Dispersal of the pesticide diuron in the Great Barrier Reef.

Pesticides from urban and agricultural runoff have been detected at concentrations above current water quality guidelines in the Great Barrier Reef (GBR) marine environment. We quantify the load of the pesticide diuron entering GBR waters using the GBR-Dynamic SedNet catchment model. After comparison of simulated distributions with observations at 11 monitoring sites we determined a half-life of diuron in GBR marine waters of 40 days. We followed diuron dispersal in the GBR (2016-2018) using the 1 km resolution eReefs marine model. The highest diuron concentrations in GBR waters occurred in the Mackay-Whitsunday region with a spike in January and March 2017, associated with 126 and 118 kg d-1 diuron loads from Plane Creek and the O'Connell River respectively. We quantify areas of GBR waters exposed to potentially ecotoxic concentrations of diuron. Between 2016 and 2018, 400 km2 and 1400 km2 of the GBR were exposed to concentrations exceeding ecosystem threshold values of 0.43 and 0.075 µg L-1 respectively. Using observed mapped coral and seagrass habitat, 175 km2 of seagrass beds and 50 km2 of coral habitats had peak diuron concentrations above 0.075 µg L-1 during this period. While the highest concentrations are localised to river plumes and inshore environments, non-zero diuron concentrations extend along the Queensland coast. These simulations provide new knowledge for the understanding of pesticide dispersal and management-use in GBR catchments and the design of in-water monitoring systems.

Functional analysis of pristine estuarine marine sediments.

Traditional environmental monitoring techniques are well suited to resolving acute exposure effects but lack resolution in determining subtle shifts in ecosystem functions resulting from chronic exposure(s). Surveillance with sensitive omics-based technologies could bridge this gap but, to date, most omics-based environmental studies have focused on previously degraded environments, identifying key metabolic differences resulting from anthropogenic perturbations. Here, we apply omics-based approaches to pristine environments to establish blueprints of microbial functionality within healthy estuarine sediment communities. We collected surface sediments (n = 50) from four pristine estuaries along the Western Cape York Peninsula of Far North Queensland, Australia. Sediment microbiomes were analyzed for 16S rRNA amplicon sequences, central carbon metabolism metabolites and associated secondary metabolites via targeted and untargeted metabolic profiling methods. Multivariate statistical analyses indicated heterogeneity among all the sampled estuaries, however, taxa-function relationships could be established that predicted community metabolism potential. Twenty-four correlated gene-metabolite pathways were identified and used to establish sediment microbial blueprints of essential carbon metabolism and amino acid biosynthesis that were positively correlated with community metabolic function outputs (2-oxisocapraote, tryptophan, histidine citrulline and succinic acid). In addition, an increase in the 125 KEGG genes related to metal homeostasis and metal resistance was observed, although, none of the detected metabolites related to these specific genes upon integration. However, there was a correlation between metal abundance and functional genes related to Fe and Zn metabolism. Our results establish a baseline microbial blueprint for the pristine sediment microbiome, one that drives important ecosystem services and to which future ecosurveillance monitoring can be compared.

Bright Spots in Coastal Marine Ecosystem Restoration.

The United Nations General Assembly calls for ecosystem restoration to be a primary intervention strategy used to counter the continued loss of natural habitats worldwide, while supporting human health and wellbeing globally. Restoration of coastal marine ecosystems is perceived by many to be expensive and prone to failure, in part explaining its low rates of implementation compared with terrestrial ecosystems. Yet, marine ecosystem restoration is a relatively new field, and we argue that assessments of its potential to answer this call should not rely on typical outcomes, but also to learn from successful outliers. Here, we review successful restoration efforts across a suite of metrics in coastal marine systems to highlight 'bright spots'. We find that, similar to terrestrial systems, restoration interventions can be effective over large spatial expanses (1,000s-100,000s ha), persist for decades, rapidly expand in size, be cost-effective, and generate social and economic benefits. These bright spots clearly demonstrate restoration of coastal marine systems can be used as a nature-based solution to improve biodiversity and support human health and wellbeing. Examining coastal marine restoration through a historical lens shows that it has developed over a shorter period than restoration in terrestrial systems, partially explaining lower efficiencies. Given these bright spots and the relative immaturity of coastal marine ecosystem restoration, it is likely to advance rapidly over the coming decades and become a common intervention strategy that can reverse marine degradation, contribute to local economies, and improve human wellbeing at a scale relevant to addressing global threats.

Influence of Human Activities on Broad-Scale Estuarine-Marine Habitats Using Omics-Based Approaches Applied to Marine Sediments.

Rapid urban expansion and increased human activities have led to the progressive deterioration of many marine ecosystems. The diverse microbial communities that inhabit these ecosystems are believed to influence large-scale geochemical processes and, as such, analyzing their composition and functional metabolism can be a means to assessing an ecosystem's resilience to physical and chemical perturbations, or at the very least provide baseline information and insight into future research needs. Here we show the utilization of organic and inorganic contaminant screening coupled with metabolomics and bacterial 16S rRNA gene sequencing to assess the microbial community structure of marine sediments and their functional metabolic output. The sediments collected from Moreton Bay (Queensland, Australia) contained low levels of organic and inorganic contaminants, typically below guideline levels. The sequencing dataset suggest that sulfur and nitrite reduction, dehalogenation, ammonia oxidation, and xylan degradation were the major metabolic functions. The community metabolites suggest a level of functional homogeneity down the 40-cm core depth sampled, with sediment habitat identified as a significant driver for metabolic differences. The communities present in river and sandy channel samples were found to be the most active, with the river habitats likely to be dominated by photoheterotrophs that utilized carbohydrates, fatty acids and alcohols as well as reduce nitrates to release atmospheric nitrogen and oxidize sulfur. Bioturbated mud habitats showed overlapping faunal activity between riverine and sandy ecosystems. Nitrogen-fixing bacteria and lignin-degrading bacteria were most abundant in the sandy channel and bioturbated mud, respectively. The use of omics-based approaches provide greater insight into the functional metabolism of these impacted habitats, extending beyond discrete monitoring to encompassing whole community profiling that represents true phenotypical outputs. Ongoing omics-based monitoring that focuses on more targeted pathway analyses is recommended in order to quantify the flux changes within these systems and establish variations from these baseline measurements.