Cross-cutting concepts - 2022 Scientific Consensus Statement

The 2022 Scientific Consensus Statement addresses 30 priority questions. The 30 questions are organised into several themes: values and threats, sediments and particulate nutrients, dissolved nutrients, pesticides, other pollutants, human dimensions of water quality improvement and emerging science. Within these themes, there are questions that cover cross-cutting concepts including ecological processes and impacts, delivery and source, management practices, and human dimensions.

For example, each pollutant group (i.e. sediments and particulate nutrients, dissolved nutrients, pesticides and other pollutants) contains at least one question examining the spatial and temporal distribution of that pollutant. Relevant questions have been grouped in these cross-cutting concepts below.

Delivery and source

Scientist taking a coral core from a Porites bommie to examine changes to terrestrial runoff over time. — Scientist taking a coral core to examine changes to terrestrial runoff over time. Eric Matson.

What evidence is there for changes in land-based runoff from pre-development estimates in the Great Barrier Reef? [Q2.3]

Aerial view of an area used for grazing and showing patchy poor vegetation cover, bare ground and an eroded streambank in the Burdekin basin. — Landscape showing different sources of erosion, Burdekin basin. Matt Curnock.

How much anthropogenic sediment and particulate nutrients are exported from Great Barrier Reef catchments (including the spatial and temporal variation in delivery), what are the most important characteristics of anthropogenic sediments and particulate nutrients, and what are the primary sources? [Q3.3]

A tree-lined meandering river at low water level with a herd of cattle. — Transport pathways for sediment export to the Great Barrier Reef. Scott Wilkinson.

What are the primary biophysical drivers of anthropogenic sediment and particulate nutrient export to the Great Barrier Reef and how have these drivers changed over time? [Q3.4]

An agricultural landscape showing a large number of flooded fields among sugarcane. — Flooded sugarcane fields in the Mulgrave-Russell basin, North Queensland. Dieter Tracey.

How much anthropogenic dissolved nutrient (nitrogen and phosphorus species) is exported from Great Barrier Reef catchments? [Q4.4]

Large volumes of water running off a sugarcane field into a drain. — Runoff from a sugarcane field in the Herbert River catchment, North Queensland. CSIRO.

What are the primary biophysical drivers of anthropogenic dissolved nutrient export to the Great Barrier Reef and how have these drivers changed over time? [Q4.5]

Aerial view of a sediment laden river following high rainfall in the Wet Tropics, meandering through an agricutural landscape, dominated by sugarcane fields. — Sediment laden river following high rainfall in the Wet Tropics, North Queensland. Dieter Tracey.

What are the primary sources of pesticides that have been found in Great Barrier Reef ecosystems and what are the key factors that influence pesticide delivery from source to ecosystem? [Q5.2]

Collection of debris including microplastics on the shoreline among seaweed with ocean in the background. — Collection of debris including microplastics on the shoreline. Jane Waterhouse.

What is the spatial and temporal distribution and risk of other pollutants in the Great Barrier Reef ecosystems, and what are the primary sources? [Q6.1]

Ecological processes and impacts

An iconic view of the Whitsundays in Queensland showing a vegetated landscape leading down to turquoise waters and white sand. — Whitehaven Beach, Whitsunday Islands. Superjoseph via Canva.

What are the socio-ecological, cultural, economic and intrinsic values of the Great Barrier Reef? [Q1.1]

Underwater scene showing seagrass on sand with corals and fish in the background — Seagrass and coral communities. Dieter Tracey.

What is the extent and condition of Great Barrier Reef ecosystems and what are the primary threats to their health? [Q1.2/1.3/2.1]

Aerial view of coastal floodplain adjacent to Bowling Green Bay in the large scale floods in 2019. — Bowling Green Bay Ramsar wetland, Lower Burdekin. Matt Curnock

How are the Great Barrier Reef’s key ecosystem processes connected from the catchment to the reef and what are the primary factors that influence these connections? [Q1.4]

Hard corals bleaching due to high water temperatures. Corals have lost their symbiotic algae and turned white in colour. — Hard corals bleaching due to high water temperatures. FishTales via Canva.

What are the current and predicted impacts of climate change on Great Barrier Reef ecosystems (including spatial and temporal distribution of impacts)? [Q2.2]

What evidence is there for changes in land-based runoff from pre-development estimates in the Great Barrier Reef? [Q2.3]

Coral reef with several bleached white corals and one bright pink coral indicating signs of severe stress following high seawater temperatues in 2017. — Bleached corals around Cairns-Cooktown in 2017. J. Stella. © Commonwealth of Australia (Reef Authority).

