates varied from 86.3 m/ka–42.4 m/ka on the exposed One Tree windward reef and 68.35 m/ka–15.7 m/ka on the protected leeward Heron reef, suggesting that wind/wave energy is not a dominant control on lateral accretion rates. This represents the most comprehensive statement of lateral accretion direction and rates from the mid-outer platform reefs of the GBR, confirming great variability in reef flat growth both within and between reef margins over the last 6 ka, and highlighting the need for closely-spaced transects.

Isolation can provide marine ecosystems with a refuge from human impacts. However, information on the biodiversity, ecology and fisheries of remote regions is often sparse. The proposed Coral Sea Marine Reserve could create one of the world's largest and most remote marine parks, yet little information is available to inform discussions. Fish captures from the Coral Sea and adjacent Great Barrier Reef (GBR) were assessed from reports contained in a chronology of spearfishing publications from 1953 to 2009, and reveal for the first time the history of recreational spearfishing in the Coral Sea. Although the area is perceived as relatively untouched, the data indicate that spearfishers have frequented Coral Sea reefs for at least 43 years and reported captures have increased exponentially. Post-1993 trophy captures in the Coral Sea (mean 23 kg) were larger than the adjacent GBR (9 kg). Reef species characterize the GBR catch, while large pelagic species characterize the Coral Sea catch. Provided that functionally important fishes are not targeted, the relatively small scale of recreational spearfishing and the focus on pelagic species suggests that spearfishing currently exerts limited pressure on the ecology of Coral Sea reefs.

Groupers and reef octopus are economically and ecologically important predators on Indo-Pacific coral reefs and known as solitary hunters. Here we describe a highly unique and unusual observation of a behavioural non-random association between the highfin grouper (Epinephelus maculatus) and the reef octopus (Octopus cyanea) in the Great Barrier Reef. Such an observation is highly novel given that the association crosses both the phyla and the invertebrate to vertebrate divide. The present study hypothesizes that the association is non-random and potentially the result of cooperative hunting but as such this requires further evidence and testing.

Innovative partnerships for conservation are required to stem the tide of continued ecosystem degradation. Nature-based tourism is one such partnership. Yet the natural attractions that nature-based tourism depends on are under increasing anthropogenic threat. Because of their dependence on international visitors, nature-based tourism enterprises are under additional pressure from socioeconomic and political crises in a globalized world. Recent research shows that lifestyle values, the motives that entice owners and staff of tourism enterprises to live and work in a chosen natural attraction, strengthen the resilience of enterprises to crises. This paper empirically explores the relationship between the lifestyle values of nature-based tourism enterprises, their resilience, and their support of and contribution to conservation of Australia's Great Barrier Reef. Semi-structured interviews with the owners and senior managers of 48 reef tourism enterprises showed that those that reported high lifestyle values had higher levels of conservation ethic and participated more extensively in conservation actions. The relationship between resilience and conservation ethic was not statistically significant. Bureaucratic, regulatory and cost constraints, and a lack of knowledge, limit enterprise participation in conservation. Conservation agencies can work to reduce some of these constraints to ensure that conservation benefits from nature-based tourism enterprises are maximized.

The taxonomy of trematodes of Great Barrier Reef (GBR) fishes has been studied in some detail for over 20 years. Understanding of the fauna has been informed iteratively by approaches to sampling, understanding of morphology, the advent of molecular methodology and a feed-back loop from the emergent understanding of host specificity. Here we analyse 658 host-parasite combinations for 290 trematode species, 152 genera and 28 families from GBR fishes. These are reported from 8 orders, 38 families, 117 genera and 243 species of fishes. Of the 290 species, only 4 (1·4%) have been reported from more than one order of fishes and just 23 (7·9%) infect more than one family; 77·9% of species are known from only one genus, and 60% from only one species of fish. Molecular studies have revealed several complexes of cryptic species and others are suspected; we conclude that no euryxenous host distribution should be accepted on the basis of morphology only. The occurrence of individual trematode species in potential hosts is patchy and difficult to predict reliably a priori or explain convincingly a posteriori. These observations point to the need for a vigorous iterative interaction between the accretion of host specificity data and its interpretation.

With the marine environment under increasing threat from multiple sources, the ability of managers to generate support from stakeholders will be vital for the success of conservation initiatives. In 2004, a new zoning plan for the Great Barrier Reef Marine Park increased no-take areas from 4.5% to 33% of the total Park area. The aims of this study were to measure recreational fishers' level of support for the plan and understand how they form attitudes towards conservation initiatives in the Park. A survey of Great Barrier Reef Marine Park recreational fishers conducted three years after implementation of the new zoning plan revealed that 68% of fishers believed that, in general, rezoning the Marine Park was a good idea, whereas 57% supported the actual zoning plan that was implemented. A majority of fishers believed that rezoning the Marine Park was necessary, that the new zoning plan had high conservation value, and that the plan had little impact on their recreational fishing activity. However, most fishers had low to moderate satisfaction with the programme used to consult the public throughout the rezoning process. Logistic regression models revealed a strong relationship between level of support for the plan and fishers' perceptions about the necessity of the plan and its conservation value, the adequacy of the consultation process, and the impact of the plan on their fishing activity. Results indicate that recreational fishers can be strong supporters of conservation initiatives in the Great Barrier Reef Marine Park if these initiatives are consistent with their values, and if efforts are made to engage them in the decision making process. These results will enhance the ability of managers to generate support from the recreational fishing community for conservation initiatives in marine environments.

