Seagrass communities of the Great Barrier Reef and their desired state: applications for spatial planning and management

The research program reported here evolved from an interest in developing ecologically relevant target criteria that, if met, correspond to desired ecological outcomes (e.g. desired state) for the Great Barrier Reef World Heritage Area (GBRWHA) and to achieving the overarching objective of the Great Barrier Reef Marine Park Authority’s Long-term Sustainability Plan. The objective of the original National Environment Science Program (NESP) Tropical Water Quality Hub (TWQ) Project 3.2.1 Deriving ecologically relevant load targets to meet desired ecosystem condition for the Great Barrier Reef: a case study for seagrass meadows in the Burdekin region was to examine relationships between catchment inputs of sediment and seagrass desired state, and to compare these against the 2018 Water Quality Improvement Plan’s ecological targets. This objective was met using a case study in Cleveland Bay based on sediment loads from the Burdekin River and other smaller catchments that discharge into the bay (Collier et al., 2020). The techniques developed in the Cleveland Bay case study are used in the present report at the scale of the whole GBRWHA for NESP TWQ Hub Project 5.4. To achieve this we followed three steps: (1) a consolidation and verification of seagrass data at the GBRWHA scale, (2) an analysis of the distribution of GBRWHA seagrass habitat and communities, and (3) an estimation of a desired state target for communities with sufficient data. To achieve step 1, we compiled and standardised 35 years of seagrass survey data in a spatial database, including 81,387 georeferenced data points. Twelve seagrass species were recorded, the deepest of which (Halophila spinulosa) was found at 76 m. This database is a valuable resource that provides coastal managers, researchers and the global marine community with a long-term spatial resource describing seagrass populations from the mid1980s against which to benchmark change. For step 2, we identified 88,331 km2 of potential seagrass habitat within the GBRWHA; 1,111 km2 in estuaries, 16,276 km2 in coastal areas, and 70,934 km2 in reef areas. Thirty-six seagrass community types were defined by species assemblages. The environmental conditions that structure the location and extent of these communities included depth, tidal exposure, latitude, current speed, benthic light, proportion of mud, water type, water temperature, salinity, and wind speed. Environmental parameters interact with the topography of the reef and changes in the coastal plain, its watersheds, and its development with latitude. We describe seagrass distributions and communities that are shaped by multiple combinations of these environmental complexities and how that may influence marine spatial planning and environmental protection initiatives (Chapter 3). For step 3, we used more than 20 years of historical data (1995-2018) on seagrass biomass for the diverse seagrass communities of the GBRWHA to develop desired state benchmarks. Of the 36 seagrass communities, desired state was identified for 25 of them, with the remainder having insufficient data. Desired state varied by more than one order of magnitude between community types, and was influenced by the mix of species in the communities and the range of environmental conditions that define community boundaries. We identified a historical, decadal-scale cycle of decline and recovery. Recovery to desired state has occurred for coastal intertidal communities following the most recent declines in 2008 - 2012. A number of the estuarine and coastal subtidal communities have not recovered to desired state biomass in recent years (Chapter 4). This body of work provides a huge step forward in our understanding of the complexities of GBRWHA seagrass communities. We discuss the relevance of these research outputs to future marine spatial planning and management. This includes zoning in “representative areas”, hierarchical monitoring design (e.g. RIMReP), and the setting of ecologically relevant sediment load targets for desired state (e.g. Lambert et al., 2019). The updated seagrass data, seagrass distribution, community classification and desired state targets provides important new information for incorporation into marine spatial planning and management that is discussed in Chapter 5. These applications include: • Future assessments of non-reef habitats within the GBRWHA and GBRMP. • Assessing how risk and spatial protection intersect with seagrass communities and the role they play in protecting seagrass, e.g. Queensland State and Commonwealth marine parks, Fish Habitat Areas, Dugong Protected Areas, Port Exclusion Zones. • Expanding our spatial analysis to areas ecologically connected but outside of the GBRWHA such as Torres Strait, the Gulf of Carpentaria, and Fraser Island coast, where we already have seagrass data. • Designing a hierarchical seagrass monitoring design with coarse scales (intertidal, subtidal, estuary, coast, reef) and fine scales (36 communities). We have identified significant knowledge gaps that should guide future monitoring efforts (e.g. RIMReP and Queensland Land and Sea Ranger Program), including a lack of consistent and recent data for reef seagrass communities. • We identified communities where data is deficient, such as in estuaries where important seagrass communities have potential exposure to multiple threats for which more consistent environmental data would be valuable. • Identifying potential restoration sites. Our work has highlighted the critical role of historical data in understanding spatial complexity and for making informed management decisions on the current state of seagrass in the GBRWHA. Our approach can be adapted for monitoring, management and assessment of pressures at other relevant scales and jurisdictions. Our results guide conservation planning through prioritisation of at-risk communities that are continuing to fail to attain desired state

