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Nutrient runoff from catchments that drain into the Great Barrier Reef (GBR) is a significant source of stress for this World Heritage Area. An alliance of collaborative on-ground water quality monitoring (Project 25) and technologically driven digital application development (Digiscape GBR) projects were formulated to provide data that highlighted the contribution of a network of Australian sugar cane farmers, amongst other sources, to nutrient runoff. This environmental data and subsequent information were extended to the farming community through scientist-led feedback sessions and the development of specialised digital technology (1622™WQ) that help build an understanding of the nutrient movements, in this case nitrogen, such that farmers might think about and eventually act to alter their fertilizer application practices. This paper reflects on a socio-environmental sustainability challenge that emerged during this case study, by utilising the nascent concept of digi-grasping. We highlight the importance of the entire agricultural knowledge and advice network being part of an innovation journey to increase the utility of digital agricultural technologies developed to increase overall sustainability. We develop the digi-MAST analytical framework, which explores modes of being and doing in the digital world, ranging from 'the everyday mystery of the digital world (M)', through digital 'awareness (A)', digitally 'sparked' being/s (S), and finally the ability of individuals and/or groups to 'transform (T)' utilising digital technologies and human imaginations. Our digi-MAST framework allows us to compare agricultural actors, in this case, to understand present modes of digi-grasping to help determine the resources and actions likely to be required to achieve impact from the development of various forms of digital technological research outputs. [ABSTRACT FROM AUTHOR]

Adaptation, as a strategy to respond to climate change, has limits: there are conditions under which adaptation strategies fail to alleviate impacts from climate change. Research has primarily focused on identifying absolute bio-physical limits. This paper contributes empirical insight to an emerging literature on the social limits to adaptation. Such limits arise from the ways in which societies perceive, experience and respond to climate change. Using qualitative data from multi-stakeholder workshops and key-informant interviews with representatives of the fisheries and tourism sectors of the Great Barrier Reef region, we identify psycho-social and structural limits associated with key adaptation strategies, and examine how these are perceived as more or less absolute across levels of organisation. We find that actors experience social limits to adaptation when: i) the effort of pursuing a strategy exceeds the benefits of desired adaptation outcomes; ii) the particular strategy does not address the actual source of vulnerability, and; iii) the benefits derived from adaptation are undermined by external factors. We also find that social limits are not necessarily more absolute at higher levels of organisation: respondents perceived considerable opportunities to address some psycho-social limits at the national-international interface, while they considered some social limits at the local and regional levels to be effectively absolute. [ABSTRACT FROM AUTHOR]

Abstract There is growing recognition that coastal water quality is interdependent with agricultural management in coastal catchments. Economic-incentive-based instruments can be used to internalize the negative externalities from coastal water pollution. Bio-physical and socio-economic heterogeneity across farms is expected to be an important factor in explaining differing rates of adoption of management practices. This paper hypothesises that: i) different types of farmers are likely to respond differently to incentive payments that promote the adoption of management practices for Great Barrier Reef water quality improvement, and ii) if policy makers account for heterogeneity, cost-effectiveness of incentive payments will increase. Results show that if government paid farmers 100% of the transition costs of moving from their current practices to improved practices, and given current technologies, water quality improvement for the case-study region would be approximately 56% (measured as a reduction of dissolved organic nitrogen at the end of river). Total costs for the region would be almost AU$ 30 M over the planning horizon of one cropping cycle of 6 years. Results furthermore show that as the policy seeks more ambitious land-use changes, from common practice to improved practice to aspirational practice, the public cost of incentive payments increase at an exponential rate. Larger farms make the shift sooner as they are able to offset fixed investments against increased revenues over greater areas. [ABSTRACT FROM AUTHOR]

Photosystem II (PS II) pesticides, recognized as a threat to ecological health, were targeted for reduction in sugarcane farming in Great Barrier Reef (GBR) catchments. Alternative herbicides, the non-PS II herbicides (including glyphosate, paraquat, 2,4-D, imazapic, isoxaflutole, metolachlor, and S-metolachlor), continue to be used in these catchments. However, the potential ecological fate, transport, and off-site environmental effects of non-PS II herbicides, with respect to their usage scheme, local rainfall patterns, and infiltration dynamics, have not been investigated previously. A vadose zone monitoring system, instrumented beneath sugarcane land in a GBR catchment, was applied for real-time tracing of pesticide migration across the unsaturated zone, past the root zone during 2017–2019. The regularly applied pesticides (fluroxypyr and isoxaflutole) exhibited substantial migration through the unsaturated zone. Within 1 month of application of fluroxypyr, it leached to 2.87 m depth in the vadose zone, with declining concentrations with depth. Isoxaflutole, which was applied yearly, was found only once, in November 2018, at 3.28 m depth in the soil profile. Other pesticides (imazapic, metolachlor, glyphosate, and haloxyfop) applied during the same period were not detected in the vadose zone. However, imidacloprid, which was not applied at the site during the monitored period, was detected across the entire vadose zone, revealing substantial resistance to degradation. The results show no evidence of any regularly applied pesticides in the site bores at the end of the study, indicating their ultimate degradation within the vadose zone before reaching the groundwater. [ABSTRACT FROM AUTHOR]

