Great Barrier Reef Water Quality: Current Issues SEPTEMBER 2001 Great Barrier Reef Water Quality: Current Issues Edited by David Haynes September 2001 GBR Water Quality 1 © Great Barrier Reef Marine Park Authority 2001 ISSN ISBN 1 876945 01 X. Published September 2001 by the Great Barrier Reef Marine Park Authority. This work is copyright. Apart from any use as permitted under the Copyright Act 1968, no part may be reproduced by any process without prior written permission from the Great Barrier Reef Marine Park Authority. Requests and inquiries concerning reproduction and rights should be addressed to the Director, Information Support Group, Great Barrier Reef Marine Park Authority, PO Box 1379, Townsville Qld 4810. The opinions expressed in this document are not necessarily those of the Great Barrier Reef Marine Park Authority. Accuracy in calculations, figures, tables, names, quotations, references etc. is the complete responsibility of the authors. National Library of Australia Cataloguing-in-Publication data: Great Barrier Reef water quality: current issues. Bibliography. ISBN 1 876945 01 X. Water quality – Queensland – Great Barrier Reef. 2. Water quality – environmental aspects – Queensland – Great Barrier Reef. 3. Ecosystem management – Queensland - Great Barrier Reef. I. Haynes, David, 1958-. II. Great Barrier Reef Marine Park Authority (Australia). III. Title. 333.91641609943 Photographic credits Front Cover: David Wachenfeld Figure 4: Peter O’Reagain Figure 29: Kirsten Michalek-Wagner Contributing authors David Haynes, Deb Bass, Jon Brodie, Caroline Christie, Michelle Devlin, Kirsten Michalek-Wagner, Sheriden Morris, Michelle Ramsay, Jamie Storrie, Jane Waterhouse and Hugh Yorkston. PO Box 1379 Townsville, Qld, 4810 Telephone 07 47 500700 Table of Contents 1 EXECUTIVE SUMMARY...............................................................................................................1 2 THE GREAT BARRIER REEF WORLD HERITAGE AREA ...................................................3 2.1 INTRODUCTION ..........................................................................................................................3 2.2 THE GREAT BARRIER REEF WORLD HERITAGE AREA...............................................................3 2.3 THE GREAT BARRIER REEF LAGOON .........................................................................................5 2.4 SOURCES OF POLLUTANTS TO THE GREAT BARRIER REEF.........................................................5 3 THE GREAT BARRIER REEF CATCHMENT...........................................................................6 3.1 CATCHMENT LAND USE ............................................................................................................6 3.2 CATCHMENT SOURCES OF POLLUTION......................................................................................7 3.2.1 Rangeland Grazing.................................................................................................................7 3.2.2 Sugarcane Cultivation............................................................................................................9 3.2.3 Other Crops..........................................................................................................................10 3.2.4 Coastal Aquaculture.............................................................................................................12 3.3 WETLAND CLEARING AND ACID SULPHATE SOILS ................................................................12 3.4 COASTAL DEVELOPMENT.........................................................................................................16 3.4.1 Settlement.............................................................................................................................16 3.4.2 Stormwater and Sewage Discharges ....................................................................................17 3.4.3 Coastal Heavy Industry........................................................................................................18 3.5 MINING.....................................................................................................................................18 3.6 DAM CONSTRUCTION ..............................................................................................................21 4 PRINCIPAL WATER QUALITY INFLUENCES ON GREAT BARRIER REEF ECOSYSTEMS ........................................................................................................................................22 4.1 NUTRIENTS ...............................................................................................................................22 4.2 SEDIMENTS AND TURBIDITY.....................................................................................................23 4.3 SALINITY ...................................................................................................................................24 4.4 OTHER POLLUTANTS................................................................................................................24 4.4.1 Organochlorine Pesticides....................................................................................................24 4.4.2 Dioxins .................................................................................................................................25 4.4.3 Modern pesticides, insecticides and herbicides.....................................................................25 4.4.4 Heavy Metals........................................................................................................................25 4.5 GLOBAL ATMOSPHERIC CHANGES ..........................................................................................26 5 GREAT BARRIER REEF CATCHMENT WATER QUALITY STATUS .............................29 5.1 RIVERS.......................................................................................................................................29 5.1.1 Water Flows..........................................................................................................................29 5.1.2 Nutrients..............................................................................................................................30 5.1.3 Sediment Discharges ............................................................................................................30 5.2 ACID SULPHATE SOILS .............................................................................................................31 6 GREAT BARRIER REEF WATER QUALITY STATUS .........................................................32 6.1 AMBIENT GREAT BARRIER REEF WATER QUALITY .................................................................32 6.2 WATER COLUMN NUTRIENTS AND CHLOROPHYLL................................................................33 6.3 TRANSPORT OF POLLUTANTS FROM CATCHMENTS TO THE SEA: FLOOD PLUMES.................33 6.3.1 Flood Plume Composition ....................................................................................................33 6.3.2 Flood Plume Spatial Variability...........................................................................................33 i 6.4 SEAWATER TEMPERATURE AND CORAL BLEACHING ...............................................................41 6.5 HEAVY METALS........................................................................................................................41 6.6 HERBICIDES...............................................................................................................................42 6.7 INSECTIDES ...............................................................................................................................43 6.8 POLLUTANTS IN MARINE MAMMALS ......................................................................................44 6.9 DIOXINS ....................................................................................................................................44 7 SHIPPING MOVEMENT AND ASSOCIATED POLLUTION ISSUES .............................48 7.1 SHIPPING MOVEMENT..............................................................................................................48 7.2 SHIPPING INCIDENTS AND POLLUTION ...................................................................................50 7.2.1 Ship Contaminants...............................................................................................................50 7.2.2 Oil Spills...............................................................................................................................54 7.2.3 Litter.....................................................................................................................................56 7.3 BALLAST WATER ......................................................................................................................57 7.4 RISK ASSESSMENT OF OIL AND CARGO SPILLS........................................................................58 8 CURRENT INSTITUTIONAL AND POLICY ARRANGEMENTS FOR WATER QUALITY MANAGEMENT........................................................................................................61 8.1 GOVERNANCE AND LEGISLATION ...........................................................................................61 8.1.1 Commonwealth Regime........................................................................................................61 8.1.2 Queensland Regime..............................................................................................................61