Deep-water seagrasses in the tropics: resilience, recovery and establishing thresholds and drivers of change

Global seagrass research and assessment efforts have focused on shallow coastal and estuarine seagrass populations. Comparatively little is known about the dynamics of deep-water (>10m) seagrasses despite evidence they form extensive meadows in some parts of the world and may be highly productive compared with their shallow counterparts. Deep-water seagrasses are subject to a similar range of anthropogenic threats as shallow meadows particularly along the Great Barrier Reef (GBR) in Queensland, where they occur close to major population centres and adjacent to the coast. We examine the dynamics of deep-water seagrass populations in the GBR through a range of research studies including long term (>8 years) assessments of change; impacts of major dredging programs; resilience and recovery from severe tropical storms and; targeted research investigating the drivers, thresholds and tolerances behind seasonal and inter-annual change. Collectively these re- search programs have provided new insight into deep-water seagrass dynamics. Despite considerable inter-annual variability deep-water seagrasses had a regular annual pattern of occurrence at some locations, a low level of resilience to reduced water quality, but a high capacity for recolonisation on the cessation of impacts. While susceptible to large scale loss from severe storms these meadows were quick to re-establish compared with nearby shallow coastal seagrasses. The results of the work are establishing a series of key management thresholds and stress indictors that can be applied to ensure greater protection of these seagrasses

A spatial analysis of seagrass habitat and community diversity in the Great Barrier Reef World Heritage Area

The Great Barrier Reef World Heritage Area (GBRWHA) in north eastern Australia spans 2,500 km of coastline and covers an area of ~350,000 km2. It includes one of the world’s largest seagrass resources. To provide a foundation to monitor, establish trends and manage the protection of seagrass meadows in the GBRWHA we quantified potential seagrass community extent using six random forest models that include environmental data and seagrass sampling history. We identified 88,331 km2 of potential seagrass habitat in intertidal and subtidal areas: 1,111 km2 in estuaries, 16,276 km2 in coastal areas, and 70,934 km2 in reef areas. Thirty-six seagrass community types were defined by species assemblages within these habitat types using multivariate regression tree models. We show that the structure, location and distribution of the seagrass communities is the result of complex environmental interactions. These environmental conditions include depth, tidal exposure, latitude, current speed, benthic light, proportion of mud in the sediment, water type, water temperature, salinity, and wind speed. Our analysis will underpin spatial planning, can be used in the design of monitoring programs to represent the diversity of seagrass communities and will facilitate our understanding of environmental risk to these habitats

Synthesizing 35 years of seagrass spatial data from the Great Barrier Reef World Heritage Area, Queensland, Australia

The Great Barrier Reef World Heritage Area in Queensland, Australia contains globally significant seagrasses supporting key ecosystem services, including habitat and food for threatened populations of dugong and turtle. We compiled 35 years of data in a spatial database, including 81,387 data points with georeferenced seagrass and species presence/absence, depth, dominant sediment type, and collection date. We include data collected under commercial contract that have not been publicly available. Twelve seagrass species were recorded. The deepest seagrass was found at 76 m. Seagrass meadows are at risk from anthropogenic, climate and weather processes. Our database is a valuable resource that provides coastal managers and the global marine community with a long-term spatial resource describing seagrass populations from the mid-1980s against which to benchmark change. We address the data issues involved in hindcasting over 30 years to ensure confidence in the accuracy and reliability of data included

A report card approach to describe temporal and spatial trends in parameters for coastal seagrass habitats