Widespread contamination of nearshore marine systems, including the Great Barrier Reef (GBR) lagoon, with agricultural herbicides has long been recognised. The fate of these contaminants in the marine environment is poorly understood but the detection of photosystem II (PSII) herbicides in the GBR year-round suggests very slow degradation rates. Here, we evaluated the persistence of a range of commonly detected herbicides in marine water under field-relevant concentrations and conditions. Twelve-month degradation experiments were conducted in large open tanks, under different light scenarios and in the presence and absence of natural sediments. All PSII herbicides were persistent under control conditions (dark, no sediments) with half-lives of 300 d for atrazine, 499 d diuron, 1994 d hexazinone, 1766 d tebuthiuron, while the non-PSII herbicides were less persistent at 147 d for metolachlor and 59 d for 2,4-D. The degradation of herbicides was 2–10 fold more rapid in the presence of a diurnal light cycle and coastal sediments; apart from 2,4-D which degraded more slowly in the presence of light. Despite the more rapid degradation observed for most herbicides in the presence of light and sediments, the half-lives remained > 100 d for the PS II herbicides. The effects of light and sediments on herbicide persistence were likely due to their influence on microbial community composition and its ability to utilise the herbicides as a carbon source. These results help explain the year-round presence of PSII herbicides in marine systems, including the GBR, but more research on the transport, degradation and toxicity on a wider range of pesticides and their transformation products is needed to improve their regulation in sensitive environments. [ABSTRACT FROM AUTHOR]

The Great Barrier Reef ( GBR) is an iconic coral reef system extending over 2000 km along the north-east coast of Australia. Global recognition of its Outstanding Universal Value resulted in the listing of the 348 000 km2 GBR World Heritage Area ( WHA) by UNESCO in 1981. Despite various levels of national and international protection, the condition of GBR ecosystems has deteriorated over the past decades, with land-based pollution from the adjacent catchments being a major and ongoing cause for this decline. To reduce land-based pollution, the Australian and Queensland Governments have implemented a range of policy initiatives since 2003. Here, we evaluate the effectiveness of existing initiatives to reduce discharge of land-based pollutants into the waters of the GBR. We conclude that recent efforts in the GBR catchments to reduce land-based pollution are unlikely to be sufficient to protect the GBR ecosystems from declining water quality within the aspired time frames. To support management decisions for desired ecological outcomes for the GBR WHA, we identify potential improvements to current policies and incentives, as well as potential changes to current agricultural land use, based on overseas experiences and Australia's unique potential. The experience in the GBR may provide useful guidance for the management of other marine ecosystems, as reducing land-based pollution by better managing agricultural sources is a challenge for coastal communities around the world. [ABSTRACT FROM AUTHOR]

The deepwater chondrichthyan fauna of the Great Barrier Reef is poorly known and life history information is required to enable their effective management as they are inherently vulnerable to exploitation. The chondrichthyan bycatch from the deepwater eastern king prawn fishery at the Swain Reefs in the southern Great Barrier Reef was examined to determine the species present and provide information on their life histories. In all, 1533 individuals were collected from 11 deepwater chondrichthyan species, with the Argus skate Dipturus polyommata, piked spurdog Squalus megalops and pale spotted catshark Asymbolus pallidus the most commonly caught. All but one species is endemic to Australia with five species restricted to waters offshore from Queensland. The extent of life history information available for each species varied but the life history traits across all species were characteristic of deep water chondrichthyans with relatively large length at maturity, small litters and low ovarian fecundity; all indicative of low biological productivity. However, variability among these traits and spatial and bathymetric distributions of the species suggests differing degrees of resilience to fishing pressure. To ensure the sustainability of these bycatch species, monitoring of their catches in the deepwater eastern king prawn fishery is recommended. [ABSTRACT FROM AUTHOR]

Scenes from the series of multispectral sensors on the Landsat satellites were used to map recent changes (between 1972 and 2004) in forest cover within and adjacent to stream networks of an intensively farmed region of the southern Great Barrier Reef catchment (Australia). Unsupervised ISODATA classifications of Tasseled-Cap transformed data (at 57 m ground resolution) mapped forest and cleared areas within 150 m of Pisoneer catchment waterways with 72.2% overall accuracy ( K hat = 0.469), when adjusted for the size of each class. Although the user’s accuracy was higher for the forest class (82.1 ± 8.4% at α = 0.05), large errors of commission (34.2 ± 8.3%) substantially affected map accuracy for the cleared class. The main reasons for misclassification include: (1) failure to discriminate narrowly vegetated riparian strips; (2) misregistration of scenes; and (3) spectral similarity of ground cover. Error matrix probabilities were used to adjust the mapped area of classes, resulting in a decline of forest cover by 12.3% and increase of clearing by 18.5% (22.4 km2 change; 95% confidence interval: 14.3–29.6 km2) between 1972 and 2004. Despite the mapping errors, Landsat data were able to identify broad patterns of land cover change that were verified from aerial photography. Most of the forest losses occurred in open forest to woodland habitat dominated by Eucalyptus, Corymbia, and Lophostemon species, which were largely replaced by sugarcane cropping. Melaleuca communities were similarly affected, though they have a much smaller distribution in the catchment. [ABSTRACT FROM AUTHOR]

Solutions to environmentally damaging human practices require cooperation between many different communities. This article explores sustainability-focused education through the lens of a current work-in-progress, Sugar vs the Reef?, which involves collaboration between sugarcane farmers and artists in the arable catchment of the Great Barrier Reef in North Queensland. This is a socially engaged art project that is addressing the fraught relationship between the region's agriculture and the fragile ecology of the Reef. We introduce some of the specific aspects of socially engaged art (SEA) which commend it as a cross-disciplinary method for bridging diverse individuals and organisations -- in particular, the notion of a "holding environment" for complex socio-ecological situations. We consider how this approach might broaden the agricultural practice of "extension" which aims to transform farming through educational outreach. Ideas emerging from contemporary socially engaged art practice may contribute to a toolkit for researchers and practitioners within and beyond the academy who are searching for ways to overcome the limitations of current methodologies and movements for social change. [ABSTRACT FROM AUTHOR]