Testing and implementation of the water quality metric for the 2017 and 2018 reef report cards

Britta Schaffelke

Led by: Dr Britta Schaffelke, AIMS

 

Project Summary

Report cards are used at various levels to summarise and communicate complex information on GBR health. The effectiveness of Reef Plan is communicated through the annual Reef Report card. In the Reef Report Card, marine water quality is reported using a metric, developed in 2009, based on satellite remote sensing of near surface concentrations of chlorophyll and total suspended solids. This provides a wide spatial and temporal coverage of marine water quality.

However, the current water quality metric has a number of issues such that the Independent Science Panel has recently expressed a lack of confidence in it and suggested that a new approach was needed. This proposal outlines a research program to deliver elements of this new approach.
 

Problem Statements

Problem

Report cards are a useful way to summarise and communicate complex information generated by monitoring and survey programs. In the Great Barrier Reef region a number of report cards are currently produced, most of which include marine water quality information in some form: the Reef Report Card; the regional reports card for the Mackay Whitsundays River2Reef Partnership, Wet Tropics (in prep.), and the Fitzroy Partnership for River health; and the Gladstone Healthy Harbour Partnership (GHHP) Report Card. In addition, the Outlook Report requires an assessment of the condition and trend of water quality across the Great Barrier Reef. Currently, all of these report cards use a variety of different indicators to describe water quality. These indicators are then combined, usually in a hierarchical manner (e.g., scoring measurements relative to a guideline value, aggregation across indicators) for communication as report card scores and grades.

A nested approach to reporting is being developed as part of the Reef Integrated Monitoring and Reporting Program (RIMReP), which will align reporting products from the Reef-wide (e.g., Outlook Report) to regional level (e.g., regionally specific / issue-related report cards). In recognition of the need to ensure consistent messages and a clear line of sight across the reported scores and the grading levels, RIMReP will seek to establish a ‘core’ set of indicators for monitoring and reporting water quality. The outcomes from this proposal will form an integral part of RIMReP, which will be developed during 2017 and implemented in 2018.

The Reef Water Quality Protection Plan (Reef Plan) is a joint Australian and Queensland government commitment that seeks to improve the quality of water entering the GBR from broadscale land use and is nested within the broader Reef 2050 Plan. The effectiveness of Reef Plan is assessed through the annual Reef Report Card, which is based on a range of monitoring programs summarising improvements in land management practices, progress towards pollutant targets, and the condition of the Great Barrier Reef and its catchments. In the Reef Report Card, marine water quality is assessed using a metric based on nearsurface concentrations of chlorophyll a (Chl-a) and non-algal particulates (NAP), reported as Total Suspended Solids in the report card (which includes suspended solids, particulate P and particulate N which also have guideline values,) from satellite remote sensing, which allows a sufficiently wide spatial and temporal coverage. The current metric is based on the relative area of the inshore water body that does not exceed the Great Barrier Reef Marine Park Water Quality Guidelines. This metric scores for Chl-a and NAP are combined and converted into grades on a five-point scale (very good, good, moderate, poor, very poor), which describe the overall condition and trend of water quality across the Great Barrier Reef and within each individual region.

Issue

The current water quality ‘metric’ used in the Reef Report Card has a number of significant shortcomings:

(i) it is only based on remote sensing-derived data. Concerns have been raised about the appropriateness of using remote sensing to evaluate inshore water quality, as there are many well-documented challenges in obtaining accurate estimates from optically complex waters. Furthermore, there are limited valid satellite observations in the wet season due to cloud cover, underlying the need to understand the limitations of remote sensing data for management purposes.

(ii) it is limited to reporting on just two indicators that are able to be assessed using remote sensing and does not incorporate other water quality data collected through the Marine Monitoring Program and IMOS; and

(iii) it is relatively insensitive to land-based input, most likely due to the binary assessment of compliance relative to the water quality guidelines and aggregation and averaging over large spatial and temporal scales.

(iv) The uncertainty and lack of precision in the water quality parameters derived from remote sensing require proper spatial and temporal evaluation, but indicate complementary methods are required.

(v) An inshore marine water quality metric that is insensitive to large terrestrial inputs is not useful for tracking land management practice improvements to water quality. While other factors may influence this metric, work is required to develop a meaningful metric.

Research and method development over the past 3 years has improved our ability to construct meaningful report card metrics, in particular – a Reef Rescue-funded project on data integration (Brando et al. 2013), and data aggregation methods developed for and used in the recent GHHP report card. There have also been substantial advancements in modelling water quality through e-Reefs since the Reef Report Card metric was developed in 2009; all of which are useful starting points for improving the way we report water quality.

In 2016, the Reef Plan Independent Science Panel (ISP) expressed a lack of confidence in the current water quality metric used in the Reef Report Card and agreed unanimously that a new approach was needed for the 2017 Report Card. It was also agreed that the water quality metric must be responsive to significant changes in river flows and loads. To address the above shortcomings, the ISP requested that:

  1. the e-Reefs marine biogeochemical model is tested for its ability to deliver a better water quality assessment than the current practice based on remote sensing,
  2. the GBRMPA water quality guidelines are reviewed to incorporate new evidence collected over the last 6-8 years in understanding coral and seagrass responses to chronic and acute pressures, ecosystem health, recovery and resilience,
  3. the utility of observational data streams from in-situ monitoring is analysed for potential inclusion in the Report Card,
  4. the current practice of scoring relative to the water quality guidelines and aggregating data over fixed spatial and temporal scales be improved to incorporate the magnitude, frequency and duration of exceedance rather than using average annual exceedance counts,
  5. the inclusion of photic depth, as derived from satellite data, into the metric is evaluated since light is the important driver for coral and seagrass productivity. The most appropriate measure of photic depth can be evaluated and related to seagrass and coral responses, and
  6. options for combining indicator scores into a single metric are evaluated, including a statistical assessment of potential metrics.

More recent Feedback from the ISP suggested priority aspects to be addressed as follows:

  • the e-Reefs marine biogeochemical model is tested for its ability to deliver a better water quality assessment than the current practice based on remote sensing,
  • the utility of observational data streams from in-situ monitoring is analysed for potential inclusion in the Report Card, the inclusion of photic depth, as derived from satellite data, into the metric is evaluated since light is the important driver for coral and seagrass productivity. The most appropriate measure of photic depth can be evaluated and related to seagrass and coral responses, and

It was agreed that there would need to be significant improvements made by April 2017 in time for the next report card with the final approach developed by April 2018 for the 2017-18 and future report cards.

Alignment with NESP Research Priorities
2a) Undertake research for the Reef 2050 Integrated Monitoring and Reporting Program (RIMReP) to develop cost-effective indicators and metrics for key GBRWHA biophysical and human dimension values and identification of associated ecosystem thresholds and guidelines for grading scores, linked to specific objectives and targets in the Reef 2050 Plan.
 

Project Keywords

Reef report card; Water quality metric; Remote sensing; Marine water quality; eReefs.
 

Project Funding

This project is jointly funded through AIMS, CSIRO, JCU, GBRMPA and the Australian Government’s National Environmental Science Programme.
 

Project Publications
Factsheet

 

 

 

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