Report cards that are designed to monitor environmental trends have the potential to provide a powerful communication tool because they are easy to understand and accessible to the general public, scientists, managers and policy makers. Given this functionality, they are increasingly popular in marine ecosystem reporting. We describe a report card method for seagrass that incorporates spatial and temporal variability in three metrics—meadow area, species and biomass—developed using long-term (greater than 10 years) monitoring data. This framework summarises large amounts of spatially and temporally complex data to give a numeric score that provides reliable comparisons of seagrass condition in both persistent and naturally variable meadows. We provide an example of how this is applied to seagrass meadows in an industrial port in the Great Barrier Reef World Heritage Area of north-eastern Australia

A comparison of threats, vulnerabilities and management approaches in global seagrass bioregions

Global seagrass habitats are threatened by multiple anthropogenic factors. Effective management of seagrasses requires information on the relative impacts of threats; however, this information is rarely available. Our goal was to use the knowledge of experts to assess the relative impacts of anthropogenic activities in six global seagrass bioregions. The activities that threaten seagrasses were identified at an international seagrass workshop and followed with a web-based survey to collect seagrass vulnerability information. There was a global consensus that urban/industrial runoff, urban/port infrastructure development, agricultural runoff and dredging had the greatest impact on seagrasses, though the order of relative impacts varied by bioregion. These activities are largely terrestrially based, highlighting the need for marine planning initiatives to be co-ordinated with adjacent watershed planning. Sea level rise and increases in the severity of cyclones were ranked highest relative to other climate change related activities, but overall the five climate change activities were ranked low and experts were uncertain of their effects on seagrasses. The experts' preferred mechanism of delivering management outcomes were processes such as policy development, planning and consultation rather than prescriptive management tools. Our approach to collecting expert opinion provides the required data to prioritize seagrass management actions at bioregional scales

The WiggleZ Dark Energy Survey: the transition to large-scale cosmic homogeneity

We have made the largest-volume measurement to date of the transition to large-scale homogeneity in the distribution of galaxies. We use the WiggleZ survey, a spectroscopic survey of over 200,000 blue galaxies in a cosmic volume of ~1 (Gpc/h)^3. A new method of defining the 'homogeneity scale' is presented, which is more robust than methods previously used in the literature, and which can be easily compared between different surveys. Due to the large cosmic depth of WiggleZ (up to z=1) we are able to make the first measurement of the transition to homogeneity over a range of cosmic epochs. The mean number of galaxies N(<r) in spheres of comoving radius r is proportional to r^3 within 1%, or equivalently the fractal dimension of the sample is within 1% of D_2=3, at radii larger than 71 \pm 8 Mpc/h at z~0.2, 70 \pm 5 Mpc/h at z~0.4, 81 \pm 5 Mpc/h at z~0.6, and 75 \pm 4 Mpc/h at z~0.8. We demonstrate the robustness of our results against selection function effects, using a LCDM N-body simulation and a suite of inhomogeneous fractal distributions. The results are in excellent agreement with both the LCDM N-body simulation and an analytical LCDM prediction. We can exclude a fractal distribution with fractal dimension below D_2=2.97 on scales from ~80 Mpc/h up to the largest scales probed by our measurement, ~300 Mpc/h, at 99.99% confidence.Comment: 21 pages, 16 figures, accepted for publication in MNRA

Interactions between a Trawl Fishery and Spatial Closures for Biodiversity Conservation in the Great Barrier Reef World Heritage Area, Australia

Background\ud The Queensland East Coast Otter Trawl Fishery (ECOTF) for penaeid shrimp fishes within Australia's Great Barrier Reef World Heritage Area (GBRWHA). The past decade has seen the implementation of conservation and fisheries management strategies to reduce the impact of the ECOTF on the seabed and improve biodiversity conservation. New information from electronic vessel location monitoring systems (VMS) provides an opportunity to review the interactions between the ECOTF and spatial closures for biodiversity conservation.\ud \ud Methodology and Results\ud We used fishing metrics and spatial information on the distribution of closures and modelled VMS data in a geographical information system (GIS) to assess change in effort of the trawl fishery from 2001–2009 and to quantify the exposure of 70 reef, non-reef and deep water bioregions to trawl fishing. The number of trawlers and the number of days fished almost halved between 2001 and 2009 and new spatial closures introduced in 2004 reduced the area zoned available for trawl fishing by 33%. However, we found that there was only a relatively minor change in the spatial footprint of the fishery as a result of new spatial closures. Non-reef bioregions benefited the most from new spatial closures followed by deep and reef bioregions.\ud \ud Conclusions/Significance\ud Although the catch of non target species remains an issue of concern for fisheries management, the small spatial footprint of the ECOTF relative to the size of the GBRWHA means that the impact on benthic habitats is likely to be negligible. The decline in effort as a result of fishing industry structural adjustment, increasing variable costs and business decisions of fishers is likely to continue a trend to fish only in the most productive areas. This will provide protection for most benthic habitats without any further legislative or management intervention