Suspected viral erythrocytic necrosis (VEN) was detected in blood films from an immature blackbar triggerfish, Rhinecanthus aculeatus, captured on a patch reef at Lizard Island, Great Barrier Reef in November 2005, probably the first record of such an infection from Australia. The fish was kept in captivity and sampled intermittently until December 2007. Giemsa-stained blood films showed initially ~18% of mature erythrocytes affected by the VEN-like condition, but accompanying erythroblasts appeared free from infection. Erythrocytes with VEN-like bodies were smooth or crenated in outline, while the inclusion bodies were intracytoplasmic, single or paired, round in outline, stained deep magenta and were between 0.5–1.7 μm across. Bodies associated with clouds of granular material, fine eosinophilic haloes, and distinct pink-stained comet-tails, were also observed. The DNA content of the VEN-like bodies was confirmed by their green fluorescence following acridine orange staining. Infection levels in this fish fell to 0.4% of mature erythrocytes by May 2006 and persisted at this level until December 2007, when the fish died after just over two years in captivity. Squashes of haematophagous, juvenile gnathiid isopods taken from this fish on initial capture, also contained eosinophilic VEN-like bodies within digesting erythrocytes, suggesting that these crustaceans may be vectors of the condition observed.

The application of no-take marine reserve status to an area is expected to increase abundance and average size of individuals of species targeted by fisheries. The majority of the evidence supporting such expectations still involves comparisons of abundance at the one time of sites with and without marine reserve protection. Very few studies have data on the abundance and size structure of species targeted by fisheries in an area before reserve status is applied. Quantitative estimates of density and biomass of coral trout, Plectropomus spp., the major target of the hook and line fisheries on the Great Barrier Reef (GBR), Australia, on inshore fringing reefs of the Palm and Whitsunday Island groups, central GBR, are provided for 3–4 years before (1983–1984), and 12–13 years after (1999–2000) the establishment of no-take reserves in 1987. Quantitative estimates of density and biomass of coral trout in areas open to fishing were also collected in 1999–2000 at these two island groups. Density and biomass of coral trout increased significantly (by factors of 5.9 and 6.3 in the Palm Islands, and 4.0 and 6.2 in the Whitsunday Islands) in the reserve sites, but not the fished sites, between 1983–1984 and 1999–2000. In 1999–2000, density and biomass of coral trout and a secondary target of the fisheries, Lutjanus carponotatus, were significantly higher in the protected zones than in the fished zones at both island groups. The density and biomass of non-target fish species (Labridae, Siganidae and Chaetodontidae) did not differ significantly between reserve and fished zones at either island group. This is the most convincing data to date that the management zoning of the world's largest marine park has been effective, at least for coral trout on inshore reefs.

What are the effects of no-take marine reserves on trophic relationships of coral reef fish? Previous studies often have lacked detailed dietary information on major predators, and have often been confounded by differences in habitat complexity between reserve and fished sites. This study investigates the effects of marine reserve protection on predator-prey interactions of coral reef fish on the inshore islands of the Great Barrier Reef (GBR). The abundance of species of prey fish of Plectropomus leopardus (Serranidae), a piscivore and the major target of the hook and line fisheries on the GBR, were estimated in protected and fished zones. These prey species were identified from previous detailed studies of the diet of P. leopardus. Fish populations and habitat characteristics were surveyed by underwater visual census. Previous studies had determined that the biomass of P. leopardus was 3–4 times higher in protected than fished zones in the Whitsunday and Palm Islands, central GBR, after 14 years of protection. Eight of the nine prey species had a higher density within fished zones than protected zones, six significantly so. The density of all prey fish was twice that in the fished than the protected zone (p < 0.001). There were no significant differences in availability of different sized refuge holes, structural complexity or live coral cover between zones. Thus, important attributes of habitat complexity did not confound the comparisons between reserve and fished zones. Finally, a significant negative correlation (r = 0.46) between coral trout biomass and summed prey fish biomass suggested that predation may be an important structuring process in this system. The results have implications for the conservation of fishery targets and their prey. The study highlights the potential ecosystem implications of the use of no-take marine reserves as conservation and fisheries management tools.

Because coral reefs are sensitive to land derived inputs of nutrient and sediment, there is concern worldwide for the effects of anthropogenic change in river catchments on reefs. Thirty-one river catchments drain directly into the waters of the Great Barrier Reef, NE Australia. This case study was undertaken on the floodplain of the Herbert River catchment in north Queensland, utilizing remote sensing and GIS to assess both spatial and temporal changes in freshwater wetlands and riparian forests. We demonstrate that there has been a very large reduction in the area of these ecosystems since European settlement in the mid nineteenth century, with an 80% decline in their extent since 1943. We provide a range of quantitative measures to show that the landscape diversity of these ecosystems has also declined. These changes are of importance in terms of regional, national and international trends. We argue that policy, planning and management reform is required if the remaining ecological, economic and social values of these systems and the adjacent Great Barrier Reef Marine Park are to be maintained.