How do water quality and climate change interact to influence the health and resilience of Great Barrier Reef ecosystems? [Q2.4]

Mulgrave-Russell River discharge following rainfall event transports runoff from land into the marine environment. — Coastal flood plume in the Wet Tropics. Dieter Tracey.

What are the spatial and temporal distributions of terrigenous sediments and associated indicators within the Great Barrier Reef? [Q3.1]

Corals with fish swimming above them. The visibility is low which is typical of inshore coral reefs due to their proximity to land-based influences driving low water clarity. — An inshore coral reef with poor water clarity. Tom Stevens.

What are the measured impacts of increased sediment and particulate nutrient loads on Great Barrier Reef ecosystems, what are the mechanism(s) for those impacts and where is there evidence of this occurring in the Great Barrier Reef? [Q3.2]

Coastal marine area showing green water which is an indicator of higher levels of nutrients. — Flood plume in the Wet Tropics. Jane Mellors, TropWATER.

What is the spatial and temporal distribution of nutrients and associated indicators within the Great Barrier Reef? [Q4.1]

Underwater scene of a large stand of algae growing on a reef. — Sargassum growing on reef. DaCILD via Canva.

What are the measured impacts of nutrients on Great Barrier Reef ecosystems, what are the mechanism(s) for those impacts and where is there evidence of this occurring in the Great Barrier Reef? [Q4.2]

A cluster of crown-of-thorns starfish eating table corals in a coral reef landscape. Some corals have died and are covered with algae. — Crown-of-thorns starfish outbreak on Rib Reef, Central Great Barrier Reef. Ciemon Caballes.

What are the key drivers of the population outbreaks of crown-of-thorns starfish (COTS) on the Great Barrier Reef, and what is the evidence for the contribution of nutrients from land runoff to these outbreaks? [Q4.3]

Different types of samplers used to measure polar and non-polar pesticides in the water column, secured on a rope using a mooring. One is a metal cage (semi-permeable membrane device) and the others are round plastic disks for integrated sampling over time. Coral in the background. — Pesticide passive samplers deployed at Fitzroy Island, North Queensland. AIMS.

What is the spatial and temporal distribution of pesticides across Great Barrier Reef ecosystems? What are the (potential or observed) ecological impacts in these ecosystems? What evidence is there for pesticide risk? [Q5.1]

What is the spatial and temporal distribution and risk of other pollutants in the Great Barrier Reef ecosystems, and what are the primary sources? [Q6.1]

Underwater photo showing a statue of a person standing over a microscope at the Museum of Underwater Art (MOUA), John Brewer Reef. — Museum of Underwater Art (MOUA), John Brewer Reef. Matt Curnock.

What are the key attributes of successful monitoring and evaluation programs to support coastal and marine water quality management, and what examples are there of innovative monitoring and evaluation frameworks, methods and approaches that are applicable to the Great Barrier Reef? [Q8.2]

Human dimensions

What are the socio-ecological, cultural, economic and intrinsic values of the Great Barrier Reef? [Q1.1]

A group of people standing in a dry vegetated landscape looking outwards. — A range of land management actions can contribute to improved water quality. Anthea Coggan.

What is the mix of programs and instruments (collectively and individually) used in Great Barrier Reef catchments to drive land management practices for Great Barrier Reef water quality benefits and how effective are they? [Q7.1]

A group of people standing on the bank of a waterbody listening to researchers in a boat. Sugarcane fields in the background. — Scientists working with landholders to support better water quality outcomes. Nathan Waltham.

What are the behavioural (attitudinal), economic, social and cultural factors that hinder or enable the uptake of management practices that aim to improve water quality outcomes for the Great Barrier Reef? [Q7.2]

Dugoo Duwalami – Heart meeting place The central component of the artwork is the roundtable for the GBR with various seats around the table representing various institutions involved in decision-making and management of the GBR. The upper half of the artwork represents the extensive pathways of engagement and involvement that these decision-making bodies for the GBR have travelled on, prior to the seat at the roundtable. The opaque section (top middle) represents diverse Traditional Owner groups that have not been effectively involved or engaged in decision-making for the GBR over a long period of time. Once resources towards building the presence, literacy, capacity and capability of Traditional Owners within existing GBR management frameworks are implemented, the head of the Rainbow Serpent (Yindinji - Butchulla) is set in motion. The roundtable is now complete and two-way knowledge sharing ensues, where Traditional Owner groups are familiar with all legislative, policy and funding frameworks underpinning management of the GBR, and the primary concept of connectivity from freshwater headwaters, through diverse habitats and peoples, down to the GBR (light blue dots) is aligned to decision-makers and decision-making for the GBR. Dugoo Duwalami ensures improved holistic outcomes for the species, habitats and people connected to the GBR through truly collaborative management. — Dugoo Duwalami – Heart meeting place. Conway Burns.