The WiggleZ Dark Energy Survey: Survey Design and First Data Release

The WiggleZ Dark Energy Survey is a survey of 240,000 emission line galaxies in the distant universe, measured with the AAOmega spectrograph on the 3.9-m Anglo-Australian Telescope (AAT). The target galaxies are selected using ultraviolet photometry from the GALEX satellite, with a flux limit of NUV<22.8 mag. The redshift range containing 90% of the galaxies is 0.2<z<1.0. The primary aim of the survey is to precisely measure the scale of baryon acoustic oscillations (BAO) imprinted on the spatial distribution of these galaxies at look-back times of 4-8 Gyrs. Detailed forecasts indicate the survey will measure the BAO scale to better than 2% and the tangential and radial acoustic wave scales to approximately 3% and 5%, respectively. This paper provides a detailed description of the survey and its design, as well as the spectroscopic observations, data reduction, and redshift measurement techniques employed. It also presents an analysis of the properties of the target galaxies, including emission line diagnostics which show that they are mostly extreme starburst galaxies, and Hubble Space Telescope images, which show they contain a high fraction of interacting or distorted systems. In conjunction with this paper, we make a public data release of data for the first 100,000 galaxies measured for the project.Comment: Accepted by MNRAS; this has some figures in low resolution format. Full resolution PDF version (7MB) available at http://www.physics.uq.edu.au/people/mjd/pub/wigglez1.pdf The WiggleZ home page is at http://wigglez.swin.edu.au

Use of Disease-Modifying Therapies in Pediatric Relapsing-Remitting Multiple Sclerosis in the United Kingdom.

OBJECTIVES: To compare the real-world effectiveness of newer disease-modifying therapies (DMTs) vs injectables in children with relapsing-remitting multiple sclerosis (RRMS). METHODS: In this retrospective, multicenter study, from the UK Childhood Inflammatory Demyelination Network, we identified children with RRMS receiving DMTs from January 2012 to December 2018. Clinical and paraclinical data were retrieved from the medical records. Annualized relapse rates (ARRs) before and on treatment, time to relapse, time to new MRI lesions, and change in Expanded Disability Status Scale (EDSS) score were calculated. RESULTS: Of 103 children treated with DMTs, followed up for 3.8 years, relapses on treatment were recorded in 53/89 (59.5%) on injectables vs 8/54 (15%) on newer DMTs. The ARR was reduced from 1.9 to 1.1 on injectables (p < 0.001) vs 1.6 to 0.3 on newer DMTs (p = 0.002). New MRI lesions occurred in 77/89 (86.5%) of patients on injectables vs 26/54 (47%) on newer DMTs (p = 0.0001). Children on newer DMTs showed longer time to relapse, time to switch treatment, and time to new radiologic activity than patients on injectables (log-rank p < 0.01). After adjustment for potential confounders, multivariable analysis showed that injectables were associated with 12-fold increased risk of clinical relapse (adjusted hazard ratio [HR] = 12.12, 95% CI = 1.64-89.87, p = 0.015) and a 2-fold increased risk of new radiologic activity (adjusted HR = 2.78, 95% CI = 1.08-7.13, p = 0.034) compared with newer DMTs. At 2 years from treatment initiation, 38/103 (37%) patients had MRI activity in the absence of clinical relapses. The EDSS score did not change during the follow-up, and only 2 patients had cognitive impairment. CONCLUSION: Newer DMTs were associated with a lower risk of clinical and radiologic relapses in patients compared with injectables. Our study adds weight to the argument for an imminent shift in practice toward the use of newer, more efficacious DMTs in the first instance. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that newer DMTs (oral or infusions) are superior to injectables (interferon beta/glatiramer acetate) in reducing both clinical relapses and radiologic activity in children with RRMS