Development of basin-specific ecologically relevant water quality targets for the Great Barrier Reef Jon Brodie, Mark Baird, Jane Waterhouse, Mathieu Mongin, Jenny Skerratt, Cedric Robillot, Rachael Smith, Reinier Mann and Michael Warne TropWATER Report number 17/38 June 2017 Development of basin-specific ecologically relevant water quality targets for the Great Barrier Reef Report prepared by Jon Brodie1, Mark Baird2, Jane Waterhouse1, Mathieu Mongin2, Jenny Skerratt2, Cedric Robillot3, Rachael Smith4, Reinier Mann4 and Michael Warne4,5 2017 1James Cook University, 2CSIRO, 3eReefs, 4Department of Science, Information Technology and Innovation, 5Centre for Agroecology, Water and Resilience, Coventry University, Coventry, United Kingdom EHP16055 – Update and add to the existing 2013 Scientific Consensus Statement to incorporate the most recent science and to support the 2017 update of the Reef Water Quality Protection Plan Input and review of the development of the targets provided by John Bennett, Catherine Collier, Peter Doherty, Miles Furnas, Carol Honchin, Frederieke Kroon, Roger Shaw, Carl Mitchell and Nyssa Henry throughout the project. Centre for Tropical Water & Aquatic Ecosystem Research (TropWATER) James Cook University Townsville Phone: (07) 4781 4262 Email: [email protected] Web: www.jcu.edu.au/tropwater/ Citation: Brodie, J., Baird, M., Waterhouse, J., Mongin, M., Skerratt, J., Robillot, C., Smith, R., Mann, R., Warne, M., 2017. Development of basin-specific ecologically relevant water quality targets for the Great Barrier Reef. TropWATER Report No. 17/38, James Cook University, Published by the State of Queensland, Brisbane, Australia. 68 pp. For further information contact: Jon Brodie Centre of Excellence for Coral Reef Studies James Cook University Email: [email protected] OR Jane Waterhouse Centre for Tropical Water & Aquatic Ecosystem Research (TropWATER) James Cook University Email: [email protected] This publication has been compiled by the Centre for Tropical Water & Aquatic Ecosystem Research (TropWATER), James Cook University. © James Cook University, 2017. Except as permitted by the Copyright Act 1968, no part of the work may in any form or by any electronic, mechanical, photocopying, recording, or any other means be reproduced, stored in a retrieval system or be broadcast or transmitted without the prior written permission of TropWATER. The information contained herein is subject to change without notice. The copyright owner shall not be liable for technical or other errors or omissions contained herein. The reader/user accepts all risks and responsibility for losses, damages, costs and other consequences resulting directly or indirectly from using this information. Enquiries about reproduction, including downloading or printing the web version, should be directed to [email protected]. Disclaimers TropWATER advises that the information contained in this publication comprises general statements based on scientific research. The reader is advised and needs to be aware that such information may be incomplete or unable to be used in any specific situation. To the extent permitted by law, TropWATER (including its employees and consultants) excludes all liability to any person for any consequences, including but not limited to all losses, damages, costs, expenses and any other compensation, arising directly or indirectly from using this publication (in part or in whole) and any information or material contained in it. Contents Definitions .................................................................................................................................................... ii Acknowledgements ...................................................................................................................................... ii 1. Introduction ..................................................................................................................................... 3 1.1 Existing pollutant load reduction targets ................................................................................ 3 1.2 Defining basin-specific and ecologically relevant targets ....................................................... 5 PART 1: Sediments and nutrients ................................................................................................................ 7 2. Sediments and nutrients—Methods ............................................................................................... 7 2.1 Load reduction scenarios......................................................................................................... 7 2.2 Defining ecological end points / criteria.................................................................................. 8 Nutrients .......................................................................................................................................... 8 Suspended sediment ..................................................................................................................... 14 2.3 Summary of final criteria ....................................................................................................... 16 2.4 Modelling approach............................................................................................................... 16 3. Sediments and nutrients: results .................................................................................................. 23 3.1 Modelling outputs for each criteria: nutrients ...................................................................... 23 3.1 Modelling outputs for each criteria: sediment ..................................................................... 27 3.2 End-of-basin water quality targets ........................................................................................ 28 Approach ....................................................................................................................................... 28 Confidence ratings ......................................................................................................................... 29 4. Comparison of targets with those in the WQIPs ........................................................................... 32 5. Calculating load reductions as tonnes ........................................................................................... 33 6. Regional and GBR-wide targets ..................................................................................................... 39 PART 2: Pesticides ..................................................................................................................................... 42 7. Setting the pesticide targets.......................................................................................................... 42 7.1 Spatial boundaries of the water bodies that contribute to the health and resilience of the Great Barrier Reef.............................................................................................................................. 42 7.2 Environmental values of water bodies to protect and conserve the status of the Great Barrier Reef Marine Park and World Heritage Area .......................................................................... 45 7.3 Aquatic species protection level............................................................................................ 45 8. Discussion ...................................................................................................................................... 47 8.1 Expected outcomes of meeting Reef Water Quality Protection Plan targets ....................... 47 What is success? ............................................................................................................................ 47 What does success mean for the Great Barrier Reef? .................................................................. 48 The need for multiple basin targets to be met ............................................................................. 49 8.2 Moving towards an improved target-setting approach ........................................................ 49 i 8.3 Synergies and the relationship between the basin targets and management priorities from Scientific Consensus Statement 2017 ............................................................................................... 49 8.4 Overall conclusions ................................................................................................................ 54 References ................................................................................................................................................. 56 Definitions Pollutants: Pollution means the introduction by humans, directly or indirectly, of substances or energy into the environment resulting in such deleterious effects as harm to living resources, hazards to human health, hindrance to aquatic activities including fishing, impairment of quality for use of water and reduction of amenities (GESAMP 2001). This document refers to suspended (fine) sediments, nutrients (nitrogen, phosphorus) and pesticides as ‘pollutants’. Within this report we explicitly mean enhanced concentrations of or exposures to these pollutants, which are derived from (directly or indirectly) human activities in the Great Barrier Reef ecosystem or adjoining systems (e.g. river catchments). Suspended sediments and nutrients naturally occur in the environment; all living things in ecosystems of the Great Barrier