What are the critical success factors for greater Indigenous involvement in water quality decision making in the Great Barrier Reef region? [Q7.3]

Landscape showing trees and grasslands along a stream. — Diverse landscapes can support multiple co-benefits. John Lamour, CSIRO.

What are the co-benefits e.g., biodiversity, soil carbon, productivity, climate resilience, of land management to improve water quality outcomes for the Great Barrier Reef? [Q8.1]

Management practices

Grazing cattle in an area of good vegetation cover showing new and established trees, and a mix of grasses. — Grazing lands showing good vegetation cover. CSIRO.

What are the most effective management practices (all land uses) for reducing sediment and particulate nutrient loss from the Great Barrier Reef catchments, do these vary spatially or in different climatic conditions? What are the costs and cost-effectiveness of these practices, and does this vary spatially or in different climatic conditions? What are the production outcomes of these practices? [Q3.5]

Aerial view of gully rehabilitation works at Strathalbyn Station. Landscape is dry with scattered vegetation. — Gully rehabilitation works at Strathalbyn Station, Bowen catchment. Damon Telfer.

What is the effectiveness of gully and streambank restoration works in reducing sediment and particulate nutrient loss from the Great Barrier Reef catchments, does this vary spatially or in different climatic conditions? What are the costs and cost-effectiveness of these works, and does this vary spatially or in different climatic conditions? What are the production outcomes of these practices? [Q3.6]

Instruments measuring stream flow within sugarcane fields locaged on a bridge in the Burdekin region. — Stream flow monitoring station among a sugarcane area, Lower Burdekin. Matt Curnock.

What are the most effective management practices for reducing dissolved nutrient losses (all land uses) from the Great Barrier Reef catchments, and do these vary spatially or in different climatic conditions? What are the costs of the practices, and cost-effectiveness of these practices, and does this vary spatially or in different climatic conditions? What are the production outcomes of these practices? [Q4.6]

Low lying constructed wetland area in between sugarcane fields. — Constructed wetland in the Moresby catchment near Mourilyan, North Queensland. Adyn de Groot.

What is the efficacy of natural/near-natural wetlands, restored, treatment (constructed) wetlands and other treatment systems in Great Barrier Reef catchments in improving water quality (nutrients, fine sediments and pesticides?) [Q4.7]

Constructed wetland adajcent to a sugarcane field in the Tully catchment. — Constructed wetland adjacent to sugarcane fields, North Queensland. Nathan Waltham.

What are the measured costs, and cost drivers associated with the use of natural/near natural wetlands, restored, treatment (constructed) wetlands and other treatment systems in Great Barrier Reef catchments in improving water quality? [Q4.8]

Natural wetlands showing aquatic plants in the foreground, a water body and well-established, mature trees in the background. — Natural wetlands provide many ecosystem services. Nathan Waltham.

What role do natural/near-natural wetlands play in the provision of ecosystem services and how is the service of water quality treatment compatible or at odds with other services (e.g., habitat, carbon sequestration)? [Q4.9]

Tractor applying pesticides to a sugarcane field using a banded sprayer which has nozzles to target sugarcane rows. — Applicaton of pesticides in sugarcane using a shielded band sprayer. Aaron Davis.

What are the most effective management practices for reducing pesticide risk from the Great Barrier Reef catchments, and do these vary spatially or in different climatic conditions? What are the costs of the practices, and cost-effectiveness of these practices, and does this vary spatially or in different climatic conditions? What are the production outcomes of these practices? [Q5.3]

What is the spatial and temporal distribution and risk of other pollutants in the Great Barrier Reef ecosystems, and what are the primary sources? [Q6.1]

What are the critical success factors for greater Indigenous involvement in water quality decision making in the Great Barrier Reef region? [Q7.3]

What are the co-benefits e.g., biodiversity, soil carbon, productivity, climate resilience, of land management to improve water quality outcomes for the Great Barrier Reef? [Q8.1]